Download Ch. 9.1: Cell Reproduction

Ch. 9.1: Cell Reproduction
Objectives:
1. Describe how cell reproduction contributes to repair
and to growth.
2. Contrast asexual and sexual reproduction.
Vocab.: asexual reproduction; sexual reproduction
Why do cells need to reproduce?
1. Repair and replacement of dead or
damaged cells.
2. Growth = increase in size
Asexual Reproduction
 Single cell duplicates its genetic material and
then splits into 2 genetically identical cells.
 1 parent
 Parent & offspring are identical
 Most single celled organisms
 Many multicellular have option (plants, marine
organisms)
Sexual Reproduction
 Genetic material from
2 parent combines.
 Offspring genetically
different fr. parents
 Involve sperm & egg
 Meiosis involved
Ch. 9.2: The Cell Cycle
Objectives:
1. Describe the structure of a chromosome.
2. Name the stages of the cell cycle and explain
what happens during each stage.
Vocab.: chromatin, chromosome, sister chromatid,
centromere, cell cycle, interphase, mitotic phase,
mitosis, cytokinesis
9.2: Cell Cycle
9.2: Chromosomes & Cell Division
Chromatin = long fibers of
DNA + proteins
Chromatin --> Chromosomes
before cell divides
Chromosomes: Condensed
threads of genetic material
formed fr. Chromatin as a
cell prepares to divide.
Humans: 46 chromosomes
(23 pair)
9.2: Chromosomes & Cell Division
Sister Chromatids: 1 pair of
identitical chromosomes
created before a cell divides.
Centromeres: Where 2 sister
chromatids are joined.
9.2: Cell Cycle
Interphase:
When cell is not
dividing.
Carrying out
metabolic fxns,
grow, etc.
~ 90% of cell life
S: DNA
duplicated
9.2: Mitosis
Mitosis
Stage of the Cell
cycle where cell
is DIVIDING.
(M phase)
Mitosis: Nucleus
& duplicated
chromosomes
divide.
Cytokinesis:
Cytoplasm
divides into 2.
Ch. 9.3: Mitosis
• Division of somatic cells (body)
Daughter Cells
Somatic Cell
Chromosomes
• Strands of DNA
• Each human has 23 pair (diploid or 2n)
– One from your mother
– One from your father
Chromosome
DNA molecule with attached proteins
Sister chromatids
Look at figure 8.2
One from Mom
One from Dad
Mitosis
• First you duplicate DNA
• Why?
– You have 2 pairs of 23
chromosomes
– If cell splits, you will only
have 1 pair
– Duplicate DNA, cell splits,
still have 2 pair
Sex chromosomes- X and Y: XX is female in humans, XY is male
Interphase
• Prior & After Mitosis
• G1 period
– 90% of cell life spent here
– Cell goes about it’s business
• S period
– DNA is duplicated
• G2 period
– Cell prepares to divide
• Cannot see DNA- uncoiled as chromatin
1. Prophase
• DNA becomes visible
as chromosomes
• Nuclear membrane
dissolves
• Centrioles migrate to
opposite poles
• Spindle fibers form
Easy to remember- Prophase- proceeding into mitosis
2. Metaphase
Pole
• Spindle fibers attach to
centromeres
• Chromosomes line up
at midline of the cell
Spindle Equator
Pole
Easy to remember- metaphase, DNA at middle
3. Anaphase
• Spindle fibers pull
apart centromeres
• One chromatid goes to
each centriole (they
look like V’s)
Easy to remember- anaphase, apart they go
4. Telophase
• Chromatids reach
centrioles
• Mitosis ends when new
nuclear membranes form
• Some evidence of cell
dividing
Easy to remember- telophase, terminal phase
Last part- Cytoplasmic division
• Technically not in mitosis
– Animal cell- pinching of cell
membrane- cleavage
– Plant cell- formation of new cell
wall- cell plate
– DNA becomes non-visible,
back to chromatin
• Daughter cells enter G1
period of interphase
Cancer
• Uncontrollable mitosis (no G1)
– Cells cease to do what they are supposed to be
doing in favor of dividing.
•
•
•
•
Pancreatic cancer- no longer in interphase
Cease production of insulin
Incomplete digestion of food
Diabetes, abdominal pain, weight loss
• Cancer does not “poison” your body…
Henrietta Lacks
• 1951, a poor 31 Year old African
American mother of 4 was dying
of cervical cancer @ Johns
Hopkins Hospital
– Dr. George Gey- sampled some of the
cancerous cells, found they could live
indefinitely and multiply outside the
body
– She died 6 months later, but cells live
on
• HeLa cells
– Used to study many different diseases
– Cure for Polio