2.1.6 cell division Flashcards
what happens during prophase
nuclear membrane disintegrates
spindle fibres form
chromatin becomes visible
what happens during metaphase
chromosomes line up along equator
what happens during anaphase
chromatids pulled apart by spindle fibres contracting
what happens during telophase
nuclear envelope reforms
cleavage furrow forms
what happens during cytokinesis
cytoplasm reforms
2 identical somatic diploid cells are produced
what is G0
resting stage for damaged cells, apoptosis, specialised cells
what is G1 for
cell growth
organelle duplication
protein synthesis
what is S phase for
DNA replication
what is G2 for
organelle duplication
protein synthesis
what does the G1 checkpoint do
checks for cell size
growth factors
organelle duplication
checks for damage
what does the G2 checkpoint do
checks for mutations
DNA is checked
what is the checkpoint in mitosis
spindle assembly checkpoint
what is interphase
G1, S phase and G2
how do you calculate mitotic index
cells in mitosis/total number of cells
what types of cells does mitosis produce
somatic diploid cells
what types of cells does meiosis produce
haploid gametes
what is homologous chromosome
each pair consists of one maternal and one paternal chromosome
(same gene, different alleles)
what is a stem cell
an undifferentiated cell that can specialise to make a specialised cell
what does totipotent mean
can differentiate into all cell types
what does pluripotent mean
can differentiate into specific cells
what does unipotent mean
can differentiate into one cell type
describe a neutrophil
engulfs bacteria by phagocytosis
has lysosomes
has a nucleus that moves
destroys pathogens
describe an erythrocyte
biconcave disc
no nucleus
haemoglobin to carry oxygen round body
describe a muscle cell
many mitochondria
lots of protein
contracts and relaxes
describe a rod cell
receptor membranes on one end
full of pigment to help you see
describe a goblet cell
cup shape to hold mucus
describe a nerve cell
many dendrites
myelin sheath carries electrical impulses along cell
describe a sperm cell
acrosome
flagellum
many mitochondria
haploid nucleus (gamete)
describe a bone cell
contains lots of calcium
provides body with structure
describe a root hair cell
large surface area
thin walls
many mitochondria
long
what are the stages of meiosis in plants
anaphase I –> meiosis II
what happens during prophase I
nuclear envelope disintegrates
chromosomes condense
spindle fibres form
bivalent formation = homologous chromosomes form a bivalent via synapsis
crossing over = non-sister chromatids intertwine and exchange segments which changes mixture of genetic info
what happens during metaphase I
bivalents line up at equator
centromere attaches chromosomes to spindle
random assortment mixes up genetic info
what happens during anaphase I
homologous chromosomes in each bivalent pulled to each pole by spindle fibres contracting
(centromeres don’t divide)
what happens during telophase I
nuclear envelopes reform
cytokinesis occurs
brief interphase
chromosomes uncoil
what happens during prophase II
nuclear envelope disintegrates
chromosomes condense
spindle fibres form
centrioles to opposite poles
(spindle in plants turns 90°)
what happens during metaphase II
chromosomes are lined up at equator with chromatids randomly assorted
what happens during anaphase II
chromosomes pulled apart
what happens during telophase II
two cells divide to make 4 genetically different haploid gametes (recombinants)
(a terrad in plants)
