Module 6 – Genetics, Evolution & Ecosystems

Question 1

C19) What is the meaning of mutation

Answer 1

A mutation is a change in the sequence of bases in DNA

Question 2

C19) What are the causes of Gene mutations

Answer 2

Substitution, deletion or insertion of one or more nucleotide within a gene.

If only one nucleotide is affected it is called a point mutation

Question 3

C19) What are the effects of substitution in gene mutations

Answer 3

Changes the codon on in which it occurs.

New codon codes for a different amino acid this will lead to a change in the primary structure of the protein

Degenerate nature of the genetic code may mean however that the new codon make code still for the same amino acids leading to no change in protein synthesis

Question 4

C19) What are the effects of insertion and deletion in gene mutations

Answer 4

Lead to a frameshift.

Each group of three bases correspond to one amino acid the addition or deletion of a nuclear tide moves the reading frame of the sequence of bases therefore changing every code on from the point of mutation

Question 5

C19) what are the effects of different genetic mutations on the phenotype

Answer 5

No effect – because normally functioning proteins are still synthesised

Damaging - than the phenotype is affected negatively because proteins are no longer synthesised or non-functional affecting with essential processes

Beneficial - very rare a protein is synthesise that results in a new and useful characteristic in the phenotype. For example a mutation in a protein in the cell surface membrane means that HIV cannot bind and enter the cells

Question 6

C19) what are the causes of mutations

Answer 6

Mutations can occur spontaneously during DNA replication but the rate of mutation is increased by mutagens

The loss of bases often occur spontaneously. The absence of a base can lead to the insertion of an incorrect base through complimentary base pairing during DNA replication

Free radicals are oxidising agents which affect the structures of nuclear tides and disrupt base pairing during DNA replication

Antioxidants vitamins that are known as anticarcinogens because of the ability to negate the effects of free radicals

Question 7

C19)What is a silent mutation

Answer 7

They do not change any proteins or the activities of any proteins synthesised meaning they have no effect on the phenotype.

Can occur inThe non-coding regions of DNA or code for the same amino acid because of the degenerate nature of the genetic code

May result in the change of the primary structure but do not change the overall structure or function of the protein

Question 8

C19)What is a nonsense mutation

Answer 8

Results in a code on becoming a stop codon instead of coding for an amino acid

Resulting in the shortening of the protein being synthesised resulting in non-functionality. Negative or harmful effect on the phenotype

Question 9

C19 what is a missense mutation

Answer 9

Result in the incorporation of an incorrect amino acid into the primary structure when the proteins synthesised

The result depends on the role of the amino acid in the structure and function of the protein

Conservative mutations occur when the amino acid change leads to an amino acid being coded for with similar properties of the original meaning the mutation is less serious

Non-Conservative mutation is when the new amino acid coded for has different properties to the original so more likely to have an effect on the protein structure and cause disease

Question 10

C19) what is an example of a beneficial mutation

Answer 10

The ability to digests lactose is thought to be the result of a mutation.

Majority of mammals become lactose intolerant after they cease to suckle

The ability to digest lactate is found in European population because they are more likely to farm cattle

The ability to drink milk and processed lactose as an adult prevents individuals with the mutation from starving from famines

Question 11

C19) What are the changes in chromosome structure after a chromosomal mutation

Answer 11

Caused by mutagens and normally occur during meiosis

Deletion – a section of chromosome breaks off and lost within the cell

Duplication - Sections get duplicated on a chromosome

Translocation - A section of one chromosome breaks off and joins another homologous chromosome

Inversion-a section of chromosome breakoff, is reversed and then joins back onto the chromosome

Question 12

C19) what are housekeeping Genes

Answer 12

Enzymes which are necessary for reactions like respiration are constantly needed and the genes that code for these are called housekeeping Genes

Question 13

C19) Why do bacteria regulate gene

Answer 13

They are able to respond to changes in their environment because of gene regulation

Expressing genes only when the products are needed also provides vital resources being wasted

Question 14

C19) What are the different ways in which genes are regulated

Answer 14

Transcriptional - Genes can be turned on or off

Post transcriptional - MRNA they can be modified which regulates translation and the types of proteins produced

Translational - translation can be stopped or started

Post-translational-proteins can be modified after synthesis which could change their function

Question 15

C19) what are different transcriptional controls for Gene regulation

Answer 15

Chromatin remodelling

Histone modification

Lac operon (Prokaryotes)

Role of Cyclic AMP (prokaryotes)

Question 16

C19) How does chromatin remodelling Regulate gene expression

Answer 16

DNA is a very long molecule that has to be wound around proteins called histones allowing to be packed into the nucleus of a cell this is DNA/histone complex is called chromatin.

Heterochromatin is tightly wound DNA causing chromosomes to be visible during cell division
Euchromatin is loosely wound DNA present during interphase

Gene transcription is not possible when DNA is tightly wound because RNA polymerase cannot access genes,So euchromatin can be translated

Does not occur during cell division but during interphase

Regulation insures the proteins necessary for cell division are synthesised in time and prevents the complex and energy consuming process taking place during cell division

Question 17

C19) How does histone modification Regulate gene expression

Answer 17

DNA coil around histones because they are positively charged and DNA is negatively charged

Histones can be modified to increase or decrease the degree of condensation

The addition of an acetyl group (acetylation) or phosphate group (phosphorylation) reduce the positive charge of the histone causing DNA to coil less tightly allowing for transcription
The addition of a methyl Group (methylation) making the histones more hydrophobic so they bind more tightly to each other causing DNA to coil tightly and preventing transcription of jeans

Question 18

C19) what is the meaning of Epigene

Answer 18

Used to describe the control of gene expression by modifying DNA

Question 19

C19) What is a lac operon

Answer 19

An operon is a group of genes that are under the control of the same regulatory mechanisms and are expressed at the same time

More common in prokaryotes because of the smaller and simpler structure of their genome

Also very efficient way of saving resources because if each gene products are not needed then all of the genes involved in the production are switched off

Question 20

C19) How does lac operon Regulate gene expression on a prokaryote

Answer 20

E. coli is glucose is in short supply lactose can be used as a Respiratory substrate.

The lack operon is a group of three genes,LacZ,LacY and LacA involved in the breakdown of lactose

They are structural genes as they code for three enzymes (beta Galactoside, lactose permease and transacetylase) and they are transcribed into a single long molecule of RNA

The regulatory gene (LacI) codes for a repressor protein which prevents the transcription of the structural genes in the absence of lactose

The repressor protein binds to an area called the operator which prevents RNA polymerase binding to DNA at the promoter and begin transcription this is called down regulation

When lactose is present and binds to the repressor protein causing it to change shape so it is no longer bound to the operator allowing RNA polymerase to transcribe the enzymes

Question 21

C19) how does the role of cyclic AMP regulate gene expression in a prokaryote

Answer 21

The binding of RNA polymerase results in slow rate of transcription which needs to be upregulated to produce the required quantity of enzymes to metabolise lactose

only possible when CRP is bound to cAMP

The transport of glucose into E. coli cells decrease the levels of CAMP reducing the transcription of the genes responsible for metabolise lactose, glucose becomes the primary. respiratory substrate

Question 22

C19) What are the post transcriptional gene expression controls

Answer 22

RNA processing

RNA editing

Question 23

C19) how does RNA processing control gene expression at the post transcriptional level

Answer 23

Transcription produces a precursor molecule called pre-mRNA this is modified forming mature mRNA before it can join to a ribosome and synthesise a protein

A cap is added to the five end and a tail is added to the three end helping to stabilise the mRNA and delay degradation in the cytoplasm. The cap binding of mRNA to ribosomes

Splicing occurs when RNA is cut at specific points. Intron (non-coding DNA) are removed and exons (coded DNA) are join together

Question 24

C19) how does RNA editing Control gene expression at the post transcriptional level

Answer 24

The nucleotide sequence of some mRNA molecule can also be changed through base addition, deletion or substitution which results in the synthesis of different proteins with different functions

This increases the range of proteins that can be produced from a single mRNA molecule or gene

