B2 cell division Flashcards
what is mitosis
they type of cell division that leads to growth or repair. 2 new cells form, both identical to each other and the original cell
what happens in stage 1 of mitosis
dna replictaes to form 2 copies of each chromosome and synthesis of new sub cellular structures (mitochondria, ribosomes and chloroplasts)
what happens in stage 2 of mitosis
one set of chromosomes is pulled to each end of the dividing cell and the nucleus divides
what happens in stage 3 of mitosis
cytoplasm and cell membranes divide to form 2 identical daughter cells
how many chromosomes are there in the nucleus of body cells?
46, arranged in 23 pairs (one mother, one father)
what are gametes
sex cells- only have one chromosome from each pair so only have 23
what is a stem cell
an unspecialised cell that can differentiate to any type of cell needed
what is a use of adult stem cells?
replace dead or damaged cells that can’t divide e.g. red blood cells and skin cells
what happens to damaged nerve cells
they don’t divide once differentiated and are not replaced by stem cells so can’t be healed
where does plant mitosis take place
in the meristem found in the shoot and root tips
what is a zygote
a single new cell formed when an egg and sperm cell fuse
what are immunosuppressant drugs used for
to stop a patient rejecting new cells after a stem cell transplant
what is a concern with embryonic stem cells?
they could cause cancer as they grow so rapidly
what is a concern with adult stem cells
they could be infected with viruses that could then infect the patient
where are embryonic stem cells found
in aborted embryos or spare cells left over from fertility treatment (ethical issues)
umbilical cord blood, amniotic fluid
