Chapter 23-24 Genetics Outline

Question 1

What is a Phenotype?

Answer 1

Physical appearance trait

Question 2

What is a Genotype

Answer 2

Alleles responsible for given trait

Question 3

What is the characteristic of the Dominant allele?

Answer 3

• Is capitalized

- Is physically apparent

Question 4

What is the characteristic of the Recessive allele?

Answer 4

• Is lowercased

- Not physically apparent; dormant

Question 5

What is a Homologous Chromosome?

Answer 5

Each PAIR of MATCHING chromosomes (homo=same)

Question 6

How many pairs of chromosomes do humans have?

Answer 6

23 chromosomes.

23 maternal + 23 paternal = 46 chromosomes

Question 7

What happens to homologous chromosomes during meiosis?

Answer 7

They separate

Question 8

Homozygous

Answer 8

Both alleles are the same

Question 9

Heterozygous

Answer 9

The two alleles are different

Question 10

Monohybrids

Answer 10

Heterozygous for one pair of alleles

Question 11

Genotype ratio

Answer 11

1 WW
2 Ww
1 ww

1:2:1

Question 12

Phenotype ratio

Answer 12

3:1

Question 13

What’s the probability of inheritance in 1-Trait crosses?

Answer 13

• The chance of two or more independent events

- Product of all chances

Question 14

What does a Punnett Square do?

Answer 14

Writes out every possibility

Question 15

What is a Dihybrid?

Answer 15

Individual that is heterozygous for two traits (a carrier of two traits)

Question 16

What is a Dihybrid Cross?

Answer 16

Cross between two individuals heterozygous for 2 traits

Question 17

When does Incomplete Dominance occur?

Answer 17

It occurs when the heterozygote (HsHc) is INTERMEDIATE between the two homozygotes

Question 18

When does Codominance occur?

Answer 18

It occurs when alleles are EQUALLY expressed in a heterozygote

Question 19

What is Multiple Allele Inheritance?

Answer 19

The gene exists in several allelic forms

Each individual has only two of the possible alleles

Question 20

What can influence the expression of genetic traits?

Answer 20

Environmental factors

Question 21

Describe Sex-linked Inheritance

Answer 21

Humans have 23 pairs of chromosomes.

• 22 pairs of autosomes
• 1 pair of sex-chromosomes (X and Y)

Question 22

What is a Sex-linked Trait?

Answer 22

Trait controlled by genes on the sex chromosomes

Question 23

What are Sex-linked Alleles?

Answer 23

Alleles on the sex chromosome

Question 24

Xb

Answer 24

colorblindness

Question 25

XB

Answer 25

Normal Vision

Question 26

Height and skiing color in humans are ____ traits

1. dominant 2. codominant 3.incomplete dominant 4. environmental 5. polygenic

Answer 26

polygenic

Question 27

Hemophiliacs are most often?

1. Male
2. Female
3. Both are equally likely

Answer 27

male

Question 28

Any chromosome that is not a sex chromosome is called a(n)?

1. asexual chromosome 2. autosome 3. chromatid 4. homologous chromosome

Answer 28

autosome