cell division (general) Flashcards
purpose of checkpoints?
- ensure that cell is developing at the right pace (not too fast + not too slow)
- make sure each phase has been completely and thoroughly
- make sure the DNA within the cell is not mutated - cell will stop division process if mutation is found.
how do checkpoints regulate the cell cycle?
they don’t allow the cell to move past that phase if it hasn’t been completed correctly/if it finds a mistake.
G1 checkpoint
- cell will determine if it is ready to divide chromosomes, checks for mistakes in DNA (don’t make more of mutated DNA)
- analyze cell size, nutrients, etc.
G2 checkpoint
- proper chromosome replication in S phase?
- will not send mutated DNA into division process (mitosis)
M checkpoint
- did all chromosomes line up in the middle (metaphase)
- are spindle fibers ready to attach
next step: finish mitosis + start cytokinesis
purpose of mitosis?
- growth, repair, + asexual reproduction
purpose of meiosis?
- genetic variety, sexual reproduction
ways to create genetic variation
- crossing over: homologous chromosomes swap parts, can happen multiple times, prophase I.
- random alignment/independent assortment: order in which the homologous chromosomes line up in metaphase I.
- random fertilization: females produce 100s of eggs in a lifetime, males produce billions of sperm, all eggs and sperm are non-identical to each other.
how many cells are at the beginning of mitosis?
1 (2n; diploid)
how many cells are at the beginning of meiosis?
1( 2n; diploid)
how many cells are at the end of mitosis?
2 (2n; diploid)
how many cells are at the end of meiosis?
4 (n; haploid)
type of cell created by mitosis?
somatic/body
type of cell created by meiosis?
gamete (sex cell)
how many phases in mitosis?
PMAT - 4
how many phases in meiosis?
PMAT I + PMAT II - 8
which process changes next generation’s genes?
meiosis
which process includes crossing over + where
meiosis - prophase I
which process occurs in skin cells?
mitosis
which process occurs in ovum cells?
meiosis
which process uses homologous chromosomes?
meiosis (I)
which process has sister chromatids?
both - mitosis + meiosis (II)
what is cancer?
unregulated cell growth - mutated DNA, forms into a tumor. starts to kill healthy cells.
germine mutations
hereditary mutations - on gametes (inherited)
somatic mutations
mutations within body cells - non-inherited, developed within a lifetime
cyclins
type of protein that control the cell cycle by binding with other molecules such as CDK (cyclin dependent kinases - enzymes)
MPF
maturation promoting factor - cyclin + CDK complex moves a cell into cell division
what send cell signals?
enough cyclin-CDK complexes triggers movement into next phase (kind of like measurement for drug-store pregnancy test)
tumor-suppressor gene
- inhibits cell divison/mitosis
- slows down the cell cycle
- causes cancer when inactivated (cannot suppress tumors -> uncontrolled growth)
- p53 gene + retinoblastoma gene
proto-oncogenes
- codes for proteins that stimulate cell division, hinder cell differentiation, + stop cell death
- speeds up cell division/mitosis
- prominent in embryonic development (growing a child in 9 months - speedy mitosis)
oncogenes
mutated version of proto-oncogene that codes for increased protein creation
causes cancer - targeted by anti-cancer drugs
CAR-T cell therapy
genetically modifies T-Cells to fight the specific form of cancer found in the patient’s body. This makes the T-cells more efficient - great results recently but the initial spike (body’s response to rapid elimination of cancer cells) can cause complications.
benign
non-life threatening, capsulated
malignant
aggressive, non-capsulated, fast spreading
angeogenesis
blood supply to tumor, getting bigger from nutrition.
other cancer treatment
kills cancer cells, but healthy cells too.
chemotherapy, radiation, etc.
