Cell division, cell diversity and cellular organisation Flashcards

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1
Q

What happens during the first stage of interphase?

A

G1 - The first growth phase: proteins from which organelles are synthesized are produced and organelles replicate. The cell increases in size

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2
Q

What happens during the second stage of interphase?

A

S - each of the chromosomes are duplicated in the nucleus

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3
Q

What happens during the third stage of interphase?

A

G2 - the cell continues to increase in size, energy stores are increased and the duplicated DNA is checked for errors.

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4
Q

What happens during mitosis?

A

The nucleus divides

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5
Q

What happens during cytokinesis?

A

The cytoplasm divides and two cells are produced,

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6
Q

What is G0

A

When a cell leaves the cell cycle either because the cell has differentiated or the DNA was damaged so the cell died

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7
Q

What are checkpoints within the cell cycle?

A

Checkpoints occur at key points within the cycle and they make sure it is ok for the process to continue.

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8
Q

What happens at the G1 checkpoint?

A

The cell checks that the chemicals needed for replication are present and for any damage to the DNA before entering S-phase.

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9
Q

What happens 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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10
Q

What happens at the metaphase checkpoint?

A

The cell checks that all the chromosomes are attached to the spindle before mitosis can continue.

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11
Q

State a general overview of what occurs during interphase.

A

The cells DNA is unravelled and replicated to double its genetic content. The organelles are also replicated so it has spare ones and its ATP content is increased to provide the energy needed for cell division.

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12
Q

State a general overview of what happens during Prophase.

A

-Chromosomes condense
-Centrioles (bundles of proteins) start moving to opposite ends of the cell forming a network of protein fibres across it called the spindle.
- Nuclear envelope breaks down and chromosomes lie free in the cytoplasm

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13
Q

State a general overview of what happens during metaphase.

A

The chromosomes (each with two chromatids) line up along the metaphase plate and become attached to the spindle by their centromere.

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14
Q

State a general overview of what happens during anaphase.

A

The centromeres divide separating each pair of sister chromatids. The spindles contract pulling chromatids to opposite ends of the cell centromere first.

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15
Q

State a general overview of what happens during telophase.

A

The chromatids reach the opposite poles on the spindle. They uncoil and are now called chromosomes again. A nuclear envelope forms around each group of chromosomes so there are now two nuclei.

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16
Q

What happens during cytokinesis?

A

The cytoplasm divides and so does the cell membrane. There are now two genetically identical daughter cells.

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17
Q

When does cytokinesis occur?

A

It starts in anaphase and ends in telophase - it is a separate process to mitosis.

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18
Q

How can you view the stages of mitosis?

A

Stain chromosomes and look at them under a microscope.

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19
Q

Why do we need mitosis?

A

Mitosis is needed for the growth of multicellular organisms and for repairing damaged tissues. It is also a methos of asexual reproduction for some plants animals and fungi.

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20
Q

Why do we need meiosis?

A

To produce the gametes (haploid cells) needed for sexual reproduction. They provide genetic variation by independent assortment.

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21
Q

What happens during prophase of meiosis 1 (first division)

A

The chromosomes condense and arrange themselves into homologous pairs and crossing over occurs ( where chromatids twist around each other resulting in them having the same genes but a different number of alleles) Centrioles start moving to opposite sides of the cell forming the spindle fibres and the nuclear envelope breaks down

22
Q

What happens during metaphase of meiosis 1?

A

The homologous pairs line up across the metaphase plate and attach to the spindle fibres by their centromeres.

23
Q

What happens during anaphase of meiosis 1?

A

The spindles contract separating the homologous pairs - one cheromosome goes to each end of the cell.

24
Q

What happens during telophase of meiosis 1?

A

A nuclear envelope forms around each group of chromosomes

25
Q

What happens after telophase of meiosis 1?

A

Cytokinesis (division of the cytoplasm) occurs and two haploid daughter cells are produced

26
Q

What happens after meiosis 1?

