Genetics & Ecosystems

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What is a point mutation?
A mutation where 1 base pair replaces another.
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What is a silent mutation?
A change to the base triplet, but it still codes for the same amino acid.
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What is a missense mutation?
A change to the base triplet, and it changes the amino acid being coded.
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What is a nonsense mutation?
A change to the base triplet, making a stop codon.
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What is an insertion mutation?
Where a nucleotide base pair is added to the amino acid sequence.
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What is a deletion mutation?
Where a nucleotide base pair is removed from the amino acid sequence.
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What are the 2 enzymes required to break down lactose?
Lactose permease and β-galactosidase.
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What is the role of lactose permease?
Allows lactose to enter the bacteria cell.
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What is the role of β-galactosidase?
Allows lactose to be hydrolysed into glucose and galactose.
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Describe the lac operon function when no lactose is present
1. Regulatory gene codes for a repressor protein 2. Repressor protein binds to operator region 3. RNA Polymerase cannot bind to the promoter region 4. Repressor protein prevents lacZ & lacY from being transcribed.
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Describe the lac operon function when lactose is present
1. Regulatory gene codes for a repressor protein 2. Lactose binds tot he repressor protein, altering its shape & preventing it from binding to the operator region 3. RNA Polymerase binds to promoter region & transcribe mRNA 4. mRNA -> 2 enzymes.
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What are transcription factors?
Proteins/ short non-coding pieces of RNA found in the nucleus that switch genes on/off.
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What are some examples of where transcription factors are used?
Cell cycle, cell division etc.
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What are introns?
Non-coding regions of DNA.
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What are exons?
Coding regions of DNA.
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What enzyme removes introns and joins exons together?
Endonuclease enzyme
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What is a homeobox gene?
A gene that controls anatomical development which contains homeobox sequences that contain homeodomain sequences.
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Describe the structure of a homeodomain sequence
2 alpha helices connected by 1 turn.
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What is a hox gene?
A gene that regulates the development of embroys along the anterior-posterior axis, controlling which body parts grow where. They encode homeodomain proteins (transcription factors).
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What is apoptosis?
Programmed cell death/suicide.
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Describe the process of apoptosis.
1. Enzymes break down cytoskeleton 2. Cytoplasm = dense with tightly packed organelles 3. Blebs form on surface membrane 4. Chromatin condenses, nuclear envelope breaks & DNA = fragments 5. Cell broken into vesicles & ingested by phagocytic cells.
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What are some cell signals that control apoptosis?
Cytokines, hormones, growth factors, nitric oxide etc.
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Not enough apoptosis, causes what?
Tumours.
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Too much apoptosis, causes what?
Cell loss & degeneration.
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What are the 3 types of gene mutations?
Physical, chemical and biological agents.
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Name some physical agents
X-rays, gamma rays, UV light etc.
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Name some chemical agents
Tobacco smoke, mustard gas, nitrous acid, aromatic amines, free radicals etc.
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Name some biological agents
Viruses, food contaminants, transposons etc.
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What are the 5 types of chromosome mutations?
Deletion, inversion, translocation, duplication and non-disjunction.
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What is deletion (chromosome mutation)?
Part of a chromosome is lost.
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What is inversion (chromosome mutation)?
Section of a chromosome is broken, inverted 180 degrees and joined.
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What is translocation (chromosome mutation)?
Piece of 1 chromosome breaks and attaches to another chromosome.
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What is duplication (chromosome mutation)?
Piece of a chromosome is duplicated.
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What is non-disjunction (chromosome mutation)?
1 pair of chromosomes/chromatids fail to separate, leaving 1 gamete with an extra chromosome.
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What is aneuploidy?
Chromosome number isn't an exact multiple of the haploid number as chromosomes/chromatids fail to separate.
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What is polyploidy?
Cells and organisms that contain more than 1 homologous sets of chromosomes.
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What are the 3 ways to create genetic variation in sexual reproduction?
Allele shuffling (crossing over in P1), independent assortment of chromosomes (M/A1) and independent assortment of chromatics (M/A2).
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What is dihybrid inheritance?
2 characteristics that are inherited together simultaneously.
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What is sex linkage?
The gene present on one of the sex chromosomes.
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What is codominance?
Where both alleles present in the genotype of a heterozygous individual contribute to the individuals phenotype.
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What is autosomal linkage?
Gene loci present on the same autosome that are often inherited together.
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What happens to autosomally linked genes if no crossing over occurs?
Linked genes are always inherited as 1 unit.
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What happens to autosomally linked genes if crossing over occurs?
Recombinant gametes are formed, producing recombinant phenotypes.
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What is epistasis?
Interaction of non-linked gene loci where 1 masks the expression of the other.
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Describe recessive epistasis
Recessive allele at the 1st locus, prevents the expression of another allele at a 2nd locus.
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Describe dominant epistasis
Presence of 1 dominant allele prevents the expression of another allele at another locus, even if its dominant.
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What does the chi-squared test show?
Shows whether the difference between observed and expected data is significant or due to chance.
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When do you use chi-squared?
Categorical data, large sample size, no 0 scores in raw data, strong biological theory for expected values, data are only raw counts etc.
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What is the null hypothesis?
No statistically significant difference between observed and expected data. Any difference is due to chance.
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How do you know if a value is significant in the chi-squared test?
The X2 value needs to be greater than the critical value for it to be significant, and thus to reject the null hypothesis.
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What is discontinuous data?
Discrete categories that do not overlap.
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What is continuous data?
Variation where quantitative traits vary by very small amounts between one group and the next.
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What is natural selection?
Mutations introduce new alleles into the population which possess an advantageous adaptation. Those with the adaptation survive better and reproduce to successfully pass on their mutation, causing allele frequencies to change.
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What is stabilising selection?
Organisms' environment remains unchanged.
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What is directional selection?
Gradual shift in the optimum value.
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What is genetic drift?
Population descends from a small number of parents = gene pool will lack genetic variation.
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What is genetic bottleneck?
Sharp decrease in size of a population due to environmental catastrophe.
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What is founder effect?
When a small sample of an original population establishes in a new area.
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What is the hardy-weinberg principle?
P + Q = 1. P2 + 2PQ + Q2 = 1
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What is speciation?
The splitting of a genetically similar population into 2(+) populations that undergo genetic differentiation & eventually reproductive isolation, leading to the evolution of 2(+) new species.
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Other cards in this set

Card 2

Front

What is a silent mutation?

Back

A change to the base triplet, but it still codes for the same amino acid.

Card 3

Front

What is a missense mutation?

Back

Preview of the front of card 3

Card 4

Front

What is a nonsense mutation?

Back

Preview of the front of card 4

Card 5

Front

What is an insertion mutation?

Back

Preview of the front of card 5
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