bio111 mitosis/meiosis

Mitosis

“identical twins (cells)”

• separates sister chromatids

• every cell is diploid

• happens with many cells

what does meiosis produce

haploid gametes

• halves cell chromosome number

• fuse during ferilization → zygote

Meiosis I

separate HOMOLOGOUS chromosomes

• haploids (one copy of each chromosome)

• only happens in gametes (egg/sperm)

Meiosis II

separates sister chromatids after homologous chromosomes split

sister chromatids

• identical copy of CHROMOSOMES

telomere

• tip of chromosome

• becomes shorter every time chromosome is replicated

what happpes when telomere too short

dies by apoptosis

telomerase

enzyme extends telomeres (cancer cells)

Interphase (mitosis)

• cell prepping to divide

• 95% of cell life

G1

• cell grows

• little visible damage to cell

• saves up energy

S (synthesis)

• DNA replicates

  • 2 copies each chromosome

• lots of energy

G0

• cell resting phase

• no growth

• ex: neurons spend whole lives in G0

G2

• cell grows more to prep for mitosis

• acquires all nutrients/energy

prophase (mitosis)

• nucleus membrane broken down → chromosome access

• sister chromatids attach to spindles

metaphase

• middle

• chromosomes aligned in middle plane

• sis chromatids lined up in center

anaphase

• split ApArt

• sis chromatids separated → 1 full set each side

telophase

• two cells

• chromosomes pulled apart

• splindle fibers break down

• build up nucleus

cytokinesis

• cell movement

• separate cytoplasm of 2 daughter cells

what do cell checkpoints do

• regulate speed of cell cycle

• prevents issue cells from dividing

• ensure cell is ready for division

G1 checkpoint

• adequate cell size and energy

• DNA damage

G2 checkpoint

• size and protein reserves

• complete chromosome replication

• DNA damage

M checkpoint

ensures chromatids are ready for division

interphase (meiosis)

double DNA to produce sis chromatids

spermatogenesis

produce 4 functional sperm cells

• genetically distinct haploids

• occurs when puberty

oogenesis

produce one functional egg cell (even tho 4 gametes)

• begins hwen female is fetus

characteristics of cancer cells

• odd shape (large nuclei, dark stain)

• unlimited cell division (telomerase)

• less specialization (malignant tumors spread to other tissues, no specific func)

• change to blood flow (angiogenisis)

• invade surrounding tissues

• move to other body parts

angiogenesis

• create new blood vessels to feed a tumor

  • gets more O2 and grows

metastasis

• spread cancer cells thru circulatory or lymphatic system

• invade more tissues