2.2: The cell cycle, mitosis & binary fission Flashcards

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1
Q

What is the cell cycle

A

the sequence of the dividing and non dividing stages in the life of a cell

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2
Q

what is the name of the non dividing stage in the cell cycle

A

interphase

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3
Q

what is the name of the dividing stage in the cell cycle

A

nuclear division

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4
Q

What are the 3 phases in interphase

A

G1 - cell growth
S phase - DNA replication
G2 - Preparation for mitosis

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5
Q

What happens after nuclear division in the cell cycle

A

cytokinesis - some cells don’t go through this stage though

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6
Q

describe the chromosome composition of diploid cells

A

1 paternal set of chromosomes and 1 maternal set

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7
Q

describe the chromosome composition of haploid cells

A

mixture of maternal and paternal chromosomes

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8
Q

what type of cell are gametes? haploid or diploid

A

haploid

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9
Q

what type of cell are somatic/body cells? haploid or diploid

A

diploid

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10
Q

how can you identify if a chromosome has a pair and so the cell is diploid

A

is the position of the centromere is the same then the chromosomes are pairs and so the cell is diploid

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11
Q

what is mitosis

A

nuclear division in eukaryotic cells

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12
Q

what is produced when a parent cell undergoes mitosis

A

two genetically identical daughter cells

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13
Q

what happens to the chromosome number when a parent cell undergoes mitosis

A

chromosome number remains the same

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14
Q

what is the sequence of phases in mitosis

A

interphase -> prophase -> metaphase -> anaphase -> telophase -> cytokinesis

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15
Q

What does the acronym ‘Icy penguins make antarctica terribly cold’ stand for

A

interphase -> prophase -> metaphase -> anaphase -> telophase -> cytokinesis

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16
Q

how can you remember the sequence of phases in mitosis

A

Icy penguins make antarctica terribly cold
interphase -> prophase -> metaphase -> anaphase -> telophase -> cytokinesis

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17
Q

what do the chromosomes do in each phase of mitosis

A

interphase = replicate
prophase = appear
metaphase = line up
anaphase = pull apart
telophase = hide
cytokinesis = CELL halves

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18
Q

what do the chromosomes in a cell do in interphase during mitosis

A

replicate

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19
Q

what do the chromosomes in a cell do in prophase during mitosis

A

appear

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20
Q

what do the chromosomes in a cell do in metaphase during mitosis

A

line up

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21
Q

what do the chromosomes in a cell do in anaphase during mitosis

A

pull apart

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22
Q

what do the chromosomes in a cell do in telophase during mitosis

A

hide

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23
Q

what does the cell do in cytokinesis during mitosis

A

halves

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24
Q

what does the acronym ‘RALPH’ stand for

A

replicate -> appear -> line up -> pull apart -> hide -> half(cell)

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25
Q

how can you remember the sequence of what the chromosomes are doing in each phase of mitosis

A

RALPH
replicate -> appear -> line up -> pull apart -> hide -> half(cell)

26
Q

what are sister chromatids

A

chromatids in a pair

27
Q

what are centromeres

A

the structure in a chromosome the holds together chromatids until they are separated by the spindle fibres

28
Q

what is cytokinesis

A

the division of the cytoplasm to give two new cells

29
Q

give a description of what happens in interphase during mitosis

A

chromosomes are not visible, cell grows, synthesis of organelles, ATP synthesis, DNA replication

30
Q

give a description of what happens in prophase during mitosis

A

centrioles move to opposite poles of the cell
chromosomes condense (shorten and thicken) and become visible as two sister chromatids joined by a centromere
spindle fibres develop from each pair of centrioles to span the cell from pole to pole
chromosomes attach to spindle fibres by their centromere
nucleolus disappears
nuclear envelope breaks down so chromosomes are free in the cytoplasm

31
Q

give a description of what happens in metaphase during mitosis

A

chromosomes are pulled along the spindle apparatus and arrange themselves across the equator of the cell
centromeres divide into two

32
Q

give a description of what happens in anaphase during mitosis

A

spindle fibres contract and shortened pulling sister chromatids apart
mitochondria located around the spindle fibres provide ATP for their contraction
chromosomes pulled to opposite poles

33
Q

give a description of what happens in telophase during mitosis

A

chromosomes reach their respective poles
nuclear envelope and nucleoli reform
spindle fibres disintegrate
chromosomes elongated becoming less visible

34
Q

give a description of what happens in cytokinesis during mitosis

A

cell membrane pinches inwards separating cytoplasm
cytoplasm divides to produce two new cells

