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Biology Finals > M2, C6 Cell Divisions > Flashcards

M2, C6 Cell Divisions Flashcards

1
Q

what happens during interphase

A
  • DNA is replicated and checked for errors in the nucleus
  • protein synthesis occurs in the cytoplasm
  • mitochondria grow and divide, increasing in number
  • in plant cells chloroplasts grow and divide
  • normal metabolic process occur like respiration
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2
Q

what are the three stages of interphase

A

G1 - protein synthesis, organelles replicate, cell increases in size
S - synthesis phase: DNA is replicated in the nucleus
G2 - cell continues to increase in size, energy stores increase and duplicated DNA is checked for errors

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3
Q

what stages does the mitotic phase include

A

mitosis - nucleus divides

cytokinesis - cytoplasm divides and two cells are produced

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4
Q

why would a cell enter G0 phase

A
  • for a cell that becomes specialised and no longer is able to divide
  • the DNA could be damaged so is no longer viable
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5
Q

what does it mean if a cell is senescent

A

it can no longer divide

you get more of these cells as you age which leads to the risk of disease

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6
Q

why are their checkpoints in the cell cycle

A

ensure the cell only divides when it has grown to the right size, there are no errors and the chromosomes are in the correct positions

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7
Q

what does the G1 checkpoint check for

A

cell size
nutrients
growth factors
DNA damage

if these are there then the cell enters S phase
if not it enters G0

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8
Q

what does the G2 checkpoint check for

A

cell size
DNA replication
DNA damage

if satisfactory then the cell enters the mitotic phase
if not then it enters resting state

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9
Q

what does the spindle assembly checkpoint check for

A

chromosome attachment to spindle

mitosis doesn’t proceed unless this checkpoint is passed

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10
Q

define mitosis

A

a type of cell division that resuslts in 2 daughter cells each having the same number and kind of chromosomes as the parent nucleus, typical of ordinary tissue growth

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11
Q

why is mitosis important

A

growth
repair tissues
asexual reproduction

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12
Q

what is the centromere

A

the region of a chromosome to which the microtubules of the spindle attach during cell division.

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13
Q

what are chromatids

A

each of the two thread-like strands into which a chromosome divides longitudinally during cell division. Each contains a double helix of DNA.

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14
Q

what are the phases of mitosis

A 
prophase
metaphase
anaphase
telophase
cytokinesis
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15
Q

what happens in prophase in mitosis

A

mitosis begins
chromatin condenses and becomes inactive
centrioles migrate in pairs to opposite poles and the nuclear evelope and nucleolus break up

the chromosomes are now tightly coiled and visible as separate bodies under the microscope
the mitotic spindle begins to form at the centrioles

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16
Q

what is chromatin

A

the material of which the chromosomes of organisms other than bacteria (i.e. eukaryotes) are composed, consisting of protein, RNA, and DNA.

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17
Q

what happens during the metaphase in mitosis

A

the mitotic spindle grows further and attaches to the centromere of each chromosome
the fibres then arrange the chromosomes to line up along the cell equator

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18
Q

what happens during anaphase in mitosis

A

the centromere of each chromosome breaks
sister chromatids separate into daughter chromosomes
the cell starts to elongate as cytokinesis begins

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19
Q

what happens during telophase in mitosis

A

new nuclear membranes and nucleoli form

the chromosomes start to unwind back into chromatin and are no longer visible under the microscope

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20
Q

what happens during cytokinesis in animal cells

A

the cytoplasm is divided between the 2 daughter cells to finish the cycle
each new cell enters interphase and resumes its normal functions

Cleavage furrow formed in the middle of the cell. cell-surface membrane pulled inwards by cytoskeleton and fuse forming two cells.

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21
Q

what happens during cytokinesis in plant cells

A

vesicles from the Golgi apparatus begin to assemble between the two nuclear envelopes
the vesicles fuse with each other and the cell surface membrane divides the cell into 2
new sections of the cell wall then form along the new membrane which splits the cell

