Lecture 9

Question 1

What are 2 things that make up the sexual life cycles of cells?

Answer 1

1. Meiosis
2. Fertilization

Question 2

What are diploid cells?

Answer 2

Somatic cells (nonreproductive) that have 2 sets of chromosomes (2 sets of 23 chromosomes)

Question 3

What are haploid cells?

Answer 3

Gametes (egg and sperm) that have only 1 set of chromosomes (23 chromosomes).

Question 4

Which is the dominant state of reproduction in animal cells?

Answer 4

The diploid state.

Question 5

What makes up meiosis?

Answer 5

Meiosis I and Meiosis II.

Question 6

What makes up Meiosis I & II?

Answer 6

Prophase I, Metaphase I, Anaphase I, Telophase I, & Prophase II, Metaphase II, Anaphase II, Telophase II.

Question 7

What is the reduction division?

Answer 7

The first meiotic division that results in daughter cells that contain one homologue from each chromosome pair.

Question 8

Is there DNA replication in meiotic division?

Answer 8

no.

Question 9

In Meiosis what happens after Interphase?

Answer 9

The germ-line cells enter meiosis I.

Question 10

What is synapsis?

Answer 10

The pairing of homologous chromosomes.

Question 11

Wheb does synapsis occur?

Answer 11

During prophase I.

Question 12

When does crossing over occur?

Answer 12

During Prophase I.

Question 13

What is the site of crossing over called?

Answer 13

Chiasmata.

Question 14

What is crossing over?

Answer 14

Genetic recombination between non-sister chromatids.

Question 15

What is the purpose of crossing over?

Answer 15

To mix up genes.

Question 16

Which phase of meiosis is the same as mitosis?

Answer 16

Meiosis I.

Question 17

What happens during prophase I?

Answer 17

The chromosomes coiled tighter, chromosomes form x’s, and synapsis occurs.

Question 18

What happens during Metaphase I?

Answer 18

Homologous chromosomes lock together after crossing over, microtubules attach, and they align in a double line.

Question 19

How are chromosomes align during Metaphase I?

Answer 19

Randomly.

Question 20

What happens during anaphase I?

Answer 20

Chiasmata break and the homologous chromosomes separate.

Question 21

What happens during Telophase 1?

Answer 21

Nuclear envelope reforms.

Question 22

What happens during Prophase II?

Answer 22

Same as Mitosis Prophase and Prophase I.

Question 23

What happens during Metaphase II?

Answer 23

The chromosomes align in a single line and microtubules attach to sister chromatids.

Question 24

What happens in Anaphase II?

Answer 24

Sister chromatids are separated

Question 25

What happens during Telophase II?

Answer 25

Nuclear membrane reforms and after cytokinesis occurs, resulting in 4 haploid cells.

Question 26

What are 4 features of meiosis that is different from mitosis?

Answer 26

1. Homologous pairing and crossing over 2. Homologous chromosome line up as a double line in metaphase I 3. Sister chromatids remain joined at their centromeres and segregating together during anaphase I 4. DNA replication is suppressed between meiosis I and Meiosis II. (4 haploid cells instead of 2 diploid cells)

Question 27

Before the 20th century what were the 2 ideas about heredity?

Answer 27

1. Heredity occurs within species 2. Traits are transmitted directly from parent to offspring

Question 28

Who discovered many of the things we know about genes?

Answer 28

Gregor Mendel.

Question 29

Why did Gregor Menel use a pea plant for his experiments?

Answer 29

1. Research showed that pea hybrids could be produced 2. Many pea varieties were available 3. Pea plants are small 4. They can self-fertilize or cross fertilize

Question 30

What was Mendel's experimental method?

Answer 30

1. Produce true-breeding strains for each trait he was studying 2. Cross-fertilize true-breeding strains having alternate forms of a trait 3. Allow the hybrid offspring to self-fertilize for several generations and count the number of offspring showing each form of trait.

Question 31

What is a dominant trait?

Answer 31

The trait that if it is present will be shown.

Question 32

What is a recessive trait?

Answer 32

The trait that will only be shown if no dominant traits are present.

Question 33

What is F1 generation?

Answer 33

Offspring produced by crossing 2 true-breeding strains.

Question 34

What is F2 generation?

Answer 34

Offspring resulting from the self-fertilization of F1 plants.

Question 35

What is the ratio of organisms with dominant traits to organisms with recessive traits?

Answer 35

3:1 (dominant to recessive).

Question 36

What is the 3:1 ratio actually?

Answer 36

1 true breeding dominant plant, 2 non-true-breeding dominant plants, 1 true-breeding- recessive plant.

Question 37

What is Mendel's 5 element model?

Answer 37

1. Parents transmit discrete factors (genes) 2. Each individual receives one copy of a gene from each parent 3. Not all copies of a gene are identical 4. Alleles remain discreate (no blending) 5. Presence of allele does not guarantee expression

Question 38

What is an allele?

Answer 38

An alternative form of a gene.

Question 39

What is a homozygous?

Answer 39

2 of the same allele.

Question 40

What is heterozygous?

Answer 40

Different alleles.

Question 41

What is a genotype?

Answer 41

A total set of alleles an individual contains.

Question 42

What is a phenotype?

Answer 42

Physical appearance.