Question 25

C19) What are the different translational controls that control Gene expression

Answer 25

Degradation of mRNA-more resistant the molecule the longer it will last of the cytoplasm therefore greater quantity of protein synthesised

Binding of inhibitory proteins to mRNA prevents it binding to ribosomes and synthesising proteins

Activation of initiation factors which aid the binding of mRNA to ribosomes (the eggs of many organisms produce large amounts of mRNA which is not required until after fertilisation with the use of initiation factors)

Question 26

C19) What are the different post-translational controls that control Gene expression

Answer 26

Addition of non-protein groups such as carbohydrate chains, lipids and phosphate

Modifying amino acids and the formation of bonds such as disulfide bridges

Folding or shortening of proteins

Modification by cAMP

Question 27

C19)What is the meaning of morphogenesis

Answer 27

The regulation of the pattern of anatomy development

Question 28

C19)What are homeobox genes

Answer 28

A homeobox genes are a group of jeans which contain a homeobox

homeobox is section of DNA coding for a part of the protein 60 amino acid long and is highly conserved in plants ,animals and fungi

A homeodomain binds to homeobox and switches other genes on and off therefore homeobox genes are regulatory genes

pa6x when mutated causes blindness in humans. Mice and fruit flies also have this gene causing them to be blind as well.

Question 29

C19) What are Hox genes

Answer 29

Are a group of homeobox genes that are only present in animals.

Responsible for the correct positioning of body parts

Found in gene clusters- mammals have four clusters on different chromosomes

The order in which the gene appears along the chromosome is the order in which the effects are expressed on the organism

Question 30

C19) What are the layouts of living organisms

Answer 30

Body plans are usually represented as cross-section through the organism following the fundamental arrangement of tissue layers

The common feature of animals is that they are segmented (backbone of vertebrals)

The segments have multiplied over time becoming specialised for different functions

Hox genes in the head control the development of mouthparts while Hox genes in the thorax control the development of wings, limbs or ribs

Question 31

C19) what is a Diploblastic animal and triploblastic

Answer 31

Animals that have two primary tissue layers

Animals that have three primary tissue layers

Question 32

C19) how are humans segmented

Answer 32

Individual vertebra and associate structures have been developed from segments in the embryo called somites

The somites on directed by Hox genes to develop in a particular way depending on their position in the sequence

Question 33

C19) What is Radial symmetry

Answer 33

It is seen in Diploblastic animals like jellyfish. They have no left or right only a top on the bottom

Question 34

C19) What is bilateral symmetry

Answer 34

Seen in most animals means the organism has both left and right side and a head and tail

Question 35

C19) What is meant by asymmetry of an organism

Answer 35

Seen in sponges which have no line of symmetry

Question 36

C19) How does mitosis and apoptosis affect the body plan of an animal

Answer 36

Mitosis which results in cell division and proliferation
apoptosis which is programmed cell death

Mitosis increases the number of cells leading to growth. apoptosis remove unwanted cells and tissue. Cells undergoing apoptosis can also release chemical signals which stimulate mitosis leading to remodelling of tissue

Controlled by hox genes

Question 37

C19) What factors are affecting the expression of regulatory genes

Answer 37

Can be affected by the environment both internal and external

Stress can be defined as the condition produced When the homoeostatic balance between an organism is upset

Can be due to external factors such as a change in temperature or intensity of light. Internal factors can change due to the release of hormones or psychological stress impact during the growth and development

Drugs can affect the activity of regulatory genes for example the drug thalidomide

Question 38

C20) what is the definition of variation

Answer 38

As a result of mutations, changes to the genetic code which are random and constantly taking place

Essential for natural selection and therefore evolution

Question 39

C20) what is chlorosis and how is it caused

Answer 39

When the leaves look pale or yellow occurs because the cells are not producing the normal amount of chlorophyll

Lack of chlorophyll reduces the ability of the plant to make food

Change in phenotype is the result of environmental factors

Question 40

C20 what are three examples of causes of chlorosis

Answer 40

Lack of light- when a toy or garden to his left on a lawn, with the absence of light plants will turn off the chlorophyll production to conserve resources

Mineral deficiencies- a lack of iron or magnesium. Iron is needed as a cofactor by some of the enzymes that produce chlorophyll and magnesium is found at the heart of the chlorophyll molecule. Plants that lack these elements simply cannot make chlorophyll

Viral infections- when the virus is infected plants they interfere with the metabolic system of cells. Common symptom is yellowing of the infected tissue as they cannot support synthesis of chlorophyll

Question 41

C20) How is animal body-mass an example of both genetic and environmental variation

Answer 41

The majority of cases dramatic variation in size such as obesity and being severely underweight or a result of environmental factors. (The amount of food eating, the quality of exercise

Obesity can be a result of the genetic make up of an organism

Question 42

c20) how does interspecific variation occur

Answer 42

Is determined by sexual reproduction involving meiosis and the random fusion of gametes at fertilisation

Question 43

C20) what is the definition of genotype

Answer 43

The combination of alleles an organism inherit for a characteristic

The genetic make up of an organism in respect of that gene

Question 44

C20) what is the definition of phenotype

Answer 44

The obvious characteristics of an organism

The actual characteristics that an organism displays are often Influenced by the environment.

Any changes the environment makes to a person are referred to as a modification

Question 45

C20 what is the definition of homozygous

Answer 45

They have two identical alleles for a characteristic

Homozygotes dominant- contains two dominant alleles for a particular phenotype

Homozygous recessive – contains two alleles for the recessive phenotype

Question 46

C20) what is the definition of heterozygous

Answer 46

They have two different alleles for a characteristic

The allele for the dominant phenotype will be expressed

Question 47

C20) what is the characteristic of continuous variation

Answer 47

Characteristic that can take any value within a range

There are two extremes, with every degree of variation possible in between

Height and weight

Many genes involved and the environment has a large effect

Question 48

C20)What is the definition of co-dominance

Answer 48

Occurs when two different alleles occurs for a gene-both of which are equally dominant

As a result both alleles of the gene are expressed in the phenotype of the organism

Question 49

C20) how do you write codominant crosses

Answer 49

A letter is chosen to represent the gene

The different alleles are then represented using a second letter which is shown as a superscript

Question 50

C20) what is the definition of multiple alleles,

Answer 50

Some genes have more than two versions

An organism can only carry two versions of a gene

Question 51

C20) how is sex determined

Answer 51

In humans sex is genetically determined

Humans have 23 pairs of chromosomes of varying sizes and shapes

In 22 pairs the members are the same

The 23rd pair known as the sex chromosome are different

Human females have 2 X chromosomes whereas males have an X and Y chromosome

The X-chromosome is large and contains many jeans not involved in sexual development.

The Y chromosome is very small containing almost no genetic information but does carry a gene that causes the embryo to develop as a male

Question 52

C20) what are the characteristics of sex linkage

Answer 52

Some characteristics are determined by genes carried on the sex chromosomes

These jeans are called sex linked

As the Y-chromosome is much shorter than the X-chromosome, there are a number of genes in the X-chromosome that males only have one copy of
meaning that any characteristics caused by a recessive allele on the section of X-chromosome which is missing the Y-chromosome occurs frequently in males

Females will have a dominant allele present in the other X-chromosome

Question 53

C20) what is the notation for sex linkage

Answer 53

The alleles are shown linked to the sex chromosome they are formed on with a superscript

Question 54

C20) What is the importance of a dihybrid cross

Answer 54

Used to show the inheritance of two different characteristics caused by two genes which may be located on different pairs of homologous chromosomes. Each gene can have two or more alleles

Question 55

C20 what is the expected ratio of a dihybrid cross

Answer 55

9:3:3:1

Question 56

C20) what are the reasons for the actual ratio of a genetic cross different to the expected ratio

Answer 56

The fertilisation of gametes is a random process so in a small sample a few chance events can lead to a skewed ratio

The genes being studied are both on the same chromosome. These are known as linked genes. If no crossing over occurs the alleles for the two characteristics always be inherited together

Question 57

C20)What is the meaning of autosomal linkage

Answer 57

Meaning that the genes are located on the same chromosome

Occurs on one of the 22 chromosomes

Question 58

C20) what is the meaning of autosomal linkage

Answer 58

When the genes that are linked are found on one of the other pairs of chromosomes

