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AS- Biology > 2.6- Cell division, cell diversity and cellular organisation > Flashcards

2.6- Cell division, cell diversity and cellular organisation Flashcards

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1
Q

What is the cell cycle?

A

The process that all body cells in multicellular organisms use to grow and divide

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2
Q

What are the two periods in the cell cycle called?

A

Interphase and M Phase (M phase involves mitosis and cytokinesis)

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3
Q

What occurs in interphase?

A

Cell growth and DNA replication

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4
Q

What occurs in M phase?

A

Mitosis and cytokinesis

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5
Q

What are the three growth stages of interphase?

A

G1,S,G2

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6
Q

What occurs during G1?

A

Cell grows and new organelles and proteins are made

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7
Q

What occurs during the synthesis phase?

A

Cells replicate DNA ready to divide by mitosis

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8
Q

What occurs during G2?

A

Cell keeps growing and proteins needed for cell division are made

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9
Q

What occurs at the G1 checkpoint?

A

That cell checks that the chemicals needed for replication are present and for any damage to the DNA (this occurs before entering S phase)

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10
Q

What occurs at the G2 checkpoint?

A

The cell checks whether all the DNA has been replicated without any damage. If it has the cell can enter mitosis.

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11
Q

What are the four stages of mitosis?

A

Prophase, metaphase, anaphase, telophone,

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12
Q

What occurs during prophase?

A
  • The chromosomes condense, getting shorter and fatter.
  • Centrioles start moving towards opposite ends of the cell
  • The nuclear envelope breaks down and chromosomes lie free in the cytoplasm
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13
Q

What occurs during metaphase?

A

What occurs during metaphase?

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14
Q

What occurs during anaphase?

A
  • The centromeres Divide separating each pair of chromatids

- The spindles contract pulling chromatids towards opposite ends of the cell

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15
Q

What occurs during telophase?

A
  • The chromatids reach the opposite poles of the spindle and uncoil and become long and thin again (they are now called chromosomes again)
  • A nuclear envelope forms around each group of chromosomes so there are now two new nuclei
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16
Q

What is cytokinesis?

A

Where the cytoplasm divides. In animal cells, a cleavage furrow forms to divide the cell membrane. There are now two daughter cells that are genetically identical to each other.
Cytokinesis is a separate process to mitosis

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17
Q

What occurs during interphase?

A
  • The cell carries out normal functions but also prepared to divide
  • The cells DNA is unravelled and replicated to double its genetic content
  • The organelles are also replicated so it has spare ones and it’s ATP content is increased
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18
Q

How can you observe the cell cycle and mitosis?

A

You can stain chromosomes (using Giemsa stain) so that you can see them under a microscope and watch what happens during mitosis.

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19
Q

What does meiosis produce?

A

Gametes for sexual reproduction

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20
Q

Why are cells produced in meiosis genetically different to each other?

A

Each new cell ends up with a different combination of chromosomes

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21
Q

What are haploid cells?

A

Cells with half the normal number of chromosomes

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22
Q

How many divisions in meiosis?

A

2, meiosis I and meiosis II

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23
Q

What happens in prophase 1?

A

The chromosomes condense
The chromosomes and arrange themselves into homologous has and crossing over occurs
Centrioles style after the ends of the cell
The nuclear envelope breaks down

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24
Q

What happens in metaphase 1?

A

The homologous pairs line up across the centre of the cell and attach to spindle fibres

25
Q

What happens in anaphase 1?

A

The spindles contracts, separating the homologous pairs

26
Q

What happens in telophase 1?

A

A nuclear envelope forms around each group of chromosomes

27
Q

What happens in prophase 2?

A

The chromosomes condense
The chromosomes and arrange themselves into homologous has and crossing over occurs
Centrioles style after the ends of the cell
The nuclear envelope breaks down

28
Q

What happens in metaphase 2?

A

The homologous pairs line up across the centre of the cell and attach to spindle fibres

29
Q

What happens in anaphase 2?

A

The pairs of sister chromatids are separated and each new daughter cell inherits one chromatid from each chromosome
Four genetically different daughter cells are produced(gametes)

30
Q

What is the overall aim of meiosis?

