Patterns of Inheritance Flashcards
What happens if alleles are autosomal linked
Higher proportion of heterozygous
Alleles not completely remixed
Why might the observed results not match the predicted results
Random fertilisation
How does dominant epistasis work
B, produces / codes for, repressor protein /
repressor polypeptide / enzyme / transcription
factor
(protein / polypeptide / product of B) binds to,
promoter (of A) / mRNA / ribosome
(product of allele B) stops, transcription /
translation (of allele A) / protein synthesis /
described
product of B inhibits the enzyme (encoded by
A)
Autosomal linkage
(both) genes / alleles, occur on same,
chromosome / autosome / chromatid
no independent assortment
(so) alleles, inherited together / end up in
same gamete
(unless) crossing over occurs / chiasma forms
between gene loci
Continuous
polymorphic
-Line graph
Antibiotics
Antibiotic is selective pressure ./ bacteria gene pool has some variation some more resistant than others
When exposed to antibiotics most resistant survive. Surving bacteria continue to reproduce making a
resistant population (under continued antibiotic pressure) antibiotic becomes ineffective
How can genetic diversity be measured
The number of polymorphic gene loci within a population
Genetic bottleneck
-Alleles and gene pool significantly reduced
-Modern population descended from a few survivors
Problems of genetic drift on an endangered population
idea that one individual or allele has
proportionally higher effect on small population
(more likely that) alleles will be lost from
population
(population) more vulnerable / likely to become
extinct due , to environmental change
Rate
Product/ time
Standard deviation - graph
If bars overlap there is not a significant difference between the means
Cm3 to Dm3
/1000
Pedigree diagrams
2 parents without the disease but have a child with the disease means that the carriers are on the recessive allele
If parents have the disease but the child does not then the disease is on the dominant allele
How do you know if the disease is sex-linked and recessive
Male has the disease as they only need one recessive allele
How do you know the disease is sex-linked and dominant
Any affected father will pass the disease to the daughter as daughter is xx and inherits one of the x chromosomes from the father
How does dominant epistasis work
the dominant allele codes for the repressor which binds to the promoter and stops transcription
Why is a genetic drift unlikely to affect a smaller population
One individual/ allele has proportionally higher effect on a smaller population
More likely alleles that will be lost from the population
Population more vulnerable to extinction/ environmental change
What to look for in a graph that shows disruptive selection
Supports because: 1) two peaks 2) at (0) and 1.2/1.4
Does not support: The second peak is not much higher than background / second peak represents
a small number of birds / there could be other explanations for more birds between 1.2-1.4
Explain the effects of stabilising pressure
Genetic variation: pre-existing ; sexual reproduction ; meiosis; mutation
Differential survival: overproduction of offspring; finches with extreme beak depth less likely to survive
inheritance: survivors possess alleles for average beak depth; alleles for average beak depth more likely to be inherited by offspring; increase frequency of these alleles from one generation to the next
Figures: Bell shaped
Changes in body length
Ref. continuous variation
Describe how DNA can be used to provide evidence to support the theory of evolution by natural selection
DNA found in all organsims - highly conserved ; compariosn of DNA between species ; similair
secquence indicates recent common ansesctor
Selection used by farmers to exaggerate certain features
Artificial selection
Explain, with reference to selective breeding, why it is important to maintain viable wild populations of crop plant species
genetic variation
* genetic resource / gene
bank
* source of useful alleles
* can be cross bred with
crop varieties
* allows introduction of
different traits
* unknown future
requirements
* potentially useful in
changing climate
* prevention of inbreeding
depression
* promotion of hybrid
vigour
* prevent dwindling gene
pool
* source of replacement if
cultivated population is in
danger
* plausible example(s) of
any of the above
How does sexual reproduction make individuals genetically unique
Crossing over; allele swapping/shuffling; between non-sister chromatids; at prophase 1; of meiosis; independent assortment of chromosomes at metaphase/anaphase 1/independent assortment of chromatids at metaphase/anaphase 2; haploid gametes; genetically unique gametes; random fertilisation/gamete combination
