The Cell Cycle

Mitosis

The Cell Cycle

The regular sequence of growth and division that cells undergo.

The Cell Cycle

6 Parts Interphase Prophase* Metaphase Anaphase Telophase Cytokinesis

• *When mitosis begins.

Stage 1: Interphase

During interphase the cell grows, makes a copy of its DNA, and prepares to divide into 2 cells. Cell grows - The cell grows to full size and

produces structures it needs. Copies DNA -Cell makes a full copy of the

DNA. This process is known as replication.• DNA is found in the chromatin.

Stage 1: Interphase

Preparing for Division - After replication has occurred, the cell copies its centrioles.

• Centrioles - Cylindrical structures that produce microtubules used in mitosis.

Stage 2: Mitosis

Mitosis - The stage during which the cell’s nucleus divides into two new nuclei.

During mitosis, one copy of the DNA is distributed into each of the two daughter cells. Daughter cells - The cells that are produced following

cell division.

Stage 2: Mitosis Part 1

Prophase - Chromatin condenses in the nucleus to form chromosomes.

• Chromosomes are made of chromatin. The two chromatids that make up a chromosome is held together in the center by a centromere. (make a diagram.)

The centrioles move to opposite sides of the nucleus. The nuclear envelope breaks down.

Stage 2: Mitosis

Part2

Metaphase -• Chromosomes line up across the center of the

cell.• Each chromosome attaches to a spindle fiber at

its centromere.• The spindle fibers are connected to the centrioles.

Stage 2: Mitosis Part 3

Anaphase - • The centromeres split, and the chromatids

separate.• Each chromatid becomes a new chromosome.• New chromosomes move to opposite ends of the

cell.• Cell begins to stretch out as the opposite ends are

pushed apart.

Stage 2: Mitosis

Part 4 Telophase -

• Chromosomes lose their rod-like appearance• New nuclear envelope forms around the bundle of

chromosomes.• Two halves separate even farther.

Stage 3: Cytokinesis

Cytokinesis is the division of cytoplasm and organelles into each of the 2 new cells.

Stage 3: Cytokinesis

During cytokinesis: Cell membrane pinches in around the middle of the

cell. Cell splits in two and divides the cytoplasm. Each daughter cell has an identical set of

chromosomes and about 1/2 the organelles. Cytokinesis leads back into interphase.

Stage 3: Cytokinesis

Cytokinesis in PLANTS is different. A cell plate forms across the middle of the

cell, which gradually develops into the new cell membranes.

The new cell walls form around the cell membranes.

DNA Structure

Double helix - Twisted ladder shape The sides of the ladder are made up of sugar

molecules called deoxyribose, and alternate with a phosphate molecule.

The rungs are made up of a pair of nitrogen bases. 4 nitrogen bases: adenine (A), thymine (T), guanine

(G), and cytosine (C).

DNA Replication Process

The DNA “ladder” unwinds and unzips, leaving 1 of the 2 nitrogen bases on either side of the “ladder”.

Bases that are floating in the nucleus pair up with its appropriate partner. Adenine pairs with Thymine Guanine pairs with Cytosine