Chapter 10.6 Flashcards Preview

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Flashcards in Chapter 10.6 Deck (13)
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1
Q

INCOMPLETE DOMINANCE

A

the heterozygote has a third phenotype that is intermediate between those of two homozygote parent (r1r1 red flowers x r2r2 white flowers

This is an example of when a heterozygous offspring does not share the phenotype of either parent

2
Q

CODOMINANCE

A

2 different alleles are expressed together in the phenotype

3
Q

Explain codominance in blood type

A

A person’s ABO blood type is determined by the I gene: which has three possible ales ; IA, IB AND ii. The I gene encodes an enzyme that inserts either an A OR a B. the allele i is recessive so ii has neither A or B and thus has type O blood.
IA, iA = A blood type
IB, iB = B blood type
However, IB IA = AB blood type ( both alleles are dominant, both are expressed)

4
Q

The difference between a recessive and dominant allele.

A

RECESSIVE: Encodes for a nonfunctional protein
DOMINANT: code for a functional protein

5
Q

Why are some conditions hard to trace in families

A

one gene may influence the phenotype in many ways; conversely multiple genes may contribute to one phono type

6
Q

PLEIOTROPY

A

one gene has multiple effects on the phenotype.

It arises when one protein is important in different biochemical pathways or affects more than one body part or process.

7
Q

EPISTASIS

A

A type of interaction ( protein ), which occurs when one one gene’s product affects the expression of another gene

8
Q

What conditions interfere with the predictability of mendelian genetics

A
1.Incomplete dominance
2 Codominance
3 Pleiotropy 
4. Protein interactions
5. Epistasis
9
Q

. How do incomplete dominance and codominance increase the number of phenotypes?

A

Incomplete dominance and codominance produce phenotypes that are intermediate between or combinations of those produced by homozygous dominant or homozygous recessive individuals.

In incomplete dominance the hetereozygote has a third phenotype that is an intermediate.
In codominance two different alleles are are expressed together as they are both dominant; in blood type gene I there a three possible alleles resulting in 6 genotype and 4 phenotype

10
Q

What is the difference between recombinant and parental chromatids, and how do they arise?

A

Recombinant chromatids are non- sister chromatids, that have a mixture of maternal and paternal alleles instead of alleles from just a single parent. In contrast, parental chromatids carry the same combinations of alleles that were inherited from the parents. Crossing over has not altered them.

11
Q

What is pleiotropy?

A

Pleiotropy occurs when a gene produces multiple phenotypic expressions. Pleiotropy results when the protein encoded by a gene enters several different biochemical pathways or affects more than one body part or process.

12
Q

How can the same phenotype stem from many different genotypes

A

Each gene encodes one protein, but many different proteins may interact in a single metabolic pathway. A mutation in a gene encoding any of these proteins may produce a flawed metabolic pathway. In this way, different genotypes can produce the same phenotype (failure of the metabolic pathway to operate properly).

13
Q

How can epistasis decrease the number of phenotypes observed in a population?

A

In epistasis, one gene affects the expression of another. The gene interaction may cause some phenotypes to appear to be missing from a population.