A

The half the chromosome number(reduction division)- this occurs during meiosis 1

31
Q

How does chromatids crossing over cause variation in meiosis?

A

During prophase 1, chromatids twist around each other and bits of chromatids swap over
The chromatids still contain the same genes but now have a different combination of Alleles

32
Q

How does meiosis produce cells which are genetically different? (2 ways)

A

Crossing over of chromatids

Independent assortment of chromosomes

33
Q

How does the independent assortment of chromosomes produce genetic variation?

A

When the homologous pairs line-up in metaphase 1 and are separated in anaphase 1, they pair up completely randomly
This leads to genetic variation

34
Q

What are stem cells?

A

Unspecialised cells that can develop into different types of cells

35
Q

Where is stem cells found in humans?

A

Early embryos - can develop into any type of human cell

Adults- can develop into a limited range of cells

36
Q

What is differentiation?

A

The process by which a cell becomes specialised for its job

37
Q

How are stem cells used in adults?

A

To replace damaged cells for skin or blood cell

38
Q

How are stem cells used in plants?

A

To make new shoots and roots throughout their lives as the plant grows

39
Q

How are blood cells created?

A

Adult stem cells in the bone marrow divide and differentiate to replace worn-out blood cells

40
Q

How could stem cells be used to treat Alzheimer’s?

A

Stem cells could help regrow nerve cells for people with Alzheimer’s

41
Q

How could stem cells be used to treat Parkinson’s?

A

Transplanted stem cells to regenerate the dopamine producing cells

42
Q

How are neutrophils specialised?

A

The flexible shape allows them to engulf foreign pathogens
The many lysosomes in the cytoplasm contain digestive enzymes to break down in golf particles
They have a lobed nucleus to squeeze through small capillaries

43
Q

How are erythrocytes specialised?

A

The biconcave disc shape provides a large surface area for gas exchange
They have no nucleus so there’s more room for haemoglobin

44
Q

How are epithelial cells specialised?

A

Ciliated epithelium of cilia that move particles away

Squamous epithelium in the lungs are very thin to allow efficient diffusion of gases

45
Q

How are sperm cells specialised?

A

They have a flagellum so they can swim to the egg
They also have lots of mitochondria to provide the energy to swim
The acrosome contains digestive enzymes to enable the sperm to penetrate the surface of the egg

46
Q

How are palisade cells specialised?

A

They contain many chloroplasts so they absorb a lot of sunlight
The walls are thin so carbon dioxide can easily diffuse in the cell

47
Q

How are root hair cells specialised?

A

They have a large surface area for absorption
They have a thin permeable cell wall for entry of water and ions
The cytoplasm contains extra mitochondria to provide energy for active transport

48
Q

How are guard cells specialised?

A

Guard cells are found in pairs with a gap between them to form a stoma
In the light, guard cells take up water and become turgid, forcing them to bend outwards allowing gas exchange for photosynthesis
They also stop water loss during the night

49
Q

What is a tissue?

A

A group of cells that are specialised to work together to carry out a particular function

50
Q

What are four examples of animal tissue?

A

Squamous epithelium
Ciliated epithelium
Muscle tissue
Cartilage

51
Q

What are two examples of plant tissue?

A

Xylem tissue

Phloem tissue

52
Q

What is an organ?

A

A group of different tissues that work together to perform a particular function

53
Q

What are two examples of organs?

A

The lungs

Leaves

54
Q

What is an organ system?

A

A group of organs working together to perform a particular function

55
Q

What are two examples of organ systems?

A

The respiratory system

The circulatory system

56
Q

What is squamous epithelium?

A

A single layer of flat cells lining a surface

It is found in many places, including the alveoli in the lung

57
Q

What is ciliated epithelium?

A

A layer of cells covered in cilia
It’s found on surfaces where things need to be moved
Example: Trachea

58
Q

What is the role of xylem tissue?

A

It transports water around the plant and it supports the plant

59
Q

What is the role of phloem tissue?

A

It transports sugars around the plant

It’s arranged into sand is made up of sieve tubes, companion cells and some ordinary plant cells

AS- Biology (12 decks)

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