Genes and Heredity

Question 1

Define haploid cell.

Answer 1

A cell with only one set (1 of each type) of chromosomes (where n = # different chromosomes).

Question 2

How many molecules of DNA are in a single stranded chromosome?

Answer 2

1 molecule of DNA.

Question 3

How many molecules of DNA are in a double stranded chromosome?

Answer 3

2 molecules of DNA.

Question 4

What are homologous chromosomes?

Answer 4

Same size, same shape, same genes, but not on the same chromosome (2 different chromosomes).

Question 5

What is the ploidy level of trisomy?

Answer 5

2n+1

Question 6

Name the possible changes in chromosome structure.

Answer 6

Inversion, translocation, deletion, and duplication.

Question 7

You have 4 different ss chromosomes in 1 cell. What is the ploidy level?

Answer 7

1n (1 of each type).

Question 8

You have 4 different ds chromosomes in 1 cell. What is the ploidy level?

Answer 8

1n (1 of each type even if ds).

Question 9

Name the functions of mitosis.

Answer 9

Growth, repair, asexual reproduction, division to produce new cells. (aging, cancer, immunity)

Question 10

What are the stages of the cell cycle?

Answer 10

1-Interphase (G1, S-phase, G2), 2-mitosis, 3-cytokinesis.

Question 11

What is the 1st checkpoint, what does it check for and what does it engage?

Answer 11

G1/S checkpoint: checks if cell double in size, growth rate is adequate and presence of growth factors.
-SPF is activated

Question 12

What does SPF do?

Answer 12

The S-phase promoting factor (SPF) initiates the S-phase, DNA replication occurs and SS chromosomes turn into DS chromosomes.

Question 13

What is the 2nd checkpoint, what does it check for and what does it engage?

Answer 13

G2/M checkpoint: checks if the DNA replication was complete and successful, checks the cell mass, the cell contents, the growth rate and the time elapsed.
-MPF is activated

Question 14

What does MPF do?

Answer 14

The mitosis promoting factor (MPF) initiates chromatin condensing into chromosomes, breakdown of the nuclear membrane and the assembly of mitotic spindle.

Question 15

What is the 3rd checkpoint, what does it check for and what does it engage?

Answer 15

The mitotic spindle checkpoint checks is all kinetochores are attached to spindle fibers correctly.
-APC is activated

Question 16

What does APC do ?

Answer 16

The anaphase promoting complex allows chromatids to separate and inactivates MPF so it allows the chromosomes to de-condense and the spindle fibers to breakdown.

Question 17

What are the phases of mitosis?

Answer 17

1. Prophase
2. Prometaphase
3. Metaphase
4. Anaphase
5. Telophase

Question 18

How are genes inherited?

Answer 18

In gametes via sexual reproduction.

Question 19

What is a centriole?

Answer 19

A cylinder composed of microtubules.

Question 20

What is a centromere?

Answer 20

Highly condensed area of a chromosome, appears as a constriction.

Question 21

What is a centrosome?

Answer 21

Organelle that creates microtubules.

Question 22

Define condensin.

Answer 22

Proteins that help chromatin condense into chromosomes.

Question 23

Define histones.

Answer 23

Proteins found in chromatin.

Question 24

Define cohesins.

Answer 24

Proteins that hold sister chromatids together.

Question 25

True or False: Mitosis only occurs in diploid cells?

Answer 25

False, it can occur in any cell.

Question 26

True or False: Centrioles are in all eukaryotic cells?

Answer 26

False, there are none in plants.

Question 27

True or False: Prokaryotes are not haploid.

Answer 27

True, haploid refers to eukaryotes only.

Question 28

Define meiosis.

Answer 28

A type of cell division (sexual) that produces 4 unique haploid cells called gametes. It is composed of 2 sets of division.

Question 29

What are the stages of meiosis?

Answer 29

1. Interphase (G1, S-phase, G2) 2. Meiosis I 3. Interkinesis (interphase without S-phase) 4. Meiosis II 5. Cytokinesis

Question 30

What are the stages meiosis I?

Answer 30

1. Prophase I 2. Metaphase I 3. Anaphase I 4. Telophase I

Question 31

What are the stages meiosis II?

Answer 31

1. Prophase II 2. Metaphase II 3. Anaphase II 4. Telophase II

Question 32

What are the functions of meiosis?

Answer 32

Create haploid gamete (egg and sperm) necessary for sexual reproduction, create genetic variation.

Question 33

How does meiosis create genetic variation?

Answer 33

1. Crossing-over between homologous pairs during Prophase I 2. Independent assortment of homologues in meiosis I 3. Random fertilization variation created by sexual reproduction

Question 34

True or False: homologous chromosomes are paired in meiosis, but not in mitosis?

Answer 34

True.

Question 35

Mosquitoes n=3. How many ds chromosomes are in each cell in G1?

Answer 35

0. G1 precedes DNA replication so chr are ss.

Question 36

Mosquitoes n=3. How many chromosomes are in Prophase I?

Answer 36

6. Prophase I is diploid.

Question 37

Mosquitoes n=3. How many chromatids are in Prophase I?

Answer 37

12. Diploid and double-stranded.

Question 38

Mosquitoes n=3. How many sets of chromosomes are in a cell in Metaphase I?

Answer 38

2. Diploid so 2 of each types, do 2 sets.

Question 39

Which features are present in Metaphase & Metaphase I?

Answer 39

DS chromosomes, homologous chromosomes, spindle fibers, kinetochores and centrosomes.

Question 40

Which features are present in Metaphase I & Metaphase II?

Answer 40

DS chromosomes, spindle fibers, kinetochores and centrosomes.

Question 41

During which phase do chromosomes align at the center of the cell?

Answer 41

In Metaphase & Metaphase II. Not in Metaphase I: tetrads align at the center.

Question 42

During which phase is the ploidy level 2n?

Answer 42

G1, G2, Prophase, Prophase I, Metaphase, Metaphase I, Anaphase I & II.

Question 43

During which phase are homologous chromosomes present?

Answer 43

G1, G2, Prophase, Prophase I, Metaphase, Metaphase I.

Question 44

Define phenotype.

Answer 44

Observable characteristic, appearance (e.g. blue eyes).

Question 45

Define genotype.

Answer 45

Combination of alleles and genes (e.g. GG).

Question 46

Define locus.

Answer 46

Position/location of a gene on a chromosome/homologues.

Question 47

Define allele.

Answer 47

Alternative versions of a gene.

Question 48

What is a dominant allele?

Answer 48

Fully expressed in the heterozygote (capital letter).

Question 49

What is a recessive allele?

Answer 49

Not observable in phenotype of heterozygote (lower case letter).

Question 50

What is a heterozygous?

Answer 50

2 different alleles.

Question 51

What is a homozygous?

Answer 51

Homozygous dominant: 2 same dominant alleles. | Homozygous recessive: 2 same recessive alleles.

Question 52

What are the probable locations of eye colour alleles on chromosomes of Gg individuals in metaphase?

Answer 52

G and g must be on homologous chromosomes. 1 chromosome has G on each chromatid and 1 chromosome has g on each chromatid (because the 2 sister chromatids are identical).