Ch 7-8

1. What is the central dogma of molecular biology?

DNA → RNA → Protein

2. How is RNA different from DNA?

Single-stranded, ribose sugar, uracil instead of thymine

3. What is transcription?

The process of making RNA from a DNA template

4. What is translation?

The process of using mRNA to build a protein

5. What does mRNA do?

Carries the genetic code (codons) from DNA

6. What does tRNA do?

Brings amino acids to the ribosome using anticodons

7. What does rRNA do?

Forms the ribosome, where proteins are made

8. Where does transcription occur?

Nucleus in eukaryotes; cytoplasm in prokaryotes

9. Where does translation occur?

Cytoplasm (in both eukaryotes and prokaryotes)

10. What is a codon?

3-base sequence in mRNA that codes for an amino acid

11. What is an anticodon?

3-base sequence in tRNA that pairs with codons

12. What is the start codon?

AUG

13. Why is the genetic code called redundant?

Multiple codons can code for the same amino acid

14. Why is the genetic code unambiguous?

Each codon only codes for one specific amino acid

15. What are the 3 steps of transcription?

Initiation, Elongation, Termination

16. What enzyme starts transcription?

RNA polymerase

17. What happens during transcription initiation?

RNA polymerase binds to the promoter on DNA

18. In what direction is RNA made?

5’ to 3’ direction

19. What are the RNA base-pairing rules?

A–U, T–A, C–G, G–C

20. What happens at transcription termination?

RNA polymerase reaches a stop signal and releases RNA

21. What is RNA splicing?

Introns are removed; exons are joined together

22. What is added to mRNA before it leaves the nucleus?

5’ cap and 3’ poly-A tail

23. What are the 3 steps of translation?

Initiation, Elongation, Termination

24. What starts translation?

Small ribosomal subunit binds to mRNA, then tRNA binds to start codon

25. What links amino acids during elongation?

Peptide bonds catalyzed by rRNA

26. What happens during translation termination?

Stop codon is reached, and the protein is released

27. What helps proteins fold correctly?

Chaperone proteins

28. What is an operon?

A group of genes regulated together in prokaryotes

29. What does the Lac Operon do?

Breaks down lactose using dual (positive and negative) control

30. What does the Trp Operon do?

Makes tryptophan using negative control

31. How is gene expression regulated in eukaryotes?

At transcription, splicing, mRNA degradation, and protein folding

32. What is a mutation?

A change in the DNA sequence

33. What causes mutations?

Errors during DNA replication that aren’t corrected

34. What are the effects of mutations?

Silent, beneficial, or harmful; may pass to offspring

35. Why are mutations important to evolution?

They introduce variation that natural selection can act on

1. What are the two types of cell division?

Mitosis and Meiosis

2. What is the purpose of mitosis?

Growth, repair, and asexual reproduction (produces identical cells)

3. What is the purpose of meiosis?

Creates gametes (sperm/egg) for sexual reproduction

4. What are somatic cells?

Body cells that divide by mitosis

5. What are gametes?

Sex cells (sperm and egg), made by meiosis

6. How many chromosomes do humans have in somatic cells?

46 chromosomes (23 pairs)

7. How many chromosomes do gametes have?

23 chromosomes (haploid)

8. What are sister chromatids?

Identical copies of a chromosome joined at the centromere

9. What is a centromere?

Region where sister chromatids are attached

10. What happens in the cell cycle?

Interphase (G1, S, G2) + M phase (Mitosis + Cytokinesis)

11. What happens during interphase?

Cell grows, DNA replicates, prepares to divide

12. What happens in G1 phase?

Cell growth and normal functions

13. What happens in S phase?

DNA is replicated

14. What happens in G2 phase?

Cell prepares for mitosis; organelles replicate

15. What are the 4 stages of mitosis?

Prophase, Metaphase, Anaphase, Telophase

16. What happens in prophase?

Chromosomes condense, spindle forms, nuclear envelope breaks down

17. What happens in metaphase?

Chromosomes align at the center (metaphase plate)

18. What happens in anaphase?

Sister chromatids separate and move to opposite poles

19. What happens in telophase?

Nuclear membranes reform, chromosomes uncoil

20. What is cytokinesis?

Division of the cytoplasm into two cells

21. What are checkpoints in the cell cycle?

Control points that regulate cell division

22. What is the G1 checkpoint?

Checks for size, nutrients, and DNA damage

23. What happens if a cell doesn’t pass the G1 checkpoint?

It enters G0 (resting state or permanent exit)

24. What is cancer?

Uncontrolled cell division

25. What causes cancer?

Mutations in genes that control the cell cycle

26. What are oncogenes?

Mutated genes that promote cell division (can lead to cancer)

27. What are tumor suppressor genes?

Genes that stop cell division; when mutated, cancer can develop

28. What is apoptosis?

Programmed cell death

29. What is meiosis?

A two-part division that reduces chromosome number by half

30. How many cells are made by meiosis?

4 non-identical haploid cells

31. What happens in meiosis I?

Homologous chromosomes separate

32. What happens in meiosis II?

Sister chromatids separate

33. What is crossing over?

Exchange of genetic material between homologous chromosomes during Prophase I

34. What is independent assortment?

Random distribution of chromosomes during meiosis

35. Why is meiosis important?

Increases genetic variation in offspring