Generating Diversity III

Question 1

What are the main characteristics of meiosis in animals? (4 things)

Answer 1

• diploid phase dominates
• haploid phase shortened
• meiosis is followed by gamete formation
• fertilization creates diploid cells

Question 2

What are the main characteristics of meiosis in most plants and some fungi? (4 things)

Answer 2

• similar to animals but they produce diploids called sporophytes
• spores are not gametes
• in plants, female gametophyte is in flower, males is in pollen
• sperm+egg- diploid zygote- mitosis- diploid sporophyte

Question 3

What are the main characteristics of meiosis in most fungi? (2 things)

Answer 3

• diploid phase is limited

- +/- haploids fuse- diploid nucleus- mitosis- haploid spores

Question 4

What are the characteristics of meiosis and chromosome numbers? (3 things)

Answer 4

• functions to create difference
• occurs only in specialized tissues
• one chromosome pair from the male parent, other from the female parent

Question 5

What are the 3 steps in genetic recombination?

Answer 5

1. Homologous DNA regions paired up, enzymes break bonds in backbone
2. Free ends of backbone are exchanged
3. Bonds reform

Question 6

What is genetic recombination?

Answer 6

cutting and pasting of DNA backbones into new combinations

Question 7

What is non-disjunction?

Answer 7

chromosome pairs are not separated and end up at the same pole, results in one gamete having 2 copies of a chromosome

Question 8

How random segregation contribute to genetic diversity?

Answer 8

in pro metaphase I spindles attach randomly to pairs which randomizes the DNA sent to daughter cells

Question 9

How does genetic recombinations contribute to genetic diversity?

Answer 9

synaptomal complex holds pairs together allowing them to exchange sections of DNA via enzymes end result is 2 cells with recombined alleles, 2 with parental alleles

Question 10

Where are the 4 places that genetic diversity happens?

Answer 10

1. Recombination
2. Anaphase I
3. Anaphase II
4. Fertilization

Question 11

What are the 9 stages of meiosis?

Answer 11

1. Prophase I
2. Prometaphase I
3. Metaphase I and Anaphase
4. Telophase I and Interkinesis
5. Prophase II
6. Prometaphase II
7. Metaphase II
8. Anaphase II
9. Telophase II

Question 12

What happens in Prophase I?

Answer 12

• sister chromatids condense and put in pairs through synapsis to form a tetrad
• pairs physically exchange DNA
• spindle forms

Question 13

What happens in Prometaphase I?

Answer 13

• nuclear envelope breaks down

- chromosomes attach to kinetochore, both sister chromatids attached to same spindle pole

Question 14

What happens in Metaphase I and Anaphase?

Answer 14

• tetrads aligned on metaphase plate
• homologous pairs separate and move to opposite spindle poles
• chromosomes at poles still sister chromatids

Question 15

What happens in Telophase I and Interkinesis?

Answer 15

• new nuclear envelope reforms
• spindle from first division dissemble and microtubules reassemble into new spindles for second division
• no DNA replication

Question 16

What happens in Prophase II?

Answer 16

• chromosomes condense

Question 17

What happens in Prometaphase II?

Answer 17

• nuclear envelope breaks down

- spindle microtubules connect at kinetochore on each chromosome

Question 18

What happens in Metaphase II?

Answer 18

• spindle move chromosomes to metaphase plate

Question 19

What happens in Anaphase II?

Answer 19

• sister chromatids separate and move to opposite spindle poles

Question 20

What happens in Telophase II?

Answer 20

• sister chromatids decondense, spindle disassembles, new nuuclear envelope starts to reform

Question 21

What is deamination?

Answer 21

removal of an amine group from a base, resulting in altered H-bonds

Question 22

What is UV radiation?

Answer 22

energy is absorbed by pyrimidine rings, altering bonding patterns and forming dimers

Question 23

What is oxidation?

Answer 23

energy absorbed by pyrimidine rings altering bonding patterns, forming dimers

Question 24

What is a tautomeric shift?

Answer 24

shift between constitutional isomers of bases= alternative H-bond patterns