Genetics

Mitosis

Cell Theory Principle

“Where a cell exists, there must have been a preexisting cell”

“Omnis cellula e cellula” (all cells come from cells)

Necessary Characteristic of Life: Cell Reproduction unicellular organism

reproduces entire organism

multicellular growth embryonic development replacement of damaged or dead cells

Binary FissionReproduction in Bacteria genome (hereditary endowment)

single, circular dsDNA associated with proteins single chromosome

replication averages minutes-3 hours

Steps of Binary Fission chromosome replication begins, one

copy of the origin moves rapidly tothe other end

one copy of the origin is now at eachend of the cell; the cell elongates

replication finishes, the plasmamembrane grows inward and anew cell wall is formed

resulting in two daughter cells

Eukaryotes vs. Prokaryotes larger cell size smaller cell sizegreater quantity of DNA lesser

quantity of DNAHistones other proteinsseveral chromosomes one chromosome

DNA Quantity in Eukaryotes Amount of DNA has no direct relationship to

the complexity of that organism ex.

Alligators have more DNA than humans frogs have more DNA than humans

DNA of Eukaryotes

Chromosomes discrete entities condensed DNA + protein state found when DNA division occurs

Chromatin mass of DNA loose coils of DNA + protein state found when DNA replication occurs

Drawing of a Chromosome

short arms

long arms

centromere

sister chromatids

www.biologycorner.com

sister chromatids

kinetochore (protein)

Eukaryotic Chromosome

composition DNA = 40% protein = 60%

average human chromosome 5 cm (2.5cm = 1 in)

46 chromosomes in each cell 2 meters of DNA 6 Billion base pairs

Karyotype

particular array of chromosomes chromosomes of one cell are arranged

according to: size number type information

extra or missing DNA gender of individual

www.biotechnologyonline.gov.au/images/contentpages/karyotype.jpg

Human Cells

somatic cells = body cells 46 chromosomes diploid (2n)

gametes = sex cells (sperm, ova) 23 chromosomes haploid number (1n or n)

Homologous Chromosomes

pair of chromosomes one paternal, one maternal

Sister Chromatids

identical replicated forms of one chromosome held together by one centromere

Chromosomes

Homologous (2) maternal, paternal

Replicated (2) 4 sister chromatids

http://www.phschool.com/science/biology_place/labbench/lab3/images/homologs.gif

Autosome vs. Sex Chromosome autosomal chromosomes

22 pairs

sex chromosomes 1 pair, XX or XY

Cell Cycle

Interphase G1 phase S G2 phase

M (mitotic) phase mitosis (P, M, A, T) cytokinesis

Interphase

Preparing a cell for division

G1 phase (first gap) growth of cell, enough cytosol for 2

S (synthesis) DNA replication, DNA in chromatin

G2 phase (second gap) chromosome condensation microtubule synthesis

M Phase

Mitosis (karyokinesis) - divide DNA, precise division prophase (prometaphase) metaphase anaphase telophase

Cytokinesis - divide the cytoplasm, rough division

MitosisProphase-Prometaphase Prophase

DNA condenses nucleoli disappear sister chromatids

visible spindle is forming centrosomes migrate

Prometaphase nuclear envelope disappear centromeres are at poles condensation increases kinetochore present microtubules attach to kinetochore

Metaphase

centrosomes conveneat the equator (plate)

kinetochores have bothmicrotubules from the opposite poles attachedto each one

Anaphase

proteins maintaining thechromosomes attachedsplit

daughter chromosomes move to the poles

cell elongates

Telophase

2 daughter nuclei form nuclear envelopes form nucleoli reappear chromosomes become

less condense END of Mitosis

Animals Plants

Cytokinesis(division of cytoplasm)

cleavage furrow cell plate

microfilaments form contractile ring and cell pinches in two

vesicles form plasma membrane, cell wall material is deposited

Cell Cycle Duration

varies from 1-24 hours example human liver cell

Interphase: G1 phase…………......9 hrs. S…………………..…10 hrs. G2 phase……..………2 hrs

M phase: mitosis……50 min. Cytokinesis……….....10 min

Controls of Cell Division Cells in tissue culture do not divide if 1. essential nutrients are missing (growth factors)

2. poisons that inhibit protein (microtubules) synthesis are present

3. cells are crowded

4. they cannot progress beyond the restriction point in late G1

5. insufficient concentration of MPF (maturation promoting factor, a complex of proteins)

6. they have reached maximum division (20-50x for cells in culture)

Tumor

mass of transformed cells benign tumor

cells remain at original site lump can be completely removed

malignant tumor invasive cells can impair functions of other organs

Cancer Cells

express abnormal cell division 1. density-dependent inhibition is

absent 2. divide excessively, immortal

HeLa cells 1951 3. can invade other tissues

(metastasis) 4. genetically transformed 5. can form malignant tumors 6. can stop dividing at random

points in the cycle

cancer cells

normal cells

ACTIVITIES

A

B

C

D

E

what organism isthis tissue from?

name the stages A-E

which of these is notan M stage?

where in the plant youfind this tissue?

what is "F"?

F

name the stage

what stage comes before and after it?

if this is a somaticcell and n=10, how many chromosomeswill it have?

name the stage

is it part of mitosis?

give a visible characteristic.

describe what happens during

this stage

The End