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Biology > 2.1.6 cell division, cell diversity and cellular organisation > Flashcards

2.1.6 cell division, cell diversity and cellular organisation Flashcards

1
Q

What are the three checkpoints in the cell cycle?

A

-G1 checkpoint
-G2 checkpoint
-Spindle fibre checkpoint

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2
Q

What is checked at the G1 checkpoint?

A

-cell size
-nutrients
-growth factors
-DNA damage

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3
Q

What is checked at the G2 checkpoint?

A

-cell size
-DNA replication
-DNA damage

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4
Q

What is checked at the Spindle fibre checkpoint?

A

-chromosome attachment to spindle

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5
Q

What happens at G0 in the cell cycle?

A

The cell leaves the cycle temporarily or permanently: for differentiation or DNA has become damaged and is not viable.

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6
Q

What happens at G1 in the cell cycle?

A

Cellular contents (apart from chromosomes) are duplicated, and protein synthesis and respiration occurs.

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7
Q

What happens at S stage in the cell cycle?

A

Each chromosome is duplicated.

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8
Q

What happens at G2 in the cell cycle?

A

Corrects any damage detected to the chromosomes, and cell increases in size.
The energy stores are also increased.

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9
Q

What happens in cytokinesis?

A

Cytoplasm is divided between the two daughter cells.

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10
Q

What happens in mitosis?

A

Nuclear division occurs-places one strand of each chromosome in each daughter nucleus.
Each nucleus is identical to parent nucleus.

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11
Q

What happens during Prophase in mitosis?

A

-Chromatin fibres condense to form chromosomes.
-Protein microtubules form spindle fibres linking to poles of the cell.
-Spindle fibres begin to move chromosomes to centre of the cell.
-Nuclear envelope disappears.

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12
Q

What happens during Metaphase in mitosis?

A

-Chromosomes are moved by the spindle fibres to form the metaphase plate.

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13
Q

What happens during Anaphase in mitosis?

A

-Centromeres divide: sister chromatids into daughter chromosomes.
-Cells elongate.

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14
Q

What happens during Telophase in mitosis?

A

-Nuclear envelope reforms.
-Chromosomes uncoil.
-Nucleolus reforms.

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15
Q

Why is mitosis important in life cycles?

A

-growth and tissue repair
-asexual reproduction

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16
Q

Why is meiosis important in life cycles?

A

-production of haploid cells
-genetic variation (by independent assortment)

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17
Q

What happens in Prophase 1 in meiosis 1?

A

-Chromosomes condense.
-Spindle formation begins.
-homologous chromosomes pair up-bivalents.

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18
Q

What happens in Metaphase 1 in meiosis 1?

A

-Bivalent pairs assemble along the metaphase plate.
-Independent assortment-paternal and maternal chromosomes can face either pole.

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19
Q

What happens in Anaphase 1 in meiosis 1?

A

-Homologous chromosomes pulled to opposite poles-chromatids stay joined.
-Sections of sister chromatids break off and re-join- exchange (genetic variation).

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20
Q

What happens in Telophase 1 in meiosis 1?

A

-Chromosomes assemble at poles.
-Nuclear membrane reforms.
-Chromosomes uncoil.

21
Q

What happens in Prophase 2 in meiosis 2?

A

-Chromosomes condense.
-Nuclear envelope breaks down.
-Spindle formation begins.

22
Q

What happens in Metaphase 2 in meiosis 2?

A

-Individual chromosomes assemble in the metaphase plate.
-Independent variation-more genetic variation.

23
Q

What happens in Anaphase 2 in meiosis 2?

A

-Chromatids of individual chromosomes are pulled to opposite poles.

24
Q

What happens in Telophase 2 in meiosis 2?

A

-Chromatids assemble at poles.
-Chromosomes uncoil.
-Nuclear envelope reforms.

25
Q

How are Erythrocytes specialised for function?

A

-Flattened biconcave shape=>increased their surface area to volume ratio, essential for transporting oxygen around the body.
-No nuclei or many other organelles=>increases space available for haemoglobin.
-Flexible=>squeeze through narrow capillaries.

26
Q

How are Neutrophils specialised for function?

