Module 2, Extensions of Mendelism Flashcards
(45 cards)
What is the chromosomal throey of inheritance?
inherited traits are controlled by genes residing on chromosomes faithfully transmitted
through gametes, maintaining genetic continuity from generation to generation
Who made the chromosomal theory of inheritance
Walter Sutton and Theodor Boveri
(BUTTON dude and alvin & the chipmunks)
Why may phenotypic ratios in real life be different than mendel’s ratios?
- Sometimes genes aren’t completely dominant/recessive
- 1 phenotype may be influenced by mroe than 1 gene
- Genes may be on nsex chromosomes
- Phenotype= impacted by environment too
- Extranuclear inheritance, resulting from the expression of genes present in the DNA found in
mitochondria and chloroplasts
What is incomplete dominance?
Phenotype of the heterozygote is
intermediate (falls within the range) between the phenotypes of the two
homozygotes
Genotypic ratio of F2 generation in complete dominance?
1:2:1
In incomplete dominance what can be said about the phenotypic and genotypic ratio? Why?
They’re very similar/the same
Phenotypic ratio of codominance and incomplete dominance?
1:2:1
Genotypic ratio of codominance and incomplete dominance
1:2:1
Molecular basis of incomplete dominance?
Insufficient expression of the gene or gene dosage may result in incomplete dominance.
Real life example of incomplete dominance? Explain how it works
Tay–Sach’s disease
How does Tay Sachs disease work?
he homozygous
recessive individuals are severely affected with a fatal lipid storage disorder, there is
almost no activity of the enzyme hexosaminidase A in those with the disease
Heterozygous person still only produces 50% of Hex-A than a normal heterozygous dominant
Codominance
Phenotype of the heterozygote includes the phenotypes of both homozygotes
What are multiple alleles
When within a group of organisms, for some loci, when more than two alleles are present (A, A’, A’’, a, a’, a’’ etc.)
Give an example of multiple alleles. How does it work?
Fur coat color in rabbits
There is an order of Dominance
C > C^ch > C^c > c
Within the genotype the more dominant allele that is present is the phenotype
What is a himilayan rabbit
A rabbit that has the temperature sensitive conditional mutant
allele that provides pigmentation only in
the colder parts of body.
Causing it to be black in cold areas (ex:ears and nose)
Which blood type is the universal donor? Why?
Individuals with blood type O negative (O-) are considered universal donors. This is because their RBCs lack A, B, and Rh antigens, making it less likely to trigger an immune response in recipients with different blood types.
Which blood type is the universal acceptor? Why?
Individuals with blood type AB positive (AB+) are considered universal acceptors. They can receive blood from any ABO and Rh type because their plasma lacks anti-A and anti-B antibodies. While this makes them highly versatile recipients, AB positive is also relatively rare, found in about 2-5% of the Indian population.
Anti bodies made by A body
B-anitbodies
Antibodies made by B body
A-antibodies
What are lethal allels
An allele that causes the death of an organism during an early stage of development often before birth so
that certain genotypes can never be observed.
Recesive lethal alleles?
Mutations resulting in the synthesis of a gene product that is nonfunctional can often be tolerated in
the heterozygous state.
* So, one wild-type allele may be sufficient to produce enough of the essential product to allow survival.
* However, the homozygous recessive individuals do not survive, so they cause lethality in recessive form.
* These mutations affect genes that are essential to life – ‘Essential Genes
What are essential genes? What do they have to do with lethal mutations?
- genes that are essential to life
- mutations affect genes that are essential to life
What is a dominant lethal mutation?
Mutations that cause ectopic production or overexpression of a toxic product.
(This allele is lethal both in the homozygotes and the heterozygotes)
