2.6 Cell Division Flashcards

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1
Q

Why do we need new cells ?

A

For growth and repair.

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2
Q

What are the stages of mitosis ?

A

(Interphase), Prophase, Metaphase, Anaphase, Telophase, (Cytokinesis).

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3
Q

What is a period of cell division called ?

A

M Phase, which involves mitosis and cytokinesis.

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4
Q

What is interphase divided into ?

A

G1, S, G2.

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5
Q

What is the cell cycle regulated by ?

A

Regulated by checkpoints, which occur at key points to make sure the process is ok to continue.

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6
Q

What occurs at interphase ?

A

-Cell prepares to divide.
-DNA is unravelled and replicated.
-Organelles replicate.
-More ATP content for mitosis to happen.

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7
Q

What is the centromere ?

A

Point where 2 chromatids join to form a chromosome.

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8
Q

What are chromatids ?

A

Separate strands of chromosome.

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9
Q

What are sister chromatids ?

A

Two strands on the same chromosome are known as sister chromatids.

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10
Q

Why are there 2 chromatids (strands) on each chromosome ?

A

Two strands because each strand is an identical copy of itself.

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11
Q

What occurs in prophase ?

A

-Chromosome condenses (shorter + fatter).
-Spindle fibres form.
-Nuclear envelope breaks down and chromosomes lie free in the cytoplasm.

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12
Q

What are centrioles ?

A

Tiny bundles of protein that move to opposite ends of cell forming spindle fibres.

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13
Q

What occurs in metaphase ?

A

-Chromosomes line up in the middle at the spindle equator and become attached by centromere.
-Checkpoint checks all chromosomes are attached to spindle.

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14
Q

What occurs at anaphase ?

A

-Centromere divides, separating sister chromatids.
-Spindle fibres contract, pulling chromatids to opposite ends of cell, centromere first.

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15
Q

What occurs at telophase ?

A

Chromatids reach opposite poles on the spindle. They uncoil and become long and thin and are now called chromosomes again.
Nuclear envelope forms around each group of chromosomes.

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16
Q

What occurs at cytokinesis ?

A

Cytoplasm divides and cleavage furrow forms to divide cells and produce 2 genetically identical daughter cells.

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17
Q

When does cytokinesis start and end ?

A

Starts at anaphase and ends at telophase and is separate to mitosis.

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18
Q

How does cytokinesis occur in animal cells ?

A

Occurs by furrowing of cytoplasm.

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19
Q

How does cytokinesis occur in plant cells ?

A

Cytokinesis is initiated with formation of cell plate in the middle of the cell.

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20
Q

How do we investigate mitosis ?

A

-Treat tips of roots in HCl and break them open carefully and spread a few on microscope slide.
-Add a few drops of stain.
-Squash under coverslip and view under microscope.

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21
Q

What are gametes ?

A

Reproductive cells such as sperm and egg cells.

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22
Q

When 2 gametes form, what does it produce ?

A

It produces a zygote.

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23
Q

Are normal body cells diploid or haploid ?

A

Diploid meaning they have 46 chromosomes, that are the same size and genes, but may be alleles.

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24
Q

What are homologous chromosomes ?

A

Pair of matching chromosomes.

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25
Q

Are gametes haploid or diploid ?

A

Haploid meaning they have 23 chromosomes, only one copy of each chromosome.

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26
Q

What is meiosis ?

A

Cell division that produces gametes. Cells formed are genetically different because each cell ends up with a combination of chromosomes.

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27
Q

Interphase in meiosis

A

This is where meiosis begins as it is where the cells DNA unravels and replicates two produce double-armed chromosomes (sister-chromatids).

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28
Q

Meiosis 1

A

It involves 2 divisions (M1 and M2)
After interphase, the cell enters M, which is the reduction division as it halves the chromosome number.

29
Q

Prophase 1

A

The chromosomes condense, getting short and fatter. Homologous chromosomes pair up and crossing over occurs. Centrioles start moving to opposite ends of the cell, forming spindle fibres and nuclear envelope breaks down.

30
Q

Metaphase 1

A

The homologous pairs line up across the centre of the cell and attach to the spindle fibres by their centromeres.

31
Q

Anaphase 1

A

The spindle fibres contract pulling pairs apart.

32
Q

Telophase 1

A

A nuclear envelope forms around each group of chromosomes. Cytokinesis occurs and 2 haploid daughter cells are formed.

33
Q

Meiosis 2

A

Daughter cells produced undergo prophase 2, metaphase2, anaphase 2, telophase 2, and cytokinesis.
Same as stages in meiosis 1 except with half the number of chromosomes.

34
Q

What is genetic variation ?

A

Difference that exists between individuals’ genetic materials. Meiosis creates genetic variation. Any egg can fuse with any sperm creating genetic variation. This means individuals have a new mixture of alleles, making them genetically unique.

