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Module 2: Foundations in Biology > Cell division, cell diversity and cell differentiation > Flashcards

Cell division, cell diversity and cell differentiation Flashcards

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1
Q

what does the cell cycle consist of

A
  • interphase and mitosis followed by cytokinesis
  • IPMATC
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2
Q

why is mitosis essential

A
  • growth
  • tissue repair
  • asexual reproduction
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3
Q

what are the stages in interphase

A

G1 (G0), S, G2, M

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4
Q

what occurs in G1

A
  • cell grows
  • organelle duplicates
  • biosynthesis
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5
Q

what occurs in G0

A
  • rest
  • apoptosis or differentiation
  • not in all cells
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6
Q

what occurs in S

A
  • DNA replication
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7
Q

what occurs in G2

A
  • cell growth
  • proteins made for division
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8
Q

where are the checkpoints during cell cycle

A
  • Metaphase checkpoint
  • G1 checkpoint
  • G2 checkpoint
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9
Q

role of metaphase checkpoint

A
  • ensures sister chromatids are attached to spindle fibres by their centromeres
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10
Q

role of G1 checkpoint

A
  • cell checks that the chemicals needed for replication are present
  • cell checked for any damage to DNA before S phase
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11
Q

role of G2 checkpoint

A
  • cell checks whether all the DNA has been replicated without any damage
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12
Q

what happens in interphase

A
  • cell continues carrying out normal function but prepared to divide
  • DNA is unravelled and replicated
  • organelles replicated
  • ATP content increased (needed for division)
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13
Q

product of mitosis

A

2 genetically identical diploid cells

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14
Q

what happens in prophase

A
  • chromosomes condense
  • nucleolus and nuclear membrane breaks down
  • centrioles move to opposite end of the cell
  • spindle fibres form between centrioles
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15
Q

what happens in metaphase

A
  • chromosomes (each with two chromatids) line up at the equator of the cell
  • chromosomes become attached to the spindle fibres by their centromeres
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16
Q

what happens in anaphase

A
  • centromeres divide, separating each pair of sister chromatids
  • spindle fibres contract, pulling chromatids to
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17
Q

chromosome vs chromatin vs chromatin

A
  • A chromosome consists of a single, double-stranded DNA molecule. ( single ‘unit’ before replication but doubles before cell division, so X is now called chromosome)
  • chromatids are two molecules of double-stranded DNA joined together in the centre by a centromere
  • chromatin is the complex of DNA and histone protein
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18
Q

what happens in telophase

A
  • chromatids reach the opposite poles on the spindle
  • they uncoil becoming long and thin again (they’re now called chromosomes again)
  • nuclear envelope forms around each group of chromosomes so there are now two nuclei
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19
Q

what happens in cytokinesis (separate process to mitosis)

A
  • cytoplasm divides
  • in animal cells, a cleavage furrow forms to divide the cell membrane
  • cytokinesis usually begins in anaphase and ends in telophase
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20
Q

meiosis is reduction division. What does this mean

A

it halves the chromosome number

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21
Q

mitosis is nuclear division. What does this mean

A

It is a process where a single cell divides into two identical copies

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22
Q

product of meiosis

A
  • 4 genetically different haploid daughter cells
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23
Q

what are homologous chromosomes

A

one of a pair of chromosomes with the same gene sequence, loci, chromosomal length, and centromere location

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24
Q

similarities between meiosis and mitosis

A
  • prophase involves chromatin condensing, nuclear membranes breaking down, and spindle formation
  • in metaphase, chromatids line along the equator attached to spindle fibres
  • in anaphase, motor proteins draw genetic material to the poles of the cell
  • telophase involves the nuclear envelopes reforming
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25
Q

differences between meiosis and mitosis

A
  • only prophase 1 involves crossing over
  • only metaphase 1 has independent assortment
  • in anaphase 1, chromosomes are pulled apart, but in 2, chromatids are
  • telophase 1 is followed by a short interphase. Telophase 2 forms 4 haploid cells
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26
Q

what is independent assortment

A

When the pair of chromosomes splits up (in anaphase), each daughter cell will receive one chromosome. The allocation of this is completely random

27
Q

outline crossing over

A
  1. chromatids twist around one another at chiasmata
  2. tension is placed on each chromatid, breaking a part off
  3. broken sections re-join with the other homologous partner
28
Q

Each homologous chromosome will go to the two daughter cells. the total number of combinations is…….(equation)

A
  • 2^n
  • n= number of chromosomes in haploid cell
29
Q

what are stem cells

A

unspecialised cell able to express all of its genes and divide by mitosis

30
Q

how do cells differentiate

A
  • genes switch off, forming specialised cells and tissues
31
Q

what things can be altered by differentiation in cells

A
  • shape
  • size
  • contents and organelle proportions
32
Q

define differentiation

A

the process by which all cells become specialised into different cell types

33
Q

what are stem cells used for in adults

A
  • replace damaged cells
34
Q

what can plant stem cells differentiate into

A
  • xylem and phloem
35
Q

what do stem cells in bone marrow differentiate into

A

blood cells to replace those lost or produce neutrophils to help fight infections

