Module 6 - Genetics, Evolution & Ecosystems Flashcards
DONE!
1
Q
Allele
A
A version of a gene
2
Q
Allopatric speciation
A
A form of speciation that occurs when 2 populations become geographically isolated due to a physical barrier
3
Q
Apoptosis
A
Programmed cell death, is important for pruning surplus cells and tissues in development
4
Q
Artificial selection
A
The process by which humans artificially select organisms with desirable characteristics and breed them to produce offspring with desirable phenotypes. Artificial selection may also be referred to as ‘selective breeding’.
5
Q
Autosomal linkage
A
When two or more genes are positioned on the same autosome. They are unlikely to be separated by crossing over during meiosis so are often inherited together
6
Q
Autosome
A
A chromosome that is not an X or Y chromosome
7
Q
Bioinformatics
A
The development of the computer tools and software required to analyse unprocessed biological data
8
Q
Chi-squares (X²) test
A
A statistical test used to determine whether a pattern of inheritance is statistically significant
9
Q
Chlorosis
A
A condition in which plant leaf cells produce insufficient chlorophyll, resulting in pale/yellow leaves. May be due to lack of light/mineral deficiencies/viral infections
10
Q
Codominace
A
When both alleles for a gene in a heterozygous organism equally contribute to the phenotype
11
Q
Computational biology
A
The use of computational techniques to analyse large amounts of biodata and build theoretical models of biological systems
12
Q
Continuous variation
A
A type of variation that cannot be categorised e.g skin colour, height. It produces a continuous range in which a characteristic can take any value. Multiple genes influence continuous variation
13
Q
Degrees of freedom (X² test)
A
Number of categories minus one
14
Q
Deletion
A
A form of gene mutation in which one or more nucleotide bases are removed from a DNA sequence. This may lead to a frameshift mutation, changing every successive codon
15
Q
Dihybrid inheritance
A
The determination of a trait by the inheritance of 2 genes
16
Q
Directional selection
A
A type of selection that favours 1 extreme phenotype and selects against all other phenotypes
17
Q
Discontinuous variation
A
A type of variation that can be categories e.g blood group. A characteristic can only appear in discrete values. 1 or 2 genes influence discontinuous variation
18
Q
Disruptive selections
A
A type of selection that favours individuals with extreme phenotypes and selects against those with phenotypes close to the mean
19
Q
DNA barcode
A
A short sequence of DNA that is used to identify a species. DNA barcodes are common to all species but vary between species
20
Q
DNA ligase
A
An enzyme that joins the sugar-phosphate backbone of 2 DNA segments
21
Q
DNA profiling
A
A technique used to determine the patterns in the non-coding DNA of an individual. It involves 5 main stages: DNA extraction, digestion, separation of DNA fragments, hybridisation and observation
22
Q
DNA sequencing
A
Determining the entire DNA nucleotide base sequence of an organism
23
Q
Dominant
A
Describes an allele that is always expressed. Represented by a capital letter C
24
Q
Electrophoresis
A
A type of chromatography that separated nucleic acid fragments/proteins by size using electric current
25
Electroporation
A method of transformation in which a small electric current is used to transfer recombinant plasmids into bacterial cells/fragments of DNA into eukaryotic cells
26
Epistasis
Describes a relationship between genes at different loci, where the alleles of 1 gene affects the expression of a different gene
27
Etiolation
A condition in plants characterised by weak stems & small, pale leaves, due to insufficient exposure to light
28
Evolution
The gradual change in the allele frequencies within a population over time, occurs due to natural selection
29
Exon
A sequence of DNA that codes for an amino acid sequence
30
Founder effect
A type of genetic drift in which a few individuals of a species break off from the population and form a new colony, results in smaller gene pools & an increased frequency of rale alleles
31
Gene mutation
A change to at least 1 nucleotide base in DNA/ arrangement of bases, gene mutations can occur spontaneously during DNA replication & may be beneficial/damaging/neutral
32
Gene therapy
Therapeutic technique in which a faulty allele is replaced with a functional allele in order to treat/prevent disease
33
Genetically Modified Organisms (GMO)
An organism that has had its genome altered
34
Genetic bottleneck
A drastic reduction in population size, leading to reduced genetic diversity within a population
35
Genetic drift
Random variations in allele frequencies in small populations, due to mutations
36
Genetic engineering
The modification of the genome of an organism by the insertion of a desired gene from another organism, enables the formation of organisms with beneficial characteristics
37
Genome
The complete genetic material of an organism
38
Genotype
An organism's genetic composition, describes all alleles
39
Germ Line cell gene therapy
A type of gene therapy, faulty allele is replaced with a functioning allele in germ cells/very early embryo, effects of this are permanent & can be inherited
40
Hardy-Weinburg priciple
A model that predicts that the ratio of dominant & recessive alleles in a population will remain constant between generations, if 5 conditions are met.