Cannot undergo normal random Shuffling of alleles during meiosis and expected ratio will not be produced in the offspring

The linked genes are inherited effectively as a single unit

Question 59

C20) What are the effects of autosomal linkage

Answer 59

Due to crossing over which results in the separation of some of the linked genes is the reason for the offspring not reaching the expected ratio

The closer the geans are on a chromosomes the less likely they are to be separated during crossing over and The fewer recombinant offspring produced

Question 60

C20) What is the meaning of recombinant offspring

Answer 60

They have different combinations of alleles than either parent

Occurs as a result of crossing over

Question 61

C20) What is the equation for recumbency frequency

Answer 61

Number of recombinant offspring/ total number of offspring

Question 62

C20) What is the recombination frequency

Answer 62

A measure of the amount of crossing over that has happened in meiosis

A recombination frequency of 50% indicate that there is no linkage and the genes are on separate chromosomes

Less than 50% indicates that the gene is linked and the random process of independent assortment has been hindered

The degree of crossing over is determined by how close the genes are on the chromosome, the closer they are the less likely they will be separated

Question 63

C20) What is the chi-squared test

Answer 63

Measures the size of the difference between the result you actually get (observed) and those you expected to get

Helps determine whether differences in the expected and observe results are significant or not

Used to test the null hypothesis: That there is no significant difference between expected and observed. Therefore is down to chance

Question 64

C20) what does a large chi-squared value mean

Answer 64

There is a statistically significance between the observed and expected results

Probability that these differences are due to chance is low

Must be a reason rather than chance for the unexpected result

Question 65

C20) What does it mean if the x2 value is less than the critical

Answer 65

There is no significant difference

We do not have significantly strong evidence to reject The null hypothesis

Therefore we accept the normal hypothesis, there is no significant difference between what we observed and what we expected

Question 66

C20) What does it mean if the x2 value is more than the critical

Answer 66

There is a significant difference

We reject the null hypothesis

Some other factor, outside our ordinary expectation is likely to be causing a significant difference between expected and observed

Question 67

C20 what is epistasis

Answer 67

The interaction of genes at different Loki

Gene regulation is a form of epistasis with regulatory genes controlling the activity of structural genes

Also occurs in biochemical pathways involving only structural genes

The characteristics of plants and animals that show continuous variation involve multiple genes and epistasis occurs frequently

Question 68

C20) How does epistasis occur

Answer 68

The products of a gene in a multi step pathway codes for an enzyme

the product of the enzyme acts as a substrate for the next enzyme

If the gene that produces the enzyme is not expressed then the intermediate molecule for the next reaction in the sequence is not produced

Therefore a lack of substrate for the next enzyme in the pathway and so the expression of this gene will not be observed in the phenotype

The gene is effectively masked by the lack of expression of the previous gene in the pathway

Question 69

C20) what is hypostatic and epistatic genes

Answer 69

A gene that is affected by another gene is said to be hypostatic

A gene that affects the expression of another gene is said to be epistatic

Question 70

C20) What is dominant and recessive epistasis

Answer 70

2 recessive alleles at the same gene Loki would cause epistasis

A dominant allele of the same gene Loki would cause epistasis

Question 71

C20) What is a gene pool

Answer 71

The sum total of all the genes in a population at a given time

The gene pool of a population include millions of jeans but you will look at the variation in the different alleles of a single gene within the gene pool

Question 72

C20) what is the allele frequency

Answer 72

The relative frequency of a particular allele in a population

The frequency an allele occurs in a population is not linked to whether it is codes for a dominant or recessive characteristic and is not fixed

Changes over time in response to changing conditions

Evolution involves a long-term change in the Allelle frequency of a population

Question 73

C20) how do you calculate allele frequency

Answer 73

The frequency of the dominant allele in the population is represented by the P

The frequency of the recessive allele in the population is represented by the q

Deployed breeding population with two potential alleles, the frequency of the dominant allele plus the frequency of the recessive allele always equals one

P+q=1

Question 74

C20) What does the hardy Weinberg principle state

Answer 74

In a stable population with no disturbing factors, the allele frequencies will remain constant from one generation to the next and there will be no evolution

Question 75

C20) What is the hardy Weinberg principle

Answer 75

P2 + 2pq +q2 = 1

P2 = frequency of homozygotes dominant genotype in the population

2pq = frequency of heterozygous genotype in the population

q2 = frequency of homozygous recessive genotype in the population

Question 76

C20) how do you do the hardy Weinberg equation

Answer 76

Work out the frequency of either the recessive or dominant genotype

Square root the frequency of either the recessive or dominant genotype

Work out what the frequency of either The recessive or dominant genotype using the equation P + Q = 1

Then plug it back into the equation after figuring out both the recessive and dominant genotypes

Question 77

C20) How can the hardy Weinberg principle be used to show disturbing the equilibrium

Answer 77

Assumes a theoretical breeding population of deployed organisms that is large and isolated, with random meeting, no mutations and no selection pressure of any type

In a natural environment these conditions virtually never occur. Species are continuously changing

These changes in allele frequency can be illustrated using the hardy Weinberg principle and upsetting the equilibrium may result in evolution

Question 78

C20) what factors affect evolution

Answer 78

Led by changes in the frequency of alleles within a population, leading to evolution

Mutation is necessary for the existence of different alleles in the first place and the formation of new alleles lead to genetic variation

Sexual selection leads to an increase in frequency of alleles which codes for characteristics that improve meeting success

Genetic flow is the movement of values between populations. Immigration and migration result in changes to a allele frequency within a population

Genetic drift occurs in small populations.A change in allele frequency due to the random nature of mutation. The appearance of a new allele will have a greater impact on a smaller population than in a much larger population where there is a greater number of alleles present in the gene pool

Natural selection leads to an increase in the number of individuals that have characteristics that improve their chances of survival. Reproduction rights of these individuals will increase as well the frequency of alleles coding for the characteristic. How changes in the environment can lead to evolution

Question 79

C20) how are larger population less affected by variation

Answer 79

The gene pool of a large population insures loads of genetic diversity owing to the presence of many different genes and alleles

Genetic diversity leads to variation within a population which is essential in the process of natural selection

Selection pressures lead to evolution

Population can adapt to change over time

Question 80

C20) how are Smaller population more affected by variation

Answer 80

Limited genetic diversity cannot adapt to changes as easily and are more likely to become extinct

A new strain of pathogen can wipe out the whole population

The size of a population can be affected by many factors

Question 81

C20) what are the two types of limiting factors of a population

Answer 81

Diversity dependent factors-are dependent on population size and increased competition, predation, parasitism and communicable diseases

Diversity independent factors-effect population of all sizes in the same way including: climate change, natural disaster, seasonal change and human activity

Question 82

C20) what is a population bottleneck

Answer 82

Large reduction in population size which lasts for at least one generation

The gene pool along with genetic diversity is greatly reduced and the effects will be seen in future generations

Takes thousands of years for genetic diversity to develop in a population through the slow accumulation of mutations

Question 83

C20) what are the positive aspects of genetic bottleneck

Answer 83

A beneficial mutation will have a much greater impact and lead to the quicker development of a new species

Question 84

C20) what is the founder affect

Answer 84

Small populations can arise due to the establishment of new colonies by a few isolated individuals

An extreme example of genetic drift

Question 85

C20) how does the founder affect affect genetic variation

Answer 85

The smaller populations have much smaller gene pools than the original population and display less genetic variation

If carried to the new population, the frequency of an allele that were rare in the original population will be much higher in the new, Smaller population and so they will have a much bigger impact during natural selection

Question 86

C20) what are the different evolutionary forces

Answer 86

Stabilising selection

Directional selection

Disruptive selection

Question 87

C20)What is a normal distribution of a population

Answer 87

The traits or characteristics of a living organism shows variation within a population

The distribution of different variance will take the form of a bell shaped curve is plotted on a graph

Taking the birth weight of babies as an example

Babies with an average birth date will be the most common and therefore form the peak of the graph. Babies with very low-birth-weight are more prone to infections and very large babies result in difficult births

Both of the extremes in weight reduces the survival chances of the babies so the number of survival a very small or very large babies remain low form in the tails of the curve

Question 88

C20) What is Stabilising selection

Answer 88

Birthweight is natural selection at work. Babies with average birth weight are more likely to survive and reproduce than underweight or overweight babies

And example of stabilising selection because the norm or average is selected for (positive selection) and the extremes are selected against (negative selection)

Stabilising selection therefore results in reduction of the frequency of alleles at the extremes and an increase in the frequency of average alleles

Question 89

C20) what is directional selection

Answer 89

When there is a change in the environment and the normal phenotype is no longer than most advantages

Organisms which are less common and have more extreme phenotypes are positively selected.

