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HL Bio > 1.6 cell division > Flashcards

1.6 cell division Flashcards

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Biology 101 flashcards
1
Q

cell division consists of…

A
  • nuclear division (karyokinesis)
  • cytoplasmic cleavage (cytokinesis)
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2
Q

what are the two types of nuclear division?

A

mitosis and meiosis

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3
Q

briefly, what is the process of mitosis?

A
  • process where a cell nucleus divides to produce 2 daughter nuclei that are genetically identical to the parent cell
  • accompanied by cytokinesis to produce 2 genetically identical daughter cells
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4
Q

what are the objectives of mitosis (2, short)

A
  1. double the no. of nuclei
  2. maintain genetic stability
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5
Q

which type of nuclear division produces genetically identical daughter cells?

A

mitosis

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6
Q

does mitosis or meiosis produce haploid daughter cells?

A

meiosis

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7
Q

briefly, what is the process of meiosis?

A
  • a process where 4 genetically different haploid nuclei is produced from a diploid nucleus
  • involves 2 consecutive divisions
  • each division accompanied by cytokinesis to produce 4 genetically different haploid daughter cells
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8
Q

name three processes in which mitosis is significant (in the syllabus)

A
  1. asexual repro
  2. growth of organism
    • embryonic development
  3. tissue repair
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9
Q

what are the phases involved in the cell cycle

A
  • interphase
    • G1 phase
    • S phase
    • G2 phase
  • mitosis + cytokinesis
  • resting phase
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10
Q

what occurs in the G1 phase?

A
  • rapid cell growth -> increase in cell size
  • new organelles, protein and cytoplasm are synthesised
  • high levels of RNA and ATP synthesis
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11
Q

_________ is synthesised continually throughout the cell cycle

A

cytoplasm

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12
Q

at which part of the cell cycle is metabolism highest?

A

at interphase

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13
Q

which phase involves DNA replication?

A

S phase

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14
Q

plant cells [have/don’t have] centrioles

A

don’t have

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15
Q

what occurs in S phase?

A
  • DNA replication
  • centrioles (for animal cells) and centrosomes replicate
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16
Q

which phases involve the synthesis of organelles?

A

G1 and G2

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17
Q

what occurs in the G2 phase?

A
  • duplication of organelles
  • synthesis of proteins + spindle fibres
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18
Q

at the end of interphase how much DNA is there?

A

4n

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19
Q

what are the four stages of mitosis

A
  • prophase
  • metaphase
  • anaphase
  • telophase
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20
Q

in which phase does chromatin supercoil?

A

prophase

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21
Q

what is the function of centrioles in cellular division? (short)

A

centrioles organise spindle fibres

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22
Q

what occurs during prophase?

A
  • supercoiling of chromatin to chromosomes → chromosomes are visible
  • nuclear envelope disintegrates
  • spindle fibres form
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23
Q

two sister chromatids are held together at the…

A

centromere

24
Q

what occurs during metaphase?

A
  • chromosomes aligne randomly at the equatorial plate of the mitotic spindle
  • spindle fibres attach to kinetochore on centromeres
25
Q

in forming the mitotic spindle, what do spindle fibres attach to (specific)

A

kinetochore proteins located at the centromeres of the chromosomes

26
Q

when in mitosis do the centromeres divide?

A

during anaphase

27
Q

what is the amount of DNA present in the cell in anaphase?

A

4n

28
Q

if the cell begins with x chromosomes how many chromosomes are there in the cell during anaphase?

A

2x

29
Q

if the cell begins with x chromosomes how many chromosomes are there in the cell during metaphase?

A

x

30
Q

what is the difference between sister chromatids and chromosomes?

A
  • chromatids are connected by centromeres
  • separate chromatids are chromosomes
31
Q

how are chromosomes counted?

A

no. chromosomes = the no. of centromeres

32
Q

what happens in anaphase

A
  • centromeres divide
  • kinetochore microtubules shorten
    • causes sister chromatids to separate
    • sister chromatids pulled to opposite poles as daughter chromosomes
33
Q

what happens in telophase?

