Biology: Mitosis (copy)

binary fission

prokaryotic reproduction
divides in half, making an exact clone

cell cycle

interphase, mitosis, cytokinesis

chromatid

one half of a duplicated chromosome
a copy of a DNA molecule produced by replication

how DNA replicates

the chromosome splits into 2 identical strands of DNA called sister chromatids, connected at the centromere

how many chromosomes per human cell

46

G2

prep for mitosis, during interphase

mitotic phase

stage when the cell is actively dividing: mitosis and cytokinesis

why do cell replicate?

multicellular organisms: replace lost cells and grow
single celled: reproduction

mitosis

division of somatic (body) cells, specifically - division of the nucleus

interphase

first and longest stage of the cell cycle
Three parts: G1, S phase, and G2

G1

growing and normal life processes

S phase

DNA is copied

chromosome

a threadlike structure that carries DNA before replication: a single chromatid after replication it has 2 chromatids connected by a centromere

chromatin

'thread' that makes up chromosomes
made up of protein, RNA, and DNA
chromatin spins into rods, making chromosomes, during prophase

Four stages of Mitosis

prophase, metaphase, anaphase, telophase (PMAT)

prophase

longest phase in mitosis
chromatin (threads) is packaged into chromosomes (rods) to make them easier to move
(in animal cells) centrioles move to opposite ends of the cell + spindle fibers form between poles
nuclear membrane disappears

metaphase

chromosomes line up in the middle of the cell, spindle fibers attached to centromeres of chromosomes

anaphase

Chromatids separate and begin to move to the opposite ends/poles of the cell.

telophase

chromatids reach the the poles
nuclear membrane starts to reform

mitosis ends

mitotic spindle

The spindle fibers that control the chromosomes in mitosis

cytokinesis

splits the cell in two --splitting of the cytoplasm
pinches the cell in half
each new cell has nucleus w/ identical chromosomes

cleavage furrow

in animal cells; where cell membrane pinches to split the cell in two

cell plate

plant cells have cell wall -- can't pinch in
a midline dividing the cell that eventually becomes the cell wall
divides the cells during cytokinesis

Acronym for cell cycle

IPMATC
Intergalactic penguins might attack, take care
Interphase, (prophase, metaphase, anaphase, telophase), cytokinesis

cancer

Cells skip checkpoints and divide uncontrollably, creating tumors

Cell Cycle Control System

checkpoints where the cell cycle stops until a go-ahead signal is received

G1 Checkpoint

most important checkpoint, checks for growth
if signal received, will usually divide completley
if signal not received, will exit cycle and enter G0 phase

G0 phase

nondividing state in which a cell has left the cell cycle

Signals in the cell cycle

Growth factors
Density-dependent inhibition
Anchorage dependence

Tumor

mass of rapidly dividing (cancerous) cells that can damage surrounding tissue

Benign Tumor

a mass of abnormal cells that remains at the site of origin

Malignant Tumor

A cancerous tumor that is invasive enough to impair the functions of one or more organs (Metastasis)

metastasis

The spread of cancer cells beyond their original site
usually through blood stream
most dangerous property of cancerous cells

possible causes of cancer-causing mutations

smoking, drugs, alcohol
uv radiation, x rays, radon gas
certain chemicals (ex. asbestos) or viruses (HIV)
certain hormones (excess estrogen)
bad diet, no exercise, genetics, age, random chance

Common cancer treatments

surgery, radiation, chemotherapy

Chemotherapy drugs

Taxol - freezes the mitotic spindle after it forms thus stopping mitosis at metaphase
Vinblastin- prevents the mitotic spindle from forming

Sister chromatids

a chromosome consists of 2 identical strands of DN called sister chromatids
- each chromatid is a copy
of a DNA molecule
produced by replication
- the chromatids are held
together at the centromere

cell division

- Single-celled organisms use cell division for asexual reproduction
- types: meiosis and miosis