The cell is going to divide!!??

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Levels of Organization Cell (animal or plant; Body or sex cell) Nucleus (Contains chromosomes) Chromosomes (divide during cell division) Gene (Segment of Chromosome) DNA (Contains genetic information)

Vocabulary Gamete: sex cells= sperm or egg Fusion of gametes forms a zygote. A zygote always has a full or diploid (2n) number of chromosomes

Each species has a characteristic number of chromosomes. Diploid (2n) number includes two sets of chromosomes of each type. Found in all the non-sex cells or autosomes of an organism's body (with a few exceptions). Examples include humans (46), crayfish (200), etc.  Haploid (n) number contains one of each kind of chromosome. In the life cycle of many animals, only sperm and egg cells(sex cells) have the haploid number. Examples include humans (23), crayfish (100), etc.

Types of Chromosomes: Autosomes = Body chromosomes or non sex chromosomes ( humans have 44 or 22 pairs) Sex Chromosomes = XX or XY (23 rd pair for humans) determines the sex of the offspring

Mitosis: the division of body cells Daughter cell 46 c hromosomes Parent cell 46 chromosomes Daughter cell 46 c hromosomes **Daughter cells are identical to Parent cell

Remember Cell size? 1cm If your cells Were this size Then

The Cell Cycle

THE CELL CYCLE *Interphase *Mitosis *Cytokinesis

Interphase *Time in between cell division (mitosis) G 1 = Cell growth S = DNA Replication G 2 = Prep for mitosis

Prophase 1. Chromosomes appear condensed 2. Nuclear envelope and nucleus disappears 3. Centrioles separate to the poles of the cell 4. Chromosome (at their centromeres)attach to spindle fibers Centromeres produce spindle fibers

Metaphase 1. Chromosomes line up in the equator (center) of the cell. (Spindle fibers help move chromosomes thru cell)

Anaphase 1. The centromere splits and chromatids separate. 2. Chromatids move to the poles of the cell

Telophase 1. Chromatids start to become diffuse (chromatin) 2. The nuclear envelope starts to reform 3. Nucleolus reforms 4. Spindle breaks apart 5. Cells begins splitting

Cytokinesis * NOT a phase of mitosis It is a process of the cytoplasm dividing after mitosis.

Interphase *2 new cells are formed *Identical to the original parent cell

THE CELL CYCLE *Interphase *Mitosis *Cytokinesis

Plant Mitosis Onion Root Tip Cells

The Cell Cycle

Cell Division: Prokaryotes The Prokaryotic Chromosome Chromosome consists of nucleoid (an irregularly-shaped region, electron-dense, and not enclosed by a membrane. Chromosome, when stretched out, is a circular loop attached to the inside of the plasma membrane; about 1,000 times the length of the cell.

3. When cell is approximately twice its original length, the plasma membrane grows inward, a new cell wall forms dividing the cell into two approximately equal daughter cells. 4. Generation times of Escherichia coli is 20 minutes; most bacteria need up to one hour to a day.