Untitled Flashcards Set

Flashcard Set: Cell Cycle and Cell Division

1. What is the function of the nucleus in a cell?

• Contains most of the cell’s DNA.

• DNA is organized into chromosomes.

• Chromosomes consist of chromatin (DNA + proteins).

2. What happens to chromatin when a cell divides?

• Chromatin condenses into visible chromosomes.

3. Who discovered chromosomes and what did he call their division?

• Walther Flemming discovered them in dividing salamander larvae.

• Named the process mitosis (meaning "thread").

4. What are the two components of chromatin?

• DNA: Made of nucleotides (phosphate, sugar, nitrogenous base).

• Histones: Proteins that help DNA coil into nucleosomes.

5. What are the four nitrogenous bases in DNA?

• Adenine (A), Guanine (G), Cytosine (C), Thymine (T).

6. What is the structure of a chromosome?

• Two sister chromatids joined at a centromere.

• Centromere attaches to spindle fibers during cell division.

7. What are genes?

• Segments of DNA coding for proteins.

• Units of heredity, passed from parents to offspring.

8. Why do cells need to divide?

• Growth, replacement, repair, reproduction.

9. What are the phases of the cell cycle?

• Interphase (non-dividing phase).

• M-Phase (dividing phase).

10. What are the three stages of interphase?

• G1 (First Growth Phase): No visible chromosome change.

• S (Synthesis Phase): DNA duplicates.

• G2 (Second Growth Phase): More RNA synthesis.

11. What are the two types of cell division?

• Mitosis: Produces diploid cells for growth.

• Meiosis: Produces haploid gametes.

12. What is mitosis and why is it important?

• One parent cell → two identical daughter cells.

• Maintains chromosome number.

13. What are the phases of mitosis?

1. Prophase: Chromosomes condense, spindle fibers form.

2. Metaphase: Chromosomes align at the equator.

3. Anaphase: Chromatids separate to opposite poles.

4. Telophase: Nuclear membrane reforms, chromosomes decondense.

14. What is cytokinesis?

• Division of cytoplasm.

• Animal cells: Cleavage furrow forms.

15. What are the functions of mitosis?

• Growth, repair, replacement, asexual reproduction.

• Maintains chromosome number.

16. What is meiosis?

• Cell division that produces gametes.

• Reduces chromosome number by half.

17. Why is meiosis important?

• Ensures correct chromosome number after fertilization.

• Creates genetic variation through crossing over.

18. What is crossing over in meiosis?

• Exchange of genetic material between non-sister chromatids.

• Forms chiasmata, leading to genetic recombination.

19. What are the differences between mitosis and meiosis?

• Mitosis: Occurs in body cells, produces 2 diploid cells, identical chromosomes.

• Meiosis: Occurs in reproductive cells, produces 4 haploid cells, genetically varied.

20. What are the two nuclear divisions in meiosis?

• Meiosis I: Reduces chromosome number (homologous pairs separate).

• Meiosis II: Similar to mitosis (sister chromatids separate).