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Biology 30 > Chap 17: Cell Division > Flashcards

Chap 17: Cell Division Flashcards

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1
Q

What is interphase?

A

it occurs between cell divisions. normal cell prepares for the mitotic phase. 90% of the cell cycle. unable to see chromosome

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2
Q

What is the G1 phase?

A

growth before division.

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3
Q

What is the S phase?

A

synthesis (S phase) replication of DNA.

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4
Q

What is the G2 phase?

A

prepares for cell division.

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5
Q

What do mitotic divisions consist of?

A

it consists of prophase, metaphase, anaphase, and telophase.

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6
Q

Why do cells divide?

A

to repair, grow and replace cells

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7
Q

What is a chromosome?

A

made of nucleic acids (DNA) and proteins.

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8
Q

What is an uncondensed chromosome?

A

long, thin strands that cannot be seen under a light microscope (interphase)

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9
Q

What is a condensed chromosome?

A

can be seen under a light microscope (prophase)

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10
Q

What is a chromatid?

A

1 of two copies of a replicated chromosome. joined together in the center by a chromosome

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11
Q

What is binary fission?

A

asexual reproduction. “mother” cell divides into 2 identical “daughter” cells. occurs in bacteria (prokaryotes)

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12
Q

What happens during mitosis?

A

double-stranded chromosomes become single-stranded. each daughter cell gets one of the single-stranded pairs. the cell uses single strands of DNA to build a complementary strand.

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13
Q

What is the purpose of mitosis?

A

to replace worn-out cells with new ones, production of body cells and tissue growth.

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14
Q

How do cells prepare themselves for mitosis?

A

new cell membranes, producing enzymes for chemical reactions and control duplication of DNA

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15
Q

What is chromatin?

A

combination of DNA and proteins. the form of chromosomes found during interphase

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16
Q

What happens during prophase?

A

chromosomes form from threadlike chromatin and they condense.
2 identical chromatids are joined at the centromere. centrioles move to opposite sides of the nucleus and provide attachment for spindle fibres.
nuclear membrane and nucleolus disintegrate

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17
Q

What happens during metaphase?

A

chromosomes with two chromatids (sister chromatids) line up at the equator.
spindle fibres attach to the centromere.
most visible stage

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18
Q

spindle apparatus

A

spindle fibers + centrioles

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19
Q

What happens during anaphase?

A

centromeres split and spindle fibres shorten one chromatid from each pair moves to opposite poles; now is called a chromosome

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20
Q

if chromatids do not separate and both move to the same pole of the diving cell, this is called:

A

nondisjunction

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21
Q

What happens during telophase?

A

spindle fibres disappear
chromosomes unwind/uncoil
two new nuclei form around each set of genetic material

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22
Q

cytoplasm begins to divide by forming a cleavage furrow at the equator. 2 daughter cells separate.

A

cytokinesis

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23
Q

why do cells stop dividing?

A

senescence and cell specialization

24
Q

What is senescence?

A

process of aging

25
Q

the more specialized a cell

A

the less able it is to undergo mitosis

26
Q

what 2 cell types in a human body escape aging?

A

sperm-producing cells, and cancer cells

27
Q

What is cancer?

A

uncontrolled cell growth and division.

28
Q

What are identical twins?

A

originate from a single cell
during mitosis (after fertilization) one of the cells breaks free and a 2nd embryo develops
same gender, blood type and similar facial structures

29
Q

What are fraternal twins?

A

originate from 2 different eggs and are fertilized by different sperm cells
don’t have the same genes

30
Q

What is cloning?

A

production of genetically identical organisms derived from a single individual by asexual means

31
Q

How does plant cloning technology work?

A

can be done through grafting, cuttings, and runners.
have predictable characteristics
undergoes mitosis to increase in size, and specializes to form roots, stems or leaves

32
Q

What are the 6 steps to clone a frog?

