3.2.2 All Cells Arise From Other Cells Flashcards
(98 cards)
1
Q
How’s dna passed onto the next generation
A
Through gametes
2
Q
Who do dividing cells pass on their genetic info to
A
Produced daughter cells
3
Q
What is dna made up of
A
Nucleotides containing deoxyribose sugar, organic base and a phosphate group
4
Q
What forms between bases in dna structure
A
Hydrogen bonds
5
Q
2 gametes
A
Egg + sperm cells
6
Q
What’s the opposite of a gamete
A
Somatic (body) cell
7
Q
What cells are gametes known as
How many chromosomes do they have
A
Haploid cells
23
8
Q
What cells are somatic (body) cells known as
How many chromosomes do they have
A
Diploid
46
9
Q
In the nucleus, what’s genetic information stored as
A
Chromosomes
10
Q
How are chromosomes arranged in humans
A
In pairs (homologous chromosomes)
11
Q
On homologous chromosomes what’s the locus
A
Position of gene within the chromosome
Pairs have same locus’
12
Q
When are sister chromatids formed
A
During replication of dna which must occur before cell division 5
13
Q
What’s a centromere
A
Circle in centre of a chromatid
14
Q
What do sister chromatids make up
A
Chromosomes
15
Q
What’s mitosis used for
A
Growth and repair
16
Q
What does meiosis produce
A
Gametes with 1/2 required genetic information
17
Q
What are the chromosomes in the nucleus surrounded by
A
Free nucleotides used to build new dna molecules
18
Q
What 2 enzymes are used to build new dna molecules
A
DNA helicase
DNA polymerase
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
20
Q
What does DNA polymerase use as a template
A
The exposes single strand from dna helicase
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
22
Q
What’s dna replication
A
Unwinding + synthesis of new strands continuing along the entire dna molecule
23
Q
Why is dna replication known as semi-conservative replication (2)
A
- Each dna molecule contains 50% original dna
2. Both new molecules are identical to each other + original
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
25
How many parts is interphase divided into (all before mitosis)
3
26
What are the 3 stages of interphase
G1 phase
S phase
G2 phas3
27
What happens in G1 of interphase (2)
The cell grows in size (gets 50% bigger)
| New nucleotides + histones (proteins) are made ready for dna replication
28
What happens in s phase of interphase (3)
DNA is replicated (with dna helicase and DNA polymerase) synthesising new dna
Doubles chromatin in nucleus
Cell continues to grow
29
What’s chromatin like
Tangles (spaghetti) dna + histones
30
What are histones
What are they used to do
What charge are they
Circular proteins
Used to coil dna
Are positively charged (+)
31
What do histones bind to and what happens
| how is this useful
Bind to negatively (-) charged dna which wraps round them
| This condenses dna so it can fit in the nucleus
32
What’s synthesised in G2 of interphase
| What forms
Tubulins (specialised proteins) are synthesised
| Form spindle fibres
33
What do spindle fibres do that makes them needed for mitosis
They pull apart chromosomes
34
What’s the cell like in G2 of interphase
50% bigger than it should be
35
How long does the cell cycle roughly take in humans
24 hours
36
When does mitosis occur
After the cell growth + dna replication (preparation)
37
What does mitosis involve
Involves division of nucleus and then the cell itself. Producing 2 daughter cells
38
How many stages of mitosis are there
| What are they
4 stages
Prophase
Metaphase
Anaphase
Telophase
39
Anagram for cell cycle and mitosis
IPMAT
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40
What happens in 1. Prophase (3)
Chromosomes coil
Chromatids become vision,e
Nuclear envelope begins to break down
41
What’s present prior to prophase
Chromatin
42
Why does the nuclear envelope begin to break down in prophase
So chromosomes can be separated into 2 new cells
43
What are centrioles
Poles of a cell
44
Where do spindle fibres (Tubulin proteins) come from
Centrioles (poles)
45
What’s all the spindle fibres known as
Spindle apparatus
46
What happens during metaphase (3)
Spindle fibres are formed (from tubulin)
Centromeres attach the chromatids to the spindle
Chromatids are arranged in the centre of the cell
47
What’s the centre of the cell called
Equator
48
Where do chromosomes line up in the cell
| What is needed for this to happen
Equator
| Spindle fibres
49
What happens in anaphase
```
Spindle fibres shorten + pull sister chromatids to opposite poles
Centromeres divide (into 2)
```
50
What shape are sister chromatids as they get pulled to opposite poles
V shaped
51
In what situation might chromatids remain at the equator during anaphase
