So how do microbescause B cells and T cells to grow and divide?

Each cell has a receptor on its cell surface that recognizes a specific part of a microbe.

That receptor triggers aSignal transduction pathway.

This triggers gene expression(transcription) that…

…leads to protein synthesis (translation) that…

…allows the cell to grow (duplicate all its proteins that help to duplicate all its organelles)

and divide (mitosis).

On to the Cell cycle!

Watch this movie to link transcription and translation to the cell cycle:

http://highered.mcgraw-hill.com/sites/007352543x/student_view0/chapter9/stimulation_of_cell_replication.html

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

http://highered.mcgraw-hill.com/sites/007352543x/student_view0/chapter9/how_the_cell_cycle_works.html

– 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

Mitosis recap:http://facweb.northseattle.edu/csheridan/Biology160_Fa12/movies/mitosis_movies/08_06bMitosisOverview_A.html

– 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