Mendelian and Molecular Genetics Flashcards
What are Mendel’s postulates?
Unit of genetic inheritance: 1 genes is inherited from each parent
Dominance/ Recessive
Segregation: Alleles are separated randomly in meiosis
Independent assortment: Alleles
what is heritability?
how much of a characteristic is due to genetics or the environment: H2 = Genetic variance/ genetic + phenotypic variance.
what is the goal of selective breeding?
To improve characteristics/ heritable qualities of the population.
What is the difference between genotype and phenotype?
genotype is the assortment of alleles, phenotype is the physical expression of the gene.
describe 3 allelic interactions.
- complete dominance: homozygous and heterozygous phenotypes are the same.
- Incomplete dominance: Where there is an intermediate phenotype.
- codominance: when the alleles affect the phenotype in separate distinguishable ways. ex) spotting gene in calico cats + piebalding gene.
what is pleiotropy?
when a gene has multiple phenotypic effects.
what is epistasis?
when an allele effects the expression of a different allele on a separate locus
what is the male sex genotype
heteromorphic XY
what are non sex chromosomes called?
Autosomes
what are bird sex chromosomes
F: ZW
M: ZZ
What animals have temperature determining sexs
Crocodiles - extreme temp = F
Australian Skinks, Australian dragon lizards
Turtles - Cold = M
What is Sry
Sex determining region on the Y chromosome (leads to testes production)
descrive XY gene
Hemizygous
Describe the gene for Haeomophilia A
X linked recessive: Factor VIII is produced, causing impaired blood clotting. a
Describe the gene for Canine Muscular Dystrophy
X linked recessive
Describe X chromosome inactivation, give an example where this is show phenotypically.
during embryological development an x chromosome will be inactivated by Lyonisation. Meaning only 1 gene in the X chromosome will be expressed (Dosage Compensation).
The inactive X chromosome will become a Barr Body within the cell.
ex) tortoiseshell cats are mainly female due to this.
One allele will code for orange fur, one for black.
How are loss of function genes expressed
If both alleles are mutated
(gain of function is dominant)
what is Heterosis
Crossing of homologous strains to form a stronger offspring.
AKA Hyprid vigor.
Used in agriculture
Describe Overdominance and give an example
when heterozygotes create a superior phenotype to homozygous ex) Sickle Cell. Heterozygous individuals will have a lower degree of sickle cell (1 dom 1 recessive) so are malaria resistant. (erythrocytes will rupture if infected, so parasite cannot reproduce).
What is Penetrance
how much a gene is expressed throughout a population
what is population genetics:
the genetic difference within and between populations ex) Dog breeds
what is the difference between quantitative genetics and qualitative genetics
qualitative is mendelian, individuals groups.
quantitative is on a scale, usually polygenetic
describe the 4 processes of population genetics
selection
mutation
genetic drift - change in alleles frequency
genetic flow - population seperated
Describe Genetic material
DNA - double helix running antiparallel, made of nucleotides linked by 5 3 phosphodiester bonds.
Bases are non overlapping.
Degenerate.
