Cell cycle & division

Importance of cell division

continuity of life - pass genetics on

mitosis

asexual reproduction

meiosis

sexual reproduction

mitosis phases

G1/g0 s, G2, m

G1

DNA checking

new organelles

G0

non-dividing can be temporary/ permanent

S

chromosomes & centrosomes duplicate

Cohesins

Holds sister chromatids together - form ring-like structure

G2 phase

confirmss no. chromosomes and orgaelles present

mitosis

division of sister chromatids, nucleus & cytoplasm

prophase

chromosomes replicated in S phase condense

mitotic spindle assemble between 2 centrosomes

prometaphase

chromosomes attach to spindlle microtubules via kinetochores

undergo active movement

metaphase

chromosomes aligned at equator of spindle

kinetochore microtubules attach sister chromatids to opposite poles

mitotic spindles

kinetechore on the centromere binded to microtubules

microtubule-based bipolar structure that segregates the chromosomes in mitosis

anaphase

Sister chromatids synchronously separate to form two daughter chromosomes

Telophase

Two sets of daughter chromosomes arrive at the spindle poles and decondense

cytokinesis

late anaphase

Contractile ring of actin and myosin filaments pinches the cell in two

2 cells created with 1 nucleus and 3 decondensed chromosomes

Cytokinesis in plants

cell plate formed by vesicles fusing together

embryonic frog cells

large cells - easy to inject test samples

rapid cell divisions

S & M phase

Binary fission

cell elongates

septum begins to form

septum completes & distinct walls form

cells separate

Budding yeast

G1, S, M

Yeast mutants

Haploid

easy to manipulate

discover cdc genes

role of chemical signals in cell cycle regulation

cell fusion experiments: fuse S phase & G1 phase