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a-level biology > 2.1.6 Cell Division, Cell Diversity and Cellular Organisation > Flashcards

2.1.6 Cell Division, Cell Diversity and Cellular Organisation Flashcards

1
Q

stages of the cell cycle

A

g1 - growth
s - synthesis
g2 - growth, preparation for cell division
mitosis or meiosis - nuclear division
cytokinesis - division of the cell

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2
Q

Gap 1 Stage of Cell Cycle

A

cell increases in volume
protein synthesis - produces enzymes used in DNA replication - produces growth factors
organelle replication

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3
Q

Synthesis Stage of Cell Cycle

A

DNA replication
ensures twice the original DNA
each daughter cell receives 1/2

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4
Q

Gap 2 Stage of Cell Cycle

A

cell increases in volume
energy stores increase
synthesising key proteins for cell division

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5
Q

Checkpoints in the Cell Cycle

A

G1/S checkpoint
G2/S checkpoint
Metaphase checkpoint

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6
Q

G1/S Checkpoint in Cell Cycle

A

checks for DNA damage
checks cell is large enough

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7
Q

G2/S Checkpoint in Cell Cycle

A

checks for correct DNA replication

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8
Q

Metaphase Checkpoint

A

spindle assembly checkpoint
checks spindle fibres are correctly attached to chromosomes

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9
Q

Cytokinesis in Cell Cycle

A

division of the cell
cell cytoplasm divides in 2

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10
Q

why is interphase not a resting phase

A

significant metabolic activity is taking place

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11
Q

which type of cells could be considered to be in a resting phase

A

cells that are not actively dividing

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12
Q

significance of mitosis in life cycles

A

production of stem cells
tissue growth and repair
asexual reproduction
clonal expansion of lymphocytes
development of body plan

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13
Q

prophase in mitosis

A

chromatin condenses - chromosomes become visible
nuclear envelope breaks down
nucleolus disappears
centrioles migrate to opposite poles of the cell
spindle fibres start to form

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14
Q

metaphase in mitosis

A

spindle fibres attach to the centromeres of each pair of sister chromatids
chromosomes line up along equator
-metaphase checkpoint-

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15
Q

anaphase in mitosis

A

spindle fibres shorten + pull sister chromatids apart and separates them to opposite poles - REQ. ATP
centromere has divided

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16
Q

telophase in mitosis

A

full set of chromosomes at each pole of the cell
nuclear membrane forms around each set of chromosomes + nucleolus reappears
chromosomes uncoil into chromatin

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17
Q

cytokinesis in an animal cell

A

cleavage furrow forms down centre of the cell
actin microfilaments contract (req. ATP) and separates 2 cells by pinching plasma membrane together - 2 genetically identically daughter cells

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18
Q

cytokinesis in a plant cell

A

vesicles containing cellulose are deposited at cell plate
cellulose molecules hydrogen bond together - microfibrils - macrofibrils
cell spilts

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19
Q

what is a stem cell

A

undifferentiated, unspecialised
self renewing
potential to become a specialised cell

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20
Q

where can stem cells be obtained

A

bone marrow
tissues
embryos

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21
Q

which types of cells can embryonic stem cells differentiate into

A

any type of specialised cell
heart, blood, brain, skin
NOT PLACENTA/UMBILICAL CORD

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22
Q

how can stem cells be used in the treatment of burns

A

use a sample of undamaged skin
put in a culture + feed it
implant onto burn

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23
Q

roles of stem cells in the body

A

repairing wounds
replacing old red blood cells

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24
Q

totipotent stem cells

A

extracted from 1-32 cells of embryo
can differentiate into ALL types of cell
has ability to form whole living organisms

