chapter 7: cell cycle + cell division

Question 0

alternation of generations

Answer 0

most plants
meioisis->haploid spores->mitosis->gametophyte->mitosis->gametes->gametes fuse to create zygote->mitosis->diploid sporophyte
back to meiosis

Question 1

haplontic organisms

Answer 1

zygote is the only diploid cell.
once formed, meiosis->haploid cells, usually spores
spores are germinated to form new haploid organism

Question 2

diplontic organisms

Answer 2

gametes are the only haploid cells

mature organism is diploid

Question 3

sexual reproduction

Answer 3

random selection of half of the diploid chromosome set to make a haploid gamete
then diffusion of haploid gametes from separate parents to form diploid cell

Question 4

segregation

Answer 4

• part of cell division where replicated dna is distributed to the two new cells
• ori regions move to opposite ends of cell
• active process

Question 5

cell division

Answer 5

1. reproductive signal
2. replication of dna
3. segregation of dna
4. cytokinesis

Question 6

binary fission

Answer 6

cell division in prokaryotes

Question 7

prokaryotic chromosome

Answer 7

ori: origin of replication site
ter: termination site of replication

Question 8

mitosis, then cutokinesis

Answer 8

• cell division in eukaryotic cells
• requirements:
  1. replication of dna
  2. segregation of dna, then mitosis
  3. cytokinesis

Question 9

interphase

Answer 9

g1 (g0). s, g2 phases

Question 10

prophase

Answer 10

• first stage of mitosis
• condensed chromosomes
• centrosome (determines spatial relationship of two new cells)
• spindle

Question 11

kinetochores

Answer 11

• specialized proteins on the centromeres of sister chromatids that help with movement
• are involved withe condensed chromosomes during prophase

Question 12

karyotype

Answer 12

number and size of condensed chromosomes

can identify organisms by it

Question 13

prometaphase

Answer 13

nuclear envelop breaks down

Question 14

metaphase

Answer 14

chromosomes line up at midline of cell, equatorial position

Question 15

anaphase

Answer 15

chromatids separate and daughter chromosomes move away from each other toward poles

Question 16

polar microtubules

Answer 16

• form framework of spindle

- from pole to pole, keepinf them apart

Question 17

kinetechore microtubules

Answer 17

• become attached to sister chromatids from opposite sides of cell
• acts as molecular motor, pulling them away from each other toward poles

Question 18

telophase

Answer 18

nuclear envelope forms around each new set of chromosomes

—>two new nuclei in cell

Question 19

contractile ring

Answer 19

furrow of cytokinesis in animal cells, pinching the cell in two

Question 20

cell plate

Answer 20

beginning of new cell wall during cytokinesis of plants

Question 21

growth factors

Answer 21

signal to stimulate cell division/differentiation in eukaryotic cells

Question 22

cyclin-dependent kinase

Answer 22

-enzyme that regulates cell cycle

growth factor->cyclin synthesis->cdk activation-> cell cycle events

Question 23

functions of meiosis

Answer 23

• reduce chromosome number from diploid to haploid
• ensures haploid products have complete set of chromosomes
• genetic diversity

Question 24

meiosis 1

Answer 24

• homologous chromosomes come together and line up
• homologous chromosome pairs separate, but the individual chromosomes (each consisting of 2 sister chromatids) remain intact

Question 25

meoisis 2

Answer 25

separates sister chromatids

result: 4 genetically different cells

Question 26

crossing over

Answer 26

• chiasma=points at which homologous chromosomes are attached
• genetic marerial is exchanged
• results in recombinant chromatids (genetic variation)

Question 27

independent assortment

Answer 27

• different possibilities of lineup at metaphase 1

- total chance for which homologous pair goes to which daughter cell

Question 28

nondisjunction

Answer 28

-meiotic error where homologous chromosome pair fails to separate in anaphase 1 or chromatids dont separate in anaphase 2

Question 29

aneuploidy

Answer 29

when nondisjuntion causes trisomy (having extra chromosome) or monosomy (missinf chromosome)

Question 30

polyploidy

Answer 30

• meiotic error when triploid, tetraploid, or higher order polyploid nuclei form
• can occur if there is an extra round of dna replication or no spindle formation
• occurs naturally in some animals, leads to speciation

Question 31

translocation

Answer 31

• meiotic error when chromatids from homologous chromosomes pairs break and rejoin
• changes location of genes relative to other dna sequences

Question 32

necrosis

Answer 32

• when cells are damaged by mechanical means or starved of nutrients
• cells swell and burst

Question 33

apoptosis

Answer 33

• genetically programmed series of events that cause cell death, aka cell suicide
• cell detaches from neighbors, hydrolizes dna into small fragments, and breaks these fragments up
• reasons:
  1. cell is no longer needed
  2. the older the cell, the more prone it is to genetic damage that could lead to cancer

Question 34

hypersensitive response

Answer 34

when plants use apoptosis to protect themselves from disease

Question 35

caspases

Answer 35

enzymes that are important to apoptosis because they hydrolyze the target molecules

Question 36

oncogene

Answer 36

• positive regulators of cell cycle in cancer cells

- stimulate cancer cells to divide more often

Question 37

tumor suppressors

Answer 37

• negative regulators of cell cycle in normal cells, but are inactive in cancer cells
• tells cell cycle to not proceed