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AS Biology > Chapter 5: Mitotic Cell Cycle (SEE DIAGRAMS OF PHASES IN NOTES AS WELL) > Flashcards

Chapter 5: Mitotic Cell Cycle (SEE DIAGRAMS OF PHASES IN NOTES AS WELL) Flashcards

1
Q

what is a chromosome

A

rod-shaped, deeply stained body that is visible in the nucleus at mitosis and meiosis,, each is made up of 2 sister chromatids

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2
Q

what are sister chromatids

A
  • 2 sister chromatids make up 1 chromosome

- each sister chromatid consists of 1 very long DNA that wraps around histone proteins

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3
Q

what is a nucleosome

A

a repeating unit in eukaryotic chromatin, made up of DNA wrapped around 8 histone proteins,, they are linked by linker DNA

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4
Q

what is chromatin

A
  • loosely coiled, thread-like nucleoprotein, found in the nucleus, which shortened, thickened and condensed into chromosomes during mitosis and meiosis
  • during interphase, chromosomes exist as chromatins (euchromatin and heterochromatin)
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5
Q

what does cell division involve

A

cell division = mitosis(nuclear division) + cytokinesis (cyto division)

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6
Q

what are the functions/uses of cell divisions

A
  • growth of multicellular organisms
  • repair/replacement
  • asexual reproduction
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7
Q

what does growth of multicellular organisms involve

A
  • cell division to increase cell number
  • cell enlargement to increase cell size
  • these both involve cell differentiation
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8
Q

what does repair/replacement involve

A
  • repair tissues by cell replacement
  • replacement of damaged cells (skins/RBC)
  • regenerate lost parts of the body in certain organisms
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9
Q

what does asexual reproduction involve

A
  • binary fission (e.g. amoeba)
  • budding (e.g. yeast)
  • asexual spore (e.g. fungus)
  • vegetative propagation
  • fragmentation
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10
Q

what is cell maturation

A

a process whereby cells specialized in structure and functions (e.g. epidermal cells, xylem element and sieve tube element)

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11
Q

what are the zones of cell maturation

A
  • zone of differentiation
  • zone of elongation
  • zone of cell division
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12
Q

what is growth

A

permanent increase in dry mass of living matter (cells and cellular content of living cells in the body exceept H2O)

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13
Q

what is living matter

A

cells and cellular content of living cells in the body (except H2O)

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14
Q

how does mitosis aid in repair and replacement

A

injured tissue is being repaired by:

  • replacing the damaged and/or dead cells by cell division
  • sometimes scar tissue is formed
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15
Q

examples of animals that can regenerate large body parts by cell division

A
  • flatworm (any part)
  • sea star (limbs and whole body if centre is intact)
  • axolotl (limbs and spine)
  • frog (tadpoles only can for limbs)
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16
Q

types of asexual reproduction involving mitosis

A
  • binary fission
  • budding
  • asexual spore
  • vegetative propagation
  • fragmentation
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17
Q

what is binary fission

A

divides into 2

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18
Q

what is budding

A
  • an outgrowth/bud is produced from parental body by cell divisions
  • the bud may detach from parental body and become a seperate organism
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19
Q

what is asexual spore

A

from fungus

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20
Q

what is vegetative propagation

A
  • new plants grows from vegetative (non flower) part of the plant by cell division
  • grows from stem, root, leaf, bud or tuber
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21
Q

what is fragmentation

A

-when the body is cut into a few parts, each part can grow into a new organism by cell division

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22
Q

what is the role/function of mitosis for organisms

A
  • growth
  • repair, replacement and regeneration
  • asexual reproduction
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23
Q

importance of mitosis

A
  • to produce daughter cells that are genetically identical among themselves and with the parent cell (same number and type of chromosomes)
  • maintain genetic stability of cells
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24
Q

what happens if cells do not undergo mitosis

A
  • mutated
  • rejected
  • removed by immune system
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25
Q

what is the cell cycle

A

period from the formation of a cell to its division into 2 daughter cells

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26
Q

what are the 3 main stages of the cell cycle

A
  • interphase (80%)
  • mitosis(15%)
  • cytokinesis (5%)
27
Q

what is gap 1 phase

A
  • growth phase of cell
  • RNA and protein synthesis
  • metabolic activities
28
Q

what is gap 2 phase

A
  • growth phase continues
  • centrioles replication
  • organelles replication
29
Q

what is synthesis phase

A
  • DNA replication

- histone protein synthesis

30
Q

what is cytokinesis

A

cytoplasmic division (mitosis is nuclear division)

31
Q

what are the 4 consecutive phases of mitosis

A
  1. Prophase
  2. Metaphase
  3. Anaphase
  4. Telophase
32
Q

what happens in prophase

A

-chromatins shorten and thicken to become chromosomes
-in animals, centrosomes (centrioles surrounded by a large number of proteins)
move to opposite poles
-asters are formed
-nucleolus disappeared
-nuclear envelop disintegrates into small vesicles
-spindle fibres (made of microtubules) are formed from centrosome (the microtubule organising center MTOC)