The allele frequency then shift towards the extreme phenotype and evolution occurs

Question 90

C20) what is disruptive selection

Answer 90

The extremes are selected for and the non selected against

Opposite to stabilising selection when the norm is positively selected

Question 91

C20) what is speciation

Answer 91

The formation of new species through the process of evolution

Organisms belonging to the new species will no longer be able to interbreed to produce fertile offspring with organisms belonging to the original species

Question 92

C20) what events lead to speciation

Answer 92

Members of the population become isolated and no longer interbreed with the rest of the population resulting in no gene flow between the two groups

Alleles within the groups continue to undergo random mutations. The environment of each group may be different or change so different characteristics will be selected for and against

Accumulation of mutations and changes in allele frequencies over many generations eventually lead to large changes in the phenotype. The members of the different populations become so different that they no longer able to interbreed to produce fertile offspring

They are now reproductively isolated and are different species

Question 93

C20) what is Allopatric speciation

Answer 93

Most common form of speciation

Happens when some members of a population are separated from the rest of the group by a physical barrier such as a river or the sea-geographically isolated

The environment of the different groups will often be different and so will the selection pressures resulting in different physical adaptations

Speciation of a small group will often result in the founder affect resulting in genetic drift further enhancing the differences between populations

Question 94

C20) what is sympatric appreciation

Answer 94

Within populations that share the same habitat

Happens less frequently than Allopatric speciation and is most common in plants and animals

Can occur when members of two different species interbreed and form fertile offspring -often happens in plant

The hybrid formed, which is a new speciesWill have a different number of chromosomes to either parent and will no longer be able to interbreed with members of either parent population

This top gene flow and rapidly isolate the hybrid organism

Question 95

C20) how are hybrid plants formed

Answer 95

Plants cross with plants of different species forming hybrids

Theindiscriminate release of large numbers of pollen grains by plants is one reason for this

The hybrids are reproductively isolated from each parent species but could still be present in the same habitat

Disruptive selection, making preference and other behavioural differences can result in individuals or small groups becoming reproductively isolated. However, still be living in the same habitat so gene flow , Even if reduce often interferes with the process of speciation

Question 96

C20) what are the different reproductive barriers

Answer 96

Pre-zygotic reproductive barriers-prevent fertilisation or the formation of a zygote

Post psychotic reproductive barriers- As a result of hybridisation, reduce the visibility or reproductive potential of offspring

Question 97

C20) what is artificial selection

Answer 97

Selective breeding is the same as natural selection except for the nature of the selection pressure applied

Instead of changes in the environment, it is the selection for breeding of plants or animals with desired characteristics by farmers or breeders

Farmers have selectively bred plants and animals since before genes were discovered or the theory of evolution was proposed

Question 98

C20) What are the steps to artificial selection

Answer 98

Individuals with desired characteristics are selected and interbred.

Offspring from this cross showing the best example of the desired traits are then selected to breed

This breeding of closely related individuals is calledinbreeding

The process is repeated over many generations resulting in changes to the frequency of alleles within the population and eventually speciation

Question 99

C20) what are problems caused by inbreeding

Answer 99

Limiting the gene pool and so decreasing genetic diversity reducing the chances of a population of inbred organisms evolving and adapting to changes in the environment

Many genetic disorders are caused by a recessive alleles. Recessive alleles are not common in most populations but to recessive alleles are needed before they are expressed and most individuals will be heterozygous

Organisms that are closely related are genetically similar and are likely to have the same recessive alleles. The breeding of closely related organisms therefore result in offspring which have a greater chance of being homozygote For these recessive traits and being affected by genetic disorder

Overtime this reduces the ability for these organisms to survive and reproduce therefore the organism become less biologically fit-less likely to survive and produce two surviving offspring to replace them

Question 100

C20) What are Gene Banks

Answer 100

See banks keep samples of seeds from both wild and domesticated variance. Important genetic resource

Gene Banks to biological samples, they are usually frozen

Because of problems caused by interbreeding, alleles from Gene Banks are used to create genetic diversity in a process called outbreeding

Breeding unrelated or distantly related varieties is also a form of outbreeding

Reduces the occurrence of homozygous recessives and increases the potential to adapt to environmental changes

Question 101

C22) what is cloning

Answer 101

Asexual reproduction is a form of cloning

Results in offspring produced by mitosis

Clones are usually genetically identical to both the parent organism and each other

Question 102

C22) What is vegetative propagation

Answer 102

Natural cleaning occurs in many species of flowering plants

Structural forms which develops into a fully differentiated new client, which is genetically identical to the parent

The new plant may be Propagated from the stem, leaf, board or root of the parent, depending on the type of plant, and it eventually becomes independent from its parent

Often involves perennating organs,Which enable pounds to survive adverse conditions. These contain stored foods from photosynthesis that can remain dormant in the soil. Often not only a means of asexual reproduction but also a way of surviving from one growing season to the next

Question 103

C22) examples of when natural plant cloning occurs

Answer 103

Bulbs - The leaf bases swell with stored food from photosynthesis. Buds form internally which develop into new shoots and new plants in the next growing generation

Runners - A lateral stem grows away from the Parent plant and roots develop where the runner touches the ground. A new plant develops-the runner eventually withers away leaving the new individual independent

Stem tubers - The tip of an underground stem becomes swollen with stored food to form a tuba or Storage organ. Buds on the storage organs develop to produce new shoots

Question 104

C22) how has natural cloning been used in horticulture

Answer 104

To produce new plants

Splitting up bulbs, removing young plants from runners

All increase plant numbers cheaply and the new plants have exactly the same genetic characteristics at their parents

It is possible to take cuttings from many plants-short sections of stems are taken and planted either directly into the ground or into pots. Rooting hormone is often applied to the base of the cutting to encourage the growth of new roots

Question 105

C22) what are the advantages of propagation from cutting

Answer 105

It is much faster -The time from planting to cropping is much reduced

Guarantee the quality of the plants

By taking cuttings from good stock, the offspring Will be genetically identical and will therefore crop well

Question 106

C22) what are the disadvantages of propagation from cutting

Answer 106

The lack of genetic variation in the offspring should any new disease or pest appear or if climate change occurs

Question 107

C22) What is micropropagation using tissue culture

Answer 107

Micropropagation is the process of making large numbers of genetically identical offspring from a single parent plant using tissue cultureTechniques

Question 108

C22) when is micropropagation using tissue cultures done

Answer 108

When a desired plant:

Does not readily produce seeds

Doesn’t respond well to naturalCloning

Is very rare

Has been genetically modified or selectively bred with difficulty

Is required to be pathogen free by growers

Question 109

C22) what are the different ways that plants on micropropagated

Answer 109

With the use of sodium dichloroisocyanurate,The sterilising tablets used to make emergency drinking water. This keeps the plant tissues sterilised without being in a sterilised lab so it is extremely useful for scientist in the field of working with a rare and endangered plant material

Large is sterilising units

Question 110

C22) What are the basic principles of micropropagation with tissue culture

Answer 110

Take a small sample of tissue from the plant you want to clone- the meristem tissue from shoot tips and axial buds are dissected out in sterile conditions to avoid contamination by fungi and bacteria. This tissue is usually virus free

The sample is sterilised, Usually by immersing it in sterilising agent such as bleach, ethanol and sodium dichloroisocyanurate. Which does not need to be rinsed off meaning the tissue is more likely to remain sterile. The material removed from the plant is called the explant

