CP BIO - Ch. 10 Cell Growth and Division
. Mitosis and Asexual Reproduction (p. 272)
· Smaller cells are more efficient - exchange with environment (surface area/volume ratio)
· For growth à increase # of cells
· For repair à replace old, damaged, or dying cells.
· For regeneration à regrow a lost body part
· For ASEXUAL REPRODUCTION p. 277
o One parent à two new organisms
o Offspring are genetically identical to parent
Prokaryotes divide by binary fission.
Eukaryotic cells have a nucleus
- must organize chromosomes before cell divides
- both daughter cells need exact copies of all DNA
Cells that divide often: Cells that never or
rarely divide
1. Skin
2. Digestive lining 1. nerves
3. Bone marrow 2. muscles
(blood stem cells) 3. cartilage
4. Embryo
5. Simple organisms
In plants: buds, stems, roots In plants: xylem; phloem
- meristem and cambium tissue
10.2 The process of Cell Division p. 279
CHROMOSOMES - made of DNA, (genes) and proteins
When a cell is NOT dividing, DNA is in CHROMATIN form
~ thread-like strands inside nucleus
~ DNA coils around histone proteins
~ these wrap and coil to form chromatin
~ organizes DNA
~ helps it fit into nucleus.
12.3 DNA REPLICATION p. 350
DNA replicates before cell can divide
- DNA molecule unzips
- “old” strands – templates for new
- nucleotides assemble according to base-pairing rule
- polymerase enzyme bonds nucleotides in a chain
- hydrogen bonds hold chains together
à two identical molecules
- one for each new cell
10.2 DNA PACKING (CONDENSING) p. 280
Before a cell divides, it packs its DNA into CHROMOSOME form
- ALREADY COPIED (replicated)
- tightly packed and condensed
- keeps copies organized and intact until cell splits
10.2 Cell Cycle p. 281
INTERPHASE – non-dividing cells, most of a cell’s life
- normal function
MITOTIC (M) PHASE – cell divides, two new cells form
G-1 à growth, normal life functions
S à “synthesis” – DNA replicates (makes identical copy)
G-2 à final growth, prepare to divide
MITOSIS - chromosomes condense, organize and divide
CYTOKINESIS – cytoplasm divides
PHASES OF MITOSIS p. 282
PROPHASE - cell prepares and organizes chromosomes
· chromatin coils/packs into chromosomes
· nuclear membrane & nucleolus disappear
· spindle fibers begin; asters form
· centrioles move apart
LATE PROPHASE – chromosomes condensed
· chromosomes move toward middle of cell
· centrioles move toward opposite poles
· spindle fibers extend from centrioles
METAPHASE - ready to divide
· chromosomes align in middle of cell
· centromeres attach to spindle fibers
ANAPHASE -doubled chromosomes separate
· spindle fibers pull chromatids apart
· single copies of chromosomes move
to opposite poles of cell
TELOPHASE - return to normal organization
· chromosomes relax/uncoil into chromatin
· nuclear membranes form; nucleoli appear
· spindle fibers disappear
· two identical daughter cells form
CYTOKINESIS (division of cytoplasm) begins
CELL DIVISION DIFFERS IN PLANTS p. 284
Spindle, but NO centrioles
Cell plate forms, then new walls
REGULATING THE CELL CYCLE p. 286
Cell Cycle Controls
Protein messengers – cyclins, growth factors
Contact with neighboring cells
Programmed cell death – “apoptosis”
CANCER – Uncontrolled cell division P. 289
Cell cycle controls fail
Cells stop functioning
Repeated and rapid cell division
tumor – mass of non-functioning cells
a. benign – not cancerous
b. malignant – cancerous
c. metastatic – spreads to other body parts
à new tumors
CELL DIFFERENTIATION p. 293
Stem cell = unspecialized cell
- can differentiate to form many kinds of cells
- depends on chemical
- signals to cell from Surrounding cells
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