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Biology Paper 2 > 2.2 All cells arise from other cells (including Required Practical 2) > Flashcards

2.2 All cells arise from other cells (including Required Practical 2) Flashcards

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1
Q

What is the cell cycle?

A

Cells that don’t divide continuously but undergo a regular cycle of division separated by periods of cell growth are said to have a cell cycle

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2
Q

What are the three stages of the cell cycle?

A
  • interphase
  • nuclear division
  • cytokinesis
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3
Q

What is interphase? (Cell cycle)

A

It occupies most of the cell cycle and is sometimes known as the resting phase because no division takes place

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4
Q

What is nuclear division?

A

When the nucleus divides either into two during mitosis or four during meiosis

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5
Q

What is cytokinesis?

A

Division of cytoplasm which follows nuclear division

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6
Q

What is the length of the cell cycle?

A
  • complete cycle length varies greatly between organisms
  • typically, a mammalian cell takes about 24 hours to complete a whole cycle (90% of this time the cell is in interphase)
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7
Q

What are the 5 stages of mitosis?

A
  • interphase
  • prophase
  • metaphase
  • anaphase
  • telophase
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8
Q

Describe interphase.

A
  • occupies most of the cell cycle, and is sometimes known as the resting phase because no division takes place
  • lots of cellular activity which includes the replication of DNA
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9
Q

Describe prophase.

A
  • the chromosomes condense (shorten and thicken) so that they can be seen
  • centrioles move to opposite ends of the cell and spindle fibres develop from them. Together spindle fibres are known as spindle apparatus
  • nucleolus disappears and nuclear envelope breaks down
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10
Q

Describe metaphase.

A
  • the chromosomes are pulled along the spindle apparatus by their centromeres and arrange themselves along the equator of the cell
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11
Q

Describe anaphase.

A
  • the centromeres divide in two and the spindle fibres pull the chromatids apart
  • the chromatids move to their respective poles and we now refer to them as chromosomes again
  • the energy for this process is provided by the mitochondria
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12
Q

Describe telophase.

A
  • chromosomes reach their respective poles and become longer and thinner, finally disappearing completely (leaving widespread chromatin)
  • spindle fibres disintegrate and the nuclear envelope and nucleolus reform
  • cytoplasm divides in a process called cytokinesis
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13
Q

What is mitosis?

A

Division of a cell that results in each of the daughter cells having an exact copy of the DNA of the parent cell (except for mutations which are rare)

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14
Q

What is the importance of mitosis?

A
  • growth
  • repair
  • reproduction (single cells organisms)
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15
Q

How can cell division take place?

A

Either by mitosis or meiosis

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16
Q

Factors of mitosis (x11)

A
  • DNA is copied exactly (if there are no mutations)
  • the daughter (new) cells are copies of the parent cell
  • daughter cells have the same number of chromosomes as the parent cell
  • chromosomes of the parent cell are duplicated in the daughter cells
  • enables a species to colonise an area quickly using asexual reproduction
  • important for the growth of plants and animals
  • produces clones
  • important for the repair of damaged tissue where new cells must be identical to damaged cells
  • the original (parent cells) become 2 daughter cells
  • when out of control, a cancerous tumour may result
  • produces cells with the diploid number of chromosomes
17
Q

Factors of meiosis (x11)

A
  • 4 daughter cells are made
  • cell division by reduction
  • forms gametes (sex cells)
  • increases the variety of offspring - provides a varied stock of individuals
  • happens only in gamete producing organs (testes, ovaries, pollen, sacs, ovules)
  • the daughter cells contain half the number of chromosomes as the parent cell
  • produces new genetic combinations in individuals
  • ensures that the number of chromosomes remains the same in sexually reproducing organisms
  • enables a species to adapt to a changing environment or to colonise new environments
  • halves the number of chromosomes in cells
  • produces cells with the haploid number of chromosomes
18
Q

Describe stem cells

A
  • the first group of cells in an embryo are initially identical
  • all cells are produced through mitosis division and contain the same genes
  • only some genes are switched on
  • different genes are switched on depending on the cells specialism
19
Q

What is cancer?

A
  • group of diseases caused by a growth disorder of cells
  • it is the result of damage to the genes that regulate mitosis and the cell cycle
  • if the cell cannot regulate its growth this could lead to uncontrolled growth and division of cells. These uncontrolled cells form a growth (tumour) which keeps growing
20
Q

Where can tumours develop?

A
  • they can develop in any organ in the body
21
Q

Where a tumours most commonly found?

A
  • most commonly in; lungs, prostate gland (in males), breasts and ovaries (in females), large intestine, stomach, oesophagus and pancreas
22
Q

When do tumours become cancerous?

A
  • if they change from benign to malignant
23
Q

What are the problems with treating cancer?

A
  • using these kinds of drugs also disrupts the cell cycle of normal cells
  • however the drugs are more effective against rapidly dividing cells such as cancer cells
  • normal body cells that divide rapidly include hair-producing cells which explains hair loss during cancer treatment
24
Q

What are the treatments for cancer?

A

-often involves killing dividing cells by blocking part of the cell cycle
- drugs used to treat cancer (chemotherapy) usually disrupt the cell cycle by preventing DNA from replicating and inhibiting the metaphase stage of mitosis by interfering with spindle formation

25
Q

What are the properties of malignant tumours?

A
  • grow rapidly
  • less compact
  • more likely to be life threatening
26
Q

What are the properties of benign tumours?

A
  • grow more slowly
  • are more compact
  • less likely to be life threatening
27
Q

What happens if the genes controlling cell growth mutate? (Benign vs malignant)

A

If the genes controlling cell growth mutate the cells will divide uncontrollably, these mutant cells are very different to normal cells in structure and function that most of them die

28
Q

What happens to any surviving mutants? (Benign vs malignant)

A

Any surviving mutants are able to divide and clone themselves which forms tumours

Biology Paper 2 (9 decks)

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