41
What are the 5 conditions which the need to be met for the Hardy-Weinburg principle
No new mutations
No natural selection
No migration
Large population
Random mating
42
What is the formula provided by the Hardy-Weinburg principle
Formula for calculating frequencies of alleles:
p² + 2pq + q² = 1.0
p = frequency of dominant allele
q = frequency of recessive allele
43
Heterozygous
When someone has 2 different allele of a gene e.g. Ff
44
High-throughput sequencing
More recent, large scale approaches to DNA sequencing that use a flow cell
Enable many clusters of DNA fragments to be sequenced simultaneously, giving efficient & rapid sequencing. Has allowed whole-genome sequencing
45
Homeobox genes
A group of regulatory genes that contain a homeobox, DNA sequence that is highly conserved in animals/plants/fungi. Homeobox genes are responsible for the development of body plans in different organisms
46
Homozygous
When someone has 2 identical alleles of a gene e.g. FF, ff
47
Hox gene
A type of homeobox gene that is present in ANIMALS ONLY
48
Inbreeding
The formation of offspring from the breeding of closely related individuals
49
Insertion
A form of gene mutation, 1≥ nucleotide bases are added to DNA sequence, may lead to a frameshift mutation
50
Intron
A non-coding sequence of DNA
51
Lac operon
A group of 3 structural genes, lacZ, lacY, lacA, are required for metabolism of lactose
52
Mature mRNA
The final mRNA product that has had introns removed, as well as having undergone other post-transcriptional changes
53
Mitosis
A form of cell division that produces 2 genetically identical diploid daughter cells. Mitosis is important for growth, increasing the no. of cells
54
Monogenic inheritance
The determination of a trait by the inheritance of a single gene
55
Multiple alleles
When a gene has more than 2 potential alleles
56
Mutagen
A chemical/biological/physical agent that increases the rate of gene mutations above normal level
57
Operon
A group of genes that are expressed together & controlled by the same regulatory mechanism
58
Phenotype
An organism's observable characteristics. Due to interactions of the genotype & environment
59
Polymerase Chain Reaction (PCR)
An in vitro technique used to rapidly amplify fragments of DNA
60
Post-transcriptional control
The level of gene regulation in which primary mRNA can be modified, controlling translation
61
Post-translational control
The level of gene regulation in which proteins can be modified post-synthesis
62
Pre-mRNA
The product of transcription before any post-transcriptional regulation
63
Recessive
Describes an allele that is only expressed in the absence of a dominant allele. Represented by a small letter (ff)
64
Recombinant DNA
A combination of DNA form 2 different organisms
65
Regulatory gene
A gene that codes for the production of proteins involved in DNA regulation. The expression of regulatory genes is influenced by internal & external stimuli
66
Repressor protein
A protein that binds to the operator, altering the transcription rate
67
Restriction endonucleases
Enzymes that cut DNA molecules at recognition sequences, creating sticky ends
68
Sanger sequencing
The 1st method of DNA sequencing that involved the formation of DNA fragments of varying lengths. Fluorescent 'terminator' bases marked the final base of each fragment, allowing the overall DNA sequence to be determined
69
Selection pressures
Factors that affect an organism's ability to survive in an environment e.g. disease, prey, competitors, H2O availability
70
Selective breeding/Artificial selection
Process by which humans artificially select organisms with desirable characteristics & breed them to produce offspring with desirable phenotypes.
