bio mod 6 defs Flashcards
(161 cards)
1
Q
What is an allele?
A
A version of a gene.
2
Q
What is allopatric speciation?
A
A form of speciation that occurs when two populations become geographically isolated due to a physical barrier.
3
Q
What is apoptosis?
A
Programmed cell death. This is important for pruning surplus cells and tissues in development.
4
Q
What is artificial selection?
A
See ‘selective breeding’.
5
Q
What is 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
What is an autosome?
A
A chromosome that is not an X or Y chromosome.
7
Q
What is bioinformatics?
A
The development of the computer tools and software required to organise and analyse unprocessed biological data.
8
Q
What is a chi-squared (X²) test?
A
A statistical test used to determine whether a pattern of inheritance is statistically significant.
9
Q
What is chlorosis?
A
A condition in which plant leaf cells produce insufficient chlorophyll, resulting in pale or yellow coloured leaves. This may be due to mineral deficiencies, lack of light, or viral infections.
10
Q
What is codominance?
A
When both alleles for a gene in a heterozygous organism equally contribute to the phenotype.
11
Q
What is computational biology?
A
The use of computational techniques to analyse large amounts of biodata and build theoretical models of biological systems.
12
Q
What is 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
What are degrees of freedom in a chi-squared test?
A
The number of categories minus one.
14
Q
What is deletion in genetics?
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
What is dihybrid inheritance?
A
The determination of a trait by the inheritance of two genes.
16
Q
What is directional selection?
A
A type of selection that favours one extreme phenotype and selects against all other phenotypes.
17
Q
What is discontinuous variation?
A
A type of variation that can be categorised e.g. blood group. A characteristic can only appear in discrete values. One or two genes influence discontinuous variation.
18
Q
What is disruptive selection?
A
A type of selection that favours individuals with extreme phenotypes and selects against those with phenotypes close to the mean.
19
Q
What is a 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
What is DNA ligase?
A
An enzyme that joins the sugar-phosphate backbone of two DNA segments.
21
Q
What is DNA profiling?
A
A technique used to determine the patterns in the non-coding DNA of an individual. It involves five main stages: DNA extraction; digestion; separation of DNA fragments; hybridisation; and observation.
22
Q
What is DNA sequencing?
A
Determining the entire DNA nucleotide base sequence of an organism.
23
Q
What does dominant mean in genetics?
A
Describes an allele that is always expressed. Represented by a capital letter.
24
Q
What is electrophoresis?
A
A type of chromatography that separates nucleic acid fragments or proteins by size using electric current.
25
What is electroporation?
A method of transformation in which a small electric current is used to transfer recombinant plasmids into bacterial cells or fragments of DNA into eukaryotic cells.
26
What is epistasis?
Describes a relationship between genes at different loci, where the allele of one gene affects the expression of a different gene.
27
What is etiolation?
A condition in plants characterised by weak stems and small, pale leaves, due to insufficient exposure to light.
28
What is evolution?
The gradual change in the allele frequencies within a population over time. Occurs due to natural selection.
29
What is an exon?
A sequence of DNA that codes for an amino acid sequence.
30
What is the 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. This results in smaller gene pools and an increased frequency of rare alleles.
31
What is gene mutation?
A change to at least one nucleotide base in DNA or the arrangement of bases. Gene mutations can occur spontaneously during DNA replication and may be beneficial, damaging, or neutral.
32
What is gene therapy?
A therapeutic technique in which a faulty allele is replaced with a functional allele in order to treat or prevent disease.
33
What is a genetically modified organism (GMO)?
An organism that has had its genome altered.
34
What is genetic bottleneck?
A drastic reduction in population size leading to reduced genetic diversity within a population.
35
What is genetic drift?
Random variations in allele frequencies in small populations, due to mutations.
36
What is genetic engineering?
The modification of the genome of an organism by the insertion of a desired gene from another organism. This enables the formation of organisms with beneficial characteristics.
37
What is a genome?
The complete genetic material of an organism.
38
What is a genotype?
An organism’s genetic composition. Describes all alleles.
39
What is germ line cell gene therapy?
A type of gene therapy in which a faulty allele is replaced with a functional allele in germ cells or a very early embryo. The effects of this are permanent and can be inherited.
40
What is the Hardy-Weinberg principle?
A model that predicts that the ratio of dominant and recessive alleles in a population will remain constant between generations if the following five conditions are met: no new mutations; no natural selection; no migration; large population; and random mating. It provides a formula for calculating the frequencies of alleles: p² + 2pq + q² = 1.0 where p is the frequency of the dominant allele, and q is the frequency of the recessive allele.
41
What does heterozygous mean?
When someone has two different alleles of a gene e.g. Ff.
