Higher Biology Flashcards
What is DNA
An organism’s inherent genetic material, that is used to code for its specific characteristics.
Where is DNA found in animal, plant and fungi cells
The nucleus
Where is DNA found in bacterial cells
Plasmids (ring-like structures of DNA) or the nucleus
What are the large molecules that DNA strands are collectivised and packaged into
Chromosomes
What is the name for a section of DNA that codes for a certain characteristic
A gene
What are the building blocks of DNA
Nucleotides
What do nucleotides comprise of
+ a deoxyribose sugar
+ a phosphate group
+ a base
How many strands does a DNA molecule have
2
What can each DNA strand be referred to as
A sugar-phosphate backbone
Within a sugar-phosphate backbone, what deoxyribose carbon is bound to a phosphate group
3’
What are the four bases
+ Adenine
+ Thymine
+ Guanine
+ Cytosine
What are the base pairing rules
Adenine-Thymine
Guanine-Cytosine
What bond forms between adjacent, complementary bases
Hydrogen bonds
A DNA molecule has an … structure
Antiparallel
What do DNA molecules coil around
Associated proteins/histones
What does the DNA’s antiparallel structure look like
One of the DNA strands has a loose phosphate group at its end, whilst the other end has a deoxyribose sugar.
What end features a deoxyribose sugar
3’
What is a prokaryote
The collective term used to describe bacterial organisms or cells.
What is a eukaryote
The collective term used to describe animal, plant or fungi organisms or cells
Characteristic of eukaryotes:
+ features a nucleus
+ linear chromosomes (in nucleus)
+ some DNA found in chloroplasts and mitochondria
Give an example of an abnormal eukaryote
Yeast cells (feature plasmids)
What is DNA replication
The synthesising of an identical, complementary copy of a DNA molecule - allowing cell division to occur
Why must cell division/DNA replication occur
To maintain an average quantity of bodily cells, as huge quantities die
What is DNA polymerase
The enzyme commonly used during replication, which monitors the addition and conjoining of nucleotides - to create a complementary strand.
From what end of a DNA strand does DNA polymerase add nucleotides
3’
Process of DNA replication (leading strand)
1: DNA molecule unwinds, as hydrogen bonds break
2: Primer attaches to 3’ end of ‘leading strand’
3: loose nucleotides align with complementary bases, from 3’ to 5’
4: DNA polymerase binds them together - creating a complementary DNA strand
5: The initial primer is removed and replaced with nucleotides
6:
Process of DNA replication (lagging strand):
1: primers place down the strand, allowing fragments of loose nucleotides to bind
2: DNA polymerase binds the nucleotides within the fragments
3: DNA ligase binds the fragments together
What are the five requirements of DNA replication
\+ template strand of DNA \+ primers \+ nucleotides with all four bases \+ enzymes (ligament and polymerase) \+ a wealth of ATP
DNA replication allows growth and maintains the…
Chromosome complement
What does PCR stand for
Polymerase chain reaction
What is the goal of PCR
To amplify the quantity of a target DNA strand
What are the 5 requirements for PCR:
\+ template section of DNA \+ a buffer solution \+ Taq polymerase enzyme \+ nucleotides with all four bases \+ primers
What is:
a) a buffer solution
b) Taq polymerase
a) a solution that the target strand of DNA is initially added to, maintaining a constant pH level
b) the enzyme used during PCR that is resistant to extremely high temperatures. It anneals loose nucleotides.
