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Biology > 2.3.2- Cell Division > Flashcards

2.3.2- Cell Division Flashcards

1
Q

What is interphase?

A

A period of cell growth and DNA replication

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2
Q

What are the three growth phases of interphase?

A

G1 S and G2

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3
Q

What happens in Gap phase 1

A

The cell grows (vol of cytoplasm) and new organelles and proteins are made.

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4
Q

What happens in the synthesis phase?

A

The cell replicates its DNA (semi-conservitively), this leads to 2 identical chromatids joined at a centromere

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5
Q

What happens in Gap phase 2

A

The cell keeps growing and proteins needed for cell division are made.

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6
Q

Describe in detail the three main events that occur during interphase.

A
  • DNA is unravelled and replicated to double genetic content
    -Organelles are replicated so it has spare ones
    -ATP content is increased as it is needed for cell division
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7
Q

Describe prophase in mitosis.

A

The chromosomes condense getting dhorther and fatter as ting bundles of proteins being the centrioles move to oppposite ends of the cell forming a network of protein fibres across it called the spindle. The nuclear envelope around the nucleus breaks down and the chromoseomes lie free in the cytoplasm.

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8
Q

Describe metaphase in mitosis.

A

The chromosomes (each with two chromatids) line up along the middle of the cell and become attached to the spindle by their centromere.

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9
Q

Describe anaphase in mitosis.

A

The centometres divide, seperating each pair of sister chromatids. The spindles contracts, pulling chromatids to opposite poles (ends) of the spindle, centrometre first. Thsi makes the chromatids appear v- shaped.

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10
Q

Describe telephase in mitosis.

A

The chromatids reach the opposite poles on the spindle. They uncoil and become long and thin again. They are now called chromosomes again. A nuclear envelope forms around each group of chromsomes, so now there are two nuclei. Then cytokineseis occures.

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11
Q

Describe cytokinesis

A

Startes during anaphase and finishes in telephase and is the division of cytoplasm. At the end of it therre are now two daughter cells that are genetically indentical to the origional cell and to eachother. Then each daughter cell starts interphase to do it all over again.

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12
Q

Why are there sister chromatids on the chromosome before mitosis begins?

A

Because during interphase, each chromosome has already made an identical copy of itself?

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13
Q

What is a sister chromatid?

A

Two strands of the same chromosome.

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14
Q

Give three uses of mitosis

A

Growth
Repair
Asexual reproduction

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15
Q

What is cancer?

A

A tumour that invades surroumnding tissue cause by uncontrolled cell division from a mutation in a gene that controlls cell division.

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16
Q

Why is cancer treatment more likely to kill cancerous cells than normal cells?

A

Because cancer cells divide much more frequently than normal cells.

17
Q

Dscribe how some cancer treatments target cell cycles.

A

During g1 chemotherapy prevents the sythesis of enzymes needed for synthesis causing it to kill itself.
During synthesis radiation and some DNA drugs damage DNA and if sever damage id detected, the cell will kill istelf both preventing tumour growth.

18
Q

In what stage of the cell cycle does all the DNA unravel.

A

The S phase.

19
Q

What os the mitotic index?

A

The proportion of cells in a tissue sample that are undergoing mitosis.

20
Q

State the formula to work put the mitotic index

A

mitotic index = number of cells with visible chromosomes ÷ total number of cells

21
Q

Give the formula for calculating actual size

A

Actual Size =Image size (with ruler)÷Magnification

22
Q

State a 2 suitable stains that can be used to investigate mitosis.

A

Toludoine
Ethano-orcein

23
Q

State the abbreviagtion of formula used to calculate magnification.

A

IAM

24
Q

What does the name ‘Binary Fission’ refer to

A

Division in Prokaryotic cells

25
Q

How is binary fission diffferent from normal mitosis?

A

There is no nuclesr envelope to breakdown
There are no spindle fibres present

26
Q

Describe the process of Binary fission

A

A single circular DNA molecule molecule undergoes DNA replication and any plasmids present. The parent cell divides into two and cytoplasm is roughkly parted between the two daugher cells.Each daughter cell contains a singular copy of the circular DNA molecule and a variable number of plasmids.

27
Q

How is it ensured each daughter cell inherits a copy of a single DNA moleucle and some plasmids?

A

If it does not receive the singular circular DNA molecule, or at least one copy of a plasmid the die.

28
Q

How come the daughter cells produced in binary fission can have different no. of plasmids but still be genetically identical?

A

The contain the same genetic code they just have less or more identical copies of that code.

29
Q

Why cant viruses undergo cell division?

A

They are parastic meaning they can only reproduve by infecting living cells (host cells).

30
Q

What stage of the cell cycle do cells spend most of their life in?

A

G1 (Interphase)

31
Q

Where does DNA syntheseis happen in a eukaryotic cell?

A

Nucleus

32
Q

Describe how to prepare squahses of cells from plant root tips

A

Cut a thin slice of a root tip(5mm) from end using scalpel and mount onto a slide
Soak root tip in HCl the rinse
Stain for DNA (end toluidine blue)
Lower coverslip using a mounted needle at 45” not trapping ait bubbles
Squash by firmly pressing down on a glass slip

33
Q

Why are root tips used in Practical 2?

A

That is where mitosis occurs

34
Q

Why is a stain used in practical 2

A

To distinguish chromosmes which are not visible otherwise

35
Q

Why press dwon on the cover of the slip when using an optical microscope to identify the stages of mitiosis

A

Thois creates a single layer of cells so light passes throught to make chromosomes visible

36
Q

Why is it important to not oush the slip sideways in Practical 2?

A

To avoid rolling cells tg and breaking chromosmes

37
Q

Why are root tips soaked in HCL in Practical 2?

A

This seperates cells/ cells walls allowing stain to diffuse into cells.This allows cells to be more easily squashed and it stops mitosis

38
Q

Descibe how to set up and use an optical microscope

A

Clip slide onto stage and turn on the light
Set power to lowest objective lens
Use coarse focusng dial to move stage close to lens then turn coarse focusing dial to move away from lens u till image comes into focus.
Add fine focusing dial to get clear image
Swap to higher objective power lens then refocus

39
Q

Describe how viruses replicate

A

Their attachment proteins attach to complementary receptors on host cells
This injects its viral RNA/DNA into the host cell
Infected host cell replicates virus particles
Nucleic acid replicated so cell produces protein/ caspid/enzymes
Virus is assmepled and then released

Biology (9 decks)

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