MULTICELLULAR CELLS

CELL DIVISION

Test: Thursday Jan. 13th

Cell division, mitosis, meiosis

Multicellular Cells

Many celled organisms

Cells are specialized to perform particular functions (can begin as stem cells)

Cells tissue organs organ system

What is the same in all of these cells??DNA!!

CELL DIVISION

Causes: DNA Overload Repair Growth Surface area to volume ratio gets

too large

Cell Cycle (pg. 245)

1) Interphase2) Mitosis3) Cytokenesis

The Cell Cycle

Interphase

Cell spends about 90% of its time in interphase

GROWTH STAGES: G1 = normal growth S = DNA doubles (where mutations can

occur) G2 = organelles double

Cell contains large nucleus with visible nucleolus

Nuclear division (pgs. 246-248)

Mitosis

Phases of Mitosis…Prophase

Chromosomes become visible

Phases of Mitosis…Metaphase

Chromosomes line up

Phases of Mitosis…Anaphase

Chromosomes separate

Phases of Mitosis…Telophase

Two new identical cells form

PLANT vs.

cell plate forms

ANIMAL cleavage furrow forms

Cytokinesis-cytoplasmic division

Plant Animal

Fig. 12.9

Mitosis Video

http://www.sumanasinc.com/webcontent/animations/content/meiosis.html

Cancer

Uncontrolled cell growth

Read stem cell article on

page 293

N= haploid # of chromosomes found in egg or sperm (gametes) Humans n=23

2N

2N

2NDiploid(2N)

=regular chromo# found in body cells (somatic)

two identical daughter cellsMitosis only occurs in somatic

cells