Chapter 13 Principles Of Inheritance

Question 0

What is the Law of Segregration?

Answer 0

The two alleles in a pair segregate into different gametes during gamete formation.

Question 1

What are Mendel’s three hypothesis?

Answer 1

1. Alternative versions of genes account for variations in inherited characteristics.
2. For each character, an organism inherits two copies of a gene, one from each parent.
3. If the two alleles at a locus differ, then one determines the organisms appearance and the other has no noticeable effect on the organisms appearance.

Question 2

What is the Law of Independent Assortment?

Answer 2

Each pair of alleles segregates independently of each other pair of alleles during gamete formation.

Question 3

What is an allele?

Answer 3

An alternative form of a gene.

Question 4

What is the difference between the dominant and recessive allele?

Answer 4

A dominant allele is an allele that is fully expressed. A recessive allele is an allele whose effect is not observed.

Question 5

What is the difference between the genotype and the phenotype?

Answer 5

The genotype is an organisms genetic make up. The phenotype is the organisms appearance.

Question 6

What does homozygous mean? Heterozygous?

Answer 6

Homozygous means that an organism has a pair of identical alleles for a gene (character) (ex. PP or pp). Heterozygous means an organism has two different alleles for a gene. (Ex. Pp)

Question 7

What is incomplete dominance?

Answer 7

Neither allele is dominant. The heterozygote is an intermediate phenotype.

Question 8

What is codominance?

Answer 8

Two alleles affect he phenotype on seperate, distinguishable ways. Heterozygote expresses both alleles.

Question 9

What does it mean to have multiple alleles?

Answer 9

Three or more alleles for a gene exist in a population.

Question 10

What is polygenic?

Answer 10

Inheritance of a trait is affected by multiple genes. Ex. Weight, height, eye color, skin pigmentation.

Question 11

What is pleiotropic?

Answer 11

A single gene has multiple phenotypic effects.

Question 12

What is epistasis?

Answer 12

The phenotypic expression of a gene at one locus alters that of a gene at a second locus. Ex. Coat color in Labrador retrievers.

Question 13

What is the chromosomal basis of sex?

Answer 13

Gender differences are obvious phenotypic characters. Chromosomal basis simple-due to presence of sex chromosomes.
Basis of sex:
Female- XX
Male- XY

Question 14

What sex chromosomes do females have? Males?

Answer 14

Female- XX

Male- XY

Question 15

How are X-linked genes inherited by daughters and sons from their mothers/fathers?

Answer 15

Fathers pass X-linked genes to all of their daughters and none of their sons. Mothers pass X-linked genes to half of all their daughters and sons.

Question 16

What is a Barr body?

Answer 16

Inactive X of a female condenses into a compact object called a Barr body.

Question 17

What is aneuploidy and what are it’s consequences?

Answer 17

Aneuploidy is one or more chromosomes present in extra copies are deficient in number. The consequences are genetic imbalance and miscarriage.

Question 18

What is polyploidy and what are it’s consequences?

Answer 18

Polyploidy is when an organism possesses more than two complete chromosome sets. It’s consequences are death, sterility, and speciation.

Question 19

What are the four types of alterations to chromosome structure that can occur?

Answer 19

1. Deletion- a chromosomal fragment is lost.
2. Duplication- a gene or entire chromosome is duplicated
3. Inversion- a chromosomal fragment may reattach to the original chromosome, but I’m the reverse orientation
4. Translocation- nonhomologous chromosomes exchange fragments

Question 20

What is genomic imprinting?

Answer 20

Typically a given allele will have the same effect regardless of whether it was inherited from mom or dad.

Question 21

What is meant by epigenetics?

Answer 21

The genome appears to “remember” certain environmental influences to which it has been exposed.