Cells and control - topic 2 (pg 13-19) paper 1 Flashcards Preview

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Flashcards in Cells and control - topic 2 (pg 13-19) paper 1 Deck (25):
1

two types of cell division

mitosis and meiosis

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mitosis happens in

body cells excluding gametes

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dividing cell is called

parent cell

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new cells formed are called

daughter cells; identical to parent cell

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mitosis makes

two new cells
genetically identical cells

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diploid means

double (two sets of) chromosomes

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Stages of mitosis

IPMAT
Interphase - chromosomes become visible, DNA has been copied
Prophase - each chromosome consists of two chromatids which condense, spindle fibre forms
Metaphase - nuclear membrane breaks down, chromosomes line up in the middle of the cell
Anaphase - chromatids are pulled to each pole of the cell, now called chromosomes
Telophase - spindle fibres disappear, nuclear membrane forms around chromosomes
Cytokinesis - cell splits in two

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mitosis is used for

growth
repair
asexual reproduction

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after growth

cells can differentiate into specialised cells

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cancer cells are

abnormal cells that divide uncontrollably

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specialised cell

cells adapted to carry out a particular function

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growth in animals

a zygote, or fertilised egg cell, divides by mitotic producing daughter cells which grow and differentiate

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growth in plants

plant cells divide by mitosis, behind tips of roots and shoots, cells enlarge, by taking water in vacuoles by osmosis, cell elongates, can then differentiate

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examples of specialised animal cells

red blood cells
egg and sperm cells
nerve cell
bone cells

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example of specialised plant cells

xylem
phloem
root hair cells
stoma cells

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Growth is a

permanent increase in size

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Percentile charts

help to show if a baby is growing correctly, slower or faster
above the 95th or below 5th percentile may be not be growing correctly
baby who's mass decreases by 2 or more percentiles in the first year may not be growing correctly

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stem cells

can divide to produce many types of cell

replace faulty cells
may not stop dividing causing cancer

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embryonic stem cells

taken from embryos at an early stage of division

repairing brain cells to treat Parkinson's
replace damaged retina cells, treat blindness

easy to extract, produce any cell
ethical issues of destroying embryos

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adult stem cells

found differentiated tissue, bone or skin - divide to replace damaged cells

treatment of leukaemiapotentially grow new tissue genetically matched to patient

no embryo destroyed, will not cause rejection
produce only s few types of cell

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Meristems

Plants, found in rapidly growing parts of the plant, divide to produce and plant cell

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Sensory neurone

carry impulses to central nervous system (CNS)
- Dendron- carries impulse towards cell body
- axon- carries impulses away from cell body
- fatty myelin sheath- insulates neuron

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Motor neurone

carry impulses from CNS to effector organs
- axon- carries electrical impulse over long distance
- nerve ending- transmits impulse to effector, muscle
- electrical impulse jumps gap in myelin sheath, speeding up rate of transmission

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Synapses

where two neurones meet, gap in-between
1) electrical nerve impulse reaches end of axon
2)electrical impulse causes chemical neurotransmitter to be released from vesicles into the gap
3)neurotransmitter diffuses across gap and fits into receptors, causing a new impulse in next neurone

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Reflex arcs

involve 3 neurones, provide fast reactions without involving the brain. Reflex arcs are:
- immediate
- involuntary
- innate
- invariable
protect from immediate harm e.g. eye blink