The explant is placed in a sterile culture medium containing a balance of plant hormones which stimulate mitosis. The cells proliferate, forming a mass of identical cells known as Callus

The callus is divided up and individual cells or clones from the callus are transferred to a new culture medium containing a different mix of hormones and nutrients which stimulate the development of tiny genetically identical plantlets

The plantlets are potted into compost where they grow into small plants

The young plants are planted out to grow and produce the crop

Question 111

C22) what are arguments for micropropagation

Answer 111

Allows for the rapid production of large numbers of plants with non-genetic make up which will yield good crop

Makes it possible to produce viable numbers of plants after genetic modifications of plant cells

It produces a way of growing plants which are naturally relatively infertile or difficult to grow from seed

Culturing meristem tissue produces disease-free plants

Question 112

C22)What are the arguments against micropropagation

Answer 112

It produces a monoculture-many plants which are genetically identical – so they are all susceptible to the same disease or changes in growing conditions

Relatively expensive process and requires skilled workers

If the source material is infected with a virus, all of the clones will also be infected

In some cases large numbers of new plants are lost during the process

Question 113

C22) how does cloning in invertebrates occur

Answer 113

Can take several forms

Some animals can regenerate entire animals from fragments of the original if they are damaged

Flat worms and sponges fragment and form new identical animals as part of their normal reproductive process

Hydra Produce small buds on the side of the body which developed into genetically identical clones

Some insects, females can produce offspring without meeting –not true cloning

Question 114

C22) how does cloning in vertebrals occur

Answer 114

Occurs in the formation of monozygotic twins

The early embryo splits to form two separate embryos. No one is sure of the trigger which causes this to happen

The frequency at which identical twins occur varies between species

When monozygotic twins are born although genetically identical, they may look different as a result of differences in their position and nutrients in the uterus

Some female reptiles and amphibians will produce offspring when no male is available. The offspring are often male rather than female, so they are not clones of their mother, all of the genetic material arises from her

Question 115

C22) what is it like to artificially clone in animals

Answer 115

Relatively easy to produce artificial clones in some invertebrals-liquidise a sponge or chop up a starfish

Much more difficult to produce artificial clones for vertebrals

Two methods are now used widely in the production of high quality farm animals and in the development of genetically engineered animals for Pharming

Question 116

C22) what are the two ways of producing vertebra artificial clones

Answer 116

Artificial twinning

Somatic cell nuclear transfer

Question 117

C22) what is artificial twinning

Answer 117

After an egg is fertilised it divides to form a ball of cells. Each of these individual cells is Totipotent- it has the potential to form an entirely new animal

In natural twinning, an early embryo splits and 2 foetuses go on to develop from the two halves of the divided embryo. In artificial twinning the same thing happens but the early embryo is manually split

The early embryo may be split into more than two pieces and results in a number of individual offspring

Artificial twinning like embryo transfer which preceded it is used by the farming community to produce the maximum offspring from particularly good dairy or beef cattle or sheep

Question 118

C22) what are the stages of artificial twinning in cattle

Answer 118

A cow with the desired trait is treated with hormones so she super ovulates, releasing more mature ova than normal

The ova must be fertilised naturally or by artificial insemination, by a ball with particularly good traits. The early embryos are gently flushed out of the uterus

Alternatively, the mature eggs are removed and fertilised by top quality bull semen in the lab

Usually before or around Day 6, when the cell are still Totipotent, The cells of the early embryo Are split to produce several smaller embryos, each capable of growing onto form a healthy food term calf

Each of the split embryos are grown in the lab for a few days to ensure all is well before it is implanted into a surrogate mother. Each embryo is implanted into a different mother as single pregnancies carry lesser risk than twin pregnancies

The embryos develop into foetuses and are born normally, so a number of identical cloned animals are produced by different mothers

Question 119

C22) why do some farmers freeze the embryos

Answer 119

This allows the success of a particular Animal to be assessed and if the stock is good, remaining identical embryos can be implanted and bought to term

Question 120

C22) what is somatic cell nuclear transfer

Answer 120

Artificial twinning clones an embryo

now possible to clone an adult animal by taking the nucleus of an adult stomatic (body) cell and transferring it to an enucleated egg cell (Nucleus removed)

Tiny electrical shock is used to fuse the egg and nucleus, stimulate the combined cell to divide and form an embryo that is a clone of the original adult

Animals of different breeds are often used as the cell donor, the egg donor and the surrogate mother to make it easier to identify the original animal at each stage

Question 121

C22)What are the stages of Stomatic cell nuclear transfer

Answer 121

The nucleus is removed from a stromatic cell of an adult animal

The nucleus is removed from a mature ovum harvested from a different female animal of the same species

The nucleus from the adult somatic cell is placed into the enucleated ovum and given a mild electric shock so it fuses and begins to divide. In some cases the nucleus from the adult is not removed-it is simply placed next to the enucleated ovum and the two cells fuse (electrofusion) and begin to divide under the influence of the electrical current

The embryo that develops is transferred into the uterus of a third animal where it develops to turn

The new animal is a clone of the animal from which the original somatic cell is derived although the mitochondrial DNA will come from the Egg cell

Question 122

C22) What are the uses of stromatic cell nuclear transfer

Answer 122

Used in pharming-The production of animals which have been genetically engineered to produce therapeutic human proteins in their milk

Can be used to produce genetically modified animals which grow organs that have the potential to be used in human transplant

Question 123

C22) what are the advantages of animal clothing

Answer 123

Artificial twinning enables high yielding farm animals to produce many more offspring than normal reproduction

Artificial twinning enables the success of a male animal at passing on desired genes to be determined. If the first cloned embryo results in a successful breeding animal, more identical animals can be raised from the remaining frozen clones

Somatic cell nuclear transfer enables genetically modified embryos to be replicated and to develop, giving many embryos from one engineering procedure. Important process in parming

Somatic cell nuclear transfer has the potential to enable rare, endangered or even extinct animals to be reproduced. The nucleus from dried or frozen tissue can be transferred to the egg of a similar living species to produce clones

Question 124

C22) What are the disadvantages of animal clothing

Answer 124

Somatic cell nuclear transfer is very ineffective process-most animals it takes many eggs to produce a single cloned offspring

Many crowned animal embryos failed to develop and miscarry or produce malformed offspring

Many animals produced by cloning have shortened lifespan

Somatic cell nuclear transfer has been relatively unsuccessful so far in increasing the population of rare organisms or allowing extinct species to be brought back to life

Question 125

C22) what are the reasons for using microorganisms

Answer 125

There are no welfare issues to consider –all data needed is the optimum conditions for growth

There is an enormous range of micro organisms capable of carrying out many different chemical synthesis or degradation that can be used

Genetic engineering allows us to artificially manipulate micro organisms to carry out synthesis reactions that they do not normally do

Micro organisms have a very short life-cycle and rapid growth rate. As a result given the right conditions huge quantities of microorganisms can be produced in a short period of time

Question 126

C22) what does indirect food production

Answer 126

Micro organisms are widely used in biotechnological processes to make food

Micro organism have an indirect effect-it is the action on other food that is important

Question 127

C22) how does baking occur

Answer 127

Yeast mixed with sugar and water to respire aerobically. Carbon dioxide produced makes bread rise

Active yeast is mixed with other ingredients and left in warm environment to rise

Cooked in the oven-the carbon dioxide bubbles expand so the bread rises more. Yeast cells are killed during cooking

Question 128

C22)How does brewing occur

Answer 128

Yeast respire anaerobically to produce ethanol. Traditionally yeast Firment at20 to 28°C but genetically modified yeast Firment at lower and therefore cheaper, temperatures and clamped together and sink at the bottom of the process

Malting-enzymes that break down starch molecules down to sugar which yeast can use. Seeds then killed by slow heating but enzyme activity retained to produce malt

Mashing -The mould is mixed with hot water and enzymes break down starch is to produce Wort. Hops are added for favour and antiseptic qualities. The wort sterilised and cold

Fermentation -Wort is inoculated with yeast. Temperature maintained for optimal anaerobic respiration. Yeast is inhibited by falling temperature and lack of oxygen

Maturation -The beer is Conditioned for days in tank

Finishing-beer is filtered, pasteurised and then bottled

Alcohol content varies between 4% and 9%

Question 129

C22) how does cheesemaking occ

Answer 129

Bacteria feed on lactose in milk changing the texture and taste and inhibiting the growth of bacteria which make milk go off

Milk is pasteurised killing off most natural bacteria and homogenised, The fat droplets evenly distributed in milk

Mixed with bacterial cultures and sometimes enzymes and kept until the milk separates into solid curds and liquid whay

The curd are cut and cooked in the whay then strain through draining moulds. Whay used as animal feed

The curd are put into steel or wooden drums and may be pressed. They are left to dry, mature and ripen before eating as the bacteria continue to act.