Describe the process of PCR
1: target DNA molecule is heated to 95 degrees Celsius, breaking the hydrogen bonds and separating the two strands
2: the molecule is the. Called to 55-60 degrees Celsius, allowing primers to anneal to the 3’ end of each strand
3: the molecule is heated to 70 degrees Celsius and Taq polymerase aligns and joins complementary nucleotides, from the 3’ end
4: the joined nucleotides form two new strands of DNA
What are three uses of PCR
+ DNA fingerprinting
+ Diagnosis of genetic disorders
+ Solving parental issues
What is an organism’s genome
Their entire store of genetic information
What is gene expresssion
The process by which the information from a gene is used to synthesis specific protein molecules
How do organisms differentiate
By masking the effects of certain genes, meaning only some proteins are produced - dictating the organism’s characteristics
What are the 5 main functions of proteins
\+ enzymes \+ antibodies \+ replication monitors \+ structural \+ hormones
What is an organism’s…
a) phenotype
b) genotype
a) the physical appearance of an organism, based on its genotype
b) the organism’s internal genetic information and sequence
What does gene expression require
RNA molecules
What are 3 structural differences between DNA and RNA molecules
+ RNA nucleotides contain a uracil base, instead of thymine
+ RNA nucleotides confiance ribose sugars, instead of deoxyribose
+ RNA molecules are single-stranded
What are the three types of RNA molecule:
+ mRNA
+ tRNA
+ rRNA
What is the role of mRNA
It synthesis a complementary copy of the nucleus’s DNA and transports it to the cell’s ribosome- as DNA molecules are too large to leave the nucleus.
What is the role of tRNA
Used during gene expression, as it locates loose amino acids and carries them to the ribosome
What is the structure of a tRNA molecule
3D and Clover-shaped, due to self-adjoining hydrogen bonds
What is the role of rRNA
Combines with structural proteins to form the ribosome
What is the first stage of gene expression and where does it occur
Transcription
Occurs in the nucleus
Process of transcription:
+ an RNA polymerase enzyme breaks the hydrogen bonds and unwinds a DNA molecule
+ RNA nucleotides align with their complementary DNA bases
+ hydrogen bonds form between the complements
+ an RNA polymerase joins the adjacent RNA nucleotides together and breaks their complementary hydrogen bonds
+ a single strand of ‘primary’ mRNA has now formed
What is required to initiate transcription
A start codon (a sequence of 3 bases that indicates to the nucleotides to join here)
What is required to end transcription
A stop codon
What is the second stage of RNA splicing and where does it occur
RNA splicing
Occurs in the nucleus
What happens during RNA splicing
Introns (non-coding DNA regions) are removed, whilst exons (coding DNA regions) are spliced back together.
What forms as a result of RNA splicing
A mature mRNA transcript, that features the exons in their officinal sequence
What is the process by which different mature mRNA transcripts are created
Alternative RNA splicing
What occurs during alternative RNA splicing
The same exons are spliced together, but in a different order OR old introns are now used as exons
What is the final stage of gene expression and where does it occur
Translation
Occurs in the ribosome
Process of translation:
+ 5’ end of mature mRNA binds to the ri so some
+ start codon begins translation
+ certain codons tell a tRNA molecule to retrieve a corresponding amino acid from the cytoplasm
+ codon and anti-codon from the acid and RNA form a weka hydrogen bond
+ tRNA molecules unbinds and repeat process
+ multiple amino acids form next to one another and join, forming a peptide bond
+ polypeptide of multiple acids forms, that folds in a certain way to create a specific protein and function
What is cellular differentiation
The process by which bodily cells specialise and gain specific function and characteristics
What must genes do during cellular differentiation
‘Switch’ on or off
Depending on their function, they require or do not require certain proteins, which require or don’t require certain genes
What are the undifferentiated areas of plant organisms known as
Meristems
They divide and specialise through mitosis
What are the two main types of meristem
+ Apical
+ Lateral
Where are apical meristems located and what is their function
Located in the roots and shoots of a plant
Primary site of vertical growth
Where are lateral meristems located and what is their function
Located in the stem of a plant
Secondary site of horizontal growth
Give two examples of specialised plant cells
+ xylem (lignin spirals)
+ phloem (sieve cells)
What are undifferentiated cells known as in animals
Stem cells
What are the two main types of stem cell
+ embryonic
+ tissue/adult
Where are embryonic stem cells found
In the blastocyst of an animal embryo. This is the bundle of cells formed before foetal development.
