cell division

Question 1

cell cycle

Answer 1

• mitotic phase and interphase alternate
• highly regulated
• checkpoints determine fate of cell

Question 2

interphase

Answer 2

• gap 1 = cell growth
• S = DNA double
• centrioles double
• gap 2 = cell growth and preparation for division, longest phase of cell cycle

Question 3

checkpoints

Answer 3

internal and external signals provide stop and go signals at checkpoints

Question 4

cyclins

Answer 4

cyclins and cyclin dependent kinases control the cell cycle

Question 5

IE Mitosis promoting factor

Answer 5

• triggers mitosis in somatic cells and egg maturation
• works best with high cyclin levels
• MPF is a complex: cyclin dependent kinase and cyclin B
• this complex phosphorylates proteins needed for mitosis

Question 6

checkpoint failure

Answer 6

• causes mutations and genomic arrangements resulting in genetic instability
• genetic instability is a major factor of birth defects and in development of many diseases, notably cancer

Question 7

mitosis

Answer 7

• division of the nucleus of diploid (2n) somatic cells

- asexual reproduction, growth, repair

Question 8

stages of mitosis

Answer 8

• replication, alignment, separation

- rate depends on cell type

Question 9

binary fission

Answer 9

• cell division of prokaryotes
• DNA doubles
• cell elongates
• cell splits in half

Question 10

differentiation

Answer 10

creates daughter cells that are different from parent

Question 11

specialized cells and cell division

Answer 11

when a cell specializes it often enters a stage where it can no longer divide. it can reenter the cell cycle when proper cues are given but some don’t

Question 12

G0

Answer 12

• takes place after G1
• cells get stuck and never return to the cell cycle
• cells of the CNS

Question 13

cytokinesis

Answer 13

• plant cells = cell plate

- animal cells = cleavage furrow

Question 14

Meiosis

Answer 14

• makes sexual reproduction possible
• creates diversity
• haploid (n) gametes are produced from germ cells
• nuclear division of gametes
• rate varies with gender (egg cells take decades to mature)

Question 15

homologous chromosomes

Answer 15

• 2 of each chromosome exist in each cell (except gametes)
• they are identical in types/location of genes
• 1 set from mom and 1 set from dad

Question 16

orientation of chromosomes in meiosis

Answer 16

random, ensuring a mix of genes in gametes

Question 17

fertilization

Answer 17

• fusion of gametes
• increases variation
• restores diploid number

Question 18

zygote

Answer 18

first cell formed after fertilization

Question 19

what is the point of meiosis I?

Answer 19

• crossing over

- chromosomes reduced to 23 duplicated chromosomes

Question 20

what is the point of meiosis II?

Answer 20

to turn 23 duplicated chromosomes into 23 unduplicated chromosomes

Question 21

what triggers cell to divide?

Answer 21

• size
• demand (sperm/muscle)
• DNA signal
• cancer/damaged DNA

Question 22

what stops cell division?

Answer 22

• DNA signal
• cells touching borders
• death
• demand changes
• gametes

Question 23

Hayflick limit

Answer 23

• number of times a cell can divide before it dies
• ~50
• telomeres get shorter with each cell division, when telomeres are gone cell dies (the ends kind of unravel)
• this is why we age and die

Question 24

telomerase

Answer 24

prevents the unraveling of telomeres and can lengthen them

Question 25

HeLa cells

Answer 25

- some cancer cells produce telomerase so they are essentially immortal - Henrietta Lacks' cells are used for research because they don't die

Question 26

HeLa cells have been used for

Answer 26

- cancer - AIDs - effects of radiation and toxic substances - gene mapping