33
Q

What happens in metaphase

A
  • chromosomes line up at equator of spindle fibres
  • spindle fibres attach to kinetochore, the protein surrounding centomere
  • each chromosome has 2 kinetochores at its centromere, one on each chromatid
34
Q

what is the role of the centrosome

A
  • attaches the 2 sister chromatids together

- for the spindle fibres to attach to

34
Q

what is the role of the centrosome

A
  • attaches the 2 sister chromatids together

- for the spindle fibres to attach to

35
Q

what happens in anaphase

A
  • shortest stage: difficult to see and least cells are seen at this stage
  • centromeres divide into 2
  • spindle fibres pull the sister chromatids apart to opposite poles
  • by shortening of the microtubules from both ends (i.e. pole end and kinetochore end)
  • sister chromatid becomes ā€œVā€ shape
  • centromeres leading towards the poles
36
Q

what happens in telophase

A
  • chromosomes arrive at the opposite poles
  • chromosomes uncoil and elongate to become chromatids
  • spindle fibres disintegrate
  • nuclear envelope reforms at each pole
  • nucleoli reappear
  • 2 daughter nuclei which are genetically identical (same number and type of chromosomes) are formed
37
Q

what happens in cytokinesis in animal cells

A
  • by furrowing (narrowing of the cell surface membrane at the equator until it cuts the cell into 2)
  • due to constriction of belt of microfilaments beneath the cell surface membrane
  • organelles are evenly distributes to the 2 daughter cells
38
Q

what happens in cytokinesis in plant cells

A
  • cannot furrow due to rigid cell walls
  • cell plate is formed at the equator from small fluid-filled vesicles from Golgi apparatus
  • cellulose in vesicles form the new cellulose cell wall
  • pectin in vesicles form the middle lamella
  • membrane of the vesicles form the new cell surface membrane
39
Q

what is a tumor

A

an irregular, solid mass of cells resulting from uncontrolled cell division

40
Q

what are the 2 types of tumours

A
  • benign tumor

- malignant tumor (cancer)

41
Q

what are the 5 steps in cancer formation

A
  • mutation
  • uncontrolled cell division
  • tumor division
  • invasion of blood vessels and lymph vessels
  • metasis
42
Q

what is mutation

A

change in the base sequences of DNA/change chromosome number and structures in genes that control cell division

43
Q

what mutation in genes control cell division

A
  • proto-oncogenes
  • tumor suppressor genes
  • oncogenes
44
Q

what are proto-oncogenes

A

before cancer is formed, this gene controls cell division and prevents cancer

45
Q

what are tumor suppressor genes

A

-slows down cell division, repairs DNA , apoptosis (programmed cell death)

46
Q

what are oncogenes

A
  • divide indefinitely
  • immortal (no apoptosis)
  • lost contact inhibition
  • does not differentiate (only divide)
47
Q

what is a carcinogen

A

an ionising radiation (x-ray, UV), carcinogenic chemical (tar in tobacco, osbestos) or viral infection that leads to the formation of cancer cells

48
Q

what are the causes of cancer

A
  • carcinogen
  • genetic heredity
  • aging
49
Q

stages of lung cancer formation

A
  • cancer cells are not differentiated
  • no cilia
  • no mucus
  • block bronchi
  • invade blood vessels
50
Q

what is a telomere

A
  • a region of repetitive nucleotide (monomer of DNA) sequence at each end of a chromosome which protects the end of a chromosome from deterioration
  • they contain a unique DNA of sequence (DNA + histone protein) which is repeated several times (base sequence)
51
Q

what is the function of telomere

A

to protect the chromosomes from damage and ensure that when DNA is replicated, the ends of the molecules are included in the replication and not left out

51
Q

what are stem cells

A

a relatively unspecialized cell that can divide an unlimited number of times by mitosis and has the potential to become a speicalised cell

  • they are in embryo or adult
  • each new cell has the potential to remain a stem cell or differentiate into one or several different cell types
52
Q

what is potency

A
  • the ability of a stem cell to produce different cell types

- it is variable

53
Q

what are the 3 potencies

A
  • totipotent
  • pluripotent
  • multipotent
54
Q

what is totipotent

A

completely undifferentiated stem cell that can produce any type of cell (e.g. zygote forming placenta and embryo)

55
Q

what is pluripotent

A

descendants of totipotent cells (mostly undifferentiated) and can differentiate into nearly all cells

56
Q

what is multipotent

A

stem cell that can differentiate into a number of cell types, but only those of a closely related family of cells

57
Q

what is stem cell therapy

A

introduction of new adult stem cell into damaged tissue to treat disease or injury
-e.g bone marrow transplantation to treat leukemia, growing of new tissues and organs

58
Q

what is cell differentiation

A

a process whereby similar cells become dissimilar and specialized to take up different structure and function by switching on different genes at different place and time

59
Q

what is asexual reproduction

A

the production of new individuals (offsprings) by one parent, whereby the offsprings are genetically identical among themselves and with the parent

60
Q

relationship between SA:V and exchange of materials

A

-a cell cannot increase in size indefinetly as the SA:V limits its size for efficient exchange of material between external and internal environment of the cell

61
Q

what are microfilaments role in cell division

A

microfilaments are involved in cytoplasmic movements, for example, during cytoplasmic streaming and cell movement, and the cytoplasmic constriction at cell division in animal cells

AS Biology (11 decks)

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