lab 4

Question 1

what is the order of mitosis?

Answer 1

interphase (G1, S phase, G2), prophase, metaphase, anaphase, telophase, cytokenisis.

Question 2

what is the order of meiosis?

Answer 2

meiosis 1- prophase1, metaphase 1, anaphase1, telophase1.
interkinesis
meiosis 2- prophase2, metaphase2, anaphase2, telophase2, cytokinesis.

Question 3

what happens during G1, S phase, and G2?

Answer 3

G1- cell grows, preforms metabolic funcs, duplication of proteins and organelles.
S- DNA replication occurs, creation of duplicated chromosomes.
G2- cell prepares for division, gain energy to divide, and synth proteins and enzymes

Question 4

what is interphase?

Answer 4

the period between cell formation and cell div

Question 5

what is mitosis?

Answer 5

the division of the parent nucleus in which replicated DNA is distributed to two new identical daughter cells.

Question 6

what is Cytokinesis?

Answer 6

the process of dividing the cytoplasm. begins during late anaphase and continues through mitosis. A ring of actin microfilaments contracts to form a cleavage furrow until the two daughter cells are pinched apart

Question 7

explain early prophase of mitosis

Answer 7

Chromatin condenses, forming visible chromosomes which are held together by centromere.
centrosome synthesizing microtubules (mitotic spindles) push each centrosome to the opposite poles of the cell. the rest of the microtubules are called asters

Question 8

explain late prophase of mitosis

Answer 8

nuclear envelope breaks up. mitotic spindles attach to kinetochores and pull chromosomes to the centre of the cell. asters push poles farther apart

Question 9

explain metaphase of mitosis

Answer 9

centromeres align at metaphase plate (centre) by spindle fibres.

Question 10

explain anaphase of mitosis

Answer 10

centromeres of chromosomes
split simultaneously, each sister chromatid now becomes a separate chromosome. Chromosomes are pulled toward their respective poles by kinetochores.
this is the shortest phase.

Question 11

explain telophase of mitosis

Answer 11

Each set of chromosomes at opp poles uncoil to form chromatin. New nuclear membranes form, nucleoli reappear and spindle fibers disappear.

Question 12

what is the function meiosis?

Answer 12

the production of gametes, introduces genetic variability, and reduces the number of chromosomes, resulting in 23 chromosomes in gametes

Question 13

what is a diploid cell? haploid?

Answer 13

dip- 2n, 46 chrom, most cells
hap- n, 23 chrom, gametes have this so they can combined w someone elses

Question 14

how many cells at the end of meiosis? how many times does DNA replicate?

Answer 14

ends with 4 genetically diff daughter cells DNA replicates only once

Question 15

explain prophase 1

Answer 15

starts w diploid cells. duplicated chroms coil, shorten and become visible as individuals. centrosomes move to opp poles of cell, spindal fibers and astral rays appear and nucleoli and nuclear mem disappear.

Question 16

what 2 ways introduce genetic variability?

Answer 16

crossing over- is the exchange of genetic material between homologous chromatids which the place where it happens is called the chiasmata, this makes them all unique, during prophase 1
independent assortment- how the 23 pairs of chromosomes align and are pulled apart, during metaphase 1

Question 17

explain anaphase 1

Answer 17

each tetrad is pulled apart towards opp poles of cell (4-2), one chromosome from each homologous pair reaches each end of the poles. chromosomes consist of a pair of chromatids held together at each centromere

Question 18

explain metaphase 1

Answer 18

tetrads line un at metaphase plate. theres a 50% chance of which way each chromosome will be pulled in either direction.

Question 19

explain telophase 1

Answer 19

nuclear mem reforms, nucleoli reform, and chromosomes gradually uncoil to become chromatin.

Question 20

what is the outcome of meiosis 1?

Answer 20

seperation of two chroms of each homologous pair. there is now two daughter cells which contain, one chromosome from homologous pair, a haploid chrom number, and chromosomes that consist of two chromatids joined at centromere.

Question 21

explain interkinesis

Answer 21

brief rest period between
meiosis I and meiosis II

Question 22

explain prophase 2

Answer 22

p-chromosomes become visible and centrioles go to opp poles. mitotic spindles attach to kinetochores and pull chromosomes to the centre of the cell. asters push poles farther apart. nuclear mem and nucleoli disappear.

Question 23

explain metaphase 2

Answer 23

each chromosome is attached at centromere. spindle fibers attached and chromatid pairs line up along metaphase plate

Question 24

anaphase 2

Answer 24

centromere of each sis chromatid pair splits and chromatids separate and are pulled to opp ends

Question 25

explain telophase 2

Answer 25

nuclear mem appears, nucleoli reappear, cytokinesis occurs

Question 26

what is the end result of meiosis?

Answer 26

4 genetically diff daughter cells that are haploid

Question 27

what are homologous chromosomes?

Answer 27

a pair of chromosomes, one maternal and one paternal that carry genes for the same traits but express them differently

Question 28

what is a chromosome?

Answer 28

condensed chromatin, composed of DNA, two sis chromatids joined at centromere

Question 29

what is a centromere?

Answer 29

links sis chromatids together, spindle fibers attach to it vid kinetochore.

Question 30

what are sister chromatids?

Answer 30

one of the two identical halves of a chromosome that has been replicated in preparation for cell division