If chemicals are added to destroy the spindle
52
What happens during telophase (4)
2 sets of chromosomes gather at opposite poles
Spindle fibres break down
New nuclear envelope forms
Chromosomes uncoil to form chromatin (spaghetti)
53
What’s the process when cytoplasm divides producing 2 new daughter cells
Cytokinesis
54
What are the 2 new daughter cells like to each other and the original
Genetically identical
55
3 types of cells where mitosis occurs constantly
Hair
Small intestine
Skin
56
What has to be tightly controlled to have a healthy organism
Cell cycle
57
When do liver cells only divide
When it’s necessary
58
What prevents cells from dividing too rapidly by mitosis
Control mechanisms
59
3 control mechanisms
Need nutrients to divide
Need growth factor (protein) - triggers mitosis
Anaphase only starts if all chromosomes attach to spindle
60
Why are naturally occurring protein structures in dividing cells
To regulate mitosis and make sure it’s safe
61
What do checkpoints check
That all crucial processes have been carried out. If not, the cell becomes a non-dividing cell
62
What’s G1, G2 and Metaphase controlled by
Stop + go signals
63
What can lead to uncontrolled division
A mutation
64
What 2 things control mitosis
2 genes
65
What are the 2 types of tumours
Benign - safe, stays in 1 site
| Malignant - dangerous, can spread
66
What cells don’t adhere to control mechanisms
Cancer cells
67
When can cancer cells be almost ‘immortal’
If given a continual supply of nutrients
68
What can tumours be caused by
Mitosis at a checkpoint (division not stopping)
69
What’s transformation
Turning a normal cell to a cancer cell (due to dna mutation impacting checkpoints )
70
What are cancer cells normally destroyed by
The immune system
71
What can cancer cells be affected by
| E.g
Choice of lifestyle
| E.g UV light, alcohol, cigarettes, genetic factors
72
What immune systems can make cancer worse
| E.g
Weak immune systems
| E.g diabetes
73
5 common organs where tumours can occur
```
Lungs
Prostrate gland
Breast
Ovaries
Large intestine
Stomach
Oesophagus
Pancreas
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74
2 examples of cancer treatment
| What do they both do
Chemotherapy
Radiotherapy
Both block part of the cell cycle to kill cells
75
What’s chemotherapy in the form of
| What does it target
Drugs put into bloodstream
| Targets fast dividing cells but also healthy cells
76
What 2 things does chemotherapy prevent
Prevents dna replication (interphase)
| Prevents spindle fibre forming (metaphase) - stops tubulin proteins
77
What’s radiotherapy
More targeted radiation
78
What does radiotherapy also disrupt
| But what’s most affected
Also disrupts the cycles of healthy cells
| Rapidly dividing cells are most affected
79
What can many mutations in cells dna make the cell over time
Malignant
80
What increases risk of mutations
| E.g
Carcinogens
E.g UV light exposure, cigarette chemicals
81
What’s a virus
Tiny particles of nucleus acid (dna/rna) enclosed within a protein coat (capsid)
82
What type of organism are viruses
| Why
Acellular organisms
| Aren’t made from cells
83
What’s the capsid of a virus formed from
Formed from protein
| Made from individual units called capsomeres
84
What on the capsid attaches to cell surface proteins of a host cell
Attatchment proteins
85
When a ci4us is attached to a host cell what does it do
It penetrates the cell and hijacks the machinery forcing the cell to produce viral rna/dna and protein to build new virus copies
86
How does the virus eventually destroy the host cell
When is eventually bursts out of the host cell, destroying it in the process
87
Are bacterial cells or viruses smaller
Viruses
88
What do some viruses have that’s additional which the attatchment proteins are on
E.g
Some have a lipid envelope
E.g HIV
89
When can viruses only show they’re living (reproduce)
If they’re inside a host cell
90
What are the 2 ways in which new virus copies can be released
Budding
| Bursting
91
What happens during budding of viruses
Virus is released in a vesicle formed from part of the cells membrane
92
How does a virus grow if it contains RNA
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
How does a virus grow if it contains DNA
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
What type of reproduction is bacterial replication
Asexual reproduction
95
How long does bacterial replication take
About 20 minutes
96
What do prokaryotic cells divide by
Binary fission
97
5 parts of binary fission process
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
3 conditions prokaryotes need for binary fission
Warm, moist, oxygen rich
