Chapter 3: Cell division and chromosome heredity

Question 1

What are the characteristics of mitosis

Answer 1

One DIPLOID parent cell produces 2 DIPLOID daughter cells

occurs in somatic cells (no egg/sperm) and spores of ASEXUALLY reproducing species

Question 2

What are the stages of mitosis

Answer 2

Interphase
prophase
prometaphase
metaphase
anaphase
telophase + cytokinesis

Question 3

What occurs in mitosis interphase?

Answer 3

Chromosomes are unwound and begin duplicating… centrosomes are on one side of the cell

Question 4

What occurs in mitosis prophase?

Answer 4

Centrosomes begin to move apart, microtubules begin to grow, chromatids condense

Question 5

What occurs in mitosis prometaphase?

Answer 5

Nuclear envelope breaks down
nucleolus disappears
microtubules begin to expand/contract, pulling chromatids to central part of cell

Question 6

What is a kinetochore?

Answer 6

Protein structure near centromere where microtubules attach

Question 7

What is a nonkinetochore microtubule?

Answer 7

Makes the cell elongate during division

Question 8

What are the negative and positive (+) ends of the microtubules from the centrosomes?

Answer 8

negative (-) : the end closest to the centriole
positive (+) : growing end of the microtubule

Question 9

Describe the process of a growing motor protein???????

Question 10

What occurs in mitosis metaphase?

Answer 10

Chromatids are pulled to the center and lined up single file
spindle and metaphase plates form

Question 11

What occurs in mitosis anaphase?

Answer 11

The chromatids are pulled apart, forming daughter chromosomes at either spindle pole

Question 12

What occurs in mitosis telophase/cytokinesis?

Answer 12

Nucleolus reforms
nuclear envelope reforms
chromosomes unwind
cytokinesis occurs (cell membrane divide)

Question 13

Describe the process of chromatids being pulled apart?

Answer 13

Prophase: chromatids held together with cohesin protein

Metaphase: Kinetochore and microtubule attaches, kinetochore movement pulls is pulling the chromatids in opposite direction

Anaphase: Separase dissolves cohesin to let the chromatids be pulled apart

Question 14

What are the characteristics of Meiosis 1 and 2?

Answer 14

2 rounds of cell division produces two HAPLOID gametes
——–one copy of each chromosome = one half of each homologous pair

Occurs in the gametes (egg/sperm) as well as spores of sexually-reproducing species

Question 15

What are the stages of Meiosis 1 during prophase I?

Answer 15

Leptotene
Zygotene
Pachytene
Diplotene

Question 16

What occurs in prophase Iduring leptotene?

Answer 16

-chromosomes begin to condense
-centriole gets ready to migrate

Question 17

What occurs in Prophase I during Zygotene?

Answer 17

-homologs align precisely and pair up with each other (four sets of chromosomes in three pairs), knwon as bivalents

Question 18

Describe the formation of the Synaptonemal complex?

Question 19

What is the purpose of meiosis I?

Answer 19

Separate homologous chromosomes

Question 20

What occurs in prophase I during pachytene?

Answer 20

Further condensation of chromosomes
synaptonemal complex is formed
crossing over occurs
nodules appear

Question 21

What are PARs and where do they play a role in meiosis I, prophase I?

Answer 21

Pseudo autosomal regions
where crossing over occurs during pachytene phase of meiosis I

Question 22

What occurs in meiosis I, prophase I, during diplotene?

Answer 22

-nuclear envelope dissolves
-centrosomes moved to opposite sides
-microtubules are formed
-crossing over complete
-chromosomes begin to move apart

Question 23

What is the chiasma?

Answer 23

Where crossing over has occurred in prophase I

Question 24

What occurs during meiosis I during metaphase I?

Answer 24

-homologs pair and line up, 2 by 2 (2 pairs of chromosomes and three sets lined up at the spindle)

Question 25

What occurs during Meiosis I during anaphase?

Answer 25

Homologs separate (both members of pairs are separated) 3/6 chromosomes move to each pole, sister chromatids remain attached

Question 26

What occurs during Telophase I and cytokinesis during meiosis I?

Answer 26

nuclear envelope reforms cleavage furrow --> cells divide

Question 27

Explain the process of chromosome separation in Meiosis I?