35
Q

what are 3 things that mitosis is important for

A

1 - growth - tissue, organism
2 - tissue repair
3 - asexual reproduction (singled celled eukaryotes)

36
Q

how can you identify a cell going through metaphase under a microscope

A

look for a groove in the middle of the cell

37
Q

how can you identify a cell going through interphase under a microscope

A

look at what the majority of the cells are

38
Q

suggest one advantage and one disadvantage of having offspring that are genetically identical to their parents

A

advantage: in stable environment, successful parents can rapidly produce successful offspring
disadvantage: in a changing environment, offspring not genetically diverse enough to adapt

39
Q

in what phases in mitosis are chromosomes visible

A

prophase, metaphase, anaphase, telophase

40
Q

How do you calculate mitotic index

A

number of cells undergoing mitosis / total number of cells (as a fraction or a percentage)

41
Q

Describe the steps of the root tip squash practical to show the stages of mitosis

A

1 - cut off 5mm off a garlic root tip
2 - put 10 drops of acetic orcein stain into watch glass
3 - add one drop of 1 mol HCl into the watch glass
4 - add the root tips
5 - place the watch glass(with lid) onto a hot plate for 30 seconds. Then remove from hot plate and leave to stand for at least 10 minutes (with lid on)
6 - using forceps, remove a root tip and place onto a microscope slide. Place a cover slip over the top
7 - immediately place filter paper over coverslip then use thumb to gently squash the root tip

42
Q

explain as to why we use the root tip to show the stages of mitosis (root tip squash prac)

A

it is the growing region where mitosis happens

43
Q

explain as to why we put 10 drops of acetic orcein stain into a watch glass to show the stages of mitosis (root tip squash prac)

A

stain makes DNA and chromosomes visible

44
Q

explain as to why we put 1 drop of 1 mole HCl into the watch glass to show the stages of mitosis (root tip squash prac)

A

to soften the cell walls so that the acetic orcein stain can enter cells more quickly

45
Q

explain as to why we put the watch glass onto a hot plate for 30 seconds to show the stages of mitosis (root tip squash prac)

A

to make movement of stain quicker and softening of walls

46
Q

explain as to why we squash the root tip before examining it under the microscope to show the stages of mitosis (root tip squash prac)

A

to see a single layer of cells and so light can pass through

47
Q

List and describe the sequence of stages of binary fission in prokaryotes

A

1 -circular DNA replicates and both copies attach to the cell membrane. Plasmids also replicate
2 - Cell membrane begins to grow between the two DNA molecules
3 - Cell membrane begins to pinch inwards dividing the cytoplasm
4 - A new cell wall forms between the two molecules of DNA fully dividing the original cell
5 - Two new identical daughter cells are formed each with a single copy of the circular DNA and a variable number of the plasmids

48
Q

List and describe the sequence of stages of replication in viruses

A

1 - virus attaches to host cell with attachment proteins. They then inject their nucleic acid into the host cell
2 - The genetic code of the injected viral nucleic acids is read by the host cell
3 - Host cell starts to produce viral components: nucleic acids, enzymes, structural proteins
4 - These components are then assembled into new viruses

49
Q

What happens in healthy cell division when a cell is differentiated

A

the cell can lose ability to divide when differentiated or only divide 20-30 times

50
Q

What happens in healthy cell division when a cell mutation occurs

A

apoptosis - programmed cell death when mutation occurs

51
Q

What happens in cancer cell division when a cell mutation occurs

A

cancer cell division is uncontrolled mitosis
apoptosis mechanism breaks down and so mutated cells do divide - resulting in multiple mutated cells and eventually a mass of cells called a tumour
which can either by benign (harmless) or malignant (cancerous)

52
Q

What is a chromosome

A

condensed chromatin

53
Q

what is chromatin

A

DNA double helix wrapped around histones

54
Q

When do chromosomes condensed

A

prophase

55
Q

When does the cytoplasm split

A

cytokinesis

56
Q

when would you use the term chromatid instead of chromosome

A

when a chromosome is attached to another by a centromere

57
Q

when do chromosomes line up along the equator

A

metaphase

58
Q

when do spindle fibres form

A

prophase

59
Q

when does the cell have 2 nuclei

A

during telophase

60
Q

what is meant by diploid (2n) and haploid (n)

A

2n = 2 sets of chromosomes
n = 1 set of chromosomes

61
Q

How many chromosomes are in a 2n human cell

A

46