3.2.2 All Cells Arise From Other Cells Flashcards

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1
Q

How’s dna passed onto the next generation

A

Through gametes

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2
Q

Who do dividing cells pass on their genetic info to

A

Produced daughter cells

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3
Q

What is dna made up of

A

Nucleotides containing deoxyribose sugar, organic base and a phosphate group

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4
Q

What forms between bases in dna structure

A

Hydrogen bonds

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5
Q

2 gametes

A

Egg + sperm cells

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6
Q

What’s the opposite of a gamete

A

Somatic (body) cell

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7
Q

What cells are gametes known as

How many chromosomes do they have

A

Haploid cells

23

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8
Q

What cells are somatic (body) cells known as

How many chromosomes do they have

A

Diploid

46

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9
Q

In the nucleus, what’s genetic information stored as

A

Chromosomes

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10
Q

How are chromosomes arranged in humans

A

In pairs (homologous chromosomes)

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11
Q

On homologous chromosomes what’s the locus

A

Position of gene within the chromosome

Pairs have same locus’

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12
Q

When are sister chromatids formed

A

During replication of dna which must occur before cell division 5

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13
Q

What’s a centromere

A

Circle in centre of a chromatid

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14
Q

What do sister chromatids make up

A

Chromosomes

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15
Q

What’s mitosis used for

A

Growth and repair

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16
Q

What does meiosis produce

A

Gametes with 1/2 required genetic information

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17
Q

What are the chromosomes in the nucleus surrounded by

A

Free nucleotides used to build new dna molecules

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18
Q

What 2 enzymes are used to build new dna molecules

A

DNA helicase

DNA polymerase

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19
Q

What does dna helicase do and so cause

A

Breaks hydrogen bonds that hold bases together

Causes dna to unwind, exposing 2 single strands

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20
Q

What does DNA polymerase use as a template

A

The exposes single strand from dna helicase

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21
Q

What does DNA polymerase do

What are the new strands like and why

A

Assembles free nucleotides into a new strand alongside the template
New strands are complementary due to the base pairing rule

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22
Q

What’s dna replication

A

Unwinding + synthesis of new strands continuing along the entire dna molecule

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23
Q

Why is dna replication known as semi-conservative replication (2)

A
  1. Each dna molecule contains 50% original dna

2. Both new molecules are identical to each other + original

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24
Q

What’s the first part of the cell cycle which must occur before a cell divides
What’s this stage known as

A

DNA replication

Interphase

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25
Q

How many parts is interphase divided into (all before mitosis)

A

3

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26
Q

What are the 3 stages of interphase

A

G1 phase
S phase
G2 phas3

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27
Q

What happens in G1 of interphase (2)

A

The cell grows in size (gets 50% bigger)

New nucleotides + histones (proteins) are made ready for dna replication

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28
Q

What happens in s phase of interphase (3)

A

DNA is replicated (with dna helicase and DNA polymerase) synthesising new dna
Doubles chromatin in nucleus
Cell continues to grow

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29
Q

What’s chromatin like

A

Tangles (spaghetti) dna + histones

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30
Q

What are histones
What are they used to do
What charge are they

A

Circular proteins
Used to coil dna
Are positively charged (+)

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31
Q

What do histones bind to and what happens

how is this useful

A

Bind to negatively (-) charged dna which wraps round them

This condenses dna so it can fit in the nucleus

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32
Q

What’s synthesised in G2 of interphase

What forms

A

Tubulins (specialised proteins) are synthesised

Form spindle fibres

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33
Q

What do spindle fibres do that makes them needed for mitosis

A

They pull apart chromosomes

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34
Q

What’s the cell like in G2 of interphase

A

50% bigger than it should be

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35
Q

How long does the cell cycle roughly take in humans

A

24 hours

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36
Q

When does mitosis occur

A

After the cell growth + dna replication (preparation)

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37
Q

What does mitosis involve

A

Involves division of nucleus and then the cell itself. Producing 2 daughter cells

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38
Q

How many stages of mitosis are there

What are they

A

4 stages

Prophase
Metaphase
Anaphase
Telophase

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39
Q

Anagram for cell cycle and mitosis

A

IPMAT

I
Play
Monopoly
At 
Tea
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40
Q

What happens in 1. Prophase (3)

A

Chromosomes coil
Chromatids become vision,e
Nuclear envelope begins to break down

41
Q

What’s present prior to prophase

A

Chromatin

42
Q

Why does the nuclear envelope begin to break down in prophase

A

So chromosomes can be separated into 2 new cells

43
Q

What are centrioles

A

Poles of a cell

44
Q

Where do spindle fibres (Tubulin proteins) come from

A

Centrioles (poles)

45
Q

What’s all the spindle fibres known as

A

Spindle apparatus

46
Q

What happens during metaphase (3)

A

Spindle fibres are formed (from tubulin)
Centromeres attach the chromatids to the spindle
Chromatids are arranged in the centre of the cell

47
Q

What’s the centre of the cell called

A

Equator

48
Q

Where do chromosomes line up in the cell

What is needed for this to happen

A

Equator

Spindle fibres

49
Q

What happens in anaphase

A
Spindle fibres shorten + pull sister chromatids to opposite poles
Centromeres divide (into 2)
50
Q

What shape are sister chromatids as they get pulled to opposite poles

A

V shaped

51
Q

In what situation might chromatids remain at the equator during anaphase

A

If chemicals are added to destroy the spindle

52
Q

What happens during telophase (4)

