Chapter 11: Genetics

Question 1

What is the “particulate” hypothesis?

Answer 1

idea that parents pass on discrete heritable units (genes)

Question 2

What is the “blending” hypothesis?

Answer 2

Genetic material from two parents blend together

Question 3

Trait

Answer 3

specific characteristic that varies from one individual to another

Question 4

Gene

Answer 4

sequence of DNA that coees for a protein and determines trait

Question 5

Allele

Answer 5

one of a number of different forms of a gene

Question 6

Hybrid

Answer 6

offspring of crosses between parents with different traits

Question 7

True-breeding

Answer 7

organisms that produce offspring identical to themselves in order to self-pollinate

Question 8

Mendel true-breeded

Answer 8

pea plants

Question 9

Describe Mendel’s 1st of Dominance.

Answer 9

Two genes mixed = 1 Dominant gene shown in F1 generation

Question 10

Segregation

Answer 10

separation of alleles during gamete formtion
- As the F1 plant flowers, the alleles are segregated so each gamete carries one single copy of that gene.
- Each f1 plant produces 2 TYPES of gametes.

Question 11

Principle/Law of Independent Assortment

Answer 11

states that genes for different traits can segregate INDEPENDENTLY during the formation of gametes
- genes of one trait do not affect genes with other traits.
- this allows us to CROSS genes for different traits.

Question 12

Cross Type: Two heterozygous

Answer 12

3 Dominant, 1 Recessive

Question 13

Two heterozygous dihybrid cross gives a ratio of:

Answer 13

9:3:3:1

Question 14

Incomplete dominance vs. codominance

Answer 14

For ex: Red x White flower
Incomplete dominance: Pink
Codominance: Red + White SPOTS

Question 15

Which blood group has multiple alleles? (As an example)

Answer 15

ABO blood

Question 16

Epistasis

Answer 16

one gene affects the expression of another

Question 17

Polygenic inheritance

Answer 17

a single phenotypic character is affected by 2 or more genes

Question 18

Pleiotropy

Answer 18

multiple phenotypic effects, possessed by most genes.
- responsible for multiple symptoms such as hereditary diseases

Question 19

norm of reaction

Answer 19

the phenotypic range of a genotype influenced by the environment
- Ex: hydrangea flowers of same genotypic range from blue-violet to pink, depending on soil acidity

Question 20

Polygenic trait

Answer 20

trait controlled by two or more genes

Question 21

Diploid vs. Haploid

Answer 21

Diploid - contains both sets of homologous chromosomes
Haploid - contains only a single set of chromosomes and 1 single set of genes

Question 22

Examples of diploid and haploid cells:”

Answer 22

Diploid: somatic (normal human body) cell
Haploid: sex cells or gametes

Question 23

What does the ‘n’ represent?

Answer 23

of unique chromosomes

Question 24

Homologous chromosomes

Answer 24

chromosomes that have a corresponding chromosome from the opposite-sex parent
- similar in shape, position, and information, but NOT IDENTICAL

Question 25

Meiosis

Answer 25

separation of homologous chromosomes in a diploid cell

Question 26

Synapsis

Answer 26

process of homologous chromsomes coming together during crossing-over

Question 27

Tetrad

Answer 27

structure containing 4 chromatids that forms during meiosis.

Question 28

Chiasmata

Answer 28

location where DNA is exchanged during crossing-over

Question 29

Crossing-over

Answer 29

process in which homologous chromosomes exchange portions of their chromatids during meiosis

Question 30

Spermatogenesis

Answer 30

formation of male gametes (sperm) - 4 genetically different gametes

Question 31

Oogenesis

Answer 31

formation of female gametes (egg) - 4 genetically different gametes, but only 1 is functional

Question 32

What was one thing that Mendel did wrong?

Answer 32

Genes don't segregate independently, it's chromosomes that undergo segregation and independent assortment.

Question 33

Thomas Hunt Morgan's discovery

Answer 33

first to associate a specific gene with a specific chromosome

Question 34

Genome

Answer 34

full set of genetic material carried by an organism

Question 35

Karyotype

Answer 35

set of photographs which shows complete diploid set of chromosomes

Question 36

Autosome

Answer 36

autosomal chromosome; not a sex chromosome

Question 37

sex chromosome

Answer 37

one of two chromosomes that determine an individual's sex - females = XX - males = XY

Question 38

Egg cells contain _____ chromosome. Sperm cells contain _____ chromosome.

Answer 38

Egg: 1 X chromosome Sperm: 1 X or 1 Y chromosome

Question 39

What determines the gender of an offspring?

Answer 39

the sperm cells - about half of zygotes = 46 XX, and half will be 46XY.

Question 40

Sex-Linked disorders are defective alleles on the __ chromosome.

Answer 40

X chromosome - since the gene of these disorders is recessive, men are more likely to acquire this genetic disorder.

Question 41

X-Chromosome Inactivation

Answer 41

Females can inactivate parts of an X chromosome and use the same genetic information from the corresponding chromosome - spotted cats