2.1.6 Cell division, cell diversity and cellular organisation Flashcards

1
Q

what is the cell cycle

A
  • the cell cycle is when cells divide in order to make new cells
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2
Q

what are parts of the cell cycle

A
  • Interphase (G1 phase, S phase, G2 phase)
  • mitosis
  • cytokinesis
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3
Q

what occurs during G1 phase

A
  • the cell is growing and carrying out its normal functions ( eg producing energy)
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4
Q

what is the main goal in G1 phase

A
  • to increase the size of the cell and make sure it has all the resources needed for DNA replication
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5
Q

What does the cell check before entering S phase

A
  • the cell checks whether the cell is large enough, has enough nutrients and is in good condition to replicate DNA
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6
Q

what occurs in S phase

A
  • cell makes an exact copy of its DNA every chromosome is replicated, so the cell now has two sets of chromosomes
    ( one for each daughter cell)
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7
Q

what is the main goal of S phase

A
  • the DNA is synthesised to ensure that when the cell divides the daughter cell will have identical genetic material
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8
Q

What occurs during G2 phase

A
  • the cell continues growing and and the new DNA which was synthesised ( during s phase) is checked for any errors.
  • other preparations are made for cell division such as production of tubulin protein.
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9
Q

what are the 4 stages of mitosis

A
  • prophase
  • metaphase
  • anaphase
  • telophase
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10
Q

what is the centromere

A

a region of a chromosome where the spindle fibres attach during cell division

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11
Q

what does each chromosome consist of

A
  • two sister chromatids joined at the centromere
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12
Q

what is a chromatid

A

one of the two identical halves of a chromosome that have been replicated for cell division

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13
Q

what occurs during prophase

A
  • chromosomes condenses (visible when stained)
  • the nuclear envelope break down
  • nucleolus disappears
  • the centrioles go to opposite side of the cell and proteins form spindle fibres attached to the centromeres of each chromosome
  • the spindle fibres move the chromosomes to the equator (center) of the cell
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14
Q

what occurs during metaphase

A
  • the spindle fibre is fully formed
  • the chromosomes are now lined up at the equator of the cell
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15
Q

what occurs during anaphase

A
  • chromatids are pulled to opposite sides of the cell
  • the centromeres divide into two and the spindle fibres shorten
  • this pulls the sister chromatids towards opposite poles of the cell.
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16
Q

what occurs during telophase

A
  • the chromatids( now called chromosomes) have reached the poles of the cell.
  • the spindle apparatus breaks down and the nuclear membrane reforms
  • the chromosomes uncoil back to a chromatid
  • the nucleolus reappears in each cell.
  • the nuclear membrane surrounds the chromatids to form a nucleus
17
Q

what occurs during cytokinese

A
  • the central cell membrane is pulled inwards by the cytoskeleton.
  • this creates a groove which deepens.
  • eventually the membranes fuse to form two independent cells
18
Q

the significance of mitosis in life cycles

A
  • important for growth
  • tissue repair
  • asexual reproduction in plants, animals and fungi
19
Q

what is meiosis

A

a type of cell division to produce gametes that produce four genetically different haploid daughter cells from one parent cell.

20
Q

what is the significance of meiosis in life cycles

A
  • it produces 4 haploid gametes.
  • there cells are genetical different by independent assortment and crossing over
21
Q

what are the mainstages of meiosis

A
  • interphase
  • prophase 1
  • metaphase 1
  • anaphase 1
  • telophase 1
  • prophase 2
  • metaphase 2
  • anaphase 2
  • telophase 2
22
Q

define homologous chromosomes

A

two chromosomes with similar genes but different alleles, one inherited from each parent

23
Q

what occurs during prophase 1

A
  • chromatin condenses
  • nuclear envelope breaks down and spindle fibres made from centrioles
  • chromosomes pair in homologous pairs
  • crossing over between non-sister chromatids occur where alleles are exchanges
24
Q

what occurs during metaphase 1

A
  • homologous chromosomes line at chromosomes line at equator to spindle the centromeres at the sides of the cell
  • pairs are arranged randomly
25
what occurs during anaphase 1
- Homologous chromosomes pulls apart by motor proteins (independent assortment) - each chromosome still has two chromatids
26
what occurs during telophase 1
- nuclear envelop forms around chromosomes and cytokinesis may occur - cells go into short interphase
27
what occurs during prophase 2
- chromatin condenses - nuclear envelope breaks down and spindle fibres made from centrioles - chromatids are different due to crossing over in prophase 1
28
what occurs during metaphase 2
- chromosomes line at equator to spindle by centromeres - chromatids randomly arranged
29
what occurs during anaphase 2
- centromere divides and chromatids pulled apart by motor proteins - chromatids randomly segregated ( independent assortment)
30
what occurs during telophase 2
- nuclear envelope forms around chromosomes and cytokinesis occurs - 4 cells made in total as each cell from meiosis 1 divides.
31
when is genetic variation achieved in meiosis
- crossing over of chromatids ( pairs of chromosomes line up and exchange some of there genetic material) occurs in prophase 1
32
how are erythrocytes specialised for its function
- red blood cells - used to carry oxygen around the body specialised - no nucleus, mitochondria or golgi, for more space function - allows for more space for oxygen specialised - packed with lots of haemoglobin function - to store more oxygen specialised - bioconcave shape function - increases surface area to volume ratio, which makes gas exchange more efficient
33
how are neutrophils specialised for its function
white blood cells - specialised to engulf and destroy pathogens specialised - contains lots of lysosome which is a digestive enzyme function - the digestive enzyme is able to break down the engulfed particle specialised - flexible function - easier to engulf larger particles
34
how are squamous epithelial cells specialised for its function
a cell which is specialised for rapid diffusion specialised - thin, flat smooth surface function - this increases the rate of diffusion due to a short diffusion distance
35
how are ciliated epithelial cells specialised for its function
a cell used to sweep dirt and debris out of the body specialised - has a lot of cilia function - lots of cilia make it easier to sweep the dirt and debris out of the body
36
How are sperm cells specialised for its function
specialised - contains lots of mitochondria function - to provide energy/ATP for movement specialised - specialised lysosome in the acrosome of the sperm function - the digestive enzyme is able to break down/digest the protective jelly coat of the egg cell. specialised - stream lined body and flagellum function - to move more quickly towards the egg cells
37
how are palisade cells specialised for its function
a cell used to carry out photosynthesis specialised - contains lots of chloroplast function - chloroplast contains chlorophyll which changes light into energy
38
how are root hairs cell specialised for its function
a cell which is used for the uptake of ions and water from the soil. specialised - a large surface area function - to increase the rate of absorption
39
How are guard cells specialised for its function
used for the control of opening and closing of the stomata specialised - it uses pressure to open and close the stomata function - the guard cell is able to control the amount of water and solutes within them