Mitotic Cell Cycle Flashcards
describe the structure of chromosomes (5)
two identical structures = chromatids held by centromere one chromatid contains one DNA molecule ends have telomeres made of chromatin
describe the structure of chromatin
made of DNA and proteins
DNA coiled tightly
euchromatin (loose)
heterochromatin (tightly)
how can chromatin be stained
when its tightly coiled
when are chromosomes in their most condensed state
metaphase
definition of mitosis
nuclear division that produces two genetically identical daughter nuclei, each containing the same number of chromosomes from parent cell
stages in interphase
G1 –> S phase –> G2
process in G1 phase
preparation for the cell (making RNA, enzymes and proteins) - decision to mitosis
process in S phase
synthesis of DNA by semi-conservative replication
assembly of nucleotides
old strand acts as template
complementary base pairing
process in G2 phase
sharp increase in tubulin for spindle fibres and cell continues to grow
stages in mitosis
PMAT
stages in early prophase (2)
chromosomes become shorter and thicker
centrosomes replicate
stages in late prophase (4)
formation of chromatids
nuclear envelope breaks down
nucleolus disappears
mitotic spindle extend to opposite poles
stages in metaphase (2)
chromosomes line up
chromatids attach to the spindle fibres
stages in anaphase (2)
spindle fibres attached to kinetochore on centromere
spindle fibres shorten and pull apart chromatids to opposite poles
stages in telophase (4)
spindle fibres break down
nuclear envelope reforms
nucleolus in each cell reforming
chromatids uncoil
stages in cytokinesis
division of cytoplasm
reproducing structures
(cell wall for plants)
significance of mitosis (4)
growth, repair tissues, asexual reproduction in eukaroytes, immune response
why it is important mitosis results in identical cells (3)
need the same number of chromosomes
produces genetic stability in cells
produce genetically identical cells
describe telomeres
structures made of DNA and short repeated base sequences to seal ends of chromosomes
purpose of telomeres
allows replication of entire strand
prevent loss of genes
what happens to cell cycle when telomeres cannot replicate
stay in G1 phase
describe stem cell
cell that can divide unlimited number of times and can turn into specialised cell
definition of potency
ability to produce any type of cell
describe totipotent cell
total potency (zygote)
describe pluripotent cell
cell can only turn to three germ layers in embryo (embryonic stem cell)
describe multipotent cell
cell can turn into some cells only (blood cell) found in bone marrow
describe cancer
uncontrolled cell division
describe process of cancer (7)
carcinogen causes mutation oncogene transformed by carcinogen rapid mitosis uncontrolled cell division tumour formed blood vessels supply
what is metatasis
tumour breaks off from origin and spread to other sites
benign tumour
isn’t cancerous
