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A Level Biology > Cell division, cell diversity and cellular organisation > Flashcards

Cell division, cell diversity and cellular organisation Flashcards

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1
Q

What are stem cells

A

Cells that are undifferentiated and have the potential to become specialised or differentiated. They are not adapted for any particular function, but are able to undergo cell division multiple times.

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2
Q

Why must division of cells take place?

A
  • Cell growth
  • Cell development
  • Tissue repair
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3
Q

Why is the activity of stem cells strictly controlled?

A

Rapid division - can lead to tumours

Slow division - can lead to ageing

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4
Q

What is cell potency?

A

A stem’s cell ability to differentiate into different types of cells.

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5
Q

Define totipotent

A

Potential to different into any type of cell

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6
Q

Define pluripotent

A

Potential to differentiate to all types of tissue, but not whole organism

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7
Q

Define Multipotent?

A

Can only differentiate into a range of cells within a certain type of tissue.

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8
Q

Describe when cells can be totipotent

A

The first 8-16 cells in an embryo

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9
Q

Describe when cells can be pluripotent

A

Early embryos

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10
Q

Describe when cells can be multipotent

A

Stem cells in bone marrow

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11
Q

Where are blood cells derived from?

A

Bone marrow

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12
Q

What is the scientific name for red blood cells?

A

Erythrocytes

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13
Q

Why do red blood cells need to be constantly replaced?

A

Short life span due to lack of nucleus

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14
Q

How long do neutrophils live for?

A

6 hours

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15
Q

What are the two types of animal stem cells?

A
  • Embryonic stem cells

- Tissue (adult) stem cells

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16
Q

What is the different between embryonic stem cells and adult stem cells?

A

Embryonic stem cells have a higher potency, and are therefore able to differentiate into more types of cells, whereas adult stem cells can only differentiate into specific tissues.

Embryonic - totipotent
Adult tissues stem cells - pluripotent

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17
Q

What is the source of plant stem cells?

A

Meristems (meristematic tissue)

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18
Q

Describe the potency of meristems

A

Pluripotent

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19
Q

What are the uses of stem cells?

A
  • Heart disease (muscle tissue)
  • Type 1 diabetes
  • Parkinson’s disease
  • Alzheimer’s disease
  • Treatment of burns
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20
Q

Explain ethical problems associated with stem cells

A

The use of embryonic stem cells is controversial due to the differing perceptions of whether an embryo is a child or not. This allows doctors to use pluripotent cells instead of Multipotent cells found in bone marrow.
- Religious objections as well

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21
Q

What are specialised cells?

A

Cells that have differentiated

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22
Q

What are examples of specialised animal cells?

A
  • Erythrocytes
  • Neutrophils
  • Sperm cells
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23
Q

How are erythrocytes specialised?

A
  • Bioconcave shape - increase SA:V
  • Don’t have nucleus - more space for haemoglobin
  • Flexible - can squeeze through capillaries
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24
Q

How are neutrophils specialised?

A
  • Multi-lobed - can squeeze through small gaps to get to site of infections
  • Granular cytoplasm contains lysosomes, that contain enzymes used to attack pathogens.
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25
Q

How are sperm cells specialised?

A
  • Tail and flagellum - aid movement
  • Many mitochondria - provides energy to swim
  • Acrosome (head of the sperm) - contains digestive enzymes to penetrate eggs.
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26
Q

What are examples of specialised plant cells?

A
  • Palisade cells
  • Root hair cells
  • Guard cells
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27
Q

How are palisade cells specialised?

A
  • Chloroplasts in mesophyll - absorb light for photosynthesis
  • Thin walls - increase diffusion rate for CO2.
  • Large vacuole - maintain tugor pressure.
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28
Q

How are root hair cells specialised?

A
  • Increased the surface area of the cell

- maximises water & mineral uptake

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29
Q

How are guard cells specialised?

A
  • Cell wall is thicker on one side, so creates a hoop shape.
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30
Q

What are examples of specialised animal tissues?

A
  • Squamous epithelium
  • Ciliated epithelium
  • Cartilage
  • Muscle
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31
Q

How is squamous epithelium specialised?

A
  • Lining the lungs - one cell thick allowing for rapid diffusion.
32
Q

How is ciliated epithelium specialised?

A
  • Contains cilia

- Contains goblet cells

33
Q

How is cartilage specialised?

A
  • Flexible - prevents ends of bones rubbing together and causing damage.
  • Keeps airways open and allows oesophagus to expand when food is swallowed.
34
Q

What are examples of specialised plant tissues?

A
  • Epidermis
  • Xylem tissue
  • Phloem tissues
35
Q

How is plant epidermis specialised?

A
  • Covered by a waxy waterproof cuticle to reduce water loss.
36
Q

How is xylem tissue specialised?

A
  • composed of elongated dead cells

- Lignified for structural support

37
Q

How are phloem tissues specialised?

A
  • Contains sieve plates, within tubes.
38
Q

What are 3 organ systems

A

The digestive system
The cardiovascular system
The gaseous exchange system

39
Q

What does the digestive system do?

