Module 2 Section: 6 - Cell division Flashcards

1
Q

What are the 3 phases of interphase?
2 phases of mitosis and explain what happens?

A

Interphase:
- growth phase 1
- synthesis
- growth phase 2
Mitotic phase:
- mitosis= nucleus divides
- cytokinesis= cytoplasm divides & 2 daughter cells produced

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2
Q

What is G0? Why might a cell enter G0?

A

The resting phase, in which the cell leaves the cycle temporarily or permanently
When a cell is specialized it no longer needs to divide, hence entering G0

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3
Q

Which cells DON’T divide?

A

DNA damaged cells and senescent cells

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4
Q

What happens at each checkpoint of the cell cycle? (3)

A

G1 checkpoint checks for:
cell size, nutrients, growth factors, DNA damage

G2 checkpoint checks for:
cell size, DNA replication, DNA error

Spindle assembly checkpoint checks for:
all chromosomes attached to spindles and being aligned

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5
Q

What happens at G1 phase?

A
  • proteins synthesised
  • organelles replicated
  • cell enlarges
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6
Q

What happens at synthesis phase?

A
  • DNA replicated
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7
Q

What happens at G2 phase?

A
  • energy stores are increased
  • DNA checked for errors
  • cell enlarges
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8
Q

what are the uses of mitosis

A

-growth
-repair
-asexual reproduction
-Production of new stem cells

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9
Q

what are the 4 division stages of mitosis in order

A

-prophase
-metaphase
-anaphase
-telophase

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10
Q

what happens in prophase

A

-chromosomes condense and become visible
-nuclear envelope breaks down
-nucleolus disappears
-centrioles move to opposite poles and release spindle fibres

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11
Q

what are the parts of the chromosomes called and where are they in the chromosome

A
  • the separate strands are called chromatids
    -the middle part that joins the strands together is called the centromere
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12
Q

what happens in metaphase

A

-chromosomes line up on the metaphase plate (equator)
-spindle fibres attach to centromere

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13
Q

what happens during the anaphase

A

-centromeres divide separating each pair of sister chromatids
-spindle fibres contract pulling the chromatids to opposite poles

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14
Q

what happens during telophase

A

-chromosomes begin to grow and become longer and thinner
-spindle fibres begin to disintegrate
-nucleus reforms
-cytoplasm splits(cytokinesis)

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15
Q

what does meiosis produce

A

gametes

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16
Q

what are all the stages of meiosis and in order

A

-prophase I
-Metaphase I
-Anaphase I
-Telophase I
-Prophase II
-Metaphase II
-Anaphase II
-Telophase II

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17
Q

what happens in Prophase I

A

-Chromosomes condense and become visible as sister chromatids
-nuclear envelope breaks down
-nucleolus disintegrates
-Homologous Chromosomes pair up and crossing over occurs
-Centrioles migrate to opposite poles and start to make spindle fibres

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18
Q

what are homologous chromosomes

A

are pairs of chromosomes that have the same genes but possibly different versions (called alleles) of those genes.

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19
Q

what is crossing over

A

where homologous chromosomes (the ones from your mother and father) swap some of their genetic material. This creates new combinations of genes.

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20
Q

What happens during crossing over in meiosis?

A

During crossing over, homologous chromosomes (chromosomes from both parents) line up next to each other in prophase I of meiosis. They exchange genetic material by swapping sections of their chromatids. This creates new combinations of genes, leading to genetic variation in offspring.

