“All cells arise from preexisting cells” (Virchow)

2 Types of ReproductionAsexual

1 parentNo fusion of nucleiOffspring are

identical to parent & to each other

No special organs/cells

Process that divides cells = mitosis In one-celled

organisms = new organism

In multi-cellular organisms = growth & repair

Sexual2 parentsFusion of sperm &

egg nucleiOffspring have a

combination of traits from both parents

Requires special organs (gonads) & cells (gametes)

Process that creates new cells = meiosisProduces sperm &

eggs

Mitotic Cell Division Occurs in body cells, also called ________

cellsInvolves nuclear division, also known as

__________Involves cytoplasmic division also known

as ___________Results in ____ daughter cells __________ to

the parent AND each other

somatic mitosis

cytokinesis

2 identical

Terms Associated with MitosisChromosomes: rod-like structures in

nucleus that contain hereditary information (DNA) & appear as long, thin threads called chromatin (at rest)

Diploid #: (2n) “having 2 sets of chromosomes” (body cells) Refers to total # found in somatic cells nucleus In humans, 2n = 46

Homologous chromosomes: the diploid # of chromosomes can be paired according to size. These pairs are called homologous. Each chromosome (homolog) of the pair

controls the same set of traits

Terms cont. Monoploid #: (n) AKA haploid

Having only one chromosome from each homologous pair

Sex cells are monoploid Double-stranded vs. single-stranded:

after mitosis, in order for the daughter cells to be identical to the parent in chromosome #, during the non-dividing period (interphase), each single-stranded chromosome makes an exact copy of itself, stays attached to the original, becoming a double stranded chromosome (this is NOT the same as being 1 member of a homologous pair)

The Cell Cycle and MitosisThe Cell Cycle: a series of events that

cells go through as they divide

Laser clip

InterphaseAn “in between” period of growth

Occurs right before mitosisDivided into 3 phases

G1 (growth/pre-synthesis): (10+ hrs.) the cell ↑ in size & makes new proteins & organelles (centriole, spindle, aster)

S (replication/synthesis): (9 hrs) chromosomes are replicated

G2 (post-synthesis): (4 hrs) many organelles needed for cell division are produced (centrioles, spindles, aster)

Then, mitosis (cell division) occurs with 4 remaining phases:

ProphaseChromatids coil &

thickenNuclear membrane &

nucleolus disintegrate Centrioles move

toward polesAsters & spindles

form

MetaphaseMeta = middleChromatids line up

in middle on “equator”

Spindle fibers attach to centromeres

Anaphase“Away”Double chromatids are

split into singlesSpindle fibers shorten

& pull chromosomes towards poles

TelophaseTwo new cells form

by “furrowing” (pinching in AKA cytokinesis)

Chromosomes uncoil back to chromatin

Each new cell is now in interphase

New nuclear membranes form

Results of Mitosis: 2 identical cells/ no varietyMitosis Maintains Chromosome #

http://www.cellsalive.com/mitosis.htm

Comparison of Plant & Animal Cell Mitosis

Animal Plant

Centrioles? Yes No

Division of the Cell

cytokinesis Cell plate formed/no furrowing

Uncontrolled division of abnormal cells = ______________

Uncontrolled division of normal cells = ________________

cancer

tumor

Aging: the process of getting olderMitosis in some cells slows down or stops Why?

Telomeres: “caps” of DNA found on the end of each chromosomeKeeps the chromosome intact; functions like

the plastic cap on the ends of shoelacesEach time a cell divides, telomeres get

shortened, thus the cell ages (b/c a cell cannot divide anymore after telomeres are gone)

Usually @ 50-70 divisions for a cell

Telomerase: enzyme that re-lengthens telomeresPresent in high concentrations in embryonic

stem cells, gametes (egg/sperm) & cancer cells

Aging video..\biomovies\aging.mov

Types of Asexual Reproduction link #2

Type Characteristics

Representative Organisms

1. Binary Fission

Production of 2 new organisms with equal division of cytoplasm

Ex. Paramecium

Type Characteristics Representative Organisms

2. Budding The production of 2 new organisms w/ an unequal division of

cytoplasm In coral, sometimes the bud stays w/ the parent & forms colonies (coral reefs)

Ex. Yeast

Ex. hydra

3. Sporulation

When spores are released from the parent & can develop into new organisms

Ex. Mold

Type Characteristics

Representative Organisms

4. Regeneration

The development of an entire organism from a part of the original organism OR the replacement of lost structures

An entire new starfish from 1 ray of the parent

Ex. Lobster claws, lizard tails

Spiny Brittlestar

Regenerating arm

Type Characteristics Representative Organisms

5. Vegetative Propagation

The process by which plants develop from roots, stems or leaves of the parent plant (asexually)

See below

a. Artificial propagation

1. cuttings: “cutting” from a

plant that develops into a new plant

2. grafting:Taking a scion from a desirable tree & attaching it to a stock of another rooted tree

Type Characteristics Representative Organisms

b. Natural propagation

1. Bulbs Short underground

stem that grows a new plant

Ex. Onion,tulip

2. TubersGrowing new plants from pieces of old plant Contains stored food Buds/eyes develop into new plant

Ex. Potato

3. Runners When a plant sends a “runner” out which puts down roots & grows into another plant(s).

Ex. Strawberry, pumpkin, squash