D2.1 Mitosis

All organisms need to produce new cells for

growth maintenance and reproduction

cell divition

A parent cell will divide to produce daughter cells

prokaryotes through

binary fission

eukaryotes through

mitosis - create somatic cells

meiosis - create gamates

cytokinesis

division of cytoplasm

cytokinesis in animals cells

Actin and myosin proteins form a contractile ring

Pinches the cell membrane together

Forms a cleavage furrow

Deepens and split the cytoplasm in two

cytokinesis in plant cells

Vesicles containing cell wall materials fuse to form a cell plate

Cell plate grows outwards until it reaches the existing cell wall

Fuses with existing cell wall to split the parent cell into two daughter cells

vesicle

phospholipid bilayer vacuole - use to transport substances

cellulose stored inside

division of cytoplasm is usually

equal

both daughter cells must what for cytokinesis

receive a mitochondrion and any other organelle that can only be made by dividing a pre-existing structure

unequal cytokinesis example

budding in yeast and oogenesis in humans

budding in yeast

Reproduce asexually through budding

Nucleus divides by mitosis

Small outgrowth (bud) on mother cell is formed

Receives one of the nuclei but only a small share of cytoplasm

Dividing wall constructed separating the two cells leaving a budding scar

Oogenesis in humans

Process of producing mature egg cells in humans

Begins with two divisions of a mother cell

First division produces one large cell with nearly all the cytoplasm and a small polar body

Large cell goes on to carry out the second division - unequal division again to form one large cell and one small polar body which does not develop further

what must occur before mitosis or meiosis

dna repllication

when does dna replication occur

interphase

After replication, each chromosome consists of

two genetically identical sister chromotids held tgt by a centromere

before nucelar division what happens

chromatin supercoils into condensed sturcture to enable efficient seperation of dna

chromatin

loosely packe dna with histones

four phases of mitosis

prophase metaphase anaphase telophase

prophase

chromatin condenses into chromosome and become shorter and fatter

nuclear membrane breaks down

Spindle fibers form from each pole of cell

metaphase

chromosomes align on equator

spindle fibres continue to grow and attach to centromeres

anaphase

each centromere divides

spindle fibre shorten and pull sister chromatids apart

telophase

chromotids reach poles (now chromosomes)

spindle fibres disintegrate

chromosomes uncoil and decondense

nuclear membrane strats form around them

cell elongates and prepares for cytokinesis

mitosis are diploid or haploid

diploid

interphase

prepration stage before mitosis

containing g1 s g2

- G1 Phase:

obtain more nutrients—increase cytoplasm volume increase in cell size

s phrase

dna replication/synthesis

g2 phase

double the amount of organelle and protein synthesis

increase transcription and translation as well (cell size also increases).

any translation or transcription during mitosis?

no because dna supercoil

mutagens

biological mutagens - viruses

chemical - cigarettes

physical - UV light

Protooncogenes

regulates the cell cycle - if mutagen - cause this gene to mutate - becomes oncogenes - leading to uncontrolled division

primary tumor

- Oncogenes / mutagen / Tumor suppressor gene

Secondary tumor -

migration of cancer cells (metastasis)

when transcription and translation occur

g2