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6 Flashcards

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1
Q

What are the main phases of the cell cycle?

A

The cell cycle consists of interphase (which includes G1, S, and G2 phases) and mitotic phase (which includes mitosis and cytokinesis).

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2
Q

What happens during interphase?

A

Interphase is the phase where the cell grows and prepares for division. It includes G1 (cell growth), S (DNA synthesis), and G2 (preparation for mitosis).

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3
Q

What happens during mitosis?

A

Mitosis is the process of nuclear division, which consists of prophase, metaphase, anaphase, and telophase, resulting in two genetically identical daughter nuclei.

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4
Q

What is cytokinesis?

A

Cytokinesis is the process where the cytoplasm divides, resulting in two distinct daughter cells.

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5
Q

What are the stages of mitosis?

A

prophase, metaphase, anaphase, and telophase.

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6
Q

What happens during prophase in mitosis?

A

In prophase, the chromosomes condense, the nuclear envelope breaks down, and spindle fibers form.

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7
Q

What happens during metaphase in mitosis?

A

In metaphase, the chromosomes align along the metaphase plate (equator) of the cell

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8
Q

What happens during anaphase in mitosis?

A

In anaphase, the sister chromatids are pulled apart by the spindle fibers and move toward opposite poles of the cell.

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9
Q

What happens during telophase in mitosis?

A

In telophase, the chromatids reach the poles, the nuclear envelope reforms around each set of chromosomes, and the chromosomes begin to de-condense.

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10
Q

How is the cell cycle regulated?

A

The cell cycle is regulated by checkpoint proteins (such as cyclins and cyclin-dependent kinases) that ensure proper progression through the stages of the cycle. These checkpoints monitor DNA integrity and cell size.

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11
Q

What happens if a checkpoint detects an issue during the cell cycle?

A

If a checkpoint detects a problem, the cell may enter a G0 phase (resting phase), undergo repair, or undergo apoptosis (programmed cell death) if the damage is irreparable.

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12
Q

What is the difference between mitosis and meiosis?

A

Mitosis results in two genetically identical diploid cells for growth, repair, and asexual reproduction, whereas meiosis produces four genetically diverse haploid cells (gametes) for sexual reproduction.

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13
Q

What is meiosis?

A

Meiosis is a type of cell division that reduces the chromosome number by half, producing four non-identical haploid cells (gametes), which are crucial for sexual reproduction.

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14
Q

What is the main purpose of meiosis?

A

The main purpose of meiosis is to produce haploid gametes (sperm and eggs), ensuring that when fertilization occurs, the diploid chromosome number is restored.

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15
Q

What are the two main divisions in meiosis?

A

Meiosis consists of Meiosis I (reduction division) and Meiosis II (equational division), both involving prophase, metaphase, anaphase, and telophase.

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16
Q

What happens during Meiosis I?

A

During Meiosis I, homologous chromosomes are separated into two daughter cells, reducing the chromosome number by half (from diploid to haploid).

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17
Q

What happens during Meiosis II?

A

Meiosis II is similar to mitosis, where sister chromatids are separated into four genetically diverse haploid cells.

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18
Q

What happens during prophase I of meiosis?

A

In prophase I, homologous chromosomes pair up and undergo crossing over, exchanging genetic material, and forming chiasmata. This increases genetic diversity.

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19
Q

What is crossing over?

A

Crossing over is the exchange of genetic material between non-sister chromatids of homologous chromosomes, resulting in genetic recombination.

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20
Q

What is a bivalent and how do they occur?

A

A bivalent is what is formed when homologous chromosomes pair up.

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21
Q

What happens during metaphase 1 in meiosis?

A

Homologous pairs of chromosomes assemble along the plate.

Orientation is random and independent.

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22
Q

What’s independent assortment?

A

When the maternal or paternal chromosomes can face either end of the pole.

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23
Q

What happens in anaphase 1 of meiosis?

A

Homologous chromosomes pulled to poles and chromatids stay joined.

Entangled sections during crossing over break off and rejoin which can result in exchange of DNA.

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24
Q

What’s chiasmata?

A

The point at which chromatids break and rejoin.

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25
Q

What causes genetic variation?

A

It arises from the new combination of alleles when genes are being exchanged and so sister chromatids are no longer identical.

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26
Q

What happens in telophase 1?

A

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

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27
Q

What happens in prophase 2?

A

Chromosomes condense and become visible again.

Nuclear envelope breaks down

Spindle formation begins

28
Q

What happens in metaphase 2?

A

Individual chromosomes assemble on metaphase plate

Independent assortment again and more genetic variation

29
Q

What happens in anaphase 2 of meiosis?

A

Chromatids of individual chromosomes being pulled to opposite poles after division of centromeres.

30
Q

What happens in telophase 2?

A

Chromatids assemble at poles.

Chromosomes uncoil and form chromatin again.

Nuclear envelope reforms and the nucleolus becomes visible..

31
Q

What happens in first cytokinesis of meiosis?

A

Divides into two cells.

Reduction of chromosome number from diploid to haploid is complete.

32
Q

What happens in second cytokinesis of meiosis?

A

Division of cells forming 4 daughter cells total.

Cells will be haploid due to reduction division.

33
Q

How does meiosis II differ from mitosis?

A

Meiosis II is similar to mitosis, but it occurs in haploid cells, and the goal is to separate sister chromatids, not homologous chromosomes.

