1. Cell Differentiation/specialization Cell Cycle
Biology STAAR Review
Session #4
Cell Differentiation/specialization Cell Cycle
Mitosis vs. Meiosis

2. Chloroplasts, cilia/flagella, dendrite/axon
Things to Know
ALL the cells of an organism have the exact same ________
DNA
If they all have the same DNA, why do they have different functions?
Some segments of DNA (genes) are turned off so only certain functions are performed.
Cells have specialized jobs because of the genes that are turned on and being used.
Often these specialized jobs require specialized structures like:
Chloroplasts, cilia/flagella, dendrite/axon

4. Stem cells
Unspecialized cells are called ____________, and they become specialized due to internal and external factors.
Internal Factors
Production of enzymes, hormones, or other chemical signals
Proteins binding to segments of DNA to activate or deactivate genes.
External Factors
Temperature changes
Supply of oxygen
Available nutrients
Pollution
Climate factors
(ex. length of day)

5. Gene Regulation/Expression means:
DNA
Transcription
Translation
Protein
Trait
Questions?

6. Cell Cycle Cancer Interphase
G1-Growth, Normal cell function/job
S-DNA replication
G2- Double check DNA & organelles to prepare for division
**G0- Cell is not growing, still performs normal function/job
Cells that are not regulated by the cell cycle will divide uncontrollably and can lead to _________________
Cancer

7. Questions? Growth & DNA Replication occurs
Chromatin condenses into chromosomes
Chromosomes line up in middle of cell
Chromosomes pull apart
(And Cytokinesis) Cell and chromosomes divide into two separate cells
Questions?

8. Somatic cells are BODY cells made by MITOSIS
Gametes are SEX cells (egg or sperm) made by MEIOSIS
Diploid cells have TWO COPIES of each chromosome (complete set) and are made by MITOSIS
Haploid cells have ONE COPY of each chromosome (half set) and are made by MEIOSIS

9. Crossing over Happens in MEIOSIS (Metaphase 1) when TETRADS form
INCREASES genetic variation

10. Process B
Meiosis
Process A
Mitosis

11. Comparing Mitosis & Meiosis
MITOSIS
MEIOSIS
Two daughter cells are formed from one parent cell
Results in forming egg or sperm cells (GAMETES)
Replication of chromosomes occurs
Doubled chromosomes pair to form TETRADS
Cells with a reduced chromosome number are formed (HAPLOID)
Four daughter cells are formed from one parent cell
Cells with the same chromosome number as original are formed (DIPLOID)
Results in forming somatic or body cells
Daughter cells are different from each other and the parent cell
Parent cell divides twice
Crossing over occurs
Chromosomes move to the cell’s center
Daughter cells are identical to the parent cell
Parent cell divides only once
Increases genetic variation                 

12. The table lists and describes three types of cells from prepared slides that students observed with a microscope.
Which of these sets of slides could students have used for their observations?
A) Squamous cell: cheek cell
Erythrocyte: skin cell
Gamete: ovum
C) Squamous cell: cheek cell
Erythrocyte: red blood cell
Gamete: sperm cell X
B) Squamous cell: red blood cell
Erythrocyte: white blood cell
Gamete: sperm cell
D) Squamous cell: ovum
Erythrocyte: white blood cell
Gamete: skin cell X

13. Which part of the model represents the S phase? I II III IV
The model represents the change in the DNA content of a cell during the cell cycle.
Which part of the model represents the S phase? I II
III IV

14. When cells leave the cell cycle, they exit during G1 phase and then enter G0 phase, a resting period. Most normal cells can leave G0 phase and reenter G1 phase before entering S phase. Cancer cells are different because they cannot enter G0 phase and are likely to do which of the following?
Fail to complete S phase
Mutate during G1 phase
Repeat the cell cycle continuously
Die after completing mitosis

15. Sexual reproduction in animals depends on the production of gametes
Sexual reproduction in animals depends on the production of gametes. Which of these processes produces gametes in animals?
Mitosis
Fertilization
Meiosis
Binary fission

16. You are going to ROCK the STAAR!!!

17. Cell Cycle, Mitosis vs. Meiosis, & Cell Differentiation
5A Describe the stages of the cell cycle including DNA replication and mitosis and the importance of the cell cycle to the growth of organisms.
5B Examine specialized cells, including roots, stems, and leaves of plants; and animal cells such as blood, muscle, and epithelium
5C Describe the roles of DNA, ribonucleic acid (RNA), and environmental factors in cell differentiation.
5D Recognize that disruptions of the cell cycle lead to diseases such as cancer
6D Recognize that gene expression is a regulated process;
6G Recognize the significance of meiosis to sexual reproduction.