71
Sex-linkage
The presence of a gene on an X/Y chromosome
72
Sexual reproduction
A form of reproduction involving the random fusion of male & female gametes, creates genetic variation
73
Somatic cell gene therapy
Type of gene therapy which a faulty allele is replaced with a functional allele in affected somatic cells. The effects of this are temporary & cannot be inherited
74
Speciation
The formation of new species due to the evolution of 2 reproductively separated populations, 2 forms: allopatric & sympathetic
75
Stabilising selection
A type of selection that favours individuals with phenotypes close to the mean & selects against extreme phenotypes
76
Sticky ends
The staggered cut formed by restriction endonucleases in double-stranded DNA
77
Structural gene
A ene that codes for the production of proteins/enzymes that aren't involved in DNA regulation
78
Substitution
A form of gene mutation which 1 nucleotide base is exchanged for another, may change a amino acid/produce the same amino acid (due to degeneracy of the genetic code)
79
Sympathetic speciation
A form of speciation that occurs when 2 populations within the same area become reproductively isolated
80
Synthetic biology
The design nd construction of new biological entitiles, as well as the reconstruction of pre-existing natural biological systems
81
Thermocycler
A machine controlled by a computer that varies temperatures at predetermined time intervals
82
Transcriptional control
The level of gene regulation in which genes are switched 'on'/'off'
83
Transcription factors
Proteins that help to switch genes 'on' or 'off' by controlling the binding of RNA polymerase to DNA
84
Transgenic organism
An organism that contains recombinant DNA
85
Translational control
The level of gene regulation in which translation can be initiated/stopped
86
Vector
A carrier used to transfer a gene from 1 organism to another e.g. plasmid
87
Artificial twinning
The artificial production of monozygotic twins from the manual splitting of the early embryo
88
Aseptic techniques
A range of techniques used to culture microorganisms under sterile conditions in order to minimise contamination
89
Batch fermentation
An individual method of fermentation that runs for a set period of time. The culture broth is not removed until the fermentation is complete
90
Bioremediation
The use of microorganisms to remove soil and water pollution
91
Biotechnology
The field of biology involving the use of living systems to produce or transform materials. Applications include agriculture, medicine and food science
92
Brewing
Production of beer from the steeping of barley in water and the fermentation of the resulting product of yeast.
93
Clones
The genetically identical offspring produced as a result of cloning
94
Cloning
A method of producing genetically identical offspring by asexual reproducation
95
Continuous fermentation
An industrial method of fermentation in which culture broth is continuously removed and extra nutrient medium is added. The fermentation conditions remain relatively constant
96
Culture
The growth of living matter in vitro in suitable conditions
97
Cutting
A small section of the root or stem of an adult plant that is used in horticulture to produce natural clones
98
Enucleation
The removal of the nucleus
99
Fermentation
A type of anaerobic respiration that doesn't involve an electron transport chain
100
Immobilised aminoacylase
An immobilised enzyme that is used to produce pure samples of L-amino acids
101
Immobilised enzymes
Enzymes which are attached to an inert, insoluble material over which the substrate passes and the reaction takes place
102
Immobilised glucoamylase
An immobilised enzyme that can be used to breakdown dextrins into glucose
103
Immobilised glucose isomerase
An immobilised enzyme that is used to convert glucose to fructose
104
Immobilised lactase
An immobilised enzyme that hydrolyses lactose to glucose and galactose in the production of lactose free milk
105
Immobilised penicillin acylase
An immobilised enzyme that is used to produce semi-synthetic penicillin from natural penicillin
106
Micropropagation
The production of large numbers of clones from 1 parent plant using tissue culture
107
Monozygotic twins
Identical twins formed from 1 fertilised egg that splits to form 2 embryos
108
Natural Clonign
A form of asexual reproduction that takes place in plants in which a new genetically identical plant grows from a structure (stem/leaf/bud/root) pf the parent plant, also known as vegetative propagation
109
Penicillin
The 1st conventional effective and safe antibiotic derived from the mould Penicillium chrysogenum
110
Somatic cell nuclear transfer (SCNT)
The production of an embryo from the transfer of the nucleus of an adult animal cell to an enucleated egg cell in the laboratory. The nucleus + egg are fused and stimulated to divide
111
Tissue Culture
The growth of cells/tissues outside of an organism in an artificial culture medium
112
Abiotic factors
A non living aspect of an ecosystem e.g. light/temp/water availability/oxygen availability/soil pH
