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foundations in biology > cell division > Flashcards

cell division Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what is the importance of mitosis?

A
  • tissue repair
  • organism growth
  • asexual reproduction
  • development
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2
Q

what is interphase?

A
  • active phase
  • preparation for successful division
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3
Q

how many stages in interphase and what are they?

A

3
- G1
- S
- G2

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4
Q

what occurs in interphase?

A
  • replication (of DNA)
  • nutrients
  • growth
  • cellular respiration
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5
Q

what happens in G1?

A
  • prepare for replication
  • cells grow
  • synthesis of proteins
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6
Q

what is being checked at the end of G1 and what happens when passes/fails?

A
  • nutrients
  • growth
  • DNA damage
    pass: enter S phase
    fail: G0
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7
Q

what is S phase?

A

DNA replication

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8
Q

what happens in G2 phase?

A
  • cell finishes growing
  • prepares for division
  • increased ATP
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9
Q

what is being checked at the end of G2 and what happens if passes/fails?

A
  • cell size
  • DNA replication
    pass: mitosis
    fail: repair DNA
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10
Q

what is G0?

A

a non dividing stage

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11
Q

why might a cell enter G0?

A
  • ageing (enter permanent cell arrest)
  • dormant (can reenter G1 later)
  • diffferentiation (specialised cells can no longer divide)
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12
Q

what happens in prophase?

A
  • chromatin fibres coil and condense to form chromosomes
  • nucleus disappears and nuclear membrane breaks down
    -protein microtubules form spindle like shapes linking to the poles of the cell
  • spindle fibres attach to the centromere and move chromosomes to the centre of the cell
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13
Q

what happens in metaphase?

A

chromosomes are moved by spindle fibres to form the metaphase plate

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14
Q

what happens in anaphase?

A
  • centromeres holding together the pairs of chromatids in each chromosome divide
  • chromatids are separated by shortening the spindle fibre
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15
Q

what happens in telophase?

A
  • chromatids reach the poles and become chromosomes
  • nuclear membrane forms
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16
Q

what happens in telophase?

A
  • chromatids reach the poles and become chromosomes
  • nuclear membrane form
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17
Q

what happens in cytokinesis in animals?

A

microtubules pull membrane inward until cells separate

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18
Q

what happens in cytokinesis in plants?

A
  • vesicles from the golgi assemble where the metaphase plate was
  • vesicles fuse with eachother and forms the new cell surface membrane
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19
Q

how many divisions occurs in meiosis?

A

2

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20
Q

how many new cells are formed in meiosis?

A

4

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21
Q

what happens in prophase I?

A
  • homologous chromosomes undergo synapsis where they pair up to form bivalents
  • they are held together at points called chiasmata where crossing over happens
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22
Q

what happens in metaphase I?

A
  • spindle fibres move towards chromosomes
  • bivalents line up along metaphase plate and independent assortment occurs
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23
Q

what is independent assortment?

A

maternal and paternal chromosomes in each pair position themselves independently of eachother

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24
Q

what happens in anaphase I?

A
  • homologous chromosomes are separate as microtubules pull chromosomes to opposite ends of the spindle
  • centromere dont divide
25
Q

what happens in telophase I?

A
  • chromosomes arrive at opposite poles
  • spindle fibres break down
  • nuclear envelopes form around the two groups of chromosomes
26
Q

what is formed at the end of the first division?

A

2 haploid cells

27
Q

what happens in prophase II?

A
  • nuclear envelope breaks down and chromosomes condense
  • spindle forms at a right angle to the old one
28
Q

what happens in metaphase II?

A

chromosomes line up in a single file line along the equator

29
Q

what happens in anaphase II?

A
  • centromeres divide and each individual chromosome is pulled to opposite poles
  • this created 4 groups of chromosomes that have half the number of chromosomes compared to parents
30
Q

what happens in telophase II?

A

nuclear membrane forms around each group of chromosomes

31
Q

what is the end product of meiosis?

A

4 haploid cells

32
Q

how does organisation of homologous chromosomes during metaphase I increase genetic variation?

A
  • independent assortment causes random arrangement of maternal and paternal chromosomes
  • chromosomes line up on the metaphase plate
  • each bivalent is genetically different
33
Q

pros of stem cells

A
  • develop life saving treatments
  • new organs can be made
  • drug production
  • treat genetic disorders
  • replace damaged tissue
34
Q

what are stem cells?