35
Q

What are stem cells ?

A

They are unspecialised cells that can develop into different types of cells. All multicellular organisms have some form of stem cells.

36
Q

Where are stem cells found ?

A

Found in early embryos and in bone marrow in adults.

37
Q

What is differentiation ?

A

Is when stem cells divide to become new cells, which then become specialised. Stem cells divide to produce more undifferentiated stem cells.

38
Q

Differentiation in animals

A

Adult stem cells are used to replace damaged cells.

39
Q

Differentiation in plants

A

Stem cells in plants are used to make new shoot and roots and can differentiate into different plant tissues. They are found in the meristem of a plant.

40
Q

How are Stem cells used for heart disease ?

A

Heart disease is when heart tissue is damaged and the body can’t replace damaged heart cells.

41
Q

How are stem cells used to treat Alzheimers ?

A

When nerve cells in brain die, resulting in memory loss.

42
Q

How are stem cells used for Parkinson’s ?

A

Causes loss of nerve cells in brain that release dopamine, controlling movement.

43
Q

What are specialised cells ?

A

When cells differentiate ton specific function. Their structure is adapted to perform function.

44
Q

What are erythrocytes ?

A

Red blood cells that carry oxygen in blood. They have a biconcave disc, which provides a large SA forges exchange. There is also no nucleus so more room for haemoglobin.

45
Q

What are neutrophils ?

A

White blood cells that defend the body against disease. They have a flexible shape to engulf pathogens. Many lysosomes in the cytoplasm that contain digestive enzymes to break down engulfed particles.

46
Q

What are epithelial cells ?

A

Cover surface of organs and join together by interlinking cell membranes.

47
Q

What is the role of ciliated epithelial cells ?

A

They are found in airways and waft particles away.

48
Q

What is the role of squamous epithelial cells?

A

Found in lungs to allow gas diffusion.

49
Q

What is the function of sperm cells ?

A

-Acrosome to break down enzymes.
-Flagella to spin for movement.
-Lots of mitochondria for energy.

50
Q

What is the function of Palisade Mesophyll cells ?

A

Where photosynthesis occurs and contains many chloroplasts to absorb sunlight. Also has thin cell walls so carbon dioxide can diffuse easily into cell.

51
Q

What is the function of root hair cells ?

A

They absorb water and mineral ions from the soil and have a large SA for absorption.
-Thin permeable cell wall to allow entry of water and ions.
-Cytoplasm contains extra mitochondria for active transport.

52
Q

What is the function of guard cells ?

A

Found in pairs, with a gap in between for stoma. In light, they take up water and become turgid and open. Thin outer and inner walls force them open by bending outward to allow for gas exchange and photosynthesis.

53
Q

What are tissues ?

A

Group of cells that are specialised to work together to carry out a particular function. A tissue can contain more than one type of cell.

54
Q

What are squamous epithelial cells (animal) ?

A

Single layer of flat cells lining a surface. It is found in the alveoli in lungs and provides thin exchange surface for substance to diffuse across quickly.

55
Q

What are Ciliated epithelium ?

A

A layer of cells covered in cilia that are found on surfaces where things need to be moved.

56
Q

What are muscle tissues ?

A

Made up of bundles of elongated cells called muscle fibres.

57
Q

Where are smooth muscle fibres found ?

A

Lining in stomach.

58
Q

Where are cardiac muscles found ?

A

In the heart.

59
Q

What is cartilage ?

A

Type of connective tissue found in joints. It shapes and supports ear, nose and windpipe.

60
Q

What does cartilage form ?

A

Forms chondroblasts that secrete an extracellular matrix (jelly substance containing protein fibres) which become trapped inside.

61
Q

What is xylem ?

A

Transport water around a plant and supports the plant. Hollow tubes, which are dead and has living parenchyma cells.

62
Q

What is phloem ?

A

Transports sugar around plant and is arranged in tubes and is made up of sieve tube elements, companion cells and some ordinary plants cells.

63
Q

What are sieve tubes elements in phloem ?

A

Each sieve cell has end walls with holes in them so that sap can move easily through them. These end walls called sieve plates.

64
Q

What are organs ?

A

Group of different tissues that work together to perform a particular function.

65
Q

Organs in plants

A

Leaf caries out gas exchange and photosynthesis. It contains palisade tissue as well as epidermal tissue, to prevent water loss, and xylem and phloem.

66
Q

What are organ systems?

A

When organs work together to form organ systems that have a particular function.

67
Q

What is the S stage in interphase ?

A

Synthesis is when DNA is replicated in the nucleus.

68
Q

What is G1 in interphase ?

A

First growth phase where proteins from which organelles are synthesised are produced and organelles replicate. Cell increases in size.

69
Q

G2 in interphase ?

A

Second growth phase and cell continues to increases in size, energy stores are increased and duplicated DNA is checked for error.