A

-Multi-lobed nucleus=>makes it easier to squeeze through small gaps to get to site of infection.
-Granular cytoplasm contains many lysosomes=>contain enzymes used to attack pathogens.

27
Q

How are Sperm cells specialised for function?

A

-Flagellum=>capable of movement
-Many mitochondria=>supply energy needed to swim.
-Acrosome on the head of the sperm contains digestive enzymes=>released to digest protective layers around the ovum and allow sperm to penetrate.

28
Q

How are Palisade cells specialised for function?

A

-Chloroplasts=>absorb large amounts of light for photosynthesis.
-Rectangular box shape=>can be closely packed to form a continuous layer.
-Thin cell walls=>increasing the rate of diffusion of carbon dioxide.
-Large vacuole=>maintain turgor pressure.
-Chloroplasts can move in the cytoplasm=>absorb more light.

29
Q

How are Root hair cells specialised for function?

A

-Root hairs(long extension)=>increase surface area of the cell, maximising the uptake of water and minerals in the soil.

30
Q

How are Guard cells specialised for function?

A

-Pair of guard cells which form small openings called stomata=>necessary for carbon dioxide to enter plants for photosynthesis.
-Change shape=>loss of water causes them to close to stop any more water being lost.
-Cell wall of guard cell is thicker on one side=>the cell does not change shape symmetrically as its volume changes.

31
Q

How is Squamous epithelium specialised for function?

A

-Made up of flat cells=>very thin
-Present when rapid diffusion across a surface is needed.
-Forms the lining of the lungs and allows rapid diffusion of oxygen into the blood.

32
Q

How is Ciliated epithelium specialised for function?

A

-Made up of ciliated epithelial cells=>cilia that move in a rhythmic manner, sweeps mucus away.
-Goblet cells present=>releasing mucus to trap any unwanted particles present in the air, prevents particles from reaching the alveoli.

33
Q

How is Cartilage specialised for function?

A

-Contains fibres of the proteins elastin and collagen.
-Firm connective tissue
-Prevents bones from rubbing together and causing damage.

34
Q

How is Muscle specialised for function?

A

-Skeletal muscle fibres contain myofibrils containing contractile proteins=>allows muscle to contract.

35
Q

What are the four main categories of tissues in animals?

A

-Nervous tissue.
-Epithelial tissue.
-Muscle tissue.
-Connective tissue.

36
Q

How is Epidermis specialised for function?

A

-Waxy waterproof cuticle=>prevents water loss.
-Stomata=>allow carbon dioxide in, and water vapour and oxygen out.

37
Q

How is Xylem tissue specialised for function?

A

-Elongated dead cells.
-Lignin coated walls=>strengthens walls which provides structural support for plants.

38
Q

How is Phloem tissue specialised for function?

A

-Composed of sieve tube elements separated by sieve plates.

39
Q

What are stem cells?

A

Stem cells are undifferentiated cells.

40
Q

What is stem cell Potency?

A

Ability of a stem cell to differentiate into different cell types.

41
Q

What is a Totipotent stem cell?

A

Stem cells can divide and differentiate into any type of cell.

42
Q

What is a Pluripotent stem cell?

A

Stem cells that can self-renew and differentiate into any type of cell (except in the placenta).

43
Q

What is a Multipotent stem cell?

A

Stem cells that can only differentiate and divide into a limited number of cell types.

44
Q

Why do blood cells need to be produced from stem cells?

A

Erythrocytes only have a life span of 120 days and so need to be replaced constantly.

45
Q

Where are blood stem cells found?

A

Blood stem cells are found in peripheral blood and bone marrow.

46
Q

How long do neutrophils live?

A

Neutrophils live for about 6 hours (producing about 1.6 billion kg per hour).

47
Q

Where are stem cells in plants found?

A

In meristem-Meristematic tissue is found wherever growth occurs in a plant.

48
Q

What treatments can stem cells provide in medicine?

A

-Heart disease.
-Type 1 diabetes.
-Parkinson’s disease.
-Alzheimer’s disease.
-Macular degeneration.
-Birth defects.
-Spinal injuries.
-Burn treatments.
-Drug trials.

49
Q

What are ethical reasons against stem cells?

A

-Using embryonic stem cells isn’t morally right, some believe life starts at conception.

Biology (25 decks)

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