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A-Level Biology > Mitosis > Flashcards

Mitosis Flashcards

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1
Q

what happens in mitosis

A

in mitosis, a parent cell divides to produce two genetically identical daughter cells

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2
Q
  • why is mitosis needed
A

Growth

repair

reproduction

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3
Q
  • why is Mitosis important for growth
A

when two haploid cells fuse together to form a diploid cell, it has all the genetic information needed to form the new organism

if the new organism is to resemble its parents, all the cells that grow from this original cell must be genetically identical

mitosis ensures this happens

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4
Q
  • why is mitosis important for repair
A

if cells are damaged or die it is important that the new cells produced have an identicle structure and function to the ones that have been lost

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5
Q
  • why is mitosis important for reproduction
A

single-celled organisms divide by mitosis to give two new organisms. Each organism is genetically identical to the parent organism

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6
Q
  • what happens when a cell cannot divide
A

they follow a cell cycle

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7
Q
  • explain the cell cycle
A

the cell cycle consists of a period of cell growth and DNA replication called interphase

mitosis happens after that interphase is subdivided into three separate growth sugars

these are called G1, S and G2

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8
Q
  • state the four phases in mitosis
A

prophase, metaphase, anaphase and telophase

interphase comes before mitosis in the cell cycle

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9
Q
  • explain the interphase
A

the cell carries out normal functions, but also prepares to divide

the cell DNA is unraveled and replicated, to double its genetic content

the organelles are also replicated so it has spare ones, and its ATP content is increased

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10
Q
  • Explain the prophase
A

chromosomes condense getting shorter and fatter ( they become visible)

centrioles move to the opposite poles of the cell. this is where protein spindle fibres are released

the nuclear envelope begins to disintergrate

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11
Q
  • explain the metaphase
A

there is no longer a nucleus in the cell, the centrioles move to opposite poles and release spindle fibers

the chromosomes align themselves at the equator of the cell each with a pair of sister chromatids

spindle fibers attach to either the chromatids or centromere

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12
Q
  • explain the anaphase
A

the chromosome divide, separating each pair of sister chromatids.

the spindles contract towards the centrioles so the centromere breaks due to the tension created

resulting in the chromatids separating by being pulled to opposite poles of the cell

this stage requires a lot of ATP from respiration

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13
Q
  • explain the telophase
A

the chromatids reach the opposite poles on the spindle

they uncoil and become long and thin again

they’re now called chromosomes again

a nuclear envelope forms around each group of chromosomes, so there are now two nuclei

Division of the cytoplasm (cytokinesis, which starts in anaphase) finishes in telophase

there are now two daughter cells that are genetically identical to the original cell and o each other.

mitosis is finished and each daughter cell starts the interphase part of the cell cycle to get ready for the next round of mitosis

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14
Q
  • how long does a cell cycle take
A

24 hours

90 percent of this is the interphase

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15
Q
  • define cancer
A

cancer is a group of diseases caused by the a growth disorder of cells.

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16
Q
  • what is cancer the result of
A

damage to the fenes that regulate mitosis and the cell cycle

this leads to uncontrolled growth and division of cells

a tumour develops and constantly expands in size

17
Q
  • what organs do tumors most commonly develop in
A

the lungs, prostate gland, breast and ovaries, large intestine, stomach, esophagus and pancreas

18
Q
  • how does a tumour become cancerous
A

if it changes from benign to malignant

19
Q
  • what affects the rate of mitosis
A

environment of the cel

growth factors

it is also controlled by two types of genes

20
Q
  • what results in uncontrolled mitosis
A

a mutation to one of the genes results in uncontrolled mitosis

21
Q
  • explain what happens to the mutant cells
A

the mutant cells formed ae usually structually and functionally different from normal cells

most mutant cells die, However, any that survive are capable of dividng to form clones of themselves and forming tumours

22
Q
  • explain the difference between malignant and benign tumours
A

malignant grow rapidly, are less compact and more likely to be life-threatening

while benign ones grow more slowly, are more compact and are less likely to be life-threatening

23
Q
  • explain the treatment of cancer cells
A

the treat ment of cencer cells often involves killing dividing cells by blockung a part of the cell cycle.

in this way the cell cycle is disrupted and cell division, and hence the cancer growth, ceases.

24
Q
  • explain how radiation can be used to treat cancer cells
A

radiation and some drugs damage DNA. at several points in the cell cycle the DNA in the cell is checked for damage. if severe damage is detected, the cell will kill itself- preventing further tumour growth

25
Q
  • How do drugs disrupt the cell cycle
A

preventing DNA from replicating

inhibiting the metaphase stage of mitosis by interfering with spindle formation

26
Q
  • what is the problem with these drugs
A

they also disrut the cell cycle of normal cells

however, the drujgs are more effective against rapidly dividing cells. as cancer cells have a particularly faster rate of division they are damaged to a greater degree than normal cells

27
Q
  • why are hair producing cells lost
A

they divide rapidly so are vulnerable to damage.

this explains the hair loss frequently seen in patients undergoing cancer treatment

28
Q

mitotic index equation

A

the number of cells in mitosis /
total number of cells x100

29
Q

define centromere

A

the central point that holds two chromatids together

30
Q

define chromatids

A

chromatids are arms of the chromosomes

31
Q

define G1 in interphase

A

all the organelles double and cell grows

32
Q

Define S in interphase

A

DNA replication

33
Q

define G2 in interphase

A

more growth occurs and DNA is checked for any mutations if detected its destroyed

A-Level Biology (14 decks)

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