Where are tissue stem cells found
In all of the organism’s bodily tissue
Why are embryonic stem cells pluripotent
As they have the capacity to specialise into all cell types, found within the organism
Why are tissue stem cells multipotent
As they only have the capacity to to specialise into a select, finite number of closely-related cells, based on their function.
What are the therapeutic uses of stem cells
+ treatment of leukaemia - through a bone marrow transplant
+ treatment of skin grafts - healthy cells replaced damaged ones
What are the research-based uses of stem cells
+ test the effects of newly developed drugs on an organism cells
+ causes of disease can be determine day examining diseased stem cells
+ develop understanding of growth and development
What are the ethical issues of stem cells
The use of embryonic stem cells, during research, requires the destruction of an embryo - which has the potential for human life. The foetus must be destroyed before 14 days of existence, or else it may develop vital organs and conscious thought
What does it mean if a cellular process is carried out “in vitro”
It occurs outside its natural location or situation
What are coding genetic sequences known as and what is their function
Genes or exons
Code for the synthesis of proteins
What are non-coding genetic sequences known as and what is their function
Introns
Regulate transcription OR form rRNA or tRNA as they wer etranscribed but never translated
What is a mutation
A sudden, random alteration to the genetic material of an organism
How do mutation manifest themselves
By changing the organism’s genetic base sequence, resulting in the creation of different proteins
How can the rate of mutation be increased
By introducing mutagenic agents, such as chemical radiation
What is a single gene mutation (SGM)
When only one of the DNA molecule’s genes is affected by the mutation, and its protein is altered or removed
What are the three main types of single gene mutation
+ substitution
+ insertion
+ deletion
What is a substitution SGM
When one of the bases, within a genetic sequence, is directly swapped for another.
What are the three types of substitution SGM
+ missense
+ nonsense
+ splice-site
What is a missense substitution
When a base is substituted, meaning a different amino acid forms
What is a nonsense substitution
When a base is substituted, meaning the resultant protein is shortened - as a premature stop codon forms
What is a splice-site substitution
When the splice site of the genome does not function properly, as a base has been substituted, altering the shape and function of the resultant proteins
What is a frame-shift mutation
When the alteration of one base leads to a domino effect of alterations- affecting all subsequent bases.
What is an insertion SGM
When a base is inserted randomly into a genetic sequence. This forces all subsequent bases to move down one, changing all the codons and the resultant protein. FRAME-SHIFT
What is a deletion SGM
When a singular base is removed from a genetic sequence. This forced all previous bases to move down one, altering the resultant codons and proteins. FRAME-SHIFT
What is a chromosome structure mutation (CSM)
When large parts of a chromosome are changed, meaning multiple genes and their resultant proteins are altered
What are the four main types of CSM
+ Duplication
+ Deletion
+ Inversion
+ Translocation
What is a duplication CSM
When a section of chromosome is replicated and this replica joins the structure
What is a deletion CSM
When a section of the chromosome or multiple genes are removed
What is an inversion CSM
When a section of the chromosome detached, rotates 180 degrees and rejoins the structure
What is a translocation CSM
When a section of chromosome detached and joins a separate chromosome
How do mutations contribute to the evolution of a species
They create variation amongst a species, as new alleles are created. This allows natural selection to occur as mutations may hinder or boost the organism’s ability to survive and reproduce - allowing the advantageous mutations to increase in frequency amongst the population.
What CSM allows evolution
Duplication
The replica is free from selection pressures, meaning there is an increased chance of further advantageous mutation
What is evolution
Th term used to describe alterations in the genetic material of an organism, due to generations of genomic variation.
What three processes does evolution involve
Inheritance, selection and speciation
Inheritance is…
The sole method of genetic transfer, between organisms of different or similar species
What are the two types of genetic transfer
+ vertical
+ horizontal
What is vertical gene transfer
Is the typical, textbook form of inheritance, as parents reproduce and transfer identical copies of their genetic material to their offspring
What is horizontal gene transfer
When prokaryotes undergo cell division, whilst maintaining the chromosome complement. Therefore, in the same generation there may be multiple copies, in tasing the likeliness of evolution.
