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biology 30 > Cell division > Flashcards

Cell division Flashcards

1
Q

What three things do we need cell division for

A
  1. growth (need more cells)
  2. repair (cells need to be replaced)
  3. reproduction (unicellular organisms use mitosis to reproduce asexually)
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2
Q

what is the SA vs V ratio of growing cells

A

when a cell grows, the volume of the CYTOPLASM grows at a faster rate than the sa of the PLASMA MEMBRANE

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3
Q

somatic cells

A

body cells. any cell in the body other than reproductive cells

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4
Q

how many chromosomes do humans have and how many from each parent

A

46 chromosomes, 23 from each parent

every cell has the same 46 chromosomes

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5
Q

difference between the splitting of organelles vs chromosomes

A

organelles can be randomly separated into daughter cells

chromosomes must split even;y so each daughter cell gets exactly same DNA

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6
Q

homogolous chromosomes

A

chromosome pairs containing maternal and paternal chromatid similar in length, position, and joined together at the centromere (belt)

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7
Q

autosomes. how many are there

A

22 pairs of chromosomes all ppl share.

the last one would be sex chromosome (XX female or XY male)

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8
Q

diploid, haploid, polyploidy

A

diploid (2n)- all pairs of chromosomes (humans-46)
haploid (n)- in gametes (humans-23)
polyploidy (3n,4n,5n…) sets of more than 2 homogolous chromosomes

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9
Q

what are benefits of polyploidy 4

A
  • more vigorous and healthy than diploid parents
  • offspring shielded from negative effects off recessive mutations cus it has twice as many copies of genes.
  • gene redundancy gives organism ability to diversify gene function over time. extra gene copies that arent used normally are used in new ways leading to new opportunities in evolutionary selection
  • self fertilization, favoring asexual reproduction. may improve fitness in stable environments
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10
Q

what is critical in oganisms with more chromosomes

A

the ability of homologs to find one another, pair, and stay together during the first meiotic division

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11
Q

spindle fibres

A

protein strands that attach to the centromere and pull chromatids to opposite ends of the cell

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12
Q

centriole

A

found only in animal cells and provide attachment for spindle fibres

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13
Q

what are the 2 different states chromosomes are in before and after they REPLICATE their dna

A

before:
one chromatid

after:
2 sister chromatid

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14
Q

what is the support protein that holds together the chromatid’s DNA called

A

histones

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15
Q

chromatin

A

the things that make up chromosomes. they are strands of DNA

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16
Q

karyotype

A

each chromosome has specific length and banding pattern, so they are matched up in a karyotype

look at sex chromosomes first and then check all pairs of autosomes

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17
Q

cell cycle phases

A

I PMAT
interphase
prophase
metaphase
anaphase
telophase

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18
Q

3 phases of interphase

A

g1- rapid growth
s- duplication of chromosomes (doubling DNA)
g2- grows and prepares to divide

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19
Q

interphase use

A

spend the most time here.
grow, divide, and undergo metabolic processes

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20
Q

prophase

A

chromosomes condense, proteins (histones) attach to the dna to shorten it to a chromosome

  • nuclear envelope disappears
  • centrioles move to opposite ends of cell
  • spindle fibres made of microtubules start to form, growing out of centrioles toward chromosomes
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21
Q

metaphase

A

short resting period where chromosomes line up on equator of cell and spindle fibers attach to centromeres

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22
Q

anaphase

A

centromeres divide. individuals go from
1 chromosome 2 chromatid
2 chromasome 1 chromatid EACH

spindle fibers contract, chromosomes pulled to positive poles, toward centrioles

each end of pole has one set of chromosomes (1 pair)

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23
Q

telophase

A

chromosomes at poles of spindle
chromosomes unwind
spindle disintegrates
nuclear envelope reforms around two sets of chromosomes and
cytoplasm divided into 2 separate cells

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24
Q

cytokinesis

A

organelles other than chromosomes divide into 2 daughter cells passively. they go w whichever cell they find themselves in