Answer 27

Diplotene/diakinesis: Kinetochore/nonkinetochore microtubules attach to kinetochore near centromere Metaphase: Kinetochore movement pulls the chromosomes in opposite directions Anaphase I: homologs are moved to separate poles

Question 28

What is the purpose of meiosis II?

Answer 28

Separate sister chromatids

Question 29

What happens in meiosis II during prophase II?

Answer 29

nuclear envelope breaks down centrosomes begin to migrate

Question 30

What happens in meiosis II during metaphase II?

Answer 30

Metaphase plate forms... chromosomes line up at spindle haploid number of chromosomes (3 instead of 6)

Question 31

What happens in meiosis II during Anaphase?

Answer 31

Chromatids separate

Question 32

What happens in meiosis II during telophase II and cytokinesis?

Answer 32

Nuclear envelope reforms cleavage furrow causes the cells to split they are not genetically identical

Question 33

Compare meiosis I with Meiosis II?

Answer 33

Meiosis I: separation of homologs Meiosis II: separation of sister chromatids

Question 34

compare the outcome of mitosis with meiosis?

Answer 34

mitosis: 2 diploid cells meiosis: 4 haploid cells

Question 35

Describe the law of segregation?

Answer 35

When an organism makes gametes, each gamete receives just one gene copy, which is selected randomly.

Question 36

Describe the law of independent assortment?

Answer 36

alleles of two (or more) different genes get sorted into gametes independently of one another.

Question 37

How many pairs of chromosomes do drosophilia have? what is the difference between the male and female?

Answer 37

three pairs of autosomes (non sex).... one pair of sex chromo Female - identical sex chromo male- non identical sex chromo

Question 38

What occurred in crosses A and B of Morgans fly experiment?

Answer 38

Cross A - Red female, white male... F1 = all red, F2 = 3:1 red and white Cross B - White female, red male... F1 = red and white 1:1.... F2 = 1:1 ratio of red to white eyes

Question 39

What happens to results when testing reciprocal crosses?

Answer 39

- the results will differ, difference in phenotypic frequencies show up in F1 or F2

Question 40

describe HOW you get the results from cross A? (3:1 F2)

Answer 40

Male white carries only ONE X gene that has the mutation, so it not expressed in the first generation, as the female has both dominant genes.... will be expressed in the second generation because the female of F1 is now a carrier... only one of the males will express the gene

Question 41

Describe how sex is determined as a fetus is developing?

Answer 41

-presence of SRY (sex determining region) - SRY --> codes for TDF --> TDF causes wolffian duct to grow (MALE) --> MIH causes mullarian ducts to regress

Question 42

What is the gene system used for birds and another animals ?

Answer 42

Z/W Females : WZ Males : ZZ

Question 43

Describe the Cross A and B of chickens?

Answer 43

Cross A: female (Zb W) x male (ZB ZB) F1 = female (ZB W) + Male (ZB Zb) (all progeny are barred) Cross B: female (ZB W) x male (Zb Zb) F1 = female (Zb W) + male (ZB Zb) (Hens are white and roosters are barred)

Question 44

Heterozygous FEMALES transmit each X-linked allele to approximately ____ daughters and _____ son.

Answer 44

1/2, 1/2

Question 45

Affected MALES transmit X-linked allele to _____ daughters and _____ sons?

Answer 45

100%. daughters, no sons

Question 46

Would you expect males that inherit an X-linked recessive allele to always express the trait?

Answer 46

Yes, they only have one X allele

Question 47

Would you expect females that inherit an X-linked recessive allele to always express the trait?

Answer 47

No, it depends on the other X allele

Question 48

Describe a Y-linked inheritance

Answer 48

all sons of affected males express traits no females express the trait

Question 49

What is the term for a gene carried on the Y chromosome?

Answer 49

Holandric

Question 50

Describe Lyonization

Answer 50

One chromosome is randomly inactivated in each cell of a female...can cause female mammals to be mosaic

Question 51

how do you determine how many barr body's are present in a cell?

Answer 51

Number of X chromosomes above 1. (ex: 3 chromosomes = 2 barr bodies)

Question 52

What are some examples of lyonization?

Answer 52

Anhidrotic ectodermal dysplasia (patches on skin with no sweat glands). Calico and tortoiseshell cats males = rare (XXY)