Lecture 4b BIO 120

Question 1

what is meiosis

Answer 1

Halves the number of chromosomes
i.e. diploid-haploid

Question 2

BIVALENT?

Answer 2

one pair of chromosomes(homologous chromosomes) in a tetrad.

Question 3

Tetrad?

Answer 3

association of a pair of homologous chromosomes(4 sister chromatids)held together physically by at least one dan crossover.

Question 4

crossing over?

Answer 4

GENETIC RECOMBINATION-meiosis-novel forms.

Question 5

chiasmata

Answer 5

X shaped structure formed due to point of contact b/w paired chromatids during prophase I

Question 6

where does exchange of genetic material occurs b/w strands of chromatids during prophase I?

Answer 6

chiasmata

Question 7

what is known as the mixing of genetic material from diff strands of DNA?

Answer 7

Recombination

Question 8

synapsis

Answer 8

pairing of homologous chromosomes

Question 9

why does the chromosomes remain bound during synapsis?

Answer 9

due to exchange of genetic info

Question 10

what aids in forming the connection during synapses and what is it structure?

Answer 10

SYNAPTONEMAL COMPLEX(protein and RNA structure)

Question 11

what are the two sets of cell division in meiosis?

Answer 11

MEIOSIS I AND MEIOSIS II

Question 12

How many chromosomes are present in daughter cells during meiosis as the parent cell

Answer 12

half

Question 13

what happens in the first cell division (MEIOSIS I)

Answer 13

Homologous chromosome separate and it results in 2 haploid daughter cells with replicated chromosomes.

Question 14

what happens in second cell division(meiosis II)

Answer 14

1.Separated replicated chromosomes(sister chromatids) into single chromosomes.
2.cell are already HAPLOID.

Question 15

what happens in interphase of meiosis I?

Answer 15

Chromosomes are replicated to form sister chromatids.

Question 16

what happens to the centrosome in interphase for meiosis I?

Answer 16

replicates, forming 2 centrosomes

Question 17

What are the 4 phases of MEIOSIS I?

Answer 17

PROPHASE I
METAPHASE I
ANAPHASE I
TELOPHASEI

Question 18

which stage of meiosis I occupies 90% of the meiosis?

Answer 18

PROPHASE I

Question 19

what happens in PROPHASE I

Answer 19

Chromosome condenses, synapsis ,crossing over, tetrad formation

Question 20

how Many chiasmata does each tetrad has?

Answer 20

one or more

Question 21

what happens in METAPHASE I?

Answer 21

tetrads lined up along the mid-region (metaphase plate)

Question 22

In what phase of meiosis I does homologous chromosome separate?

Answer 22

Anaphase I

Question 23

What happens in ANAPHASE I of meiosis I?

Answer 23

homologous chromosome separate, move to the opposite poles with the help of spindle apparatus

Question 24

what happens at beginning of telophase 1?

Answer 24

each half of cell-haploid set of chromosomes, each chromosome still has 2 sister chromaticds

Question 25

how does cytokinesis occurs in meiosis I?

Answer 25

simultaneously of telophase 1: forming 2 haploid daughter cells

Question 26

formation of what takes place in animal and plant cells during cytokinesis?

Answer 26

animal cells-cleavage furrow formation plant cells-cell plate formation

Question 27

no __________ occurs b/w end of meiosis i and beginning of meiosis ii because the chromosomes are already ______?

Answer 27

chromosome replication, replicated

Question 28

PLOIDY?

Answer 28

Number of set of chromosomes Haploid=n diploid=2n=homozygous chromosomes

Question 29

haploid number of chromosomes in the human body?

Answer 29

gametes

Question 30

when is a replicated chromosome formed?

Answer 30

when.a single chromosome undergoes DNA synthesis

Question 31

What is a genotype?

Answer 31

genetic makeup of an individual cell or organism

Question 32

is DNA duplicated during meiosis I?

Answer 32

no, interphase

Question 33

where does meiosis occurs in animals or humans?

Answer 33

production of gametes ovary or testes

Question 34

What happens in prometaphase II?

Answer 34

Nuclear envelope starts disntegrating,spindle microtubules attach to the centromere

Question 35

what processes take place in TELOPHASE I?

Answer 35

replicated chromosomes arrive at pole and begin to uncoil,nuclear envelope reappears, spindle apparatus disappears, cytokinesis begins.

Question 36

Does DNA replication occurs in MEIOSIS II?

Answer 36

no

Question 37

is their s phase between meiosis I AND II

Answer 37

NO

Question 38

What is interkinesis

Answer 38

interphase like stage that occurs between meiosis I and II unlike interphase it has no DNA replication and is for a very short period of time.

Question 39

are the sister chromatid in metaphase II genetically identical or variable?why or why not?

Answer 39

genetically variable because of crossing over in MEIOSIS I

Question 40

What is the end result of meiosis II?

Answer 40

4 daughter cells, each with a haploid set of unreplicated chromosomes

Question 41

what are the 3 events unique in meiosis than mitosis?

Answer 41

1.synapsis and crossing over in prophase I-physically connect and exchange genetic info 2.at the metaphase plate their are homologous chromosomes(tetrads) instead of individual replicated chromosomes(sister chromatids) 3.at anaphase I, homologous chromosomes instead of sister chromatids that are separated and carried out to diff poles.

Question 42

what is meiosis II similar with?

Answer 42

Mitosis