A
  • nuclear transplant, extracts the nucleus from an unfertilized egg cell (n)
  • cell is enucleated
  • insert a nucleus from a cell of another frog (2n)
  • egg cell with a transplanted nucleus divides normally and grows into an adult frog
  • an adult is a clone of the frog that donated the nucleus
33
Q

What is a somatic cell?

A

all body cells except sex cells, diploid cells (2n)

34
Q

What does totipotent mean?

A

describes a cell that is able to bring a cell to turn into any type of cell (STEM cells)

35
Q

What is a telomere?

A

caps at the ends of chromosomes. reduce in length each time a cell goes through a cell cycle and divides

36
Q

What is telomerase?

A

an enzyme that affects the length of the telomere. not present in most normal cells.

37
Q

what is the goal of meiosis?

A

cell reduction

38
Q

what are the benefits of sexual reproduction?

A
  • genetic variation
  • 2 sets of chromosomes, can act as back-up
  • repair mechanisms
39
Q

what are the disadvantages of sexual reproduction?

A
  • costly/lots of energy
  • infection possibility
  • only passes on half of our genes to offspring
40
Q

ova (eggs), sperm cells. are the only cells in the body NOT produced by mitosis.

A

gametes

41
Q

where does meiosis occur?

A

in germ cells of gonads (reproductive organs)

42
Q

46 chromosome number is

A

diploid (2n)

43
Q

23 chromosome number is

A

haploid (n)

44
Q

paired chromosomes are:

A

homologous chromosome

45
Q

meiosis
2 cell divisions produce

A

4 haploid cells

46
Q

What happens in prophase 1 (5 points)

A
  • chromosomes form homologous pairs which form tetrads (2 pairs of joined chromatids)
  • joining of these chromosomes is called synopsis
  • crossing over (exchange of genetic material) occurs and genetic info is switched; genes aren’t lost - they are recombined with genes from the other chromatids
  • nuclear membrane disappears
  • centrioles move apart
47
Q

What happens in metaphase 1?

A
  • homologous chromosomes (tetrads) attach themselves to spindle fibres and line up along the equatorial plate. (HINT: if u see double dating, its meiosis)
48
Q

What happens in anaphase 1? (4 points)

A
  • homologous chromosomes move toward opposite poles.
  • segregation - reduction division occurs. joined chromatid pairs of each tetrad pulled to opposite poles
  • chromatids do NOT separate yet
  • each chromosome remains double stranded
49
Q

What happens in telophase 1? (4 points)

A
  • chromosomes form chromatin by unwinding/uncoiling
  • nuclear membranes reappear
  • cytokinesis begins
  • 2 daughter cells with a haploid number
50
Q

What happens in meiosis 2?

A

occurs at approximately the same time in each haploid daughter cell. NO S phase, NO duplication of DNA

51
Q

What happens in prophase 2? (3 points)

A
  • nuclear membrane dissolves
  • spindle fibres begin to form
  • chromosomes appear
52
Q

What happens in metaphase 2? (2 points)

A
  • arrangement of chromosomes, each with 2 chromatids, along an equatorial plate (Single File)
  • chromatids remain pinned together by a centromere
53
Q

What happens in anaphase 2? (2 points)

A
  • the movement of sister chromatids to opposite poles
  • nuclear membrane begins to form around chromosomes
54
Q

What happens in telophase 2?

A
  • 2nd division of cytoplasm is completed
  • nuclear membranes reform
  • four haploid daughter cells are produced
55
Q

are gametes haploid or diploid?

A

haploid

56
Q

What happens in spermatogenesis? (2 points)

A
  • production of sperm which occurs in the seminiferous tubules of the male testes
  • sperm cells receive equal amounts of cytoplasm
57
Q

What happens in oogenesis?

A
  • production of an egg by the female which occurs in the ovaries
  • one cell (out of the 4 produced) receives most of the cytoplasm while the smaller ones form polar bodies that degenerate

Biology 30 (3 decks)

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