cell cycle and cell division (mitosis and meiosis)

Question 1

differentiate between asexual reproduction and sexual reproduction

Answer 1

asexual: produces offspring genetically identical to the one parent
sexual: combining genetic material from 2 parents

Question 2

define chromosome

Answer 2

carries genetic information in the form of genes

Question 3

define homolog/homologous

Answer 3

same features and patterns of genes

Question 4

define diploid

Answer 4

containing two complete sets of chromosomes, one from each parent

Question 5

define somatic cell

Answer 5

any part of the body cell

Question 6

define haploid

Answer 6

having a single set of unpaired chromosomes

Question 7

gamete cell

Answer 7

germ cell (egg, sperm)

Question 8

what are the subphases of interphase, and what happens at each?

Answer 8

G1: gap 1, growth, cell carries out typical function
S: synthesis, DNA replication
G2: gap 2, growth, prep for cell division

Question 9

identify pictures of and explain the processes that occur in:

• prophase
• prometaphase
• metaphase
• anaphase
• telophase

Answer 9

• Prophase: chromosomes condense, DNA wrapped up around histone proteins, chromosomes become visible/distinct
• prometaphase: nuclear envelope breaks down, kinetochore microtubules attach to the chromosomes
• metaphase: chromosomes line up in the middle at the equatorial plate
• anaphase: sister chromatids separate, chromosomes are pulled toward the centrosomes
• telophase: chromosomes at opposite poles, nuclear envelope reforms around each set of chromosomes, chromosomes de-condense, spindle microtubules disassemble, 2 nuclei in one cell

Question 10

identify the structures found in sister chromatids:

• the individual chromatid
• centromere
• kinetochore proteins

Answer 10

see notebook for diagram
the individual chromatid is one half of the sister, the centromere is were the 2 chromatids are held together (the middle), the kinetochore proteins are what attach to the centromere

Question 11

explain role of centrosomes in the mitotic spindle apparatus

Answer 11

the 2 poles, where the chromosomes move to

Question 12

explain role of centrioles in the spindle

Answer 12

cylinders of microtubules, in centrosomes

Question 13

explain role of microtubules in spindle

Answer 13

make up the cylinders of the centrioles, makes up cytoskeletal structure

Question 14

explain role of tubulin in spindle

Answer 14

makes up cytoskeletal structures, and microtubules

Question 15

explain role of kinetochore microtubules in spindle

Answer 15

attach to kinetochore proteins and pull sister chromatids apart

Question 16

explain role of polar microtubules in spindle

Answer 16

pushes 2 poles apart

Question 17

what are differences in the process of cytokinesis as it occurs in animal cells and plant cells?

Answer 17

in animals: contractive ring: microfilaments (made of actin protein) and myosin (motor protein that walks on microfilaments) pinches membrane until it separates

in plants: cell plate: formed by vesicles from golgi, vesicles delivered to center of cell by kinesin

Question 18

explain the role of cyclin-dependent kinases (CDKs) in the cell cycle. what does the kinase do? when is it present in the cycle? what does the cyclin do? when is it present in the cycle?

Answer 18

adding phosphate groups to target proteins. the kinase is always present, not always active. its activity is allosteric regulation. the cyclin is not always present. it binds and activates kinases

Question 19

what are the differences between mitosis and meiosis

Answer 19

Meiosis has two rounds of genetic separation and cellular division while mitosis only has one of each. In meiosis homologous chromosomes separate leading to daughter cells that are not genetically identical. In mitosis the daughter cells are identical to the parent as well as to each other.

Question 20

identify pictures of and explain the processes that occur in meiosis I

Answer 20

prophase I: chromosomes condensing, spindle forms
-synapsing: homologous chromosomes pair up/bind to each other
-crossing over: recombination/exchange of DNA
prometaphase I: same as mitosis except kinetochore MTs attach to a sister chromatid from one pole only
metaphase I: a double row of chromosomes lined up at the equatorial plate, arrangement of maternal and paternal chromosomes on either side of the plate is random
anaphase I: chromosomes will be split, centromeres are not broken, the synapses are broken
*independent assortment: random distribution of maternal/paternal chromatids at each pole (dodgeball)
telophase I/cytokinesis: same as mitosis

Question 21

identify pictures/explain processes of meiosis II

Answer 21

everything same as mitosis

**note that in anaphase II, centromeres ARE broken

Question 22

what is the final result of meiosis

Answer 22

4 daughter cells each with one copy of each chromosomes

Question 23

describe 2 ways in which DNA is shuffled in meiosis in order to create genetic diversity in the resulting gametes

Answer 23

independent assortment: random distribution of maternal/paternal chromatids at each pole (dodgeball) 8 mil. possibilities
crossing over: increases the level of DNA shuffling

Question 24

what is nondisjunction?

Answer 24

lack of separation

Question 25

define aneuploidy

Answer 25

odd number of chromosomes

Question 26

explain how trisomy arises

Answer 26

having an extra chromosome in gamete

Question 27

explain how monosomy arises

Answer 27

missing a chromosome in a gamete