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25
pluripotent stem cells
extracted from 64-256 cells of embryo can differentiate into most cell types not placental/umbilical cord cells
26
multipotent stem cells
in bone marrow - haematopoietic can differentiate into some cell types blood cells: phagocytes, lymphocytes, erythrocytes
27
unipotent stem cells
only differentiate into 1 cell type
28
induced pluripotent stem cells (iPSCs)
reprogramme differentiated cells to become embryonic/pluripotent stem cells potential in areas like regenerative medicine
29
uses of stem cells in medicine
developmental biology regenerative medicine treating neurodegenerative diseases repair of damaged tissues
30
prophase 1 of meiosis 1
chromatin condenses - chromosomes become visible nuclear envelope breaks down nucleolus disappears spindle fibres start to form
31
crossing over - variation in prophase 1 of meiosis 1
non-sister chromatids within the same homologous pair exchange short sections of DNA forms new combinations of alleles
32
metaphase 1 of meiosis 1
each homologous pair lines up along the equator spindle fibres attach to centromeres
33
independent assortment - variation in metaphase 1 of meiosis 1
orientation of each homologous pair along the equator is random more possible combinations of alleles in daughter cells
34
anaphase 1 of meiosis 1
spindle fibres shorten and separate each member of a homologous pair to opposite poles centromere remains intact
35
telophase 1 of meiosis 1
unpaired chromosomes at each pole nuclear envelope reforms nucleolus reappears chromosomes relax for cytokinesis to occur
36
before vs after meiosis 1
before: 1 parent cell, 46 chromosomes, 92 chromatids (after S phase) after: 2 haploid daughter cells with 23 chromosomes, 46 chromatids
37
stages before meiosis 2
a short cell cycle occurs but without DNA replication
38
prophase 2 of meiosis 2
chromatin condenses chromosomes become visible nuclear envelope breaks down nucleolus disappears spindle fibres start to form
39
metaphase 2 of meiosis 2
chromosomes line up along equator spindle fibres attach to centromeres
40
independent assortment - variation in metaphase 2 of meiosis 2
random orientation of chromosomes along the equator, which determines which daughter cell each sister chromatid is separated to - produces new combinations of alleles in daughter cells
41
anaphase 2 of meiosis 2
spindle fibres shorten centromere divides sister chromatids are pulled to opposite poles
42
telophase 2 of meiosis 2
nuclear membrane forms around each set of chromatids at each pole nucleolus reappears chromatids relax
43
significance of meiosis in life cycles
production of haploid cells produce genetic variation by independent assortment and crossing over
44
homologous chromosomes
pairs of chromosomes that contain the same genetic information
45
how are erythrocytes adapted to carry out their function?
**very small** = large SA:V ratio: oxygen can diffuse across membranes easily **biconcave shape:** increases SA:V ratio **elastic membrane - flexible:** allows cell to change shape, twist & turn through narrow capillaries **little organelles:** provides more space for Hb moleucles
46
function of erythrocytes
carry oxygen from the lungs to respiring cells
47
function of neutrophils
destroy pathogens by phagocytosis and the secretion of enzymes
48
how are neutrophils adapted to carry out their function?
**flexible/mutilobed nucleus:** allows cells to squeeze through cell junctions in the capillary wall **lots of lysosomes:** digestive enzymes help to digest and destroy invading cells
49
function of sperm cells
reproduction - to fuse with an egg, initiate the development of an embryo and pass on paternal genes
50
how are sperm cells adapted to carry out their function?
**many mitochondria:** site of aerobic repiration to provide ATP for movement **acrosome contains digestive enzymes:** can break down the outer layer of an egg cell **tail:** propells cell forwards, allowing it to move towards the egg
51
function of squamous epithelial cells
ensure efficient gas exchange
52
how are squamous epithelial cells adapted to carry out their function?
**thin cross-section of cells:** reduces diffusion distance that substances pass through **permeable:** allows easy diffusion of gases
53
function of ciliated epithelial cells
maintains health of gas exchange system move substances across the surface of tissues
54
how are ciliated epithelial cells adapted to carry out their function?
**cilia (hair-like structures):** beat in a coordinated way - wafts material along surface of epithelium tissue **goblet cells:** secrete mucus - helps to trap dust, dirt and microorganisms - preventing them from entering vital organs, causing infection
55
function of palisade cells
carry out photosynthesis to produce glucose and oxygen
56
how are palisade cells adapted to carry out their function?
**lots of chloroplasts:** maximise the absorption of light for photosynthesis **tall and thin shape:** allows light to penetrate deeper, many cells can be densely packed together
57
function of root hair cells
absorption of water and mineral ions from soil
58
how are root hair cells adapted to carry out their function?
**root hair:** increases SA, so the rate of water uptake by osmosis is greater **thin walls:** short diffusion distance, water can move through easily **permanent vacuole contains cell sap:** more concentrated than soil water, maintains water potential gradient **mitochondria:** active transport of mineral ions
59
function of guard cells
control the opening of the stomata to regulate water loss and gas exchange
60
how are guard cells adapted to carry out their function?
**inner cell walls are thicker than outer cell walls:** allows the cell to bend when turgid **high density of chloroplasts and mitochondria:** play a role in the opening of the stomata

a-level biology (26 decks)

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