Smith Module 1-3.1

Question 1

What was the historical perspective on inheritance?

Answer 1

Blending inheritance–the idea that offspring traits were an intermediate of those of each parent–hypothetically should give rise to uniform populations over time

Question 2

Describe Mendel’s monohybrid or single-character cross

Answer 2

This is when a single gene with different alleles is bred. The experiment is started with subjects that each bred true for the alleles

Question 3

What is hybridization?

Answer 3

Involves mating two individuals with different characteristics (traits or alleles)

Question 4

What is a reciprocal cross?

Answer 4

where the mother’s phenotype in the first cross is the father’s phenotype in the second cross and the father’s phenotype in the first cross is the mother’s phenotype in the second cross

First cross: ♂ is purple, ♀ is white
Reciprocal cross: ♂ is white, ♀ is purple

Question 5

What is the loci of a gene (gene locus)?

Answer 5

Location on the chromosome

Question 6

What is a genome?

Answer 6

An organisms complete set of DNA

Question 7

How to calculate ratios from experimental data?

Answer 7

Divide all values by the lowest number: giving the lowest a value of 1

Question 8

What does it mean if a gene is latent or masked?

Answer 8

recessive gene that is not seen as a phenotype

Question 9

What is Mendel’s first law in Inheritance

Answer 9

The law of independent segregation which means the alleles of a gene segregate independently in gamete formation

Question 10

Describe a Test Cross

Answer 10

A cross involving an individual that shows a dominant phenotype with an individual that is homozygous recessive for the trait being considered

Question 11

What is a secondary use for test crosses?

Answer 11

Useful to determine if two genes involved in a dihybrid cross are on the same chromosome or on a different chromosome (determining linkage)

Question 12

Describe a dihybrid cross

Answer 12

A cross involving two genes, each gene having two contrasting alleles

Question 13

What is Mendel’s second law of inheritance?

Answer 13

Law of the independent assortment of alleles; states that alleles of genes on different chromosomes assort independently of each other during gamete formation

Question 14

In humans, random segregation has the potential to generate ___ different combinations of maternal and paternal chromosomes during gamete formation.

Answer 14

2 to the power of 23

Question 15

Describe incomplete dominance

Answer 15

Alleles of some genes can exhibit different degrees of dominance in relation to each other
Ex) think red, white, and pink flowers
(superscript letters used)

Question 16

Describe multiple alleles and codominance

Answer 16

Three or more alleles; codominance is when alleles have approx. equal effects in individuals making alleles equally detectable in the phenotypes of heterozygotes
Ex) human blood types

Question 17

What is pleiotropy?

Answer 17

The determination of several seemingly unrelated phenotypic traits by a single gene

Question 18

Describe sex linkage

Answer 18

These are genes found on the sex chromosomes (X or Y, usually X). Also called X-linked when on the x chromosome

Question 19

What is the function of the SRY gene on the Y chromosome?

Answer 19

Directs development towards maleness at an early stage of embryological development

Question 20

True or False? All humans have the genes to produce both the male and female reproductive systems but which system will develop is determined by: the protein produced by the SRY gene

Answer 20

TRUE

Question 21

Is the SRY gene pleiotropic?

Answer 21

Yes because it affects many tissues in the developing embryo

Question 22

What are recombinants?

Answer 22

In linked genes recombination is produced by the crossing over process in Prophase I of meiosis

Question 23

What are parental gametes?

Answer 23

gametes that maintain original linkage of alleles in the chromosomes

Question 24

If the genes are ___ or more units apart, recombinant frequencies will suggest the alleles of these two genes are assorting independently

Answer 24

50

Question 25

What is epistasis?

Answer 25

alleles of one gene can mask the expression of the alleles of another gene or an interaction between two or more genes to control a single phenotype

Question 26

What is polygenic inheritance?

Answer 26

involves two or more genes affecting the outcome of a single trait
Typically, the genes are large in quantity but small in their effect on the phenotype Ex) hand width