Download Activating Strategy AP Lesson #33 Where it all began… Getting from

Activating Strategy
• Index Card Round Robin
– Write down everything you know about cell
reproduction in 30 seconds
– Pass your index card to the next person
– Add information you know is true & cross off
anything that you know is untrue
• Create a Class Wide List
Where it all began…
AP Lesson #33
EQ: What is cell reproduction and
why is it important to cells?
And now look at me…
I started as a cell smaller than
a period at the end of a sentence…
Zygote
How did I get
from there to
here?
Getting from there to here…
• Going from egg to baby….
the original fertilized egg has to divide…
and divide…
and divide…
and divide…
• Cells must reproduce!
Why do cells divide?
• For reproduction
– asexual reproduction
• one-celled organisms
– Sexual reproduction
• Creates variation
• For growth
– from fertilized egg to multicelled organism
amoeba
• For repair & renewal
– replace cells that die from
normal wear & tear or from
injury
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• Cell division is an integral part of the cell cycle
– life of a cell from the time it is first formed until it
divides into two cells.
– Must have the ability to pass identical genetic
material to cellular offspring
– Must have checkpoints to ensure cell division can
and should occur
– Division creates daughter cells
100 µm
(a) Reproduction
• exact copy of genetic material = DNA
– mitosis
• organelles, cytoplasm, cell membrane,
enzymes
– cytokinesis
20 µm
200 µm
(b) Growth and
development
What must be passed on to daughter cells?
(c) Tissue renewal
How does the cell organize its genetic material?
• All the DNA in a cell
constitutes the cell’s
genome
– single DNA molecule
(prokaryotic cells)
– many DNA molecules
(common in eukaryotic
cells)
E. coli
H. sapiens
• Packaged into
chromosomes
• Eukaryotic cell division consists of:
– Mitosis, the division of the nucleus
– Cytokinesis, the division of the cytoplasm
• Gametes are produced by a variation of cell
division called meiosis
• Meiosis yields non-identical daughter cells that
have only one set of chromosomes, half as
many as the parent cell
chromosomes (stained orange)
in kangaroo rat epithelial cell
→notice cytoskeleton fibers
Are all chromosomes created equal?
• Each eukaryotic species has a
characteristic number of
chromosomes
• Somatic cells
– (nonreproductive cells) have two
sets of chromosomes = Ex. Skin
cells, Liver cells
– # of chromosomes varies by
species
• Gametes
– (reproductive cells) have half as
many chromosomes as somatic
cells = Ex. sperm and eggs
Summarizing Strategy
• Let’s revisit your Index Card
– What can we add?
– What should we change?
– What questions do you still have?
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Assessment
• HW: Read Chapter 12.2
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