Cell Reproduction

• Check this out!!

• Breast cancer cells dividing:

• http://www.youtube.com/watch?v=Hm03rCUODqg&NR=1&feature=fvwp

The Cell Cycle– Eukaryotic cells that grow and divide undergo an orderly

sequence of events called the cell cycle.– The cell cycle consists of two distinct phases:

• Interphase– Cell growth

– Sub-phases:

» G1

» S phase

» G2

• Mitotic phase– Cell division

– OK, we’ve talked about how to transcribe and translate one gene found on the DNA in our nuclei into a functioning protein. But we have more than just one gene….

– Almost all of the genes of a eukaryotic cell

• Are located on chromosomes in the cell nucleus.

From One gene to 25,000 genes

Transcription and Translationoccur all throughout Interphase:

when the cell is growingand duplicating all of its cell structures and organelles!!

Eukaryotic Chromosomes– Each eukaryotic

chromosome contains one very long DNA molecule,

• Typically bearing thousands of genes.

– The number of chromosomes in a eukaryotic cell

• Depends on the species.

– Detailed representations of DNA• Notice that the bases pair in a complementary

fashion.

DNA Replication– When a cell or

whole organism reproduces, a complete set of genetic instructions must pass from one generation to the next.

– This happens during S phase

Figure 10.8

The Cell Cycle– Eukaryotic cells that grow and divide undergo an orderly sequence

of events called the cell cycle.– The cell cycle consists of two distinct phases:

• Interphase– Cell growth– Sub-phases:

» G1» S phase» G2

• Mitotic phase– Cell division

Mitosis and Cytokinesis

– Mitosis • Is the division of the chromosomes.• Is preceded by interphase.

From movie folder play: - AnimalMitosis_SV.mpg

– Chromosomes• Are made of chromatin, a combination of DNA

and protein molecules.• Are not visible in a cell until cell division occurs.

– The DNA in a cell is packed into an elaborate, multilevel system of coiling and folding.

– Before a cell divides, it duplicates all of its chromosomes, resulting in two copies called sister chromatids.

– When the cell divides, the sister chromatids separate from each other.

G2 phase

G1 phase

S phase

M phase

Figure 8.8.1

– Mitosis consists of four distinct phases:• Prophase• Metaphase• Anaphase• Telophase

Figure 8.8.2

Figure 8.8.3

– Cytokinesis• Typically occurs

during telophase.

• Is the division of the cytoplasm.

• Is different in plant and animal cells.

Figure 8.9b

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Cancer Cells: Growing Out of Control

– Normal plant and animal cells have a cell cycle control system.

– Cancer is a disease of the cell cycle.– Cancer cells do not respond normally to

the cell cycle control system.

http://www.youtube.com/watch?v=Hm03rCUODqg&NR=1&feature=fvwp

– Cancer cells can form tumors,• Abnormally growing masses of body cells.

– If a tumor is malignant,• It can spread to other parts of the body.

Cancer Treatment

– Cancer treatment can involve• Radiation therapy, which damages DNA and disrupts

cell division.• Chemotherapy, which uses drugs that disrupt cell

division.

• Turn and talk: How would damaging the DNA of a cell disrupt cell division?

– Cancer cells are often grown in culture for study.

Cancer Prevention and Survival

– Cancer prevention includes changes in lifestyle:• Not smoking• Exercising adequately• Avoiding exposure to the sun• Eating a high-fiber, low-fat diet• Visiting the doctor regularly• Performing regular self-examinations