Vertical transfer is carried out by…
Horizontal gene transfer is carried out by…
Eukaryotes and prokaryotes
Prokaryotes only
What is natural selection
A non-random process by which the frequency of advantageous genomes, that increase the chance of survival increase, whilst disadvantageous genome frequency decreases
How does natural selection occur
Organism whom possess advantageous DNA survive and reproduce, meaning their offspring inherent this genome. On the other hand, those without the advantageous DNA are killed off. This means that, over time, the majority of the population has the advantageous DNA sequence.
What are the three modes of selection
+ stabilising
+ directional
+ disruptive
What is stabilising selection
When the extreme DNA sequences are discriminated
This results in reduced diversity, as those who survive all possess average traits
What is directional selection
When one DNA extreme is benefited
This results in a highly unique population, as the average and opposite extreme individuals are discriminated and killed.
What is disruptive selection
When both DNA extremes are benefited
This produce a highly varied population, as there are no normal or average individuals - as they have been discriminated and killed
What is a species
A group of organisms who have the ability to interbreed with one another, to produce fertile offspring
What is speciation
The process by which new species emerge, as a result of evolution
What are the two main types of speciation
+ Allopatric
+ Sympatric
What is an isolation barrier
A geographical, behavioural or ecological obstruction that separates a population indefinitely
Characteristics of prokaryotes:
+ features no nucleus
+ circular chromosomes
+ plasmids
What is allopatric speciation
When the population of a singular species is separated by a geographical isolation barrier.
What is sympatric speciation
When the population of a singular species is separated and isolated by behavioural (lifestyle) or ecological (niche) isolation barriers.
Which form of speciation occurs more regularly, in the modern world
Allopatric, due to man’s gentrification of the globe
What is genomics
The study of an organism’s genome, by determining its DNA base sequence and the resultant proteins formed
What are the three research and therapeutic uses of genomics
+ identification and treatment of conditions
+ likeliness of disease predicted
+ reception to drugs predicted (pharmacogenetics)
What is the ethical issue of such uses of genomics
It is not decided wether this information should be made available to people, such as employers or children - to prepare for the future.
Describe speciation
+ species population is separated into two sub-populations by a geographical, behavioural or ecological barrier
+ sub-populations expérience random mutation
+ evolution occurs in each sub-population, meaning these different mutations manifest themselves and changes the individuals in each
+ sub-populations evolve differently to a point where they can no longer interbreed to produce fertile offspring, melanin two new species have formed
What end features a loose phosphate group
5’
What is bioinformatics
The study of the determined genome, using computer technology and statistical analysis. This involves comparative genomics, as the genomes of similar species are compared to determine what causes their differences.s
What is an example of mass genomics
The human genome project
An initiative, launched in 1990, that aimed to sequences all 3 billion bases in a typical human genome. It was finally completed in 2003.
What is phylogenetics
The study of how closely relayed certain organisms are, based on their evolutionary status
What two sources of information are required during phylogenetic
+ fossil evidence
+ genome sequence data
What is the underlying rule of phylogenetic
As the genomes of two organisms increases in similarity, so too does their evolutionary relatedness. This means that as the number of mutations increases, they become increasingly distant
What graph indicates the evolutionary relatedness, based on the time since they shared a common ancestor
A phylogenetic tree
What does the molecular clock state
The higher the number of mutation observed, between two organisms, the greater the time since they shared a common ancestor
Based off the molecular clock, what are the three domains of life that split from the first common ancestor
+ Bacteria
+ Archaea (extreme prokaryotes)
+ Eukaryotes
Sequence of life:
Prokaryotes formed —> eukaryotes evolved from prokaryotes —> eukaryotes evolved into multicellular organisms—> vertebrae evolved —> land plants evolved
What acronym can be used to remember the sequence of life
Percy Prokaryotes Emma Eukaryotes Matthew Multicellular organisms And Animals Violet Vertebrae Left together Land plants
What is an organism’s metabolism
The collective term used to describe all the chemical processes that occur within the organism.
