cell division Flashcards
list the stages of the cell cycle in order + outline what happens at each
G1 phase - organelles and cytoplasm duplicated
S phase - chromosomes are duplicated
G2 phase - checks duplicated chromosomes for mistakes continues to grow
M phase - mitotic/ division phase
3 stages of interphase and what happens in each
G1 - organelles etc.. replicated and cell grows
S - chromosomes are duplicated
G2 - increase in size, centrosomes duplicate
list the two stages of the mitotic phase + what happens in each
mitosis - nuclear division
cytokinesis - cellular division
outline the role of checkpoints in the cell
ensure each division is successful in producing two genetically identical daughter cells - monitor each stage to ensure is completed before allowing to move onto the next stage
3 examples of checkpoints
G1 checkpoint - at end of G1 checks cell size, growth factors, nutrients and DNA damage
G2 checkpoint - at end of G2 cell size DNA replication and DNA damage
spindle assembly check point - at end o metaphase chromosome attached to spindles
link between cell cycle regulation and cancer
cancer is uncontrolled cell division - happens when proteins that regulate cell cycle at checkpoints don’t function properly and so division is uncontrolled - tumors form
define mitosis
nuclear division stage of mitotic phase - results in two daughter cells with same number and kind of chromosomes as parent cell
define chromosomes
structure of condensed and coiled DNA in form of chromatin
become visible under light microscope when cell is preparing to divide
define sister chromatid
two identical copies of DNA joined at the centromere
define chromatid
each of the two thread like strands which chromosomes divide into during mitosis
define centromere
region where two chromatids are held together
define centrioles
part of the cytoskeleton composed of microtubules
define spindle fibres
network of filaments which are involved in the division of the chromosomes in nuclear division
define homologous pair
matching pair of chromosomes one inherited from each parent
how is DNA packaged in a chromosome
double stranded DNA loops around histones forming the nucleosome the nucleosome can be packaged to form chromatin fibres which condense into chromosomes during mitosis
list the stages of mitosis in order
prophase
metaphase
anaphase
telophase
explain the role of centrioles and spindle fibres in mitosis
spindle fibres formed from centrioles - they attach to sister chromatids and are responsible for separating them and pulling them towards opposite poles
compare the process of cytokinesis in animals and plants
animals - cleavage furrow forms, cytoskeleton pulls membrane in until its enough to fuse to form two separate cells
plants - vesicles from the Golgi line up along middle of cell forming new membranes. New sections of cell wall then form around membrane
explain the purpose of cell division + roles of mitotic division
purpose - to create more identical cells
roles - growth, repair, replace, asexual reproduction
define diploid
a cell with 2n chromosomes (2 copies of each chromosome one from each parent)
define haploid
a cell with n chromosomes (one copy of each chromosome)
define gamete
a haploid germ cell - fuse at fertilization to produce a zygote
define zygote
cell resulting from fusion of haploid egg cell with haploid sperm cell