A
  • daughter chromosomes uncoil to form chromatin
  • nuclear envelope reforms around chromatin → nucleolus appears
  • spindle fibres disintegrate
34
Q

how does cytokinesis occur in plant cells? (4 short)

A
  • vesicles produced by golgi apparatus gather at equator
  • vesicles fuse tgt to form cell plate
  • cell plate stretches across the cell → forms middle lamella
  • cellulose builds up on each side of the middle lamella → forms cell walls of 2 new plants cells
35
Q

how does cytokinesis occur in an animal cell?

A
  • centre of the cell ‘pinches’ in along the equatorial plane
  • cleavage furrow forms
  • furrow deepens and plasma membrane on each side joins up → gives 2 separate cells
36
Q

how do you calculate mitotic index?

A

(no. of cells in mitosis)/(total no. of cells)

37
Q

what is the mitotic index

A

indication of the percentage of cells undergoing cell division

38
Q

what controls the cell cycle?

A

cyclins

39
Q

what are cyclins?

A

a family of proteins that activate cyclin-dependent kinases (Cdk) to control the progression of cell through controlling the cell cycle

40
Q

cylins bind to…

A

Cdk

41
Q

what does Cdk do to proteins?

A

it phosphorylates them

42
Q

how do cyclins regulate the cell cycle?

A
  • relative amts of diff cyclins at ea phase control the cell cycle
  • they bind to and activate diff Cdk
  • Cdk phosphorylates and activates diff regulatory proteins
    • the quantity and type of regulatory proteins fluctuate throughout the cell cycle → drives the cell cycle
43
Q

what are mutations?

A

mutations refer to changes to the gene sequence of a cell which result in a change in gene expression

44
Q

tumours form because cells that ________ or _______ (actions) _________ _____________ , which normally limits their growth

A

avoid, overcome, control mechanisms

45
Q

what is metastasis?

A

the spread of cancer cells from the primary tumour to another part of the body via the bloodstream or lymphatic system, forming a secondary tumour

46
Q

exposure to ________ increases the chances of cancer

A

mutagens

47
Q

why is cancer more common for older people?

A

as a person grows old they accumulate gene mutations

48
Q

what are oncogenes?

A

genes that originally regulate the cell cycle but when mutated can cause cancer

49
Q

how do oncogenes cause cancer?

A
  • they originally regulate the cell cycle
  • when mutated, this causes a malfunction in the regulation of the cell cycle
  • thus leads to uncontrolled cell division -> cancer
50
Q

what are the 6 hallmarks of cancer?

A
  1. self-sufficiency in growth signals
  2. insensitivity to anti-growth signals
  3. evasion of apoptosis
  4. limitless cell division
  5. angiogenesis
  6. tissue invasion + metastasis
51
Q

what mutation enables self-sufficiency in growth signals in cancer cells?

A

mutation of proto-oncogenes to oncogenes

52
Q

what gene mutation causes insensitivity to anti-growth signals and the evasion of apoptosis?

A

tumour suppressor genes

53
Q

how does the expression of the gene encoding for telomerase lead to cancer?

A
  • expression of gene encoding for telomerase maintains telomeres
  • makes cells immortal
  • thus enables limitless cell division
54
Q

what occurs in angiogenesis?

A

new blood vessels are formed to transport O2 and nutrients to support the tumour

55
Q

what mutation enables tissue invasion and metastasis?

A
  • changes in genes expression for:
    • cell adhesion molecules on the surface of cancer cells
      • thus can dislodge
    • the recruitment of proteases
      • digest surrounding tissues to enter bloodstream and metastasise
56
Q

why does smoking have high correlation with cancer?

A
  • there are carcinogens in cigarettes
  • this greatly increases the chances of cell mutations in mouth, oesophagus, lungs

HL Bio (53 decks)

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