Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Biology A Level > Mitosis > Flashcards

Mitosis Flashcards

(71 cards)

Start Studying
1
Q

How can a cell’s life be described?

A

A cells life can be described through a series of stages.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are these stages known as?

A

Stages of a cell cycle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What do all multicellular organisms use the cell cycle to do?

A

The cell cycle is the process that all body cells from multicellular organisms use to grow and divide.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How many phases is the cell cycle divided into?

A

The cell cycle is divided into 2 phases:

  1. Interphase
  2. The M phase
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How long does it take a cell in a human embryo to complete one cycle?

A

It takes about 24 hours

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What percentage of the cell cycle is spent in interphase?

A

95%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How long does the M phase last?

A

About 30 minutes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the name of the first section of interphase?

A

G1 phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What happens in G1?

A

Growth of cell
Growth of organelles
Organelles duplicate synthesis of proteins (e.g. Making enzymes for DNA replication)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the second section of interphase called?

A

S - synthesis phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What does it mean in terms of the cell’s commitment to completion once its entered the S phase?

A

Once the cell has entered the S phase it is committed to completing the cell cycle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What happens in the S phase?

A

DNA REPLICATION

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Why is the S phase so rapid?

A

The S phase is rapid because the exposed DNA bases are susceptible to mutagenic agents. The rapidness of the S phase reduces the chance of spontaneous mutations occurring.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the G2 phase?

A

The G2 phase is the second growth phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What happens in G2?

A

In G2 the cell continues to grow and energy stores (ATP) are increased

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Why in G2 are energy stores increased?

A

Mitochondria increase the energy stores

Energy is needed by cell’s cytoskeleton to transport chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

During G2 what form is DNA in ?

A

During G2 the chromosomes coil back into chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What happens during the M phase?

A

Cell growth stops
Nuclear division mitosis
Cytokinesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What does each chromosome pair contain?

A

1 paternal chromosome

1 maternal chromosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are homologous chromosomes ?

A

Matching chromosomes
that are the same length/size,
have the same genes/bonding pattern which occurs at the same position loci are known as homologous chromosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the definition of an allele?

A

An allele is different forms of the same gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

When a cell is not dividing why can you not see any of the chromosomes?

A

When a cell is not dividing you cannot see any of the chromosomes. This is because the DNA is ‘unwound’ chromatin and spread out in the nucleus.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the name of the protein molecules in which DNA is wrapped around?

A

The DNA is wrapped around protein molecules called HISTONES

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Why happens during the S phase?

What happens just before a cell begins to divide to produce 2 new daughter cells?