A

2 sets of chromosomes gather at opposite poles
Spindle fibres break down
New nuclear envelope forms
Chromosomes uncoil to form chromatin (spaghetti)

53
Q

What’s the process when cytoplasm divides producing 2 new daughter cells

A

Cytokinesis

54
Q

What are the 2 new daughter cells like to each other and the original

A

Genetically identical

55
Q

3 types of cells where mitosis occurs constantly

A

Hair
Small intestine
Skin

56
Q

What has to be tightly controlled to have a healthy organism

A

Cell cycle

57
Q

When do liver cells only divide

A

When it’s necessary

58
Q

What prevents cells from dividing too rapidly by mitosis

A

Control mechanisms

59
Q

3 control mechanisms

A

Need nutrients to divide
Need growth factor (protein) - triggers mitosis
Anaphase only starts if all chromosomes attach to spindle

60
Q

Why are naturally occurring protein structures in dividing cells

A

To regulate mitosis and make sure it’s safe

61
Q

What do checkpoints check

A

That all crucial processes have been carried out. If not, the cell becomes a non-dividing cell

62
Q

What’s G1, G2 and Metaphase controlled by

A

Stop + go signals

63
Q

What can lead to uncontrolled division

A

A mutation

64
Q

What 2 things control mitosis

A

2 genes

65
Q

What are the 2 types of tumours

A

Benign - safe, stays in 1 site

Malignant - dangerous, can spread

66
Q

What cells don’t adhere to control mechanisms

A

Cancer cells

67
Q

When can cancer cells be almost ‘immortal’

A

If given a continual supply of nutrients

68
Q

What can tumours be caused by

A

Mitosis at a checkpoint (division not stopping)

69
Q

What’s transformation

A

Turning a normal cell to a cancer cell (due to dna mutation impacting checkpoints )

70
Q

What are cancer cells normally destroyed by

A

The immune system

71
Q

What can cancer cells be affected by

E.g

A

Choice of lifestyle

E.g UV light, alcohol, cigarettes, genetic factors

72
Q

What immune systems can make cancer worse

E.g

A

Weak immune systems

E.g diabetes

73
Q

5 common organs where tumours can occur

A
Lungs
Prostrate gland
Breast
Ovaries
Large intestine
Stomach
Oesophagus
Pancreas
74
Q

2 examples of cancer treatment

What do they both do

A

Chemotherapy
Radiotherapy

Both block part of the cell cycle to kill cells

75
Q

What’s chemotherapy in the form of

What does it target

A

Drugs put into bloodstream

Targets fast dividing cells but also healthy cells

76
Q

What 2 things does chemotherapy prevent

A

Prevents dna replication (interphase)

Prevents spindle fibre forming (metaphase) - stops tubulin proteins

77
Q

What’s radiotherapy

A

More targeted radiation

78
Q

What does radiotherapy also disrupt

But what’s most affected

A

Also disrupts the cycles of healthy cells

Rapidly dividing cells are most affected

79
Q

What can many mutations in cells dna make the cell over time

A

Malignant

80
Q

What increases risk of mutations

E.g

A

Carcinogens

E.g UV light exposure, cigarette chemicals

81
Q

What’s a virus

A

Tiny particles of nucleus acid (dna/rna) enclosed within a protein coat (capsid)

82
Q

What type of organism are viruses

Why

A

Acellular organisms

Aren’t made from cells

83
Q

What’s the capsid of a virus formed from

A

Formed from protein

Made from individual units called capsomeres

84
Q

What on the capsid attaches to cell surface proteins of a host cell

A

Attatchment proteins

85
Q

When a ci4us is attached to a host cell what does it do

A

It penetrates the cell and hijacks the machinery forcing the cell to produce viral rna/dna and protein to build new virus copies

86
Q

How does the virus eventually destroy the host cell

A

When is eventually bursts out of the host cell, destroying it in the process

87
Q

Are bacterial cells or viruses smaller

A

Viruses

88
Q

What do some viruses have that’s additional which the attatchment proteins are on

E.g

A

Some have a lipid envelope

E.g HIV

89
Q

When can viruses only show they’re living (reproduce)

A

If they’re inside a host cell

90
Q

What are the 2 ways in which new virus copies can be released

A

Budding

Bursting

91
Q

What happens during budding of viruses

A

Virus is released in a vesicle formed from part of the cells membrane

92
Q

How does a virus grow if it contains RNA

A

Virus enters host cell + capsid is removed
The rna goes to the ribosomes of the host cell
Ribosomes produce enzymes needed to make viral proteins

93
Q

How does a virus grow if it contains DNA

A

Virus enters host cell + capsid is removed
The DNA provides the code to produce viral RNA
The RNA goes to the ribosomes of the host cell
Ribosomes produce enzymes needed to make viral proteins

94
Q

What type of reproduction is bacterial replication

A

Asexual reproduction

95
Q

How long does bacterial replication take

A

About 20 minutes

96
Q

What do prokaryotic cells divide by

A

Binary fission

97
Q

5 parts of binary fission process

A
  1. Circular naked dna replicates + both copies of dna attatch to the cell membrane at opposite ends of the cell
  2. Plasmids are replicated too
  3. Cell grows in size
  4. Cell membrane grows between the 2 dna molecules. It pinches inwards and cytoplasm begins to divide
  5. A new cell wall forms between the 2 copies of dna. Original prokaryotic cell becomes 2 identical daughter cells
98
Q

3 conditions prokaryotes need for binary fission

A

Warm, moist, oxygen rich