21
Q

what happens in meta phase I

A

-Homologous Chromosomes align at the metaphase plate
-Independent assortment occurs
-spindle fibres attach to sister chromatid centromere

22
Q

what is independent assortment

A

how chromosomes are randomly distributed to gametes

23
Q

what is the process of independent assortment (answer from marksheet)

A

-(homologous
chromosomes) line up,
across the centre of the cell
on the equator / on the
metaphase plate
- maternal or paternal
chromosomes / either one
of the homologous pair,
can end up, facing either
pole / in either (daughter) cell

24
Q

what is a sister chromatid

A

two identical copies of a single chromosome formed during DNA replication

25
Q

what is the Chiasmata

A

point where crossing over occurs

26
Q

what occurs in anaphase I

A

Spindle fibre contract and Homologous Chromosomes separate and move to opposite sides of the cell

27
Q

What happens in Telophase I

A

-nuclear envelope reforms
-spindle fibres breakdown
-cytokinesis

28
Q

What happens in Prophase II

A

-nuclear envelope breaks down
-Chromosomes condense and become visible
-Centrioles move to opposite poles and release spindle fibres

29
Q

what happens in metaphase II

A

-Chromosomes line up on the metaphase plate
-Spindle fibres attach to the centromeres

30
Q

what happens in anaphase II

A

-Spindle fibres attach back to centromere causing the centromere to divide and chromatids to go to each pole

31
Q

what happens in telophase II

A

-Chromosomes start to grow and become longer and thinner
-spindle fibres begin to disintegrate
-Cytoplasm reforms

32
Q

what 2 events in meiosis lead to genetic variation

A

-crossing over and Independent assortment

33
Q

what are senescent cells

A

cells that have stopped dividing and have reached a stage of permanent growth but don’t die

34
Q

what is a stem cell

A

undifferentiated cells which have the potential to differentiate into a range of specialised cell types

35
Q

what do stem cells in bone marrow differentiate into

A

blood cells

36
Q

What do stem cells in the meristem differentiate into

A

xylem and phloem

37
Q

How could stem cells cure Alzheimer’s

A

as with Alzheimer’s nerve cells in the brain die causing memory loss, researchers are hoping to use stem cells to regrow healthy nerves

38
Q

How could stem cells cure Parkinson’s

A

as people with Parkinson’s suffer from tremors they cannot control and the disease causes the loss of a particular type of nerve cell that releases dopamine and stem cells could help regenerate dopamine-producing cells

39
Q

what is the structure and function of neutrophils

A

f: a type of white blood cell that defends the body against disease
s: flexible shape to engulf foreign particles, many lysosomes to break down engulfed particles

40
Q

what is the structure and function of erythrocytes

A

f: red blood cells that carry oxygen in the blood
s: biconcave disc provides large surface area, no nucleus so more space for haemoglobin,

41
Q

what is the structure and function of epithelial cells

A

f: cover the surfaces of organs
s:cilated epithelia have Cilia to beat particles away, squamous epithelia are thin for short diffusion pathway

42
Q

what is the structure and function of sperm cells

A

f: to fertilise the egg
s: have flagellum to swim to the egg, lots of mitochondria to provide it with energy, acrosome has digestive enzymes to allow it to penetrate the surface of the egg

43
Q

what is the structure and function of palisade mesophyll cells

A

f: carry out most of photosynthesis
s: many chloroplasts , thin walls for short diffusion pathway of co2

44
Q

what is the structure and function of root hair cells

A

f: absorb water and mineral ions from the soil
s: large surface area for absorption, thin cell wall for entry of water and ions, cytoplasm has extra mitochondria for energy for active transport

45
Q

where are embryonic stem cells found and what do they differentiate into

A

in the inner embryo, any type of cells

46
Q

what is totipotent cells

A

totipotent cells can develop into any cell type, including extra-embryonic tissues;

47
Q

what is Pluripotent cells

A

Pluripotent cells can form almost all cell types but cannot form extra-embryonic tissues;

48
Q

what is Multipotent cells

A

Multipotent cells can give rise to a limited range of related cell types.

49
Q

Suggest three ways in which the use of embryonic stem cells in research has practical benefits to
biological knowledge.

A

(can be grown into different tissues
to) test how effective new medicinal
drugs are (1)

(can be grown into different tissues
to) test for side effects / toxicity of
new drugs (1)

(can be grown and) studied to see
how they develop into different cell
types (developmental research) (1)

cell function can be studied to find
out what can make it fail to work
properly in certain (named) diseases