Question 130

C22) how does yoghurt making occur

Answer 130

Bacteria often forms ethanol And lactic acid. Both produce extracellular polymers that give yoghurt its smooth thick texture

Skimmed milk powder is added to milk and the mixture is pasteurised and homogenised and cooled

The milk is mixed with a 1:1 ratio of the two bacterial and incubated

At the end of the fermentation the yoghurt may be put into cartons at a lower temperature

Thickset yoghurts are mixed and Ferment in the pot

Yoghurt has a shelf life of about 19 days

Question 131

C22) what is direct food production

Answer 131

People have eaten fungi for thousands of years in the form of mushrooms. Facing potential protein shortage around the world scientists are developing more ways of using micro organisms to directly produce protein that we can eat known as single celled protein

QuranMade of single celled fungus that is grown in large fermenters using glucose syrup as a food source. The microorganisms are combined with albumen(Egg white) then compressed and formed into meat substitutes

Not suitable for vegetarians but a healthy choice as it is high in protein and low in fat

People are very conservative in their food choices and the new food was launched without the mention of fungi being used in its production

Question 132

C22) what are the advantages of using micro organisms to produce human food

Answer 132

Microorganisms reproduce fast and produce protein faster than animals and plants

Micro organisms have a high protein content with little fat

Can be genetically modified to produce the protein required

Production of micro organisms is not dependent on whether, breeding cycle

No welfare issues when growing microorganisms

can be made to taste like anything

Question 133

C22)What are the disadvantages of using micro organisms to produce human food

Answer 133

Some micro organisms can also produce toxins if the conditions are not maintained and the optimum

The micro organisms have to be separated from the nutrient broth and processed to make the food

Often involve genetic manipulated organisms and many people have concerns about eatingGenetically modified food

The protein has to be purified to ensure it contains no toxins or contaminants

Has little natural flavour

Question 134

C22) why is penicillin produced the way it is produced

Answer 134

The Mould needs relatively high oxygen levels and a rich nutrient medium to grow well

Sensitive to pH and temperature affecting the way it has produced commercially

Semi continuous batch process is used.

Question 135

C22) How is penicillin produced

Answer 135

First stage of the production process the fungus grows

The second stage it produces penicillin

Finally, The drug is extracted from the medium and purified

The process uses relatively small fermenters because it is very difficult to maintain high levels of oxygenation in very large bioreactors

The mixture is continuously stirred to keep it oxygenated

There is a rich nutrient medium

Growth medium contains a buffer to maintain pH around 6.5

The bioreactors are maintained at 25 to 27°C

Question 136

C22) why is insulin produced the way it is produced

Answer 136

People with type one diabetes and some people with Type II diabetes regularly inject insulin to control blood sugar levels

In the past insulin was extracted from the pancreas of animals usually pigs or cattle slaughtered for meat.

This meant the supply was erratic because it depended on the demand for meat – when few animals were killed less insulin was available but the number of peopleWith diabetes stayed the same

Some people were allergic to the animal insurance as it was often in pure, very pure forms were developed to overcome the problem

peak activity of animal Insulin is several hours after the injection making calculations when to eat meals difficult

Some faith groups using pig products was not permitted

Question 137

C22)How is insulin produced

Answer 137

Genetically engineered bacteria can make human insulin

Bacteria are grown in fermenters and downstream processing results in a constant supply of pure human insulin

Question 138

C22) what is bioremediation

Answer 138

Micro organisms are used to Breakdown pollutants and contaminants in soil or in the water

Byron mediation takes place on the site of contamination, sometimes material is removed for decontamination

Most cases natural microorganisms outperform genetically modified ones

Question 139

C22) what are the different approaches to bioremediation

Answer 139

Using natural organisms- many microorganisms naturally break down organic material producing carbon dioxide and water. Soil and water pollutants are often biological
if naturally occurring Microorganisms are supported they will break down and neutralise many contaminants. By adding nutrients to encourage microbial growth

Genetically modified organisms-scientists are trying to develop genetically modified bacteria which can break down contaminants which they could not naturally encounter for example mercury. Aim is to develop filters containing these bacteria

Question 140

C22) why must the correct health and safety procedures be followed even when the microorganisms are expected to be Harmless

Answer 140

Always the risk of mutations taking place, making the strain pathogenic

May be contamination with pathogenic microorganisms from the environment

Question 141

C22) how do you culture microorganisms

Answer 141

Micro organisms need food as well as the right conditions of temperature, oxygen and pH

Food provided for micro organisms is best known as the nutrient medium

Either in liquid form (broth) or in solid form (agar)

Nutrients are often added to these to provide a better medium for microbial growth

Some microorganisms need precise balance of nutrients but often the medium is enriched with good protein sources

Enriched nutrient medium allows samples containing a small number of organisms to multiply rapidly

The nutrient medium needs to be kept sterile until it is ready to use using aseptic techniques are important

Question 142

C22) What is the process of inoculation

Answer 142

Once the nutrient medium is prepared the bacteria must be added in this process

Question 143

C22) how do you inoculate broth

Answer 143

Make a suspension for the bacteria to be prone

Makes a known volume with the sterile nutrient broth in the flask

Stopper the flask with cotton wall to prevent contamination from the air

Incubate at a suitable temperature, shaking regularly to aerate the broth providing oxygen for the growing bacteria

Question 144

c22)How do you inoculate agar

Answer 144

The wire inoculating loop must be sterilised by holding it in a Bunsen burner until it glows red hot. Not be allowed to touch any surface as it caused to avoid contamination

Did the sterilised loop in the bacterial suspension. Remove the lid of the petri dish and make a zigzag streak across the surface of the agar. Avoid the loop digging into the agar by holding it almost horizontal. The surface of the agar must be kept intact

Replace the lid of the petri dish. Should be held down with tape but not completely sealed so oxygen can get in, preventing the growth of anaerobic bacteria. Incubate at suitable temperature

Question 145

C22)What are the four stages of the growth curve of bacteria

Answer 145

The lag phase when bacteria are adapting to the new environment. They are growing, synthesising the enzymes they need and are not yet reproducing at the maximum rate

The log or exponential phase when the rate of bacteria reproduction is close to or at its theoretical max

The stationary phase occurs when the total growth rate is zero-the number of new cells formed by binary fusion is cancelled down by the number of cells dying

The decline or death Phase comes when reproduction has almost seized and the death rate of cells is increasing

Question 146

C22)What are several limiting factors which prevent exponential growth in a cultural of bacteria

Answer 146

Nutrients available- initially plenty of food but as the number of organisms multiply exponentially it is used up. Nutrient level become insufficient to support further growth and reproduction

Oxygen level- as the population rises, so does the demand for respiratory oxygen

Temperature- enzyme controlled reactions within microorganisms are affected by the temperature of the culture medium. Slower temperatures slowdown growth and reproduction higher temperatures speeded up to an extent and then it denatures the enzyme killing the microorganism

Buildup of waste- as bacteria numbers rise, buildup of toxic material may inhibit further growth and even poison and kill the culture

Change in pH- carbon dioxide produced by respiration increases the pH of the culture falls until a point where the low pH affects enzyme activity and inhibit population growth

Question 147

C22) what are primary and secondary metabolites

Answer 147

You want as much micro organisms as possible because the microorganisms itself is the product to be sold

