Biology 101: Unit 5

First few days: Cell Cycle, Asexual vs Sexual Reproduction, Chromosome Number

THE ANSWER TO YOUR QUESTION IS: YES!

GENETICS II:

• Cell Cycle• Asexual vs Sexual Reproduction• Meiosis (friday)• Mon- finish meiosis- Reebops Lab• DNA Mutations• Genetics Disorders

IMPORTANT DATES TO KNOW:

• Benchmark: USA TEST PREP: Thurs 10/17

• MIDTERM: 10/18: will include all information up to this point on this test

Getting Started…

• If you were the prosecutor in this criminal case, who would you want arrested? Why?

• What is the DNA Technology that is used in this situation called?

How does cell division differ in uni and multicellular organisms?

• Unicellular: reproduce by binary fission, budding, fragmentation= asexual reproduction

• Multicellular: involves the production of sex cells

Compare internal/external fertilization

• Fertilization- joining of sex cells• External fertilization- gametes are

released into the environment• Internal fertilization- sperm are deposited

inside female’s body

What are chromosomes?• Carriers of genetic

material found in nucleus

• Made up of DNA

What is involved in Chromosome structure?

• Chromosomes are made up of two chromatids which are held together with a centromere

• Human chromosome number is 46 in body cells; 23 in sex cells

Compare haploid/diploid number

• Haploid number- (n) “half-number” typically found in gametes only

• Diploid number- (2n) “double-number” found in somatic cells (body cells)

How is gender determined in humans?

• Females have XX as last set of chromosomes (sex chromosomes)

• All eggs are X

• Males have XY as last set of chromosomes• Half of sperm are X sperm; half are Y

sperm• Males determine gender of offspring

Activity:

• Chromosome Worksheet: Chromosome Number practice

What is the cell cycle?

• Sequence of growth and division in the cell

1. Interphase is the growth period where replication occurs

2. Mitosis

What is mitosis?

• division of cells producing two cells with the same number of chromosomes

• Ex: 46 chromosomes in human body cells, so ALL body cells should have 46

What is involved in Prophase?• Chromatin (normal

form of DNA) coils into chromosomes

• The nucleus disappears

• Centrioles form and move to opposite poles of cell

• Spindle fibers form from centrioles and begins to cross cell

What is involved in Metaphase?

• Chromosomes line up in the middle of the cell

• Spindle forms across the cell from centrioles

What is involved in Anaphase?

• Spindle fibers begin to shorten

• Chromosomes pulled apart

• Move to opposite poles

What is involved in Telophase?

• Chromosomes unwind into chromatin

• Spindle fibers break down

• Nucleolus and nuclei reform

• Plasma membrane begins to pinch in

What is Cytokinesis?• Division of cytoplasm• In animal cells: cell membrane

continues to pinch in until two cells are formed

• In plant cells: cell plate forms in center of cell and eventually splits cells

• At the end of mitosis, two new cells are produced; called “daughter” cells

Thurs: 10/10 Quick Quiz 11. Which part of the cell cycle involves the copying of the

DNA? a. interphase b. mitosis

2. What is the division of the cytoplasm called? a. cytolysis b. cytofission c. cytokinesis

A. Prophase B. Metaphase C. Anaphase D. Telophase

3. Which phase involves the splitting of the chromosomes?4. Which phase involves the chromosomes lining up in the

center of the cell?5. Which phase involves the formation of chromosomes?6. In which phase does a cell plate form in a plant cell?7. The nucleus begins to disappear and spindle fibers begin to

form across the cell?

Review of The Cell Cycle: Mitosis

• Chromosome Structure/Number• Gender• Interphase• Mitosis- P-M-A-T-Cyto• Review Mitosis and Cancer Reading

Activity 1: Cell Cycle

• Using supplies available in class, create a Cell Cycle Flipbook:

MUST INCLUDE:

1) ALL steps of the cell cycle: Interphase-Cytokinesis

2) Show LABELED diagrams and a description of what is happening in each stage

Activity 2: Mitosis Lab

• Onion Root Tip Lab

1) Complete lab in lab area;

2) Use caution with microscope slides and the microscope

Asexual vs. Sexual Repoduction• Asexual Reproduction

– No sperm or egg are used– Newly produced cells are

genetically identical to parent cell- clones

– If it occurs in… • human body cells (like the

skin)- called mitosis• single-celled organisms like

bacteria or protists- called binary fission

• simple animals (like sponge)- called budding

• Sexual Reproduction– Sperm and egg are

produced & fused– Newly produced cells are

genetically different from each other and the parent cell.

– This creates genetic diversity

– If it occurs in• human body cells- called

meiosis• Single-celled organisms like

bacteria or protists- called conjugation.

Homework: Thurs 10/10

HW: Why Sex is Good Case Study- ALL

**If needed: Mitosis matching WS for practice with stages