Review for exam 2

Question 1

What are the four levels of protein structure and their functions?

Answer 1

-Primary: Sequence of amino acids (determines overall shape/function)
- Secondary: Alpha helices & beta sheets (stabilized by H-bonds)
- Tertiary: 3D folding of a polypeptide (determines protein’s specific function)
- Quaternary: Multiple polypeptides together (e.g., hemoglobin)

Question 2

Name 5 membrane-bound organelles and their functions.

Answer 2

1. Nucleus – Stores DNA, controls cell activities
2. Mitochondria – Produces ATP via cellular respiration
3. Endoplasmic Reticulum (ER) –
   
   • Rough ER: synthesizes proteins
   • Smooth ER: synthesizes lipids, detoxifies
4. Golgi Apparatus – Modifies, packages, ships proteins/lipids
5. Lysosome – Breaks down waste and old organelles

Question 3

What are the three parts of the cytoskeleton and their functions?

Answer 3

1. Microfilaments – Cell movement and shape (actin)
2. Intermediate filaments – Structural support and stability
3. Microtubules – Movement of organelles and chromosomes (e.g., spindle fibers)

Question 4

What is glycolysis and what happens after it?

Answer 4

• Glycolysis: Breaks glucose into 2 pyruvate, makes 2 ATP and 2 NADH
• Next steps:
  
  • With oxygen: Pyruvate enters the mitochondria → Krebs Cycle → ETC (aerobic respiration)
  • Without oxygen: Fermentation (e.g., lactic acid fermentation)
• Importance: Glycolysis is the first step in energy production

Question 5

What is lactic acid fermentation and why is it important?

Answer 5

• Process: Pyruvate → Lactic acid (using NADH, regenerates NAD⁺)
• Importance: Provides ATP when oxygen is low (e.g., during intense exercise

Question 6

How are photosynthesis and cellular respiration connected?

Answer 6

• Photosynthesis: Converts CO₂ + H₂O + light → glucose + O₂
• Cellular Respiration: Uses glucose + O₂ → CO₂ + H₂O + ATP
• Connection: The products of one are the reactants of the other

Question 7

Why and how does the Calvin Cycle depend on light-dependent reactions?

Answer 7

-Why: Needs ATP and NADPH produced in the light reactions
- How: Light reactions convert solar energy to chemical energy for use in Calvin Cycle

Question 8

Where does the Calvin Cycle occur and why is it important?

Answer 8

-Location: Stroma of the chloroplast
- Importance: Fixes carbon to make glucose (stores energy from sunlight)

Question 9

What are the products of glycolysis?

Answer 9

• 2 Pyruvate
• 2 ATP (net)
• 2 NADH