Cell Division Flashcards

Ch 14

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1
Q

Definition of cell continuity?

A

means that all cells develop from pre-existing cells.

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2
Q

What are chromosomes?

A

are coiled threads of DNA and protein.

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3
Q

Humans have how many chromosomes in each body cell?

A

46.

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4
Q

Discuss chromosomes when a cell is not dividing?

A

they exist as long, thin threads called chromatin.

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5
Q

At cell division, chromatin…?

A

contracts to form a number of clearly distinguishable chromosomes.

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6
Q

What’s a gene?

A

a section of DNA that contains the instructions for the formation of a protein.

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7
Q

Definition of a haploid cell?

A

has one set of chromosomes.

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8
Q

Definition of diploid cell?

A

has two sets of chromosomes.

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9
Q

Haploid is symbolised by what letter?

A

n.

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10
Q

Diploid is symbolised as what?

A

2n.

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11
Q

What’s a homologous pair?

A

is two chromosomes of similar size with the same sequence of genes.

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12
Q

The cell cycle describes what?

A

the life cycle of a cell.

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13
Q

Definition of interphase?

A

state of non division.

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14
Q

What’s the longest phase in the cell cycle?

A

interphase.

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15
Q

Interphase accounts for over what % of the cycle?

A

90%.

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16
Q

Name 4 things that happen in interphase?

A
  • photosynthesis,
  • respiration,
  • DNA replication,
  • protein synthesis.
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17
Q

Definition of mitosis?

A

cell/nuclear division, forming two identical (daughter) cells.

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18
Q

What’s function of mitosis in unicellular organisms?

A

reproduction.

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19
Q

What’s function of mitosis in multicellular organisms?

A

growth/repair of tissue.

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20
Q

Name 4 human cells not produced by mitosis?

A
  • sperm,
  • egg,
  • sex cell,
  • gamete.
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21
Q

What is cancer?

A

uncontrolled mitosis.

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22
Q

What does benign mean?

A

kind.

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23
Q

What happens in a benign tumour?

A

the cells stop dividing after some time.

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24
Q

Are benign tumours life threatening? Why/why not?

A

no as they don’t invade other tissues.

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25
Q

Give 2 examples of benign tumours and how they are caused?

A
  • warts, caused by a virus.
  • skin ‘tags’, small blobs of raised skin.
26
Q

What cells form a malignant tumour?

A

abnormal cells.

27
Q

Are malignant tumours life threatening? Why/why not?

A

they can be as they can invade other cells and can move from one place to another in the body.

28
Q

The movement of malignant cells is called?

A

metastasis.

29
Q

What are oncogenes?

A

cancer-causing genes formed from altered normal genes.

30
Q

What are carcinogens?

A

cancer-causing agents.

31
Q

Name 3 common carcinogens?

A
  • cigarette smoke,
  • asbestos fibres,
  • ultraviolet radiation.
32
Q

Name 3 treatments for cancer and describe them.

A
  • surgery.
  • radiation: burn out cancer.
  • chemotherapy: use of chemicals that slow down mitosis.
33
Q

What’s meiosis?

A

a form of nuclear division in which the four daughter nuclei contain half the chromosome number of the parent nucleus.

34
Q

3 functions of meiosis?

A
  • produce gametes (for sexual reproduction).
  • allow for diploid number.
  • restore chromosome number.
35
Q

Give 2 reasons meiosis allows for variation?

A
  • rearrange genetic material.
  • produces non-identical cells.
36
Q

Four stages of mitosis in order?

A

prophase, metaphase, anaphase, telophase.

37
Q

What starts to chromatin in prophase?

A

starts to contract early.

38
Q

What starts to contract in prophase?

A

chromatin.

39
Q

What become visible as double-stranded structures in prophase?

A

chromosomes.

40
Q

Chromosomes become visible as what in prophase?

A

double-stranded structures.

41
Q

The point at which the strands are attached in a double-stranded chromosome is called?

A

a centromere.

42
Q

The fibres that appear in the cytoplasm in prophase are called?

A

spindle fibres.

43
Q

In prophase the spindle fibres collectively form a structure called the what?

A

spindle.

44
Q

What happens the nuclear membrane in prophase?

A

starts to break down.

45
Q

What happens the nuclear membrane in metaphase?

A

completes it’s breakdown.

46
Q

What happens the chromosomes in metaphase?

A

line up across the middle, or equator, of the cell.

47
Q

What happens the spindle fibres in anaphase? What does it cause?

A

spindle fibres contract causing the centromeres to split.

48
Q

What happens the chromosomes in anaphase?

A

pulled apart to opposite poles of the cell.

49
Q

What happens spindle fibres in telophase?

A

break down.

50
Q

What begin to re-form in telophase?

A

one or more nucleoli (singular: nucleolus).

51
Q

What forms around the chromatin at each end of the cell in telophase?

A

nuclear membrane.

52
Q

What happens at the end of mitosis in telophase?

A

divided into two identical nuclei.

53
Q

Cell division follows immediately after what?

A

mitosis.

54
Q

Cell division occurs in animals by a process called?

A

cleavage.

55
Q

What forms during cell division in animals?

A

cleavage furrow forms.

56
Q

What forms during cell division in plants?

A

plate forms.

57
Q

Differences between mitosis and meiosis?

A

Mitosis: 2 cells are formed.
Meiosis: 4 cells are formed.

Mitosis: daughter cells have identical genes on their chromosomes.
Meiosis: daughter cells have different genes on their chromosomes.

Mitosis: chromosome number stays the same.
Meiosis: chromosome number is halved 2n-n.

58
Q

Describe prophase.

A
  • at end of interphase/early prophase, chromatin starts to contract.
  • chromosomes become visible as double-stranded structures. The point at which the strands are held together is called a centromere.The two strands in a chromosome have identical genes, each strand is a chromosome.
  • fibres that are in cytoplasm are called spindle fibres. Collectively they form a structure called the spindle.
  • nuclear membrane starts to break down.
  • double stranded.
59
Q

Describe metaphase.

A
  • nuclear membrane completes it’s break down.
  • a spindle fibre from each end/pole of the cell attaches to each centromere.
  • chromosomes lineup across the middle or equator of the cell.
60
Q

Describe anaphase.

A
  • spindle fibres contract. Causes the centromeres to split.
  • one strand/chromosome from each double-stranded chromosome is pulled to opposite poles of the cell. Meaning the cell has 8 chromosomes here. The 4 chromosomes pulled to each pole have identical genes.
61
Q

Describe telophase.

A
  • the 4 chromosomes at each pole begin to lengthen and become hard to distinguish.
  • spindle fibres break down.
  • one or more nucleoli (sing: nucleolus) begin to re-form.
  • nuclear membrane forms around the chromatin at each end of the cell.
  • at end of mitosis the original nucleus has divided into 2 identical nuclei.