A
  • Takes in food and breaks down the large insoluble molecules into small soluble ones.
  • Absorbs nutrients into the bloodstream.
40
Q

What does the cardiovascular system do?

A

Moves blood around the body to provide an effective transport system.

41
Q

What does the gaseous exchange system do?

A

Brings air into the body so oxygen can be extracted for respiration and CO2 can be expelled.

42
Q

What is the importance of mitosis?

A
  • Ensures daughter cells are genetically identical
  • Growth, replacement and repair of tissues.
  • Necessary for asexual reproduction
43
Q

How does bacteria divide?

A

Binary fission

44
Q

When does DNA replicate during cell division?

A

During interphase, before mitosis

45
Q

What is the name given to DNA that has replicated during interphase?

A

Chromatids

46
Q

At what region are identical chromatids joined?

A

Centromere

47
Q

What are the 4 stages of mitosis?

A
  1. Prophase
  2. Metaphase
  3. Anaphase
  4. Telophase
48
Q

Describe Prophase during mitosis

A
  1. Chromatin coils creating chromosomes
  2. Nuclear membrane breaks down.
  3. Centrioles migrate to opposite poles
  4. Centrioles form spindle fibres, that attach to specific areas of the centromeres.
49
Q

Describe metaphase during mitosis

A

The chromosomes are moved by the spindle fibres to form a plate in the centre of the cell, called the metaphase plate.

50
Q

Describe anaphase during mitosis

A

The centromeres divides, separating each chromatids, which is pulled to opposite poles of the cells, by shortening spindle fibres.

51
Q

Describe Telophase during mitosis

A

Chromatids are now at poles and nuclear envelope reform around them. Chromosomes start to uncoil and nucleolus is formed.

52
Q

What is cytokinesis?

A

Actual division of the cytoplasm and the cell into two separate cells.

53
Q

What are the 4 phases of the cell cycle (not mitosis)

A
  • Mitotic phase
  • G1
  • S phase
  • G2
54
Q

Describe the mitotic phase

A
  • Mitosis and Cytokinesis
55
Q

Describe the G1 stage?

A
  • Organelles replicate
  • Transcription/Translation
  • Size of cell increase
56
Q

What does the S Phase mean?

A

Synthesis phase

57
Q

Describe the S phase

A
  • DNA synthesis

- Chromosomes replicated

58
Q

Describe the G2 Phase

A
  • Energy stores replaced
  • Transcription/translation
  • Chromosome repair
  • Size of cell increases
59
Q

What occurs at the metaphase checkpoint?

A

Checks for chromosomes spindle attachment

60
Q

What occurs at the G1 Checkpoint?

A

Checks for nutrients, growth and DNA damage

61
Q

What occurs at the G2 checkpoint?

A

Checks for cell size and DNA replication

62
Q

What is the purpose of meiosis occur?

A

- Production of gametes

- Produces genetic variation

63
Q

What type of process is meiosis?

A

Reduction division

64
Q

What type of cells are created by mitosis?

A

Diploid

65
Q

What type of cells are created by meiosis?

A

4 haploid cells

66
Q

What stages are in meiosis?

A

Interphase

Meiosis 1:

Prophase 1
Metaphase 1
Anaphase 1
Telophase 1

Meiosis 2:
Prophase 2
Metaphase 2
Anaphase 2
Telophase 2
67
Q

What happens in meiosis 1?

A

Reduction division where homologous chromosomes are separated into two cells

68
Q

What happens in meiosis 2?

A

The second division involves each daughter cell being separated, forming two cells.

69
Q

What happens on Prophase 1 in meiosis?

A

Chromosomes condense, nuclear envelope disintegrates, and spindle formation.

Crossing can occur, leading to genetic variation

70
Q

What happens in Metaphase 1 in meiosis 1?

A

Homologous pairs of chromosomes assemble along the metaphase plate, instead of individual chromosomes.

71
Q

What happens in Anaphase 1 in meiosis 1?

A

Homologous chromosomes are pulled to opposite poles, however chromatids stay joined.

Sections of genes break off and recombination of genes lead to genetic variation.

72
Q

What happens in Telophase 1 of Meiosis 1?

A

Chromosomes assemble at each pole and nuclear reforms. Chromosomes uncoil.

Cytokinesis then takes place.

73
Q

What happens in Prophase 2 in Meiosis 2?

A

Chromosomes coil and nuclear envelope breaks down and spindle formation begins.

74
Q

What happens in Metaphase 2 in Meiosis 2?

A

Individual chromosomes assemble on the metaphase, and independent assortment occurs - causing genetic variation.

75
Q

What happens in Anaphase 2 in meiosis 2?

A

Chromatids of the individual chromosomes are pulled to opposite poles after division of the centromeres, towards the centrioles.

76
Q

What happens in Telophase 2 in metaphase 2?

A

Chromatids assemble at the poles. Chromosomes uncoil and nuclear envelope reforms.

Cytokinesis results in division of cells forming four daughter cells in total.

A Level Biology (13 decks)

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