Mitosis and Cytokinesis Notes

Big Picture 쓰지마! (Don’t write this down..) For what is DNA used? To make proteins (it’s a blueprint) To make copies of itself (blueprint copies) Why are proteins made? Duh, Mr. Long! For our bodies n’ stuff! (Structures and functions = traits) Why are copies of DNA made? Cell division: growth and repair via new cells. Cell Division: asexual reproduction

Who would win in court?

Many organisms, especially unicellular organisms (ex Many organisms, especially unicellular organisms (ex., bacteria, some protists), reproduce by means of cell division – called asexual reproduction – Ex: paramecium (100x)

Multicellular dudes and dudettes (i.e. like us): Growth and repair! 10X Magnification of Stained Human Cheek Cells

Can you name these parts of the Human Cheek Cell?

Are human cheek cells big or small? (Compared to our Protist friends?) Parts of the Human Cheek Cell at 40X Magnification Are human cheek cells big or small? (Compared to our Protist friends?)

Protist ex: Paramecium 100x

Parts of the Human Cheek Cell at 40X Magnification Are human cheek cells big or small? (Compared to our Protist friends?)

Now, back to DNA!

How are chromatin, chromosomes, and chromatids similar? They are all made up of DNA and protein 쓰세요! (Write this down!)

What is chromatin? Unwound DNA and proteins in the nucleus of a non-dividing cell

What is a chromosome? DNA and protein in a coiled rod-shaped form that occurs during cell division.

What is a chromatid? One of two identical parts of a chromosome Centromere: the site where the two chromatids meet

쓰지마! Chromosome number Every organism has its own specific number of chromosomes Examples: Human = 46 chromosomes or 23 pairs Dog = 78 chromosomes or 39 pairs Goldfish = 94 chromosomes or 47 pairs Lettuce = 18 chromosomes or 9 pairs

All somatic (body) cells in an organism have the same kind and number of chromosomes Examples: Human = 46 chromosomes Human skin cell = 46 chromosomes Human heart cell = 46 chromosomes Human muscle cell = 46 chromosomes Fruit fly = 8 chromosomes Fruit fly skin cell = 8 chromosomes Fruit fly heart cell = 8 chromosomes Fruit fly muscle cell = 8 chromosomes

What is the cell cycle? 쓰세요! The repeating set of events that make up the life of a cell Interphase - the time between cell divisions

What are the 3 phases of interphase?

1. G1 (1st Gap) Cell makes new proteins, RNA and other molecules Cell grows

2. S phase (DNA synthesis) Cell duplicates its DNA; 2 complete, identical sets results

3. G2 (2nd Gap) Similar to G1, but molecules often produced in smaller amounts.

Think-Pair-Share Giraffes are big. Do they have bigger cells than us…or… do they have more cells than us? AND WHY DO YOU THINK SO? Form a hypothesis.

Microscope Activity - Cells Fold a paper into quadrants. Write name, period, and Assn# top left. Draw a large circle in each quadrant (microscope view) View four microscope slides and draw what you see (moving w/ group to each table). Answer questions A & B on the back of your paper. Are the cells of small plants or animals smaller than those of larger plants/animals? Compare the number and size of cells in small organisms to those in larger organisms.

MITOSIS

What is mitosis? A type of cell division that results in new cells with genetic material that is identical to that of the original cell

What are the phases of mitosis? Prophase DNA shortens and tightly coils into rod-shaped chromosomes Nuclear membrane breaks down and disappears Centrioles (found only in animals cells) begin moving to opposite ends of the cell

2. Metaphase Spindle fibers move chromosomes to middle of the dividing cell

3. Anaphase The chromatids of each chromosome separate @ the centromere and slowly move toward the opposite sides of the cell.

4. Telophase After the chromosomes reach opposite ends of the cell, the spindle fibers disappear The chromosomes return to a less coiled chromatin state Nuclear membrane reappears

What is cytokinesis? The process in which the cytoplasm of the cell divides during telophase In animal cells, it begins with a pinching inward of the cell membrane midway between the dividing cells two poles, cleavage furrow In plant cells, in the middle of the dividing cells, a membrane-bound cell wall is being formed called the cell plate