Primary metabolite are substances which form an essential part of the normal functioning of a micro organism

Secondary metabolites are substances which are not essential for normal growth but are still used by cells and are often the required product in a bioprocess

Question 148

C22) what are the types of bioprocesses

Answer 148

Two of the main ways of growing microorganisms are batch fermentation and continuous fermentation

Depends on the Micro morganism chosen and the ideal size and shape of the bioreactor

Question 149

C22) what are the stages of batch fermentation

Answer 149

That micro organisms are inoculated into a fixed volume of medium

As growth takes place, nutrition are used up and Both new biomass and waste products buildup

As the cultures reach the stationary phase overall growth Ceases but during this phase The micro organisms often carry out biochemical changes to form the desired and product

The process is stopped before the death phase and the product is harvested. The whole system is then cleaned and sterilised and a new batch culture started up

Question 150

C22) what are the stages of continuous culture

Answer 150

Micro organisms are inoculated into sterile nutrient medium and start to grow

Sterile nutrient medium is added continuously to the culture once it reaches exponential point across

Culture broth is continuously removed - the medium, waste product, micro organisms and products-keeping the cultural volume in the bioreactor constant

Enables continuous balanced growth with levels of nutrients, pH and metabolic products kept more or less constant

Question 151

C22) what is the importance of bioreactors in culturing on an industrial level

Answer 151

Both methods of operating a bioreactor can be adjusted to ensure either the maximum product of the biomass or the maximum product of the primary secondary metabolite

Adapted for maximum yield of metabolites.

Majority of industrial processes used batch or semi continuous cultivation

Continuous calculation is largely used for the Production of single celled protein and in some waste water treatment processes

All bioreactors produce a mixture of unused natural Broth, micro organisms, primary metabolites, second metabolites and waste products

Useful parts of the mixture has to be separated out by downstream processes

Question 152

C22) what are the factors that need to be controlled in a bioreactor

Answer 152

Temperature- if the temperature is too low the micro organism will not grow quickly enough. If the temperature is too high the enzyme start to the nature and the micro organisms are inhibited or destroyed.
They often have heating and cooling system is linked to temperature sensors and a negative feedback system to maintain optimal conditions

Nutrients and oxygen- oxygen and nutrition mediums can be added in controlled amounts to the broth when probes or sample tests indicate the levels are dropping

Mixing things up- inside are large volumes of liquid which may be quite thick and viscous due to the growth of microorganisms.
Simple diffusion is not enough to ensure all microorganisms receive enough food and oxygen all the mixture is kept at the right temperature
Most bioreactors have a mixing mechanism and many are stirred continuously

Asepsis- Contamination by Micro organisms from the air or from workers can affect the yield.
Most bioreactors are sealed, aseptic units. If the process involves genetically engineered organisms it is legally required to be contained in the bioreactor

Question 153

C22) what are the advantages of using isolated enzymes instead of the whole of the whole organism

Answer 153

Less wasteful- whole organisms use up substrate growing and reproducing. Producing biomass rather than product. Isolated enzymes do not

More efficient- isolated enzymes work at a much higher concentration than is possible when they are part of the whole microorganism

More specific- no unwonted enzymes present, no wasteful side reactions take place

Maximise efficiency- isolating enzymes can be given ideal conditions to maximise product formation, which may differ from those needed for the growth of the whole organism

Less downstream processing- pure product is produced by isolated enzymes. Whole organism gives a variety of products in the final breath, making isolation of design products more difficult and therefore expensive

Question 154

C22)Why are extracellular enzymes for micro organisms used as isolation enzymes instead of intracellular

Answer 154

Generally easier and therefore cheaper

Extracellular enzymes are secreted making them easy to isolate and use

Each micro organism produces relatively few extracellular enzyme making it easy to identify and isolate the required enzyme. In comparison each Micro organism produces hundreds of intracellular enzymes which would need extracting from the cell and separating

Extracellular enzymes tend to be more robust than intracellular enzymes. Conditions outside a cell are less tightly controlled then conditions in the cytoplasm, so extracellular enzymes are adapted to cope with greater Variation in temperature and pH then intracellular enzymes

Question 155

C22) when are intracellular enzymes used

Answer 155

Because of the bigger range of intracellular enzymes

They can provide the ideal enzyme for a process

The benefits of using and very specific intracellular enzymes outweigh the disadvantages of the more expensive extraction and isolation process needed for the more tightly controlled conditions

Penicillin actlase for converting natural penicillin into semi synthetic drug

Question 156

C22) what are immobilising enzymes

Answer 156

Isolated enzymes are More efficient than whole organisms but using three enzymes is often very wasteful

Enzymes are not cheap to produce but at the end of the process they cannot usually be recovered and so simply lost

Increasingly enzymes in industrial processes are immobilised-attached to and inert support system over which the substrate passes and is converted to product

Technology mimicking nature- enzyme in cells are usually bound to membranes to carry out the repeated cycle of catalase

Immobilised enzymes are held stationary during the catalase process can be recovered from the reaction mixture and used time after time

The enzymes do not contaminate the end product,Less downstream processing is needed

Process more economical

Question 157

C22) what are the advantages of using immobilised enzymes

Answer 157

Enzymes can be Reused-cheaper

Easily separated from the reactants and products of the reaction they are catalysing - reduced downstream processing-cheaper

More reliable- high degree of control over the process as the insoluble support provides a stable microenvironment for the immobilised enzyme

Greater temperature tolerance- immobilised enzymes are less easily denatured by heat and work at optimum levels over a much wider range of temperatures, making bioreactors less expensive to run

Easy to manipulate- the catalytic properties of immobilised enzymes can be altered to fit a particular process much easily than those of free enzymes. Keep bioreactors running continuously for longer periods without emptying or cleaning helps to keep costs down

Question 158

C22) what are the disadvantages of using immobilised enzymes

Answer 158

Reduced efficiency- process of immobilising an enzyme may reduce its activity rate

Higher initial costs of materials- immobilised enzymes are more expensive than free enzymes or micro organisms but unlike three enzymes immobilised enzymes do not need to be repeatedly replaced

Higher initial cost of bioreactors- system needs to use immobilised enzyme is different from traditional fermenters so they are costly initially

More technical issues- reactors which use immobilised enzymes are more complex than simple fermenters- more things can go wrong

Question 159

C22) what are the different ways that enzymes are immobilised

Answer 159

Surface immobilisation- absorption to inorganic carriers

Surface immobilisation – covalent or ionic bonding to inorganic carriers

Entrapment- in the matrix

Entrapment-membrane entrapment in microcapsules or behind a semipermeable membrane

Question 160

C22) what are the advantages and disadvantages of surface immobilisation through absorption to inorganic carriers

Answer 160

Simple and cheap to do
Can be used in many different processes
Enzymes very accessibility to substrate and the activity is virtually unchanged

Enzymes can be lost from matrix relatively easily

Question 161

C22) what are the advantages and disadvantages of surface immobilisation through covalent or ionic bonding to inorganic carriers

Answer 161

Cost varies
Enzymes are strongly bound and therefore unlikely to be lost
Enzymes very accessibility to substrate
PH and substrate concentration often have little effect on enzyme activity

Cost varies

Active site of the enzyme may be modified in process making it less effective

Question 162

C22) what are the advantages and disadvantages of Entrapment-in the matrix

Answer 162

Widely applicable to different processes

May be expensive
Can be difficult to entrap
Diffusion of substrate to and product from the active site can be slow and hold up the reaction
Effects of entrapment on enzyme activity very variable, depending on matrix

Question 163

C22) what are the advantages and disadvantages of Entrapment-in Micro capsules or a semipermanent membrane

Answer 163

Relatively simple to do
Relatively small effect on enzyme activity
Widely applicable to different processes

Relatively expensive
Diffusion of the substrate to and product from the active side can be slow and hold up the reaction

Question 164

C22) what are examples of using immobilised enzymes

Answer 164

Immobilised glucose isomerase used to produce fructose from glucose.Fructose is sweeter than sucrose or glucose and widely used as a sweetener in food production.

