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A-Level Biology🌼 > Mod 2 Chap 6 - Cell Division > Flashcards

Mod 2 Chap 6 - Cell Division Flashcards

1
Q

Main phases of the cell cycle

A

The main phases of the cell cycle are the interphase and the mitotic (division) phase

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2
Q

What happens in the interphase of the cell cycle?

A

Interphase of the cell cycle
-Growth of cells
-No divisions taking place
-DNA is replicated
-Protein synthesis in the cytoplasm
-Mitochondria grow and divide
-Chloroplasts grow
-Metabolic processes occuring

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3
Q

Three stages of the interphase

A

3 stages of the interphase:
-G1 = synthesis of proteins, organelles replicate. Cells increase in size
-S = DNA replication
-G2 = cell increases more in size, energy stores increase, duplicated DNA checked for errors

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4
Q

The two stages of the mitotic phase of the cell cycle?

A

Mitosis (cell divides) and cytokineses (cytoplasm divides and two cells produced)W are the stages of the mitotic phase of the cell cycle

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5
Q

Why do cells leave the cell cycle?

A

Cells leave the cell cycle because of:
-Differentiation = specialised cells no longer divide
-DNA of the cell may be damaged, and so enters permanent cell arrest and no longer divides. This increases with age, or with diseases such as cancer

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6
Q

It is vital that the cell only divides when…

A

It is is vital that the cell only divides when it is big enough in size, DNA is error-free/repaired, chromosomes are in correct positions for mitosis

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7
Q

What are the control mechanisms of the cell cycle?

A

Checkpoints are the control mechanisms of the cell cycle to monitor that a phase has been done correctly

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8
Q

Where is the metaphase checkpoint of the cell cycle?

A

The metaphase checkpoint of the cell cycle is is the point in mitosis where all chromosomes are attached to spindles and have aligned

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9
Q

Why is mitosis important?

A

Mitosis is important for tissue growth and repair, and for asexual reproduction to produce genetically identical cells

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10
Q

Why is it important that chromosomes are kept together in cell division?

A

It’s important for chromosomes to be kept together in cell division so they can be precisely manoeuvred and segregated equally, one each into the new daughter cells

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11
Q

Stages of mitosis

A

Stages of mitosis are the prophase, metaphase, anaphase, telephase

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12
Q

What happens during prophase of mitosis?

A

Prophase of mitosis:
-Chromatin fibres coil and condense to form chromosomes, which takes up the stain to be viewed with a light microscope
-Nuclear membrane begins to break down
-Protein microtubules form spindle fibres that that link poles of the cell
-Nuclear envelope dissapeares at end of stage

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13
Q

What happens during the metaphase of mitosis?

A

Metaphase of mitosis:
-Chromosomes pulled to equator by spindle fibres to form a centre called metaphase plate

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14
Q

What happens during the anaphase of mitosis?

A

Anaphase of mitosis:
-Centrosomes divide, so chromosomes are pulled apart and the chromatids seperate to poles

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15
Q

What happens during the telophase of mitosis?

A

Telophase of mitosis:
-Nuclear envelope reforms around them
-Chromosomes uncoil and and nucleolus forms
-Cytokenesis (cell division) begins

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16
Q

Cytokenesis in animal cells

A

Cytokenesis in animal cells:
-Cell surface membrane forms and is pulled inwards by cytoskeleton until it’s close enough to centre to fuse around middle and form two cells

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17
Q

Cytokenesis in plant cells

A

Cytokenesis in plant cells:
-Vesicles from golgi apparatus form where the metaphase plate was
-Vesicles fuse with eachother and surface membrane to divide cell into two

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18
Q

What is a diploid?

A

A diploid is two chromosomes of each type (one inherited from each parent)

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19
Q

Term for a fertilised egg

A

A fertilised egg is a zygote

20
Q

What is a haploid?

A

A haploid has half the number of chromosomes as the parent cell

21
Q

What is meiosis also known as?

A

Meiosis is also known as reduction division - this is because cel;s go from diploid to haploid as the number of chromosomes are halved

22
Q

What are alleles?