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22
Q

how are gametes formed

A

meiosis

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23
Q

why is a gamete said to be haploid

A

contains half the chromosome number of the parent cell

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24
Q

what are homologous chromosomes

A

a pair of same chromosomes, one from each parent

have the same genes but can different alleles of each gene

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25
what are alleles
different versions of the same gene | the genes have the same locus and the centromeres will be in the same position
26
in meiosis 1 what happens during prophase
``` chromosomes condense nuclear envelope disintegrates nucleolus disappears spindle formation begins homologous chromosomes pair up, forming bivalents chromatids entangle - crossing over ```
27
in meiosis 1, what happens during metaphase
homologous pairs of chromosomes assemble along the metaphase plate the orientation of the pair is random the maternal or paternal chromosomes can end up facing either pole - independent assortment - leads to genetic variation
28
in meiosis 1, what happens during anaphase
homologous chromosomes are pulled to opposite poles and chromatids stay joined together the entangled chromatids break off and rejoin - sometimes exchanges DNA when exchange occurs, recombinant chromatids form genetic variation arises from a new combination of alleles - sister chromatids are no longer identical
29
in meiosis 1, what happens during telophase
chromosome assemble at each pole nuclear membrane reforms chromosomes uncoil cell undergoes cytokinesis and divides into 2 cells the reduction of chromosome number from diploid to haploid is complete
30
in meiosis 2, what happens during prophase
chromosomes that have 2 chromatids condense and become visible again nuclear envelope breaks down spindle formation begins
31
in meiosis 2, what happens during metaphase
the individual chromosome assemble on the metaphase plate | due to crossing over, chromatids are no longer identical so there is independent assortment and more genetic variation
32
in meiosis 2, what happens during anaphase
chromatids of the individual chromosomes are pulled to opposite poles after division of the centromeres
33
in meiosis 2, what happens during telophase
chromatids assemble at the poles chromosomes uncoil and form chromatin again nuclear envelope reforms and the nucleolus becomes visible cytokinesis results in division of the cells forming 4 daughter cells the cells will be haploid due to the reduction division they are all genetically different from each other and the parent cell
34
what does a differentiated cell mean
they are specialised to carry out very specific functions
35
how are erythrocytes specialised
have a flattened biconcave shape increases surface area : volume essential for transporting oxygen no nucleus or organelles to maximise space for haemoglobin flexible to squeeze through narrow capillaries
36
how are neutrophils (type of white blood cell) specialised
have a multi-lobed nucleus so they can squeeze through small gaps to get to the site of infection contain many lysosomes to attack pathogens
37
how are sperm cells specialised
tail or flagellum for movement lots of mitochondria to supply energy acrosome on the head contains digestive enzymes to break through the egg
38
how are palisade cells specialised
contain lots of chloroplasts which can move in the cytoplasm to absorb large amounts of light for photosynthesis rectangular box shape to tightly pack in a continuous layer thin cell walls for increased diffusion of co2 large vacuole to maintain turgor pressure
39
how are root hair cells specialised
long extensions called root hairs to increase surface area | maximises uptake of water and minerals from the soil
40
how are guard cells specialised
when guard cells lose water and become less swollen as a result of osmotic forces - they change shape and the stoma closes to prevent further water loss cell wall is thicker on one side so cell doesn't change shape symmetrically as its volume changes
41
what are the 4 main categories of animal tissues
nervous tissue epithelial tissue muscle tissue connective tissue
42
how is squamous epithelium tissue specialised
very thin - one cell thick for rapid diffusion forms the lining of the lungs for diffusion of oxygen into the blood
43
how is ciliated epithelium tissue specialised
cilia that move in a rhythmic manner to move mucus along | goblet cells are also present to release mucus to trap pathogens
44
how is cartilage tissue specialised
connective tissue contains elastin and collagen firm and flexible prevents ends of bones rubbing together
45
how is muscle tissue specialised
able to shorten in length in order to move bones | contains contractile proteins and myofibrils
46
how is epidermis tissue specialised
covered by a waxy, waterproof cuticle to reduce loss of water closely packed cells contains stomata which can open and close due to the guard cells allows water, oxygen and carbon dioxide in and out
47
how is xylem tissue specialised
composed of dead cells walls are strengthened by lignin which is waterproof structural support for plants
48
how is phloem tissue specialised
composed of columns of sieve tube cells separated by perforated walls called sieve plates transported organic nutrients from leaves and stems to parts of the plant where it's needed
49
define an organ
collection of tissues that are adapted to perform a particular function in an organism
50
give examples of animal organ systems
``` digestive system cardiovascular system (movement of blood) gaseous exchange system ```
51
what organs are involved in the digestive system
``` oesophagus rectum stomach large intestine small intestine liver mouth anus ```
52
what organs are involved in the nervous system
nerves | brain
53
what organs are involved in the urinary system
bladder ureter kidneys urethra
54
what organs are involved in the circulatory system
veins arteries heart capillaries
55
what organs are involved in the respiratory system
trachea bronchi bronchioles lungs
56
what organs are involved in the musculoskeletal system
muscles | bones
57
what are stem cells
undifferentiated cells so they don't have a specific function they have the potential to differentiate into a specialised cell
58
what is the term for a stem cells ability to differentiate
potency
59
define totipotent
these stem cells can differentiate into any type of cell, forming a whole organism eg. a fertilised egg
60
define pluripotent
these stem cells can form all tissue types but not whole organism
61
define multipotent
these stem cells can only form a range of cells within a certain type of tissue
62
what stem cells have blood cells derived from
stem cells in the bone marrow
63
what are the sources of animal stem cells
embyros - these are totipotent tissues like bone marrow - these are multipotent umbilical cords - multipotent
64
what are the sources of plant stem cells
meristematic tissue (meristems) - found wherever growth is occurring in plants or between xylem and phloem - it is pluripotent
65
what are the potential uses of stem cells
heart disease - repair muscle tissue in the heart type 1 diabetes - for insulin-producing cells Parkinson's disease - for dopamine-producing cells in the brain Alzeihmer's disease - brain cells macular degeneration - treat blindness birth defects spinal injuries
66
what are stem cells currently being used for
treatment of burns - new skin drug trials - can be tested on stem cells before animals developmental biology
67
what are the reasons for using stem cells
- saves lives - improves peoples lives - embryos have been donated, were going to be discarded of anyway - could save NHS lots of money as people wouldn't need medicine or operations
68
what are the reasons against using stem cells
- embryos are destroyed - religious objections - belief life begins at conception so destroying embryos is murder - costs a lot of money - too much of a risk

Biology Finals (19 decks)

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