42
What is high-throughput sequencing?
More recent, large-scale approaches to DNA sequencing that use a flow cell. They enable many clusters of DNA fragments to be sequenced simultaneously, giving efficient and rapid sequencing. This has allowed whole-genome sequencing.
43
What are homeobox genes?
A group of regulatory genes that contain a homeobox, a DNA sequence that is highly conserved in animals, plants and fungi. Homeobox genes are responsible for the development of body plans in different organisms.
44
What does homozygous mean?
When someone has two identical alleles of a gene e.g. ff.
45
What is a Hox gene?
A type of homeobox gene that is present in animals only. The terms “Hox gene” and “homeobox gene” can be used interchangeably.
46
What is inbreeding?
The formation of offspring from the breeding of closely related individuals.
47
What is insertion in genetics?
A form of gene mutation in which one or more nucleotide bases are added to a DNA sequence. This may lead to a frameshift mutation, changing every successive codon.
48
What is an intron?
A non-coding sequence of DNA.
49
What is the lac operon?
A group of three structural genes, lacZ, lacY and lacA, that are required for the metabolism of lactose.
50
What is mature mRNA?
The final mRNA product that has had introns removed, as well as having undergone other post-transcriptional changes.
51
What is mitosis?
A form of cell division that produces two genetically identical diploid daughter cells. Mitosis is important for growth, increasing the number of cells.
52
What is monogenic inheritance?
The determination of a trait by the inheritance of a single gene.
53
What are multiple alleles?
When a gene has more than two potential alleles.
54
What is a mutagen?
A chemical, biological or physical agent that increases the rate of gene mutations above normal level.
55
What is an operon?
A group of genes that are expressed together and controlled by the same regulatory mechanism.
56
What is a phenotype?
An organism’s observable characteristics. Due to interactions of the genotype and the environment.
57
What is the Polymerase Chain Reaction (PCR)?
An in vitro technique used to rapidly amplify fragments of DNA.
58
What is post-transcriptional control?
The level of gene regulation in which primary mRNA can be modified, controlling translation.
59
What is post-translational control?
The level of gene regulation in which proteins can be modified post-synthesis.
60
What is pre-mRNA?
The product of transcription before any post-transcriptional regulation.
61
What does recessive mean?
Describes an allele that is only expressed in the absence of a dominant allele. Represented by a small letter.
62
What is recombinant DNA?
A combination of DNA from two different organisms.
63
What is a regulatory gene?
A gene that codes for the production of proteins involved in DNA regulation. The expression of regulatory genes is influenced by internal and external stimuli.
64
What is a repressor protein?
A protein that binds to the operator, altering the transcription rate.
65
What are restriction endonucleases?
Enzymes that cut DNA molecules at recognition sequences, creating sticky ends.
66
What is Sanger sequencing?
The first 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.
67
What are selection pressures?
Factors that affect an organism’s ability to survive in an environment e.g: disease, prey, competitors, water availability.
68
What is selective breeding?
The process by which humans artificially select organisms with desirable characteristics and breed them to produce offspring with desirable phenotypes. Selective breeding may also be referred to as ‘artificial selection’.
69
What is sex-linkage?
The presence of a gene on an X or Y chromosome.
70
What is sexual reproduction?
A form of reproduction involving the random fusion of male and female gametes. This creates genetic variation.
71
What is somatic cell gene therapy?
A type of gene therapy in which a faulty allele is replaced with a functional allele in affected somatic cells. The effects of this are temporary and cannot be inherited.
72
What is speciation?
The formation of new species due to the evolution of two reproductively separated populations. Two forms: allopatric and sympatric speciation.
73
What is stabilising selection?
A type of selection that favours individuals with phenotypes close to the mean (average) and selects against extreme phenotypes.
74
What are sticky ends?
The staggered cut formed by restriction endonucleases in double-stranded DNA.
75
What is a structural gene?
A gene that codes for the production of proteins or enzymes that are not involved in DNA regulation.
76
What is substitution in genetics?
A form of gene mutation in which one nucleotide base is exchanged for another. This may change an amino acid or produce the same amino acid (due to the degeneracy of the genetic code).
77
What is sympatric speciation?
A form of speciation that occurs when two populations within the same area become reproductively isolated.
78
What is synthetic biology?
The design and construction of new biological entities, as well as the reconstruction of pre-existing natural biological systems.
79
What is a thermocycler?
A machine controlled by a computer that varies temperatures at predetermined time intervals.
80
What is transcriptional control?
The level of gene regulation in which genes are switched ‘on’ or ‘off’.
81
What are transcription factors?
Proteins that help to switch genes ‘on’ or ‘off’ by controlling the binding of RNA polymerase to DNA.
