Cells and control - topic 2 (pg 13-19) paper 1 Flashcards
two types of cell division
mitosis and meiosis
mitosis happens in
body cells excluding gametes
dividing cell is called
parent cell
new cells formed are called
daughter cells; identical to parent cell
mitosis makes
two new cells
genetically identical cells
diploid means
double (two sets of) chromosomes
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
mitosis is used for
growth
repair
asexual reproduction
after growth
cells can differentiate into specialised cells
cancer cells are
abnormal cells that divide uncontrollably
specialised cell
cells adapted to carry out a particular function
growth in animals
a zygote, or fertilised egg cell, divides by mitotic producing daughter cells which grow and differentiate
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
examples of specialised animal cells
red blood cells
egg and sperm cells
nerve cell
bone cells
example of specialised plant cells
xylem
phloem
root hair cells
stoma cells
Growth is a
permanent increase in size
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
stem cells
can divide to produce many types of cell
replace faulty cells
may not stop dividing causing cancer
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
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
Meristems
Plants, found in rapidly growing parts of the plant, divide to produce and plant cell
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
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
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
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
