Cell Growth

• Before a cell gets too large, it divides forming two “daughter” cells.

Cell Division- the process by which a cell divides into two new daughter cells

• A cell must copy its genetic information before cell division begins

• Each daughter cell then gets a complete copy of that information.

Types of Reproduction

•Asexual reproduction

•Sexual reproduction

Asexual Reproduction

•Binary fission•Budding•Vegetative propagation

Binary fission

• In prokaryotes (bacteria), one cell divides to form two identical cells.

• The cells are the same size and carry the same genetic information.

Budding

•Similar to binary fission except the cytoplasm divides unequally.

•The result is two cells with the same genetic information, but one is larger than the other.

•E.g. Yeast cells

Vegetative Propagation

•Occurs in plants•Complete new plants develop from parts of the parent plant, such as the root, stem and leaf

•E.g. Potatoes

• All cells come from other cells by cell division.

• For living things to grow and repair, their cells must divide over and over again.

• In a cell containing a nucleus, the nucleus and cytoplasm divide by separate processes.

• Division of the nucleus through a series of events is called mitosis.

• In eukaryotes, cell division occurs in two main stages

» - mitosis- the division of the nucleus

»- cytokinesis- the division of the cytoplasm

Cell Cycle

• A series of events cells gothrough as they grow and divide.

During the cell cycle, a cell grows, prepares for division, and divides to form two daughter cells. Each daughter cell then begins the cycle again.

The phases of the cell cycle include interphase and cell division.

• Interphase is divided into three phases: G1, S, and G2

– During the G1 phase- Cells increase in size and make new proteins and organelles

– In the S phase- the copying of chromosomes take place

– During the G2 phase- many of the organelles and molecules needed for cell division are produced.

• So what does the M stand for?

http://www.sci.sdsu.edu/multimedia/mitosis/anim_samples.html

Wrap-Up

•When a cell makes an exact copy of its DNA it is called?

Warm-Up 1/28/08Justify your answer!

Which statement describes the major role of lipids within a cell?

A. They cause DNA to replicate.

B. They move RNA in the cytoplasm.

C. They catalyze chemical reactions in the cell cytoplasm.

D. They are the main structural components of membranes.

Mitosis and Cytokinesis

• Biologists divide the events of mitosis into four phases: Prophase, metaphase, Anaphase and telophase.

http://nobelprize.org/educational_games/medicine/2001/

Interphase

ProphasePro- = before

• Chromosomes condense and become visible

• Centrioles separate and move to opposite poles

• Chromosomes attach to fibers in the spindle

• Nuclear envelop breaks down

http://www.sci.sdsu.edu/multimedia/mitosis/anim_samples.html

MetaphaseMeta- = middle

• Chromosomes line up across the center of the cell

Anaphaseana- = back

• The centromeres joining sister chromatids split. The sister chromatids become individual chromosomes. The two sets of chromosomes move apart.

Telophasetelo- = end

• Chromosomes move to opposite ends of the cell.

• They lose their distinct shapes.

• Two new nuclear envelops form.

Cytokinesis-kinesis = movement

• Occurs at the same time as telophase.

• In most animal cells, the cell membrane pinches the cytoplasm into two nearly equal parts.