36
Q

where are stem cells in plants

A
  • meristematic tissue in meristems (found in soot tips, roots and cambium of vascular bundles)
37
Q

vascular cambium vs meristem

A

The vascular cambium is a layer of meristematic cells

38
Q

application of stem cells

A
  • researching developmental biology
  • replaced damaged cells in disorders like Alzheimer’s and Parkinson’s
39
Q

how can stem cells be used to treat in Alzheimer’s

A
  • nerve cells in brain die in increasing numbers resulting in memory loss
  • researchers are hoping to regrow healthy nerve cells
40
Q

how can stem cells be used to treat in Parkinson’s

A
  • patients suffer from tremors that they can’t control
  • This disease causes the loss of a particular type of nerve cell found in the brain. These cells release dopamine
  • Transplanted stem cells may help to regenerate the dopamine-producing cells
41
Q

how can stem cells be used in developmental biology

A
  • research into how organisms grow and develop
  • help understand disorders and cancer
42
Q

sources of stem cells

A
  • embryos
  • umbilical-cord blood
  • bone marrow
  • induced pluripotent stem cells, iPS ( genes in cells witched on in lab to make them undifferentiated)
43
Q

define pluripotent

A

capable differentiating into several different cell types

44
Q

examples how can stem cells be used to repair damaged tissue

A
  • treat mice with type 1 diabetes by programming iPS cells to become B cells
  • bone-marrow stem cells made to develop into hepatocytes to treat liver disease
  • used in regenerative medicine to grow organs for transplanting, if patients’ cells obtained turned into iPS then there’s no need for immunosuppressant drugs
  • may eventually be used to treat burns and vision loss
45
Q

why do multicellular organisms need specialised cells and tissues to survive

A

small SA:V

46
Q

define tissue

A

a group of similar cell working together to perform the same specific function

47
Q

define organ

A

a group of similar tissues working together to perform the same specific function

48
Q

define organ system

A

a group of organs working together to perform the same specific function

49
Q

difference between erythrocytes and neutrophils

A
  • erythrocytes carry oxygen from the lungs to respiring cells
  • neutrophils ingest invading pathogens
50
Q

how are erythrocytes specialised

A
  • vary small so large SA:V (easy diffusion of O2 into cell)
  • flexible due to well developed cytoskeleton so can twist and turn as it travels through narrow capillaries
  • most organelles lost at differentiation which provides more space for Hb in them
51
Q

how are neutrophils specialised

A
  • twice the size of erythrocytes with multilobed nucleus
  • attracted to sites of infection by chemotaxis
  • function is to ingest bac and fungi by phagocytosis
52
Q

how are sperm cells specialised

A
  • many mitochondria for ATP for energy which allows tail to move and propel cell towards the ovum
  • small, long and thin so they can move easily
  • head has acrosomes that digest outer layer of ovum so sperm cell can enter
  • head contains haploid male gamete nucleus and very little cytoplasm
53
Q

how are epithelial cells specialised

A
  • lining tissue
    -squamous epithelial cells are flattened in shape
  • many have cilia
54
Q

how are palisade cells specialised

A
  • long and cylindrical so can pack together closely but little space between cells so CO2 in these air spaces diffuse into cells
  • large vacuole near periphery of cell so short diffusion diffusion distance
  • many chloroplasts
  • cytoskeleton and motor proteins move chlorophyll nearer to upper surface when light intensity is low but further down when its high
55
Q

how are guard cells specialised

A
  • in lower epidermis so don’t photosynthesise
  • light energy used to produce ATP
  • ATP used to for active transport of K+ into cell to lower water pot so water moves into cell by osmosis
  • guard cell swells but as tips of cell wall are more flexible and more rigid at the thicker middle part, stomata enlarges
  • open stomata allow gas exchange and as CO2 is used for photosynthesis, conc gradient is maintained
  • transpiration is an inevitable consequence when stomata are open
56
Q

how are root hair cells specialised

A
  • hair-like projections increases SA for absorption of water
  • mineral ions actively transported into cell by special carrier proteins
  • ATP produced for the process
57
Q

features of epithelial tissue: ciliated and squamous

A
  • lines organs, airways and tubes
  • has a role in absorption, secretion and protection
  • cells attach in sheets and receive nutrients vis diffusion from connective tissue ( as epithelial tissue has no blood vessels)
  • cell have short cell cycles as it replaces cells regularly
58
Q

features of connective tissue

A
  • consists of cells and non-living matrix
  • Cartilage is a type of connective tissue that adds structural strength and cushions joints
59
Q

features of muscle tissue

A
  • contracts using long protein filaments which contain actin and myosin proteins, these myofilaments allow contraction
  • well vascularised
  • 3 types:
  • smooth lining tubes and propels substances along them
  • skeletal for movement
  • cardiac in heart which allows heart to beat and pump blood
60
Q

features of epidermal tissue

A
  • flattened sheets of cells forming a protective covering for the leaf
  • some cell walls impregnated with waxy substance to reduce water loss
61
Q

what’s the vascular bundle in plants composed of

A
  • xylem vessels which carry water and minerals from roots to all parts of the plant
  • phloem sieve tubes which transfer sucrose in solution from leaves to all parts of the plant that don’t photosynthesise (roots, flowers)
62
Q

features of plant stem cells

A
  • thin walls with very little cellulose
  • no chloroplasts
  • don’t have a large vacuole
  • divide by mitosis and differentiate into other cell types
63
Q

how do cambium cells differentiate into xylem vessels

A
  • lignin deposited in cell walls to reinforce and waterproof cells but this kills them
  • ends of cells break down forming continuous columns with wide lumens to carry water and minerals
64
Q

how do cambium cells differentiate into phloem sieve plates

A
  • most organelles lost, sieve plates develop between cells
  • companion cells retain organelles and continue metabolic functions for active loading of sugars into sieve tubes

Module 2: Foundations in Biology (6 decks)

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