Immobilise lactase used to produce lactic free milk. Some people and cats are lactose intolerant. Immobilised lactase hydrolysis lactose to glucose and galactose giving lactose free milk

Immobilised aminoacylase -Produce a pure source of L amino acid used in the production of pharmaceuticals

Question 165

C21) how do you produce a DNA profile

Answer 165

Extract the DNA
DNA must be extracted from a tissue sample, at the start it had to be large samples. Now using a technique called polymerise chain reaction, the thinnest fragment of tissue can be give scientist enough DNA for a profile

Digest the sample
Strands of DNA or cut into small fragments using special enzymes called restriction endonucleases .Different Restriction endonuclease Cut DNA at specific nucleus sequences known as a restriction site or recognition site. All restriction endonuclease make 2 cut one through each strand of DNA double helix.
Restriction endonuclease gives scientist the ability to cut DNA strands and defined points in the introns

Separate the DNA fragments
The cut fragments of DNA need to be separated to form a clear and recognisable pattern. Damage using electrophoresis, utilising the way charged particles move through a gel medium under the influence of electrical currents. Larger DNA strands move further down. Gel immersed in alkali in order to separate the DNA double strands into single strands. Single-stranded DNA fragments transferred into a membrane for southern blotting

Hybridisation
Radioactive or fluorescent DNA probes are now added in excess to the DNA fragments on the membrane. DNA probes are short DNA or mRNA sequence is complimentary to a known DNA sequence. They bind to the complimentary strand of DNA called hybridisation

See the evidence
Radioactive labels were added to the DNA probe, x-ray images are taken of the paper/membrane. If fluorescent labels were added to the DNA probe the paper/membrane would be placed on the UV lights so the fluorescent tags glow-Most common used today. Fragments give a pattern of bars-DNA profile-unique to every individual

Question 166

C21) how do you set up polymerise chain reaction

Answer 166

The DNA sample to be amplified, and excess of the four nucleotide bases A, T, C and G, Small primer DNA sequence and the enzyme DNA polymerase are mixed in a violent that is placed in a PCR machine

Question 167

C21)What is the importance of the PCR machine

Answer 167

The temperature within the PCR machine is carefully controlled and changes rapidly and programmed intervals triggering different stages of the process

The reaction can be repeated many times by the PCR machine through the program temperature settings

Question 168

C21) what are the stages of polymerised chain reaction

Answer 168

Separating the strands
PCR machine increases to 90 to 95°C denaturing the DNA by breaking the hydrogen bonds holding the DNA strands together so they separate

Annealing the primer
Temperature is decreased to 55 to 60°C and the primer bind (annuals) to the end of the DNA strands needed for the replication of the strand to occur

Synthesis of DNA
Temperature increased to 72 to 75°C as it is the optimal temperature for DNA polymerase to work best. DNA polymerase adds bases to the prime of building up complimentary strands of DNA and producing double-stranded DNA identical to the original strand

Question 169

C21)What are the uses of DNA profiling

Answer 169

Field of forensic science especially criminal investigation. Performing on traces of DNA left at the crime scene

Use to prove paternity of a child when it is in doubt

Identifying individuals who are at risk of particular diseases

Question 170

C21) how is DNA sequencing set up

Answer 170

The DNA is chopped into fragments and each fragment is sequenced new power

The process involves terminator bases, modified versions of the 3 nucleotide bases which stop DNA synthesis when they are included.

A terminator. DNA synthesis at the location that a base would be added, a C terminator where a C base would go

Terminator bases are given a colour fluorescent tag

Question 171

C21) What are the stages of DNA sequencing

Answer 171

The DNA for sequencing is mixed with a primer, DNA polymerase, and excess of normal nucleotides and terminator bases

The mixture is placed in a thermal cycler that rapidly changes temperature and programmed intervals in repeated cycles, the double-stranded DNA separates into single strands, the primer anneal to the DNA strand

DNA polymerase starts to build up new DNA strands by adding nucleotides with the complimentary base of the single-stranded DNA template

Each time a terminated base is incorporated instead of a normal nucleotide, the synthesis of DNA is terminated as no more basis can be added. The chain terminating bases are present in lower amounts and are added at random this results in many DNA fragments of different lengths depending on where the chain terminating bases have been added during the process. After many cycles all the possible DNA chains will be produced with the reaction at every base. DNA fragments separated by length using capillaries sequencing like electrophoresis in capillaries tubes. The fluorescent terminator bases are used to identify the final base of each fragment. Lasers detect the different colours and the order of the bases

The order of bases in the capillary tubes showed the sequence of the new complimentary strand of DNA which had been made.Used to build up the sequence of the original DNA strand

The data from the sequencing processes fed into a computer that resembles the genome by comparing all the fragments and finding the areas of overlap between them

Question 172

C21) what is the next generation of sequencing

Answer 172

Instead of using a gel or capillary, the sequencing reaction takes place on a plastic slide known as a flow cell

Millions of fragments of DNA are attached to the slide and replicated in situ using PCR to form clusters of identical DNA fragments

Still uses the principle of adding a coloured terminator base to stop the reaction so an image can be taken

As all of the clusters have been sequenced and imaged at the same time the technique is known as massively parallel sequencing

Question 173

C21) what is the meaning of bioinformatics

Answer 173

Is the development of the software and computing to is used to organise an analyse raw biological dataIncluding the development of algorithms, mathematical models and statistical test to help us to make sense of the enormous quantities of data being generated

Question 174

C21) what is Computational biology

Answer 174

Uses this data to build theoretical models of biological systems, which can be used to predict what will happen in different circumstances

Computational biology is the study of biology using computational techniques, especially in the analysis of huge amounts of biodata

Question 175

C21) what is genomics

Answer 175

The field of genetics that applies DNA sequencing methods and computational biology to analyse the structure and function of genomes

Question 176

C21)How has the human genome been analysed

Answer 176

Computers can analyse and compare the genome of many individuals, revealing patterns in the DNA we inherit and the diseases of which we are vulnerable

Enormous implication for health management and the field of medicine in the future. Genomic‘s is changing the face of epidemiology

Scientists increasingly recognise with the exception of a few relatively rare genetic diseases caused by changes in single genes, our genes work together with the environment to affect our physical characteristics, our physiology and all likelihood of developing certain diseases

Question 177

C21) How has sequencing the genomes of pathogens becoming fast and relatively cheap enabled doctors to do

Answer 177

Find out the source of an infection

Identify antibiotic resistant strains of bacteria, ensuring antibiotics are only used when they will be effective and help prevent the spread of antibiotic resistance

To tackle the progress of an outbreak of potential Serious diseases and monitor potential epidemics

To identify regions in the genome of pathogens that may be useful targets in development of new drugs and to identify genetic markers for use in vaccines

Question 178

C21) how can scientists identify species

Answer 178

Using traditional methods of observation, it can be very difficult to determine which species an organism belongs to or if a new species have been discovered.

Gene analysis provides scientist with another tool to aid in species identification by comparing to a standard sequence for the species

Challenge for scientists is to produce stock sequences for all the different species.

Useful technique is to identify particular sections of the genome that are common to all species but vary between them, so comparison can be made –DNA barcoding

Scientists identified species using relatively short sections of DNA from a conserved region of the genome

For animals the region chosen is a 648-based pair section of the mitochondrial DNA in the gene cytochrome C oxidise, that codes for an enzyme involved in cellular respiration. This section is small enough to be sequenced quickly and cheaply yet varies enough to give clear differences between species

Inland plants, this region of DNA does not evolve quickly enough to show clear differences between species but two regions in the DNA of the chloroplast have been identified that can be used in a similar way to identify species

Question 179

C21) what is the problem with the barcode in the system

Answer 179

Scientists have not come up with a suitable region for fungi and bacteria and they may not be able to do so

Had a big impact on classification

Question 180

C21) How has gene sequencing become a powerful tool for evolution relationships between organisms

Answer 180

DNA sequences of different animals can be compared because the basic mutation rate of DNA can be calculated scientists can calculate how long ago to species diverged from a common ancestor

DNA sequencing enable scientists to build up evolutionary trees with an accuracy like never before