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Flashcards in B2 cell division Deck (17):

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


what is therapeutic cloning

an embryo is made to have the same genetic information as the patient so there is no chance of rejection


what is a use of plant stem cells

they can be used to make clones of the parent plant quickly and economically which can prevent extinction

produce crops with special features e.g. disease resistance