What is a metabolic pathway
A sub-section of the organism’s overall metabolism, that concerns a series of interconnected reactions.
What are metabolic pathways controlled by
Enzymes
What are the two types of metabolic pathway
+ anabolic
+ catabolic
Describe an anabolic reaction
+ one large molecules is synthesised from two smaller ones
+ energy/ATP is required
Describe a catabolic reaction
+ a large molecule is broken down into two or more smaller molecules
+ energy/ATP is released
What is the role of ATP, in metabolic pathways
It transfers energy between anabolic and catabolic reactions
Where are metabolic pathways localised
Cell or organelle membranes
Describe the plasma membrane
+ fluid mosaic model
+ phospholipid balayer
+ irregular proteins
Within metabolic pathways, what are the three types of possible protein
+ pores
+ pumps
+ enzymes
What is a protein pore
A membrane protein that features a hollow, internal channel. Allows large molecules to pass through the membrane.
What is a protein pump
A membrane protein that carries substances across the membrane itself. They do so by carrying out active transport, using up ATP
What are enzymes
Biological catalysts, that increase the rate of a chemical reaction, without being used up in the process.
What is a chemical reaction’s activation energy
The amount of energy required to convert reactants into products
What is the effect of introducing an enzyme in a reaction’s activation energy
It decreases
What is the process by which enzymes and substrates interact
Enzyme action
Describe enzyme action
+ enzymes locate their specific substrate
+ they bind at their complementary active sites
+ enzyme-substrate complex forms
What is enzyme-substrate affinity
The level of specificity between the two molecules (the measure of how complementary their active sites are)
What do enzymes create, in an attempt to increase their substrate affinity
An induced fit
Describe the process of induced fit
+ enzyme and substrate bind at complementary active site
+ small molecule fill tiny gaps between active sites
+ orientation of substrate, within the complex, alters
+ affinity of the enzyme-substrate complex increases, as they are brought into closer contact.
What are the 4 ways to alter the rate of a metabolic reaction/pathway
+ alter the substrate concentration
+ alter the enzyme concentration
+ change the temperature (enzyme optimum)
+ change the pH (enzyme optimum)
What is the process by which enzyme action is stopped or hindered
Inhibition
What are the 3 main types of inhibition
+ competitive
+ non-competitive
+ feedback
Describe competitive inhibition
+ inhibitor molecule binds to enzyme active site
+ substrate cannot enter or bind
+ reaction does not take place
What can competitive inhibition be reversed or reduced by
The increase of the reaction’s substrate concentration, as substrates are now more likely to reach the enzyme before the inhibitor
Describe non-competitive inhibition
+ inhibitor binds to the enzyme, at a site located away from the active site
+ shape of the enzyme alters, altering the active site shape
+ enzyme active site is no longer complementary to substrate’s
+ molecules cannot bind, meaning the reaction can not occur
Is non-competitive inhibition reversible
No
Describe feedback inhibition
+ final product of metabolic pathway is over-produced to a critical concentration
+ product used as a non-competitive inhibitor of earlier enzyme
+ pathway cannot proceed
What is respiration
A series of metabolic pathways that produced energy (in the form of ATP) from food/glucose
Present in all living organisms and domains of life
What is ATP
Adenine tri-phosphate is a molecule that stores internal energy within cells
What is the process by which ATP forms and what are the two reactants
Phosphorylation
ADP + Pi (adenine di-phosphate + phosphate)
What is the role of dehydrogenase enzymes, during respiration
They remove hydrogens and elections from molecules and pass them co-enzyme NAD. This then forms NADH
What is the first stage of respiration and where does it occur