113
Abundance
The number of individuals per species in a specific area at any given time
114
Ammonification
The production of ammonium compounds when decomposers feed on organic nitrogen-containing molecules
115
Azotobacter
A type of nitrogen-fixing bacteria that lives freely in the soil
116
Belt transect
A line along a sampled area, quadrats placed on at intervals to determine abundance and distribution of organisms in an ecosystem
117
Biomass
The total mass of organic material, measure in specific are over set time period, can be calculated in terms of dry mass
118
Biotic factors
The living components of an ecosystem e.g. pathogen/food availability/predators/other species
119
Carbon cycle
The cycle through carbon moves between living organisms & environment, involving respiration/photosynthesis/combustion
120
Carrying capacity
The maximum population size that can be indefinitely supported by an enviro
121
Climax community
The stable community of organisms that exist at the final stage of ecological succession
122
Conservation
The maintenance of ecosystems & biodiversity by humans in order to preserve the Earth's resources
123
Consumers
Organisms that feed on other organisms to obtain energy
124
Decomposers
Organisms that release enzymes which catalyse the breakdown of dead plant and animal material into simpler organic matter
125
Deflected succession
Changes to the natural flow of succession due to human activity that result in a stable community known as a plagioclimax
126
Dentrification
The conversion of nitrate ions to nitrogen gas by denitrifying bacteria
127
Denitrifying bacteria
Anaerobic microorganisms, waterlogged soils, responsible for the reduction of nitrate ions to nitrogen gas
128
Distribution
The spread of living organisms in an ecosystem
129
Ecological efficiency
The efficiency of energy/biomass transfer between trophic levels
130
How to calculated ecological efficiency
ecological efficiency=(energy/biomass available after transfer/energy/biomass available before transfer)x100
131
Ecosystem
The community of organisms & non-living components of an area and their interactions
132
Food chain
Describes feeding relationships between organisms & resulting stages of biomass transfer:
producer⟶primary consumer⟶secondary consumer⟶tertairy consumer
133
Interspecific competition
A type of competition that takes place between members of different speciesI
134
Intraspecific competition
A type of competition that takes place between members of the same species
135
Limiting factor
A variable that limits the rate of a particular process
136
Line transect
A line along a sampled area, species touching transect at regular intervals are recorded to determine the abundance & distribution of organisms in an ecosystem
137
Nitrification
The conversion of ammonium ions to nitrate ions by nitrifying bacteria, takes place in 2 stages: ammonium ions are oxidised to nitrite ions, nitrite ions are oxidised to nitrate ions.`
138
Nitrifying bacteria
Aerobic microorganisms found in soil responsible for oxidation of ammonium ions to nitrate ions
139
Ntirobacter
A genus of nitrifying bacteria that oxidises nitrites into nitrates
140
Nitrogen cycle
Cycle: nitrogen moves between living organisms & environment, involving ammonification, nitrification, nitrogen fixation and dentrification
141
Nitrogen fixation
The conversion of atmospheric nitrogen gas into ammonia by nitrogen-fixing bacteria in the soil/root nodules of legumes
142
Nitrogen-fixing bacteria
Microorganisms responsible for the conversion of atmospheric nitrogen gas into nitrogen-containing compounds, can be free living/mutualistic
143
Nitrosomonas
A genus of nitrifying bacteria that oxidises ammonium compounds into nitrites
144
Peat bogs
Areas of peat soil in wetland habitats formed by accumulation of partially decayed organic matter, store carbon & commonly referred to as 'carbon sinks'
145
Pioneer species
Species that can survive in hostile environments & colonies bare rock/sand
146
Plagioclimax
Stage in succession, artificial factors prevent formation of a natural climax community
147
Populationo
All organisms of same species living with 1 another in habitat at same time
148
Predator
An organism that eats other organisms
149
Preservation
The restriction of human interference in an area in order to protect & maintain the ecosystem
150
Prey
An organism that is eaten by predators
151
Primary succession
A type of succession in which pioneer species colonise a newly formed/exposed are of land
152
Producers
Photosynthetic organisms at the start of the food chain the manufacture biomass for all living things
153
Quadrat
A square grid used in sampling to determine abundance of organisms in a habitat
154
Rhizobium
Type of nitrogen-fixing bacteria that lives inside the root nodules of leguminous plants
155
Succession
Describes changes in the community or organisms occupying a certain area over time
156
Sustainable
The ability to maintain something for future generations
157