plant and animal cells divide cytoplasm differently

interphase again

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25
what are two differences between animal and plant cells in mitosis
animal: cleavage furrow. cytokinesis occurs by CONSTRICTION of microtubules plant: cytokinesis occurs by growth of cell plate of cellulose animal: has centrioles and involves spindle formation plant: lack centrioles
26
what happens in cytokinesis specifically in animal cells
ring of ACTIN FIBERS (microfilaments are composed of actin) forms around cell equator and contacts, pinching the cell in half
27
what happens in cytokinesis specifically in plant cells
new cell wall made of cellulose forms between two nuclei
28
max amount of cell divisions before cells die
50
29
cell division is stopped by cell what?
cell specialization
30
only what two kinds of cells casn divide endlessly
cancer and spermatogonia cells
31
meisosis
cell division to form gametes, sperm and egg
32
are gametes diploid, haploid, or polyploid
haploid. one copy of every gene. need to choose 1 copy of each gene randomly
33
what happens to good and bad combinations of alleles between parents and offspring in gametes?
bad combinations die without reproducing and good combinations survive to reproduce more
34
alleles
one of two or more alternative forms of a gene that are created by MUTATION and are found at the same place on a chromosome
35
gene
section of the chromosome that codes for a protein
36
meiosis overview
starts with homologues XX separate homologues X X separate chromatids II II
37
key outcomes of meiosis 2
1. reduction division, daughter cells have fewer chromosomes 2. recombination, daughter cells have diff comb of genes
38
what are two important events that cause variations in MEIOSIS 1
crossing over in prophase //// \\\\ >> ///\ \\\/ random pairing of homologues in metaphase 1st possibility: // // \\ \\ 2nd: /\ /\ \/ \/
39
crossing over
replicated homologous pair of chromosomes come together (in synapsis) and sections of chromosomes are exchanged. creates new combinations of alleles on each chromosome chromosomes neither entirely paternal or maternal but contains genes from both parents occurs randomly several times on every chromosome results in mixing of genes inherited from parents
40
how does crossing over contribute to genetic diversity
crates new combinations of genes in gametes that are not found in either parent (blue x blue = brown eyes)
41
independent assortment
alleles of 2 diff genes get assorted into gametes independent of each other // // \\ \\ or /\ /\ \/ \/
42
prophase 1
each pair of homologous chromosomes align side by side (synapsis/crossing over)
43
what is a tetrad in prophase 1
2 chromasomes next to each other (or 4 chromatids) that have crossed over, created in prophase 1. chromosomes have different alleles.
44
homologous chromosomes
chromosomes that have same genes but diff order. after crossing over
45
metaphase 1
pairs of homologous chromosomes line up side by side independent assortment occurs here.
46
anaphase 1
instead of the centromeres breaking apart, the chromatids stay together. spindle fibers shorten and separate homologous chromosomes from one another.
47
results of meiosis 1
go from 1 to 2 cells. each daughter cell contains 1 copy of EACH CHROMOSOME humans: 2 cells containing 23 chromosomes as a result of crossing over ,each chromosome is the mixture of original homologues.
48
interkinesis
in some species. cells enter a brief interphase, or interkinesis, before entering meiosis 2 lacks S phase, so chromosomes are not duplicated. (replicates DNA to make two sister CHROMATIDS)
49
difference and similarities between meiosis II and mitosis
meiosis is jusst like mitosis except there is no dna replication before it begins each cell is a haploid in meiosis II
50
prophase Ii
if the chromosomes decondensed in telophase I, they will condense again centrioles that were duplicated during interkinesis move away from each other toward opoositte poles and new spindles are formed.
51
metaphse I and Ii comparison
I- homologous chromosomes PAIR at equator II- chromosomes line up and chromatids split I: -XX- -xx- II: -X- -x-
52
anaphase I and II comparison
I- homologous chromasomes seperate II- chromatids seperate
53
telophase ii
chromosomes arrive at opposite poles and decondense nuclear envelopes form around chromosomes cytokinesis separates two cells into four unique haploids newly formed nuclei are both haploid (one chromatid per chromosome) (diploid: XX (pair) haploid: II(different chromosomes))
54
telophase I and II comparison
I- haploid cell, chromatids still attached II- haploid cells, 4 unique cells produced (chromatids no longer attached)
55
summary of meiosis
- 2 cell divisions - start w 2 copies of each chromosome (homologues), each w 2 chromatids - meiosois 1: crossing over in prophase and mixing alleles between homologues - ends with 4 cells, each having a copy of each chromosome with 1 chromatid each
56
in male animals, what do all 4 products of meiosis develop into
sperm cells
57
each sperm is a diploid/haploid/polyploid with _____ number of chromosomes
each sperm is haploid with 23 chromosomes
58
oogenesis
formation of female gametes cell division of meiosis are asymmetric in female cells, most of cytoplasm goes into 1 out of the 4 meiotic products, which becomes the egg. other 3 are small "polar bodies" which degenerate
59
nondisjunction
failure of homologous chromosomes or sister chromatids to separate during meiosis produces gametes that have too many or too few chromosomes (n+1 or n-1)
60
disorders due to nondisjunction
zygote w 45 chromosomes has only one copy of particular chromosome: MONOSOMY zygote w 47 chromosomes has three copies of particular chromosome: TRISOMY *only humans
61

biology 30 (2 decks)

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