Glycolysis
Occurs in the cell’s cytoplasm
What occurs during glycolysis
+ Glucose is broken down into intermediate enzymes
- ADP + Pi are produced from ATP (energy investment)
+ Intermediate enzymes are broken down into pyruvate
- ATP is produced from ADP + Pi (energy investment) - NADH is produced from NAD
What is the second stage of respiration and where does it occur
The fate of pyruvate
Occurs in the matrix of the cell’s mitochondria
Describe the fate of pyruvate
+ pyruvate is brown. Down into acetyl co-enzyme a
+ CO2 is produced
What is the third stage of respiration and where does it occur
The citric acid cycle
Occurs in the matrix of the mitochondria
Describe the citric acid cycle
+ oxalo-acetate and acetyl co-enzyme a combine to form citrate
+ intermediate enzymes form from citrate
+ CO2 is produced twice
+ NADH is produced twice from NAD
+ ATP is produce from ADP + Pi
What is the fourth stage of respiration and where does it occur
The electron transport chain
Occurs in the inner mitochondrial membrane
What does NADH transfer to the electron transport chain
Hydrogen ions and electrons
What do electrons do during the electron transport chain
They release energy by flowing through protein acceptors
Describe the route of hydrogen ions during the electron transport chain
They first travel across the membrane, through protein pumps, before returning back through a protein pore. They then combine with the present oxygen and electrons - forming water.
What is the protein pore that returns the hydrogen ions back across the membrane
ATP synthase
Rotates, propelling the ions across the membrane and producing ATP from ADP + Pi
What is hydrogen known as, within the process of respiration
The final hydrogen and electron acceptor
What is the alternative process that occurs, instead of respiration, if oxygen is not present
Fermentation
Describe fermentation
Glycolysis occurs, before the final product are synthesised from pyruvate
What is the product of fermentation in animals
Lactate
What are the products of fermentation in plants
Ethanol and CO2
What are the differences between fermentation and respiration
+ 2 molecules of ATP produce din fermentation, 38 in respiration
+ fermentation is anaerobic
What is an organism’s metabolic rate
The amount of energy used up by the organism in a given time interval (speed of metabolism)
What are the three ways by which metabolic rate can be determined
+ rate of oxygen consumption
+ rate of carbon dioxide production
+ rate of heat energy production
As an organism’s mass increases, its metabolic rate…
Increases
How many times does blood pass through the heart in the circulatory system of a…
a) fish
b) amphibians or reptile
c) bird or mammal
a) 1
b) 2
c) 2
What is the pressure of blood at gas exchange capillaries in the circulatory system of a…
a) fish
b) amphibian or reptile
c) bird or mammal
a) high
b) high
c) high
What is the pressure of blood at body tissue capillaries in the circulatory system of a…
a) fish
b) amphibian or reptile
c) bird or mammal
a) low
b) medium
c) high
How many atria does the heart have in the circulatory system of a…
a) fish
b) amphibian or reptile
c) bird or mammal
a) 1
b) 2
c) 2
How many ventricles does the heart have in the circulatory system of a…
a) fish
b) amphibian or reptile
c) bird or mammal
a) 1
b) 1
c) 2
What type of system is found in the circulatory system of a…
a) fish
b) amphibian or reptile
c) bird or mammal
a) single
b) double incomplete
c) double complete
How much mixing of oxygenated and deoxygenated blood is there in the circulatory system of a…
a) fish
b) amphibian or reptile
c) bird or mammal
a) low
b) high
c) low
What is the efficiency of the circulatory system in…
a) fish
b) amphibians and reptiles
c) fish and mammals
a) low
b) medium
c) high
What is the metabolic rate of…
a) fish
b) amphibians and reptiles
c) birds and mammals
a) low
b) medium
c) high
Name 3 external factors that may affect an organism’s metabolic rate
+ surrounding pH
+ surrounding salinity
+ surrounding temperature