Sustainable resource
A resource that can be continuously renewed, it won't diminish/run out
158
Trophic level
The position of an organism in a food chain
159
What is a mutation
An alteration to DNA base sequence, often spontaneously during DNA replication
160
Addition mutations
1 or more nucleotides are inserted into DNA sequence, more likely to be either harmful/beneficial due to frame shift
161
Deletion mutations
1 or more nucleotides are deleted from DNA sequence, harmful/beneficial due to frame shift
162
Substitution mutation
Nucleotide in DNA sequence is replicated by another, more likely to be neutral mutation, no change occurs in amino acid sequence
163
How is gene expression regulated at transcription level
Transcription factors-proteins that initiate/inhibit transcription of genes, only certain parts of DNA are expressed
164
Function of lac operon in low lactose concentration
E.coli can use lactose as respiratory substrate vie use of enzyme,
When lactose con. is low, lac operon binds to gene that makes this enzyme & inhibits its expression
165
Function of lac operon in high lactose concentration
Lactose binds to operon causing it to change shape & unattach from gene, allows RNA polymerase to bind & gene to be expressed
166
How is gene expression regulated at post-transcriptional level
Splicing, primary mRNA contains coding (exons) & non-coding regions (introns). Introns removed to produce mature mRNA ready for translation
167
How is gene expression regulated at post-translational level
Activation of proteins, adrenaline, when it binds to receptor, an enzyme is activated-converts ATP to cyclic AMP, promotes further enzyme reactions, activates the protein
168
How is development controlled by homeobox genes
Codes for transcription factors that activate genes when they're needed during development of zygote, sequences are similar in plants/animals/fungi
169
How is development controlled by mitosis
Mitosis, primary mechanism of growth, genes regulating mitosis respond to various stimuli, both internal & external, order to control rate of growth
170
How is development controlled by apoptosis
Programmes death of cells, highly controlled & keeps cell division at constant rate to prevent cancer
171
Pheotype
Expression of an organism's genetic constitution, e.g. low metabolism, combined with its interaction with the environment e.g. diet
172
How can meiosis bring about genetic variation
Random arrangement of chromosomes when lining up
crossing over of chromatids before 1st division
173
How does random fertilisation bring about genetic variation
Gametes=haploid cells, meaning only contain 1/2 person's DNA, is determined by meiosis every gamete contains different DNA, produce genetically different offspring
174
Monogenic inheritance
One phenotype characteristics is controlled by 1 gamete
175
Dihybrid inheritance
2 phenotypic characteristics are determined by 2 different genes present on 2 different chromosomes at same time
176
Sex-linkage
An allele is located on 21 of the sex chromosomes, its expression depends on sex of individual
177
Multiple alleles
Gene with more than 2 alleles
178
Codominant alleles
2 dominant alleles that both contribute to phenotype, by showing blend of characteristic/characteristics appearing together
179
Autosomal linkage
2≥genes are located on same (non-sex) chromosome, only 1 homologous pair is needed for all 4 alleles to be present, for genes that aren't linked 2 homologous pairs are needed
180
Epistasis
2 non-linked genes interact, 1 gene either masking/suppressing the other gene
181
Chi-squared test
Statistical test to find out whether difference between observed & expected data is due to chance/real effect, can be used to compare expected phenotypic ratios with observed ratios
182
How is chi-squared test performed
Formula results in no. is compared to critical value, if no. is ≥ critical values we conclude no significant difference & result occurred due to chance
183
Discontinuous variation
Characteristics determined by 1 gene (monogenic inheritance)
184
Continuous variation
Characteristic determined by ≥ 1 gene (polygenic inheritance)
185
Stabilising selection
Occurs in environmental conditions stay the same, individuals closes to mean are favoured, & any new characteristics are selected against, =low diversity
186
Directional selection
Occurs when environmental conditions change , individuals with phenotypes suited to new conditions will survive & pass on genes, over time the mean of population will move towards these characteristics
187
Genetic drift
Change in population's allele frequencies that occurs due to chance rather than selective pressures, caused by sampling error during reproduction
188
Genetic bottleneck
Catastrophic event dramatically reduces size of population, decreasing variety of alleles in gene pool & causing large changes in allele frequencies not reflective of original population
189
Hardy-Weinberg principle
Allows us to estimate the frequency of alleles in population as well as if allele frequency is changing over time
