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Cell Cycle and Mitosis
Learning Objective: I can describe how cells divide and the different phases of the cell cycle.
Essential Question for this Unit: What is the process cells undergo before they become specialized?
A little History Until the late 1600s, scientists used to think new cells came from
Spontaneous Generation (nonliving things giving rise to living things)
1668: Maggots come from flies! Francesco Redi discovered that maggots came from flies, not from
decaying meat
1675: Microorganisms become a thing! Microorganisms were discovered- which reopened debate about where
living things come from
1864- Microorganisms come from other microorganisms! Louis Pasteur proved that microorganisms came from other microorganisms
Theory of Biogenesis All life comes from other life
Thanks Pasteur.
Ready for some Chromosomes? Chromosomes- rod-shaped structures composed of DNA and proteins
DNA- the genetic code for organisms Chromatin- a loosely coiled DNA strand Chromatid- a single strand of coiled DNA (replicated, condensed chromosome)
Centromere- holds the two chromatids together
DNA- the genetic code for organisms in a double helix
Chromosomes- rod-shaped structures composed of DNA and proteins
Quiz Time! Use your notes!What are chromosomes? A. rod-shaped structures composed of DNA and proteins
B. the genetic code for organisms
C. a loosely coiled DNA strand
D. a single strand of coiled DNA
What are chromosomes? A. rod-shaped structures composed of DNA and proteins
B. the genetic code for organisms
C. a loosely coiled DNA strand
D. a single strand of coiled DNA
What is DNA?A. rod-shaped structures composed of DNA and proteins
B. the genetic code for organisms
C. Structure that holds the two chromatids together
D. a loosely coiled DNA strand
What is DNA?A. rod-shaped structures composed of DNA and proteins
B. the genetic code for organisms
C. Structure that holds the two chromatids together
D. a loosely coiled DNA strand
What is a Centromere?
A. A structure that holds two chromatids together?
B. a single strand of coiled DNA (replicated, condensed chromosome)
C. a loosely coiled DNA strand
D. the genetic code for organisms
What is a Centromere?
A. A structure that holds two chromatids together
B. a single strand of coiled DNA (replicated, condensed chromosome)
C. a loosely coiled DNA strand
D. the genetic code for organisms
What is Chromatin?
A. A structure that holds the two chromatids together
B. a single strand of coiled DNA (replicated, condensed chromosome)
C. a loosely coiled DNA strand
D. rod-shaped structures composed of DNA and proteins
What is Chromatin?
A. A structure that holds the two chromatids together
B. a single strand of coiled DNA (replicated, condensed chromosome)
C. a loosely coiled DNA strand
D. rod-shaped structures composed of DNA and proteins
What is this?
A. DNA
B. A Chromosome
C. A Centromere
D. A Chromatin
What is this?
A. DNA
B. A Chromosome
C. A Centromere
D. A Chromatin
What structure is labeled A? A. DNAB. A centromereC. A chromatidD. A chromosome
What structure is labeled A? A. DNAB. A centromereC. A chromatidD. A chromosome
What are the structures labeled B?A. A chromosomeB. A centromereC. A chromatidD. DNA
What are the structures labeled B?A. A chromosomeB. A centromereC. A chromatidD. DNA
Now that you’ve got the basics…
Let’s move on to the cell cycle
Cell Cycle Overview Interphase
G1 Phase S Phase (Synthesis) G2 Phase
Mitosis Prophase Metaphase Anaphase Telophase
Cytokinesis
G1 Phase
S Phase
G2 Phase
MitosisPro
MetaAna
Telo
Cytokinesis
Draw this!
https://www.youtube.com/watch?v=ZeW8HaCUtOQ
Cells that Divide Stem cells divide to become specialized cells
Cells that DON’T divide Most cells!
Specialized cells like neurons, cardiac cells, and muscle cells have already divided and won’t ever divide again
Interphase1. Interphase- starts right after cell division; longest phase of a cell’s “life”
a. G1 Phase- Cell grows
b. S Phase- DNA is copied into sister chromatins
c. G2 Phase- Cell grows and prepares for cell division (mitosis)
G1 Phase
S Phase
G2 Phase
Mitosis The division of the nucleus (PMAT)
Prophase Metaphase Anaphase Telophase
Prophase1. Nucleoli disintegrates2. Chromatin condenses into chromatids and chromosomes3. Centrioles migrate to ends of the cell4. Spindle fibers form from centrioles
Centrioles
Spindle fibers
Nucleoli (disappearing)
Chromosomes
Draw these!
Metaphase Chromosomes move to the center of cell
Centrioles and spindle fibers
Anaphase Chromatids separate into
individual chromosomes
Migrations towards poles (sides of cell) begins
Telophase Nuclear membrane
reforms
Chromatin lengthen
Cytokinesis The division of the cell into
daughter cells Plasma membrane pinches
together in animal cells Cell plate appears in plant cells
Animal Cytokinesis
Cleavage furrow forms
Membrane splits in two
Plant Cytokinesis Cell plate forms
Membrane splits
Cell plate becomes cell wall
Cells that Divide Stem cells divide to become specialized cells
Cells that DON’T divide Most cells!
Specialized cells like neurons, cardiac cells, and muscle cells have already divided and won’t ever divide again
THE BIG PICTURE The Goal: Create more
identical cells
In humans, a cell with 46 chromosomes will divide into two daughter cells, both with 46 chromosomes
G1 Phase
S Phase
G2 Phase
MitosisPro
MetaAna
Telo
Cytokinesis