Based on their response to external factors, what are the two categories of organism
+ Conformers
+ Regulators
What is a conformer
An organism that changes its internal environment, as the external environment changes
What is a regulator
An organism’s that maintains a constant internal environment, regardless of the external environment - suing physiological mechanisms
How do conformers adapt to changing external environments
By using behavioural adaptations that alter their internal environment
E.g. basking in the sun to increase their body temperature, as the surroundings become cooler
How do regulators adapt to cheating external conditions
Through a high energy process known as homeostasis (a form of negative feedback)
Describe homeostasis/negative feedback
External conditions deviate —> organism’s receptor cells detect the change —> effector organ produces appropriate internal change
Can conformers or regulators assume a wider range of niches and habitats
Regulators
Give another example of negative feedback
Thermoregulation - the maintenance of the body’s core temperatures within a tolerable range
What region of the brain controls thermorégulation
The hypothalamus
What are the cells that detect external changes in temperature
Thermo-receptors
What happens to animals, as their external temperature increases
+ blood vessels widen (vasodilation)
+ sweat glands release more perspiration, increasing heat evaporation
+ decrease in metabolic rate, decreasing heat production
What happens to animals, as their external temperature decreases
+ blood vessels narrow (vasoconstriction)
+ hair erector muscles contract and flatten, trapping warm air
+ metabolic rate increases, increasing heat production
+ shivering occurs
Why must mammals and birds maintain a body temperature of around 37 degrees Celsius
This is the optimum temperature for the majority of their reaction-controlling enzymes
How is information relayed between muscles, during negative feedback
As electric impulses, within nerves
What are the two mechanisms that reduce an organism’s metabolic rate
+ dormancy
+ torpor
What is dormancy
An annual occurence, as an organism decreases its metabolic rate to conserve energy and heat - by decreasing its amount of action and movement. This occurs in response to adverse conditions and often appears as a period of extended rest or sleep.
What are the two types of dormancy
+ predictive
+ consequential
What is predictive dormancy
When an organism enters dormancy prematurely, before the adverse conditions arrive.
What is consequential dormancy
When an organism enters dormancy, as a result of the arrival of adverse conditions. Allows the animals to make full use of all available resources, but increases their chance of death.
What is aestivation
A form of dormancy, during which animals enter this period of lowered activity and metabolic rate, in response to high temperatures in summer months.
Give an example of two animals that enter aestivation
Crocodiles and frogs
What is hibernation
A form of dormancy, during which animals enter this period of lowered activity and metabolic rate, in response to low temperatures and food scarcity in winter months.
Give an example of two animals that undergo hibernation
+ hedgehogs
+ field mice
What is torpor
A similar process to dormancy, during which an organism’s metabolic rate and activity decrease. However, this process usually involved the organism’s metabolic activity event reduced for a shorter time
What 4 changes occur during torpor
+ breathing rate decreases
+ body temperature falls
+ heat production decreases
+ oxygen consumption decreases
What is daily torpor
When animals enter a state of torpor for short amounts of the day, increasing their energy content when they are awake and active
Give an example of when daily torpor may occur
Migration
Allows organisms to travel at increased speeds when active
What is migration
The long distance movement of a population or individual, a steely move from adverse conditions to favourable one’s - that are increasingly suited to the organism’s niche.