190
Hardy-Weinberg equation for calculating allele frequency
Frequencies of each allele for characteristic must add to 1.0
p+q=1
p=frequency of dominant allele
q=frequency of recessive allele
191
Hardy-Weinberg equation for calculating genotype frequency
Frequencies of each characteristic must =1.0
p² + 2pq + q² = 1
p²= frequency of homozygous dominant
2pq=frequency of heterozygous
q²=frequency of homozygous recessive
192
Speciation
Population is split & isolated, are different selective pressures on 2 groups, if genetic makeup changes to the extent the 2 groups can no longer interbreed, have become separate species
193
Allopatric speciation
Speciation resulting from physical barrier e.g. river, environments occupied by 2 groups are different & different alleles are favouredSy
194
sympatric speciation
Speciation resulting form a non-physical barrier e.g. mutation that no longer allows 2 organisms to produce fertile offspring, any changes in anatomy/behaviour may prevent breeding
195
Artificial selection
Humans chose particular organisms to breed together in order to produce a desired characteristic in offspring
196
Examples of artificial selection in plants & animals
Plants=seeds used from plants that produce larger fruit & veg
Animals=cows with higher milk yield are chosen & selectively bred
197
Why is it important to keep a resource of genetic material when selective breeding
Allows ant traits the]at were accidently bred out to be reintroduced/reverted back to point before any negative traits were introduced
198
Ethical issues around the use of artificial selection
Anatomical changes in animals e.g. respiratory issues in pugs
higher susceptibility to disease in both plants & animals
199
DNA sequencing
identifying the base sequence of a DNA fragment
200
How have sequencing methods changed over time?
Used to be manual process, now its automated
Entire genomes can now be read
201
Benefits of genome-wide comparisons
Comparing between species allows us to determine evolutionary relationships
Comparing between individuals of same species allows us to tailor medical treatment to individual
202
how can DNA sequencing be used in synthetic biology
Knowing sequence of gene, allows us to predict sequence of amino acids that will make up polypeptide it produces, allows for development of synthetic biology
203
DNA profiling
Identifying unique areas of person's DNA, in order to create a profile that is individual to them
204
Uses of DNA profiling
Forensics=DNA obtained during crime investigations, compared to victims/suspects
Medicine=screen for particular base sequence to identify heritable diseases
205
How can we amplify DNA fragments in order to sequence them?
Use Polymerase Chain Reaction (PCR), makes millions of copies of fragment, are cut at different lengths in order to be sequenced
206
Reaction mixture in fist stage of PCR
Contains DNA fragment to be amplified, primers that are complementary to start of fragment, free nucleotides to match up to exposed bases & DNA polymerase to create new DNA
207
PCR process
1.Heated to break apart DNA strands
2.Cooled to allows primers to bind
3.Heated to activate DNA polymerase & allow free nucleotides to join
4.New DNA acts as template for next cycle
208
How is gel electrophoresis used in DNA profiling
●DNA fragments of varying lengths are placed at one end of a slab of gel
●Electric current applied, DNA fragments move towards the other end of gel
●Shorter fragments travel further, pattern of bands created is unique to each individual
209
Genetic Engineering
DNA fragment form 1 organism is inserted into DNA of another organism, sometimes across different species. Is done through use of vector & host cell
210
Process of isolating DNA fragment
Restriction enzymes (RE) cut DNA at specific sequences. Different REs cut at different points, 1 RE will always cut at the same sequence, using a particular REs allows you to cut out a certain gene of interest
211
Process of inserting DNA fragment into a vector
A plasmid is used as a vector & is cut using same REs as the DNA, so that the ends are complementary. DNA ligase joins fragments & plasmid together
212
Process of inserting vector into a host cell
Host cells (bacteria) are mixed with vectors in ice-cold solution, then shocked to increase permeability of cell membrane (electroporation) which encourages the cells to take up vectors
213
Ethical issues around genetic engineering
+insect resistance can be introduced to crops
+GE animals used to produce pharmaceuticals (pharming)
+GE pathogens can be produced for research
-GE seeds would be hard to acquire for poorer farmers
214
Gene therapy
Replacing a faulty allele with a normal allele, 2 types are somatic and germ line
215
Somatic gene therapy
Allele introduced to target cells only
Short-term needs repeating
216
Germ line gene therapy
allele introduced to embryonic cells so it is present in all resultant cells, permanent will be passed to offspring
217
How can we produce natural clones of plants
Vegetative propagation.
