B2 Flashcards
what is mitosis?
type of cell division, which is responsible for growth, making identical cells
first stage of mitosis cell division
prophase: chromosomes inside the nucleus
second stage of mitosis cell division
metaphase:
spindles from the centrioles attach to chromosomes, aligned at the equator of the spindle
third stage of mitosis cell division
anaphase:
chromosomes separate, each half attached to a spindle at the end of a centriole
fourth stage of mitosis cell division
telophase:
two separate nucleuses, containing the same number of half chromosomes
fifth stage of mitosis cell division
cytokinesis:
two separate identical cells, cytoplasm and cell membrane divide
how many chromosomes do humans have
46 chromosomes, 23 from each parent
what is a diploid
a cell with 2 sets of chromosomes (46 pairs)
what is a haploid
a cell with only 1 set of chromosomes (23 pairs)
what is a gamete
reproductive cells: egg cells, sperm cells
what is the cell cycle
a series of events that take place as a cell grows and divides
cell cycle G1
growth, preparation for DNA synthesis
cell cycle S
DNA replication
apoptosis
the cell does not pass the checkpoint and gets destroyed
advantages of quick cell division
good for the enzymes in the digestion process
cell cycle G2
preparation for mitosis, growth
cell cycle M
mitosis:
prophase, metaphase, anaphase, telophase
what causes cancer
uncontrolled cell growth
what percentage of a cells life is spent in interphase?
90%
what is a cell checkpoint?
checks to see if the cell is replicating DNA and growing properly before mitosis
why do people lose their hair during chemotherapy?
chemo targets fast-growing cells, such as hair cells
stem cell definition
an undifferentiated cell with the potential to form a wide variety of different cell types
embryonic stem cells
stem cells from an early embryo that can differentiate to form the specialised cells of the body
adult stem cells
stem cells that are found in adults that can differentiate and form a limited number of cells
how can stem cells be used
they can help medical conditions by replacing damaged cells from disease or chemotherapy
why are stem cells problematic
people believe it offends human dignity or harms/destroys human life
growth of an egg cell
zygote once a sperm fertilises the egg, embryo, fetus, baby
growth definition
a permanent increase in size as a result of cell division or cell enlargement
differentiate definition
the process where cells become specialised for a particular function
differentiation in plant cells
plant cells retain the ability to differentiate throughout life
differentiation in animal cells
animal cells can only differentiate at an early stage
where does plant cell differentiation take place
meristems - tissues found in the tips of the roots and shoots of plants