What are the 4 factors that trigger migration
+ a decreasing number of daylight hours
+ changes in surrounding temperature
+ changes in food availability
+ genetic factors
What are the three methods by which scientists may track an organism’s migration route
+ Banding - attach a metal band to an individual, and identify them as they complete the migration
+ Tagging - same as banding but with a tag
+ Transmission - microchips are fitted in the organism, relaying their location via satellite
What is an innate migration
An inherited migration that is carried out by all members of a species, during adverse conditions
What is a learned migration
One that develops amongst certain individuals, due to their experience
What is an extremophile
An organism that exist and thrives in adverse or extreme conditions
E.g. Taq Polymerase enzyme
What is a microorganism
Minuscule forms of life, found in all three domains of life
Why are micro-organisms used for research and industry
+ easy to culture
+ reproduce rapidly
+ create a variety of useful products
What is a micro-organism’s growth medium
The object or substance that supports the life of the micro-organism, by providing raw materials and energy for growth
Why do some substances require complex additions to their growth medium
As they are unable to produce the complex substances required for biosynthesis, such as amino acids
Give an example of a substance that may be added to such micro-cultures, to supply complex substances
Beef extract
What 4 factors must be controlled to ensure that the growth medium is optimum for microorganism growth
+ sterility
+ temperature
+ pH
+ oxygen concentration
How does one control the…in a bioreactor
a) sterility
b) temperature
c) pH
d) oxygen concentration
a) ensure aseptic techniques are carried out
b) increase the flow of warm/cold water
c) introduce a buffer or add acid/alkali
d) allow increased amounts of air to enter the reactor
What is a micro-organism’s mean generation time
The time taken for the organism’s cells to divide once
What are the 4 stages of micro-organism growth
+ lag
+ log
+ stationary
+ death
What is the lag phase
As the micro-organism adjusts to the conditions of the growth medium, it does not divide. Biosynthesis occurs as cells combine nucleic acids and enzymes.
What is the log phase
When the micro-organism divides at its maximum rate, meaning the culture population doubled at regular intervals
What is the stationary phase
As the micro-organism begins to exhaust its substrate wealth and a toxic concentration of secondary metabolites forms, the cell death rate equals the cell growth rate
What is the death phase
When the culture fully exhausts its substrate concentration and the toxic secondary metabolites kill the cells, the death rate finally exceeds the growth rate
What is a primary metabolite
A metabolite that is produced during periods of active micro-organism growth (lag or log) and concerns the biosynthesis of microbes.
What is a secondary metabolite
A metabolite that is not produced until cells have established themselves in the medium (log, stationary, death). They confer an ecological advantage and are often highly useful to humans. However, they can also be toxic and dangerous
How can metabolite production be increased, at a controlled rate
+ precursors (increased primary metabolite conc.)
+ enzyme inducers
+ enzyme inhibitors
What are the two methods by which wild micro-organisms are altered, for human benefit
+ mutagenesis
+ recombinant DNA
What is mutagenesis
When micro-organisms are exposed to mutagens (agents that increase the rate of mutation) in an attempt to improve their genome through a mutation
Give an example of a mutagen
Ultraviolet light
What is a disadvantage of mutagenesis
Once mutated, the wild micro-organisms often revert to their original state and are harmful in these civilised environments
What is recombinant DNA technology
When the DNA of a plant or animal is placed inside that of a bacteria, in an attempt to increase the rate of production of the plant or animal protein - as the bacteria reproduce quickly
Describe the process of recombinant DNA technology
+ animal/plant gene is extracted rim chromosome, using endonuclease enzyme
+ enzyme recognised restriction sites and cuts gene out
+ enzyme repeats process with section of bacterial plasmid
+ complementary sticky ends bind, with the help of DNA ligament enzyme
+ plasmid features animal/plant gene and produces its protein in excess
What is a plasmid an example of..
A micro-organism vector, as it simply acts as a body of transfer for the plant/animal gene
What else is a vector
Artificial chromosomes which act in the same way as plasmids but can carry larger sections of DNA
What is a restriction site
A sequence of DNA bases that indicates to the endonuclease enzyme to extract this section of DNA
What is the origin of replication
The site of a plasmid where DNA synthesis begins, as it contains genes that control self-replication. Furthermore, it contains regulatory sequences, which carry out self-replication
What are marker genes
Genes in a plasmid that indicate wether or not the plasmid has taken up the animal/plant gene
E.g. antibiotic resistant gene
Why might a recombinant protein be non-functional
As eukaryotic proteins are often mis-shapen, when cultured in a bacterial cell, as RNA splicing does not occur properly
What is the way to prevent recombinant proteins from becoming non-functional
Use a yeast cell, as it is eukaryotic but acts similarly to a bacterial cell OR use artificial chromosomes. Both options ensure that the resultant protein is shaped correctly and, therefore, functional
