Cell Cycle, Mitosis, and DNA

Cell Cycle

The regular sequence of growth and division that cells undergo

Phases of Cell Cycle In Order

G1 (Gap 1), S (DNA Synthesis), G2 (Gap 2), M (Mitosis and Cytokinesis)

Stages of Interphase

G1, S, and G2

Gap 1 Phase of Cell Cycle (G1)

Period of growth for a newly formed cell. New organelles and enzymes are made.

DNA Synthesis Phase of Cell Cycle (S)

Cell makes copy of its DNA (Resulting in a total of 92 chromosomes).

Gap 2 Phase of Cell Cycle (G2)

Cell prepares for cell division (checks DNA for damage and produces proteins necessary for cell division)

Mitosis

Process by which the nucleus and duplicated chromosomes of a cell divide and are evenly distributed, forming two daughter nuclei. Makes identical body cells to allow organisms to grow and repair tissue.

Cytokinesis

Division of the cytoplasm during cell division. Occurs after mitosis.

4 Phases of Mitosis, In Order

Prophase, metaphase, anaphase, telophase

Prophase

First phase of mitosis in which duplicated chromosomes condense to form chromosomes, the nuclear envelope dissolves, and spindle fibers begin to form.

Metaphase

Phase of mitosis in which chromosomes line up in the middle of the cell, attaching to the spindle apparatus by their centromeres.

Anaphase

Phase of mitosis in which chromatids of a chromosome separate at the centromere and more to opposite poles of the cell.

Telophase

Phase during which chromatids reach the poles of the cell, uncoil into chromatin, and the nuclear membrane reforms.

Cytokinesis in Plant Cells

In plant cells, a cell plate forms across center of cell and extends towards edges of cell. Cell wall forms on either side of the plate and original cell splits in two.

Cytokinesis in Animal Cells

The cell membrane is drawn in until the cytoplasm is pinched into two equal parts. Each part contains its own nucleus and organelles.

Chromosomes

A doubled rod of condensed chromatin; contains DNA that carries genetic information. Visible during cell division only.

Chromatids

One of two identical "sister" parts of a duplicated chromosome

Centromere

Region of a chromosome where the two sister chromatids attach

Centrioles

Structure in an animal cell that helps to organize cell division

Spindle Fibers

The fibers that attach to and pull apart the chromatids.

DNA Structure

DNA consists of two long chains of nucleotides twisted into a double helix and joined by hydrogen bonds between the complementary bases adenine and thymine or cytosine and guanine.

DNA Replication

The process of making identical copies of DNA before cell division. Unzipped DNA strands serve as templates for complementary strands. Occurs during interphase of the cell cycle.

Nitrogen Bases

Make up the rungs or 'steps' of the DNA ladder. Adenine and thymine pair together as do cytosine and guanine.

Sides of DNA Ladder

Made of alternating sugar (deoxyribose) and phosphate groups