Cell Reproduction Part 1 “All cells come from pre-existing cells.”

Cells must divide for... n Growth n Repair n Reproduction

The Star of Our Show

n Prior to division, chromosomes are duplicated. n A single stranded chromosome becomes a double stranded chromosome. n The two strands are IDENTICAL

n The identical strands are called sister chromatids. n They are held together by a centromere. centromere chromatids

The Cell Cycle

n The life of a eukaryotic cell is traditionally shown as a cycle. The Cell Cycle

Cell Cycle Summary n G1 – Cell growth phase n S – New DNA is synthesized n G2 – Preparation for cell division n M & C - Cell division

Mitosis n Division of the nucleus to form two new nuclei with the same number and type of chromosomes as the parent cell.

Cytokinesis n The division of the cytoplasm to form two new cells.

Before Mitosis n Interphase is the period between cell division. (G1, S & G2) n Cell growth. n Chromosomes duplicate. n Synthesis of organelles and materials needed for cell division.

Now it’s Mitosis Time! Cells spend 90% of their lives during Interphase. So, once we get to Mitosis – it’s GO time!

Prophase n Chromatin condenses into chromosomes. n The nuclear membrane disappears.

Metaphase n Chromosomes line up across the equator, or center, of the cell.

Anaphase n Sister chromatids are pulled to opposite sides of the cell & away from each other.

Telophase n New nuclear membranes appear. n Cytokinesis begins. n Chromosomes uncoil.

After Mitosis n Cells undergo Cytokinesis –The cytoplasm of the cell is divided in half –The cell membrane grows to enclose each cell n Results in TWO genetically IDENTICAL cells

Animal Cell Cytokinesis n The cell membrane is pinched in half by a belt of protein threads

Plant Cell Cytokinesis n A cell plate forms in the center of the dividing cell then fuses to make a new cell wall.

1. Name That Phase!

2. Name That Phase!

3. Name That Phase!

4. Name That Phase!

LABEL THIS! 5. What is A? 6. What is B? A B

Question #7 n A human cell contains 46 chromosomes. n How many chromosomes will each of its daughter cells have following mitosis?

Question #8 n __________ is the division of the nucleus to form two new nuclei with the same number and type of chromosomes as the parent cell.

Question #9 n __________ is the division of the cytoplasm to form two new cells.

Question #10 n Chromosomes must ____________ prior to mitosis. A. split in half B. duplicate B. duplicate C. dance around C. dance around D. pass the AIMS test D. pass the AIMS test

1. Name That Phase! PROPHASE

2. Name That Phase! TELOPHASE

3. Name That Phase! METAPHASE

4. Name That Phase! ANAPHASE

LABEL THIS! 5. What is A? 6. What is B? A B CENTROMERE SISTER CHROMATIDS

Question #7 n A human cell contains 46 chromosomes. n How many chromosomes will each of its daughter cells have following mitosis? ANSWER: 46

Question #8 n __________ is the division of the nucleus to form two new nuclei with the same number and type of chromosomes as the parent cell. MITOSIS

Question #9 n __________ is the division of the cytoplasm to form two new cells. CYTOKINESIS

Question #10 n Chromosomes must ____________ prior to mitosis. A. split in half B. duplicate B. duplicate C. dance around C. dance around D. pass the AIMS test D. pass the AIMS test *

B