A
  • the DNA of each chromosome replicates (DNA REPLICATION)
  • Chromatin must be coiled up (supercoiled) to form visible chromosome
    EACH CHROMOSOME IS SHORT AND STURDY ENOUGH TO BE AROUND EASIER
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Does every cell in the body contain exactly the same DNA?
Yes | Every cell in the body contain exactly the same DNA
26
What is peculiar about using the term homologous pair?
They're still referred to as homologous pair although there are 4 chromosomes
27
What happens when a single chromosome is replicated?
When a single chromosome is replicated it forms 2 copies of itself These 2 copies are called SISTER CHROMATIDS
28
Describe sister chromatids?
Each sister chromatid is an exact copy of the original(single chromosome) and they remain held together at a point called the centromere
29
What is the centromere ?
The centromere is a region of DNA typically found near the middle of a chromosome Centromeres are involved in linking 2 identical sister chromatids together
30
What is a pair of homologous chromosomes made up of?
A pair of homologous chromosome is made up of sister chromatid pairs
31
Can condensed chromosomes perform their normal functions?
Condensed chromosomes can be moved around easier BUT CANNOT perform their normal functions in the cell So they spend as little time as possible coiled up
32
What happens as chromosomes are being replicated ?
Proof-reading enzymes move along the DNA strands and check that the copying has been done properly.
33
Why is it so important that the genetic information is copied and CHECKED?
If there is a mutation faulty DNA would be produced Resulting in daughter cells not having the identical information Therefore the daughter cells would not function
34
Once a cell has gone through interphase what is the next phase of the cell cycle that it is ready for?
Once the cell has done through interphase it is then ready for the next stage of the cell cycle This next stage is called mitosis
35
What happens in the M-phase?
CELL DIVISION
36
What do all eukaryotic multicellular organisms each develop from?
All eukaryotic multicellular organisms each develop from a single original cell
37
What is the single original cell from which all eukaryotic multicellular organisms develop from also known as?
Fertilised egg | Zygote
38
What does repeated divisons of the zygote by a process of cell division called mitosis give rise to?
Repeated division of the zygote (by mitosis) gives rise to all the cells that make up a multicellular organisms
39
What percentage of the correct amount of chromosomes does a haploid cell contain?
50% the number of chromosomes
40
What percentage of the correct number of chromosomes does the diploid cell contain?
100%
41
Describe the process in order to produce an early embryo?
Gametes (haploid) --> zygote (diploid) zygote divides repeatedly by mitosis --> to initially produce a ball of genetically identical cells (early embryo)
42
What is the function of mitosis?
The function of mitosis is to produce new identical daughter cells
43
Describe what the daughter cells' chromosomes are like?
The new identical daughter cells each receive a set of chromosomes identical to those of the original parent cell that gave rise to them
44
Why is mitosis so important?
1. Development - the formation of a multicellular organism from a single fertilised egg (zygote) 2. Growth of cell - involves an increase in size though the division of cells by mitosis 3. Replacement (repair) - many cells within a multicellular organism are constant dying and being REPLACED by MITOSIS
45
Where are epithelial cells found?
Epithelial cells are found lining the intestine
46
How are epithelial cells lining the intestine continually replaced?
Epithelial cells lining the intestine are continually being replaced by mitosis
47
How many days does it take for the whole intestine lining to be replaced due to the fact that the epithelial cells are constantly being replaced?
Entire lining is replaced every 5 days
48
Where are dead layers of cells found?
There are dead layers of cells at the surface of the skin
49
What is constantly happening to the dead layers of cells at the surface of the skin?
The dead layers of cells at the surface of the skin are constantly being lost and are replaced by the mitotic divisions of the CELLS IN THE LAYER BENEATH THEM
50
What other separate factor can mitosis be important in?
Mitosis can also be important in ASEXUAL REPRODUCTION
51
What can some organisms do to ensure only one parent is needed?
Some organisms (e.g. PARAMECIUM, a singled cell organism) and plants can reproduce asexually so that only 1 parent is needed
52
What are the cons of asexual reproduction?
- no genetic variation - therefore small gene pool - therefore increased susceptibility to being wiped out
53
Mitosis is a continuous process but for convenience is divided into 4 main stages. Name the 4 main stages:
``` PLEASE MAKE ANOTHER TWO Prophase Metaphase Anaphase Telophase (cytokinesis) ```
54
Interphase is the previous stage to mitosis | Summarise what happens in interphase:
- during interphase the DNA of the chromosomes replicate (chromatin) - DNA is checked for errors - protein synthesis - synthesis of organelles - ATP production - cell growth
55
What organelles only replicate in animal cells and not plant cells?
Centrioles only replicate in animal cells
56
What do the chromosomes look like in prophase?
- chromosomes condense (shorten and thicken) becoming visible - the chromosomes consist of 2 chromatids joined by a centromere
57
In prophase why do the centrioles move to the poles of the cell?
In prophase centrioles move to the poles of the cell and form spindle fibres
58
What happens to nuclear envelope during prophase?
The nuclear envelope breaks down
59
Why does the nuclear envelope break down?
The nuclear envelope breaks down in order to allow the spindle fibres to attach to the chromosomes To make it easier to move chromosomes
60
During metaphase where do the chromosomes move to?
The chromosomes align at the equator
61
Where do the spindle fibres then attach to during metaphase?
Spindle fibres attach to centromere
62
What happens to the centromere at anaphase?
The centromere splits Causing the chromatids to separate The spindle fibres then contract pulling the chromatids to the opposite poles of the cell
63
Describe what is meant by the phrase the centromere leads?
Because after the centromere splits during anaphase the chromatids are pulled to the opposite poles of cell - with their centromeres leading first
64
Where are the chromatids positioned in telophase?
The chromatids reach the opposite poles on the spindle
65
What do the chromatids then do?
They uncoil and de-condense
66
In telophase do the spindle fibres remain intact?
No, the spindle fibres begin to disintegrate
67
What then forms around each group of chromosomes?
A NUCLEAR ENVELOPE REFORMS around each group of chromosomes
68
What happens to the cytoplasm during cytokinesis?
During cytokinesis the cytoplasm divides and now there are two daughter cells that are genetically identical to the original cell and to each other
69
What happens during cytokinesis to the centrioles?
The centrioles are replicated
70
Each of the cells created in telophase are diploid cells - what does this mean?
Each cell is a diploid cell and contains 2 complete sets (2n) of chromosome
71
How does cell division differ in plants?
- no centrioles - cell plate/wall forms between new cells - cell division only occurs in MERISTEM PLANTS

Biology A Level (36 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions