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