34
Q

How does independent assortment increase genetic variation?

A

Independent assortment is the random distribution of homologous chromosomes into gametes during metaphase I, resulting in different combinations of chromosomes in each gamete.

35
Q

What is genetic recombination?

A

Genetic recombination refers to the process by which new combinations of alleles are created in offspring due to crossing over and independent assortment.

36
Q

What are recombinant chromatids?

A

Recombinant chromatids are chromatids that have undergone crossing over and contain a mix of genetic material from both homologous chromosomes.

37
Q

How do crossing over and independent assortment work together to increase diversity?

A

Crossing over creates new allele combinations within chromosomes, while independent assortment ensures that different combinations of chromosomes are distributed to gametes.

38
Q

What is cell specialisation?

A

Cell specialisation is the process by which cells become adapted for specific functions in the body, allowing them to carry out particular tasks efficiently.

39
Q

How does cell specialisation relate to differentiation?

A

Differentiation is the process by which unspecialised cells become specialised to perform specific functions, resulting in different cell types within an organism.

40
Q

What are stem cells?

A

Stem cells are undifferentiated cells that have the potential to become specialised into different types of cells, such as muscle, nerve, or blood cells.

41
Q

What are some examples of specialised animal cells?

A

Erythrocytes, neutrophils, sperm cells.

42
Q

What are some examples of specialised plant cells?

A

Palisade cells, root hair cells, guard cells.

43
Q

What are the four main categories of tissue in animals?

A

Nervous tissue - adapted to support transmission of electrical impulses

Epithelial tissue - adapted to cover body surfaces

Muscle tissue - adapted to contract

Connective tissue - adapted to to hold other tissue together or to act as transport medium

44
Q

What is epidermis tissue adapted to do?

A

To cover plant surfaces

45
Q

What is vascular tissue adapted to do?

A

Transport water and nutrients.

46
Q

What is an organ?

A

Is a collection of tissue that are adapted to perform a particular function in an organism.

47
Q

How many times can stem cells undergo cell division?

A

As many times until they become specialised which is when they enter G0

48
Q

What is potency?

A

A stem cells ability to differentiate into different cell types.

The greater the number of cell types it can differentiate into, the greater its potency.

49
Q

What are the main types of stem cells?

A

Totipotent, Pluripotent and multipotent

50
Q

What is totipotent?

A

These stem cells can differentiate into any type of cell.

51
Q

What is pluripotent?

A

These stem cells can form all tissue types but not whole organisms.

52
Q

What is multipotent?

A

Can only form a range of cells within a certain type of tissue.

53
Q

How are erythrocytes specialised?

A

Flattened biconcave shape to increase SA:V ratio.
No nucleus or many other organelles to increase space for oxygen.
Are flexible to squeeze through capillaries.

54
Q

How are neutrophils specialised?

A

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

55
Q

How are sperm cells specialised?

A

Have tail/flagellum - allows movement
Many mitochondria - supply energy needed to swim
Acrosome - located on head of sperm and contains digestive enzymes used to digest protective layers around ovum to penetrate.

56
Q

How are palisade cells specialised?

A

Contain chloroplast to absorb lots of light for photosynthesis.
Cells are rectangular box shapes and can be closely packed
Have thin cell walls - increases rate of diffusion of CO2
Have large vacuole - maintains turgid pressure

57
Q

How are root hair cells specialised?

A

Have long extensions called root hairs - increases SA of cell. This maximises uptake of water and minerals from soil.

58
Q

How is squamous epithelium specialised?

A

One cell layer thick - allows for rapid diffusion.

59
Q

How is ciliated epithelium specialised?

A

The cells have cilia that move in rhythmic manner.
Lines trachea to waft mucus away from lungs
Goblet cells produce mucus to trap unwanted particles

60
Q

How is the epidermis specialised?

A

Is a single layer of closely packed cells
It is covered by a waxy, waterproof cuticle to reduce water loss
Has guard cells by stomata to controls gases entering and exiting

61
Q

How are xylem tissue specialised?

A

Composed of elongated dead cells.
Walls contain lignin to strengthen it and provide support for plants

62
Q

What are the sources of animal stem cells?

A

Embryonic stem cells, tissue (adult) stem cells

63
Q

What are embryonic stem cells

A

Are present at very early stage of embryo development and are toripotent.
After 7 days - blastocyst is formed and cells are now in pluripotent stage
Remains in this state til fetus birth.

64
Q

What is a blastocyst?

A

A mass of cells

65
Q

What are tissue stem cells?

A

Are present throughout life.
Are multipotent.
Can be stored if needed

66
Q

What are the source/s of plant stem cells and explain?

A

Stem cells present in meristematic tissue.
Meristematic tissue is located between phloem and xylem.
The tissue is found where growth is occurring e.g at roots and shoots

67
Q

What do stem cells have the potential of being tested in to treat?

A

Heart disease - muscle tissue in heart is damaged
Type 1 diabetes - body’s immune system destroys insulin producing cells
Parkinson’s disease - shaking and rigidity caused by death of dopamine cells in brain
Alzheimer’s - brain cells are destroyed due to build up of abnormal proteins
Macular degeneration- causes blindness in elderly and diabetics
Birth defects
Spinal injuries

Biology (17 decks)

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