Part of a plant is separated then develops into a new plant genetically identical to original
218
How should a plant cutting be taken for cloning
Stem is cut between leaf & nodes, replanted & allowed to grow, sometimes with use of plant hormones
219
How can we produce artificial clones of plants
●Tissue culture, sample placed on various nutrient-containing mediums to encourage cell division & shoot growth
●Micropropagation, material produced from tissue cultures is rapidly multiplied to produce large numbers of plants
220
Evaluate use of artificial plant cloning in agriculture
+large no. of plants can be produced regardless of weather conditions
-reduced genetic variation, making them susceptible to disease
221
Example of natural cloning in animals
Monozygotic twins, embryo splits during development to produce 2 genetically identical individuals
222
Producing artificial clones of animals
●somatic cell nuclear transfer, differentiated cell from parent fused with an enucleated egg cell, the cell develops into an embryo & can be implanted into a womb
●Embryo splitting, same process by which twins form, performed artificially
223
Arguments surrounding cloning in animals
+quick process suited to growing population of Earth
+can preserve endangered species
-cloned animals often suffer from health problems
-low genetic diversity
224
Why are microorganisms suited for use in biotechnological processes
●rapid growth in variety of environmental conditions
●can be genetically engineered
Reduces use of chemical, beneficial to environment
225
Ways microorganisms are used in biotechnological processes
●food: baking, brewing, yogurt, cheese
●medicine: penicillin, insulin
●Environmental: removing pollution (bioremediation)
226
Advantages of using microorganisms to produce food for human consumption
+Production rate easily varied
+Not dependent on climate
+Long-lasting
+Uses waste products
227
Disadvantages of using microorganisms to produce food for human consumption
-lacks flavour
-proteins must be isolated and purified
-contains different amino acids to animal proteins
228
Technique that should be used to culture microorganisms
Aseptic technique: everything must be kept completely sterile so no unwanted microorganisms are present in culture
229
Three steps of growing microorganisms
1.Sterilisation
2,Inoculation, microorganism introduced to agar plate by streaking, seeding or spreading.
3.Incubation, placed in warm environment for 24-48hrs to grow
230
Batch fermentation
Closed environment , competition for resources, maintains culture in stationary phase, easy to set up, less efficient
231
Continuous fermentation
Products continually removed, maintains culture in log phase, difficult to set up more efficient
232
How are growth conditions manipulated to maximise yield
●Temperature maintained at optimum
●Sufficient nutrient supply
●Aerobic conditions to prevent products of anaerobic respiration
●pH kept constant to maximise enzyme activity
233
Phases of growth curve of a microorganism in closed culture
Lag=cells increase in size & take in water, population constant
Log=cells divide, population increases exponentially
Stationary=nutrient levels decrease, slowing growth rate, population stabilises
Death=toxic metabolites increase to point that kills cells, population declines
234
Formula for bacterial growth
N=N0 X 2^n
N=no. of bacteria currently in population
N0=no. of bacteria in population at beginning
n=no. of divisions
235
Immobilised enzyme
Enzyme attached to an inert material in order to restrict its movement & hold it in place during a reaction so that it can be reused
236
Methods of immobilised enzymes
1.Bonding-enzyme binds with support ionically (adsorption)/covalently
2.Entrapment-enzyme placed in a semi-permeable material that allows diffusion of the substrate & product
3.Membrane separation-partially permeable membrane separates enzyme from substrate
237
Uses of immobilised enzymes
●Glucose→fructose conversion
●Semi-synthetic penicillin production
●Lactose to glucose/galactose conversion
●Pure samples of amino acids
●Dextrins→glucose conversion
238
Evaluate use of immobilised enzymes
+Product isn't contaminated by enzyme, so doesn't need to be purified
+Enzymes can be reused
+Enzymes are protected from harsh environment
-Expensive
-Reaction rate is slower as enzymes cannot move
239
Ecosystem
All living organisms found in 1 area & non-living aspects of their environment.
