Explain the following:Explain the following: "It is not a simple life to be a

single cell, although I have no right to say so, having been a single cell so long ago myself that I have no memory at all of that stage of my life." —Lewis Thomas (1913–1993) author, biologist, physician

"It is not a simple life to be a single cell, although I have no right to say so, having been a single cell so long ago myself that I have no memory at all of that stage of my life." —Lewis Thomas (1913–1993) author, biologist, physician

Cell CycleCell Cycle

The Cell CycleThe Cell Cycle A period of growth, DNA

replication and cell division that MOST cells go through

Examples of cells that don’t: nerve, brain and muscle Examples of cells that do: blood, intestinal and skin

Blood cells-2.4 million per second

Cell Cycle is divided into 3 phases Interphase Mitosis Cytokinesis

A period of growth, DNA replication and cell division that MOST cells go through

Examples of cells that don’t: nerve, brain and muscle Examples of cells that do: blood, intestinal and skin

Blood cells-2.4 million per second

Cell Cycle is divided into 3 phases Interphase Mitosis Cytokinesis

The Cycling CellThe Cycling Cell Scientists used to think of interphase as a resting phase

during which not much happened, but they now know that this is far from the truth. It is during interphase that

chromosomes—the genetic material—are copied and cells typically double in size. While this is happening, cells continue to do their jobs: Your heart muscle cells contract and pump blood, your intestinal cells absorb the food you eat, your thyroid gland cells churn out

hormones, and so on. In contrast, most of these activities cease during mitosis while the cell focuses on dividing. But as you have probably figured out, not all cells in an organ undergo mitosis at the same time.

While one cell divides, its neighbors work to keep your body functioning.

http://publications.nigms.nih.gov/insidethecell/chapter4.html#10

Scientists used to think of interphase as a resting phase during which not much happened, but they now know

that this is far from the truth. It is during interphase that chromosomes—the genetic material—are copied and cells typically double in size. While this is happening, cells continue to do their jobs: Your heart muscle cells contract and pump blood, your intestinal cells absorb the food you eat, your thyroid gland cells churn out

hormones, and so on. In contrast, most of these activities cease during mitosis while the cell focuses on dividing. But as you have probably figured out, not all cells in an organ undergo mitosis at the same time.

While one cell divides, its neighbors work to keep your body functioning.

http://publications.nigms.nih.gov/insidethecell/chapter4.html#10

INTERPHASEINTERPHASE Interphase

Longest phase of the cell cycle Consists of 3 distinct periods

Interphase Longest phase of the cell cycle Consists of 3 distinct periods

G1 phase Proteins are produced, organelles

increase (multiply) Cells grow during this phase, increase

in size Cells acquire ATP (energy) for later

use

G1 phase Proteins are produced, organelles

increase (multiply) Cells grow during this phase, increase

in size Cells acquire ATP (energy) for later

use

S phase DNA synthesis (DNA is replicated)

S phase DNA synthesis (DNA is replicated)

G2 phase Changes in cytoskeleton to prepare

cell for mitosis Cell undergoes more growth Cell acquires more energy (ATP)

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_the_cell_cycle_works.html

G2 phase Changes in cytoskeleton to prepare

cell for mitosis Cell undergoes more growth Cell acquires more energy (ATP)

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_the_cell_cycle_works.html

INTERPHASE Specifics!INTERPHASE Specifics!

Nucleolus is present Individual chromosomes are NOT

visible (DNA is known as chromatin)

Nuclear membrane is present

Nucleolus is present Individual chromosomes are NOT

visible (DNA is known as chromatin)

Nuclear membrane is present

InterphaseInterphase

MitosisMitosis Nuclear division, it is the process

of forming identical daughter cells by replicating and dividing the original chromosomes, in effect making a cellular Xerox copy.

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__mitosis_and_cytokinesis.html

Nuclear division, it is the process of forming identical daughter cells by replicating and dividing the original chromosomes, in effect making a cellular Xerox copy.

http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__mitosis_and_cytokinesis.html

Prophase: 1st stage of mitosis

Prophase: 1st stage of mitosis

Chromatin forms chromosomes (chromosomes become visible)

Centrioles separate, start to move to opposite ends

Spindle fibers form Nuclear envelope (membrane) breaks down Spindle fibers attach to centromeres

Chromatin forms chromosomes (chromosomes become visible)

Centrioles separate, start to move to opposite ends

Spindle fibers form Nuclear envelope (membrane) breaks down Spindle fibers attach to centromeres

ChromatidsChromatids

Referred to as “sister” chromatids Referred to as “sister” chromatids

ProphaseProphase

Metaphase: 2nd stage of mitosis

Metaphase: 2nd stage of mitosis

Chromosomes move to center of the cell and line up in the middle of cell

Site where chromosomes gather is called the metaphase plate

Chromosomes move to center of the cell and line up in the middle of cell

Site where chromosomes gather is called the metaphase plate

MetaphaseMetaphase

Anaphase: 3rd stage of mitosis

Anaphase: 3rd stage of mitosis

Shortest stage of mitosis Spindle fibers pull apart chromatids Chromatids move to opposite ends of

the cell

Shortest stage of mitosis Spindle fibers pull apart chromatids Chromatids move to opposite ends of

the cell

AnaphaseAnaphase

Telophase: 4th stage of mitosis

Telophase: 4th stage of mitosis

End of mitosis (terminal stage) Spindle fibers (disassemble) break

apart Nuclear envelope re-forms around

chromosomes Chromosomes begin to break apart Two identical nuclei exist in the cell Nucleolus starts to re-form

End of mitosis (terminal stage) Spindle fibers (disassemble) break

apart Nuclear envelope re-forms around

chromosomes Chromosomes begin to break apart Two identical nuclei exist in the cell Nucleolus starts to re-form

TelophaseTelophase

CYTOKINESISCYTOKINESIS Division of cytoplasm following mitosis

Results in two daughter cells

Animal cells?

Plant cells?

Division of cytoplasm following mitosis

Results in two daughter cells

Animal cells?

Plant cells?