A

undifferentiated and unspecialised cells

35
Q

what are totipotent cells?

A
  • can produce any body cell
  • embryonic development in mammals
  • unspecialised
36
Q

what are pluripotent cells?

A
  • develop from totipotent cells
  • used to treat disorders
  • can become all tissue types
37
Q

what are multipotent cells?

A
  • mature animals
  • develop into a limited number of cells
38
Q

explain why a zygote would undergo mitosis rather then meiosis

A
  • mitosis is required for the growth of the zygote
  • this means genetically identical cells need to be produced
  • meisosis would produce haploid cells
39
Q

suggest why hydra reproduces asexually when conditions are favourable

A
  • produce genetically identical offspring
  • all offspring will have the same favourable adaptations
40
Q

how can embryonic stem cells be used in research to benefit biological knowledge?

A
  • grown into different tissue to observe the effects of different drugs
  • test toxicity of new drugs
  • see how they differentiate into new cells
41
Q

why is a leaf described as an organ?

A
  • group of different tissues working together to perform a specific function
  • made of tissues like palisade mesophyll to carry out photosynthesis
42
Q

what features of adult stem cells make them suitable for regeneration of tissues in the kidney?

A
  • they are multipotent
  • can differentiate into any cell within the kidney
43
Q

explain the role of embryonic stem cells in the development of the embryo

A

they are undifferentiated and can differentiate into any type of cell

44
Q

explain why the cells of the inner cell mass are not totipotent stem cells

A

they cannot form any type of cell so cannot give rise to any extra embryonic tissue

45
Q

where are erythrocytes and neutrophils formed?

A

bone marrow

46
Q

how are erythrocytes adapted for function?

A
  • biconcave for larger sa:v ratio
  • flexible to squeeze through blood vessels
  • no nucleus so has more room for haemoglobin and oxygen
47
Q

how are neutrophils adapted for function?

A
  • many lysosomes and hydrolytic enzymes to digest waste from phagocytosis
48
Q

how is the squamous epithelium adapted for function?

A
  • flat and very thin for shorter diffusion distance
  • fit tightly together
  • rapid diffusion of oxygen and carbon dioxide in alveoli
49
Q

how is the ciliated epithelium adapted for function?

A

hair like structures to waft dust, microbes and mucus out of the lungs

50
Q

what is the process that contributes to genetic variation in metaphase 1+2?

A

independent assortment of chromosomes ad chromatids

51
Q

how does prophase 1 contribute to genetic variation?

A

crossing over of alleles between homologous chromosomes and non sister chromatids

52
Q

why is genetic variation in meiosis two is reliant on crossing over?

A
  • crossing over enables exchange of genetic info between non sister chromatids
  • chromatids assort randomly
53
Q

discuss the ways in which genetic variation is produced including the role of nuclear division

A
  • independent assortment of bivalents occurs in metaphase 1 and chromatids in metaphase 2
  • crossing over of alleles in prophase 1
  • these produces a variety of allele combinations
  • mutations in DNA base sequences due to the faults in the check at the end of G2 phase
  • random fertilisation means that gametes will be genetically different
54
Q

how is a molecule prepared and secreted after translation?

A
  • moved by transport vesicle from RER to golgi apparatus
  • packaged, modified and moves in a secretory vesicle along the cytoskeleton to the plasma membrane
  • vesicle fuses with the plasma membrane and leaves via exocytosis
55
Q

what are two potential sources of human stem cells and for one source, describe an ethical
issue associated with the use of stem cells?

A
  • bone marrow
  • embryonic
  • some people believe the embryo is killed which gives rise to a debate about whether and embryo needs to consent
56
Q

why is transcription needed for protein synthesis?

A
  • DNA is transcribed into mRNA
  • DNA is too large to fit through nuclear pores
57
Q

compare prophase in mitosis and meiosis

A
  • mitosis forms chromatids and meiosis forms bivalents
  • both have spindle fibres
  • crossing over occurs in meiosis not mitosis
  • meiosis has 2 prophases
  • nuclear membrane breaks down in both
58
Q
A

foundations in biology (6 decks)

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