A

The two daughter cells undergo prophase 2 metaphase 2 anaphase 2 telophase 2 and cytokinesis - a lot like mitosis.

27
Q

What happens in anaphase of meiosis 2?

A

The pairs of sister chromatids are separated - each new daughter cell inherits one chromatid from each chromosome. This is what produces 4 genetically diffferent haploid daughter cells - gametes.

28
Q

How are neutrophils specialised for a particular function?

A

They (WBC’s) defend the body against disease so have a flexibile shape that allows them to engulf foreign particles or pathogens. They have many lysosomes which contain digestive enzymes to break down the particles.

29
Q

How are erythrocytes specialised for a particular function?

A

Erythrocytes (RBC’s) carry oxygen in the blood. The biconcave disc shape provides a large surface area for gas exchange. They have no nucleus so theres more room for haemoglobin.

30
Q

How are squamous epithelial cells specialised for a particular function?

A

Squamous epithelia cells in the lungs are very thin to allow efficient diffusion of gases.

31
Q

How are ciliated epithelial cells specialised for a particular function?

A

Ciliated epithelial cells in the airway have cilia that beat to move particles away

32
Q

How are sperm cells specialised to perform a particular function?

A

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

33
Q

How are the palisade cells specialised to perform a particular funtion?

A

They contain many chloroplasts so they can absorb a lot of sunlight for photosynthesis. Their walls are thin so carbon dioxide can easily diffuse into the cell.

34
Q

How are root hair cells specialised to perform a particular function?

A

They have a large surface area and a thin permeable cell wall to help them absorb water and mineral ions from the soil. They contain extra mitochondria to provide energy for active transport.

35
Q

How are guard cells specialised to perform a particular function?

A

They are found in pairs with a gap between them called a stoma, this is used for gas exchange. In the light, guard cells take up water and become turgid, their thin outer walls and thickened inner walls force them to bend outwards opening the stomata and allowing for gas exchange for photosynthesis.

36
Q

What is a tissue?

A

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

37
Q

Name the animal tissues you need to know.

A

Cartilage
muscle
ciliated epithelium
squamous epithelium

38
Q

Name the plant tissues you are required to know.

A

Xylem tissue
Plant tissue

39
Q

Describe squamous epithelium.

A

A single layer of flat cells lining a surface. It is found in many places including the alveoli of the lungs.

40
Q

Describe the ciliated epithelium.

A

A layer of cells covered in cillia. Found on the surfaces where things need to be moved e.g in the trachea where the cilia waft mucus along.

41
Q

Describe the muscle tissue.

A

Made up of bundles of elongated cells called muscle fibres. There are three types: smooth, cardiac and skeletal.

42
Q

Describe the Xylem tissue.

A

a plant tissue that contains hollow xylem vessel cells which are dead and living parenchyma cells.

43
Q

Describe the phloem tissue.

A

Arranged in tubes and made up of sieve cells, companion cells and some ordinary plant cells. Each sieve cell has end walls (sieve plates) with holes in them so that sap can move easily through them.

44
Q

Describe the cartilage tissue.

A

Connective tissue found in joints and ears and nose.

45
Q

What are stem cells?

A

A renewing source of undifferentiated cells

46
Q

Where are stem cells found in adult humans?

A

Bone marrow

47
Q

Where are stem cells found in plants?

A

Meristems

48
Q

What do cells in the meristem differentiate into?

A

Xylem and Phloem

49
Q

What do stem cells in the bone marrow differentiate into?

A

Erythrocytes and neutrophils.

50
Q

How are stem cells being used to treat Alzheimer’s

A

Researchers are hoping to use stem cells to regrow healthy nerve cells in people with alzheimer’s

51
Q

How are stem cells being used to treat parkinsons?

A

Transplanted stem cells may help to regenerate the dopamine-producing cells in order to release more dopamine and and control movement.

52
Q

Besides neurological conditions how else can stem cells be used?

A

Developmental biology.