82
What is a transgenic organism?
An organism that contains recombinant DNA.
83
What is translational control?
The level of gene regulation in which translation can be initiated or stopped.
84
What is a vector in genetics?
A carrier used to transfer a gene from one organism to another e.g. plasmid.
85
What is artificial twinning?
The artificial production of monozygotic twins from the manual splitting of the early embryo.
86
What are aseptic techniques?
A range of techniques used to culture microorganisms under sterile conditions in order to minimise contamination.
87
What is batch fermentation?
An industrial method of fermentation that runs for a set period of time. The culture broth is not removed until the fermentation is complete.
88
What is bioremediation?
The use of microorganisms to remove soil and water pollution.
89
What is biotechnology?
The field of biology involving the use of living systems to produce or transform materials. Applications include agriculture, medicine and food science.
90
What is brewing?
The production of beer from the steeping of barley in water, and the fermentation of the resulting product with yeast.
91
What are clones?
The genetically identical offspring produced as a result of cloning.
92
What is cloning?
A method of producing genetically identical offspring by asexual reproduction.
93
What is 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.
94
What is culture in biology?
The growth of living matter in vitro in suitable conditions.
95
What is cutting in horticulture?
A small section of the root or stem of an adult plant that is used in horticulture to produce natural clones.
96
What is enucleation?
The removal of the nucleus.
97
What is fermentation?
A type of anaerobic respiration that does not involve an electron transport chain.
98
What is immobilised aminoacylase?
An immobilised enzyme that is used to produce pure samples of L-amino acids.
99
What are immobilised enzymes?
Enzymes which are attached to an inert, insoluble material over which the substrate passes and the reaction takes place.
100
What is immobilised glucoamylase?
An immobilised enzyme that can be used to breakdown dextrins into glucose.
101
What is immobilised glucose isomerase?
An immobilised enzyme that is used to convert glucose to fructose.
102
What is immobilised lactase?
An immobilised enzyme that hydrolyses lactose to glucose and galactose in the production of lactose-free milk.
103
What is immobilised penicillin acylase?
An immobilised enzyme that is used to produce semi-synthetic penicillins from natural penicillins.
104
What is micropropagation?
The production of large numbers of clones from one parent plant using tissue culture.
105
What are monozygotic twins?
Identical twins formed from one fertilised egg that splits to form two embryos.
106
What is natural cloning?
A form of asexual reproduction that takes place in plants in which a new genetically identical plant grows from a structure (stem, leaf, bud or root) of the parent plant. Also known as vegetative propagation.
107
What is penicillin?
The first conventional, effective and safe antibiotic derived from the mould Penicillium chrysogenum.
108
What is somatic cell nuclear transfer (SCNT)?
The production of an embryo (clone) from the transfer of the nucleus of an adult animal cell to an enucleated egg cell in the laboratory. The nucleus and egg are fused and stimulated to divide.
109
What is tissue culture?
The growth of cells or tissues outside of an organism in an artificial culture medium.
110
What are abiotic factors?
The non-living aspects of an ecosystem e.g. light, temperature, water availability, oxygen availability and soil pH.
111
What is abundance in ecology?
The number of individuals per species in a specific area at any given time.
112
What is ammonification?
The production of ammonium compounds when decomposers feed on organic nitrogen-containing molecules.
113
What is Azotobacter?
A type of nitrogen-fixing bacteria that lives freely in the soil.
114
What is a belt transect?
A line along a sampled area upon which quadrats are placed at intervals to determine the abundance and distribution of organisms in an ecosystem.
115
What is biomass?
The total mass of organic material, measured in a specific area over a set time period. This can be calculated in terms of dry mass.
116
What are biotic factors?
The living components of an ecosystem e.g. food availability, pathogens, predators and other species.
117
What is the carbon cycle?
The cycle through which carbon (in the form of carbon dioxide) moves between living organisms and the environment, involving respiration, photosynthesis and combustion.
118
What is carrying capacity?
The maximum population size that can be indefinitely supported by an environment.
119
What is a climax community?
The stable community of organisms that exists at the final stage of ecological succession.
120
What is conservation?
The maintenance of ecosystems and biodiversity by humans in order to preserve the Earth’s resources.
121
What are consumers in an ecosystem?
Organisms that feed.
122
What is food availability?
Food availability refers to the presence of food resources in an ecosystem, which can be influenced by various factors such as pathogens, predators, and other species.
123
What is the carbon cycle?
The carbon cycle is the cycle through which carbon (in the form of carbon dioxide) moves between living organisms and the environment, involving respiration, photosynthesis, and combustion.
124
What is carrying capacity?
Carrying capacity is the maximum population size that can be indefinitely supported by an environment.
125
What is a climax community?