A

Alelles are different types of the same gene

23
Q

Two divisions involved in meiosis

A

The two divisions involved in meiosis:
-Meisosis I = pairs of homologous chromosomes seperated into two cells, the cells are haploid as each cell contains one full set of genes instead of two
-Meiosis II = pairs of chromatids in each daughter cell seperated, two more cells are formed

24
Q

Meoisis: Meiosis I: Prophase I

A

Prophase I:
-Chromosomes condense
-Nuclear envelope disintegrates
-Nucleolus dissapears
-Spindle formation
-Chromosomes arranged in homologous pairs (forms BIVALENTS)
-Crossing over takes place

25
Q

Meiosis: Meiosis I: Metaphase I

A

Metaphase I:
-Bivalents line at equator of spindle
-Independant assortment takes place: paternal and maternal chromosomes become independant > leads to genetic variance

26
Q

Meiosis: Meiosis I: Anaphase I

A

Anaphase I:
-Homologous pairs seperated as chromosomes pulled to poles by spindle fibres - centromeres DON’T divide

27
Q

Meiosis: Meiosis I: Telephase I

A

Telephase I:
-Chromosomes at poles
-Spindle fibres break down
-Nuclear envelope and nucleolus reforms

28
Q

Meiosis: Meiosis II: Prophase II

A

Prophase II:
-Nuclear envelope breaks down and chromosomes condense
-Spindle formation

29
Q

Meiosis: Meiosis II: Metaphase II

A

Metaphase II:
-Chromosomes line up single file at centre of cell

30
Q

Meiosis: Meiosis II: Anaphase II

A

Anaphase II:
-Centromeres divide and individual chromosomes pulled to poles
-This creates four groups of chromosomes that have half the number of chromosomes compared to the original parent cell

31
Q

Meiosis: Meiosis II: Telephase II

A

Telaphase II:
-Chromosomes at poles of cell
-Nuclear envelope and nucleolus reformation

32
Q

Cytokenesis in meiosis II

A

In cytokenesis of meiosis II, 4 daughter cells have been produced, each being haploid due to the reduction division, and each is genetically different to eachother due to crossing over and independant assortment

33
Q

Totipotent

A

Totipotent is when stem cells can differentiate into any cell type

34
Q

Pluripotent

A

Pluripotent is when stem cells can differentiate into any cell type but cannot make whole organisms

35
Q

Multipotent

A

Multipotent is when stem cells can only a form a certain range of cells within a certain type of tissue

36
Q

Two sources of adult stem cells

A

Sources of adult stem cells;
-Embryonic = totipotent
-Adult stem cells = found in specific areas eg bone marrow = multipotent, but can be artificially triggered to become pluripotent

37
Q

Advantages of harvesting adult stem cells from umbilical cords

A

Advantages:
-Plentiful supply
-By using own persons umbilical cord, stem cells will not be rejected

38
Q

Source of plant stem cells

A

Plant stem cells come from meristematic tissue (located on tips of roots and shoots, and between phloem and xylem tissues. They are pluripotent

39
Q

Diseases where stem cells can be used

A

Diseases where stem cells can be used:
-Heart disease - to replace heart tissue thats been damaged due to heart attacks
-Type 1 diabetes - to make insulin-producing cells
-Parkinsons disease - to make dopamine-producing cells
-Alzheimers disease - replacing damaged brain cells
-Macular degeneration
-Birth defects
-Spinal injuries

40
Q

Where are stem cells already being used?

A

Stem cells are currently used in the treatment of burns and for drug trials and developmental biology

41
Q

Erythrocytes adaptations

A

Erythrocytes adaptations:
Biconcave shape + having no nucleus allows erythrocytes to fit through narrow cappilaries

42
Q

Neutrophils adaptations

A

Neutrophils adaptations:
Multi-lobed nucleus that makes it easier to squeeze through small gaps

43
Q

Palisade cells adaptations

A

Palisade cells adaptations:
-Thin cell walls > allows for rapid diffusion of carbon dioxide

44
Q

Describe how a gene is a code for the production of a polypeptide

A

-Base nucleotide sequence arranged in triplets which determines the amino acid sequence

45
Q

What is the fixed position called that’s occupied by a gene on a DNA molecule?

A

Genes are located on loci/locus on DNA molecules

46
Q

Difference between pre-mRNA and mRNA strands

A

Pre-mRNA has introns and exons for splicing wheras mRNA only has exons

47
Q

Structural differences between tRNA and mRNA

A

Structural differences between tRNA and mRNA:
-tRNA contains hydrogen bonds wheras mRNA dont
-mRNA contains codons wheras tRNA contains anticodons

A-Level Biology🌼 (25 decks)

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