Chapter 13: Textbook

Question 1

Cystic fibrosis is an autosomal

Answer 1

Recessive disorder

Question 2

Heredity

Answer 2

Transmission of traits from one generation to the next

Question 3

Hereditary units

Answer 3

Genes

Question 4

Define gene locus

Answer 4

A gene’s specific location along the length of a chromosome

Question 5

Define asexual reproduction

Answer 5

A single individual is the sole parent and passes copies of all its genes to its offspring without the fusion of gametes

Question 6

Define clone

Answer 6

An individual that reproduces asexually gives rise to a clone

Question 7

Define sexual reproduction

Answer 7

2 parents give rise to offspring that have unique combinations of genes inherited from the two parents

Question 8

Define life cycle

Answer 8

Generation to generation sequence of stages in the reproductive history of an organism from conception to reproduction

Question 9

Ordered display of chromosomes from longest to shortest

Answer 9

Karyotype

Question 10

Homologous chromosomes

Answer 10

The two chromosomes of a pair have the same length, centromere position and staining pattern

Question 11

Any cell with two chromosomes is called

Answer 11

A diploid cell

Question 12

For humans the diploid number is

Answer 12

46
2n = 46
n = 23

Question 13

Gametes are

Answer 13

Haploid cells (23 chromosomes)

Question 14

Define fertilization

Answer 14

Union of gametes culminating in fusion of their nuclei

Question 15

Zygote

Answer 15

Resulting fertilized egg

Question 16

Gamete formation involves

Answer 16

Meiosis

Question 17

What happens as a result of meiosis

Answer 17

Human sperm and egg is haploid, fertilization restores the diploid condition by combining two haploid sets together

Question 18

Define the steps of Meiosis I

Answer 18

Prophase I
- nuclear envelope breaks down
- chromosomes condense
- crossing over occurs: DNA molecules of non sister chromatids are broken and are rejoined to each other

Metaphase I
- pairs of homologous chromosomes are now arranged at the metaphase plate

Anaphase I
- breakdown of proteins the hold sister chromatids together
- move towards opposite poles

Telophase I and cytokinesis
- each half of the cell has a complete haploid set
- cytokinesis forms two haploid daughter cells

Question 19

Meiosis I creates

Answer 19

2 haploid daughter cells

Question 20

Describe meiosis II

Answer 20

Prophase II
- A spindle apparatus forms

Metaphase II
- The chromosomes are positioned at the metaphase plate as in mitosis
- Because of crossing over, the two sister chromatids of each chromosome are not genetically identical

Anaphase II
- breakdown of proteins holding sister chromatids. Chromatids move toward opposite poles

Telophase II and cytokinesis
Chromosomes begin de condensing
- produces four daughter cells each with a haploid set of chromosomes

Question 21

Crossing over

Answer 21

When one or both of chromatids include regions of the non sister chromatid DNA

Question 22

Describe the process of crossing over

Answer 22

Each gene on one homologue is aligned with the responding gene on the other homologue. The DNA of two nonsister chromatids are broken down by specific proteins. Synaptonemal complex holds one homologue tightly to the other. This association is called the synapsis and during it the DNA breaks are closed up so that each broken end is joint to the corresponding segment to join paternal to maternal chromatid

Question 23

Three unique events to meiosis

Answer 23

1. Synapsis and crossing over
2. Alignment of homologue pairs at the metaphase plate
3. Separation of homologues

Question 24

Differences in roles of mitosis and meiosis

Answer 24

Mitosis: enables multicellular animal or plant to arise from a single cell
Meiosis: produces gametes

Question 25

Define independence assortment

Answer 25

The alleles of two or more different genes get sorted into gametes independently of one another

Question 26

Define recombinant chromosomes

Answer 26

Individual chromosomes that carry genes derived from two different parents