A climax community is the stable community of organisms that exists at the final stage of ecological succession.
126
What is conservation?
Conservation is the maintenance of ecosystems and biodiversity by humans in order to preserve the Earth’s resources.
127
What are consumers?
Consumers are organisms that feed on other organisms to obtain energy.
128
What are decomposers?
Decomposers are organisms that release enzymes which catalyse the breakdown of dead plant and animal material into simpler organic matter.
129
What is deflected succession?
Deflected succession refers to changes to the natural flow of succession due to human activity that result in a stable community known as a plagioclimax.
130
What is denitrification?
Denitrification is the conversion of nitrate ions to nitrogen gas by denitrifying bacteria.
131
What are denitrifying bacteria?
Denitrifying bacteria are anaerobic microorganisms, found in waterlogged soils, responsible for the reduction of nitrate ions to nitrogen gas.
132
What is distribution in ecology?
Distribution refers to the spread of living organisms in an ecosystem.
133
What is ecological efficiency?
Ecological efficiency is the efficiency of energy or biomass transfer between trophic levels.
134
What is an ecosystem?
An ecosystem is the community of organisms (biotic) and non-living (abiotic) components of an area and their interactions.
135
What is a food chain?
A food chain describes the feeding relationships between organisms and the resulting stages of biomass transfer, taking the form: producer ⟶ primary consumer ⟶ secondary consumer ⟶ tertiary consumer.
136
What is interspecific competition?
Interspecific competition is a type of competition that takes place between members of different species.
137
What is intraspecific competition?
Intraspecific competition is a type of competition that takes place between members of the same species.
138
What is a limiting factor?
A limiting factor is a variable that limits the rate of a particular process.
139
What is a line transect?
A line transect is a line along a sampled area where the species touching the transect at regular intervals are recorded to determine the abundance and distribution of organisms in an ecosystem.
140
What is nitrification?
Nitrification is the conversion of ammonium ions to nitrate ions by nitrifying bacteria, taking place in two stages: ammonium ions are oxidised to nitrite ions; nitrite ions are oxidised to nitrate ions.
141
What are nitrifying bacteria?
Nitrifying bacteria are aerobic microorganisms found in the soil responsible for the oxidation of ammonium ions to nitrate ions.
142
What is Nitrobacter?
Nitrobacter is a genus of nitrifying bacteria that oxidises nitrites into nitrates.
143
What is the nitrogen cycle?
The nitrogen cycle is the cycle through which nitrogen moves between living organisms and the environment, involving ammonification, nitrification, nitrogen fixation, and denitrification.
144
What is nitrogen fixation?
Nitrogen fixation is the conversion of atmospheric nitrogen gas into ammonia by nitrogen-fixing bacteria in the soil or root nodules of legumes.
145
What are nitrogen-fixing bacteria?
Nitrogen-fixing bacteria are microorganisms responsible for the conversion of atmospheric nitrogen gas into nitrogen-containing compounds. They can be free-living or mutualistic.
146
What is Nitrosomonas?
Nitrosomonas is a genus of nitrifying bacteria that oxidises ammonium compounds into nitrites.
147
What are peat bogs?
Peat bogs are areas of peat soil in wetland habitats formed by the accumulation of partially decayed organic matter. They store carbon and are commonly referred to as ‘carbon sinks’.
148
What are pioneer species?
Pioneer species are species that can survive in hostile environments and colonise bare rock or sand, e.g., lichens.
149
What is a plagioclimax?
A plagioclimax is a stage in succession in which artificial factors prevent the formation of a natural climax community.
150
What is a population?
A population is all organisms of the same species living with one another in a habitat at the same time.
151
What is a predator?
A predator is an organism that eats other organisms.
152
What is preservation?
Preservation is the restriction of human interference in an area in order to protect and maintain the ecosystem.
153
What is prey?
Prey is an organism that is eaten by predators.
154
What is primary succession?
Primary succession is a type of succession in which pioneer species colonise a newly formed or exposed area of land.
155
What are producers?
Producers are photosynthetic organisms at the start of the food chain that manufacture biomass for all living things.
156
What is a quadrat?
A quadrat is a square grid of known area used in sampling to determine the abundance of organisms in a habitat.
157
What is Rhizobium?
Rhizobium is a type of nitrogen-fixing bacteria that lives inside the root nodules of leguminous plants.
158
What is succession?
Succession describes changes in the community of organisms occupying a certain area over time.
159
What does sustainable mean?
Sustainable refers to the ability to maintain something for future generations.
160
What is a sustainable resource?
A sustainable resource is a resource that can be continuously renewed; it will not diminish or run out.
161
What is a trophic level?
A trophic level is the position of an organism in a food chain.