Can range in size, e.g. rock pool/tree/field. Known as 'dynamic' as they depend on interactions between biotic & abiotic factors
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Biotic factor
Living features of an ecosystem e.g. predators/disease
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Abiotic factor
Non-living features of an ecosystem e.g. light/temperature
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How is biomass transferred & how it is measured
Transferred up trophic levels through consumption, can be measured in terms of mass of carbon/dry mass of tissue
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Formula for efficiency of biomass
Efficiency=(biomass transferred / biomass intake) x100
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How can human activities affect biomass transfer
●Light/water/temperature maximised
●Increased nutrients in soil
●Pests & weeds removed
●Growth rates boosted through steroids/selective breeding ect.
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Roles of microorganisms in the nitrogen cycle
●Nitrogen-fixing bacteria in roots (Rhizobium) & soil (Azotobacter), convert gaseous nitrogen into ammonia
●Nitrifying bacteria (Nitrosomonas) convert ammonia compounds into nitrites to nitrates
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Role of organisms in the carbon cycle
●Respiration of plants & animals add carbon dioxide into atmosphere
●Photosynthesis of plants removes carbon dioxide from atmosphere
●Decomposers (microorganisms) decay plant & animals material into carbon dioxide
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Primary succession
An area previously devoid of life is colonised by a community of organisms
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Process of primary succession
●Pioneer species, able to survive harsh conditions, colonise the area
●They die, decompose & add nutrients to ground
●Over time, allows more complex organisms to survive
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Climax community & how its reached
Final stage of succession, ecosystem is balanced 7 stable, is reached when the soil is rich enough to support large trees/shrubs & environment is no longer changing
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Deflected succession
Where succession is interrupted, usually by human interference
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Sampling
Selecting a group of individuals that will represent whole target population, allows us to measure the distribution & abundance of organisms
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Methods of sampling & how they are used
●Quadrats=used in small areas, randomly/regularly placed across habitat, frequency/% cover calculated
●Transects=used in larger area, sample taken along a line that crosses the habitat, can be combined with quadrats in form of a belt transect
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Carrying capacity
Maximum population size that a habitat can support, defined by the presence of limiting factors
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Factors that limit maximum size of a population
●Food
●Water
●Light
●Oxygen
●Nesting sites
●Shelter
●Parasites
●Predators
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Pattern of a typical predator-prey relationship in terms of population change
●Prey is eaten by predator, resulting in predator population increasing & prey population decreasing.
●Fewer prey means increased competition for food, so predator population decreases
●Fewer predators means more prey survives & cycle begins again
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Intraspecific competition=between organisms of the same species
between organisms of the same species
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Interspecific competition
Between organisms of different species
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Conservation
Maintains biodiversity of a habitat by allowing sustainable use of resource there
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Preservation
Maintains biodiversity of a habitat by minimising human impact
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Why we conserve & preserve habitats
Economic=Food source, natural pests control boost tourism
Social=Organisms can be used in medicine, aesthetics
Ethical=Responsibility to maintain habitats for future generations
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Sustainability
Using resources in a way that also maintains them for future generation
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Methods allowing sustainable use of ecosystem's resources
Timber production=coppicing to encourage growth, replacing felled trees, selective cutting
Fishing=stocks not depleted, no overfishing, can continue indefinitely
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Example of how conflict between conservation & human needs can be balanced
Terai region (Nepal), over-exploited for use in fuel, locals now have responsibility to look after forrest, 'Corridors' places to enable migration
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Example of how human effects are controlled in sensitive ecosystems
Galapagos islands, endangered due to hunting & tourism. New species introduced, caused damage to native species, trying to find balance
