ap bio semester 1 final

AP Biology Study Guide: Systems Interactions

Unit 1: Chemistry of Life

1. Properties of Water (Due to Hydrogen Bonding)

Cohesion & Adhesion:

Cohesion: Water molecules stick to each other via hydrogen bonds (important for surface tension).

Adhesion: Water sticks to other surfaces (important for capillary action in plants).

Universal Solvent:

Water dissolves many substances due to its polarity, allowing for biochemical reactions in cells.

Surface Tension:

Hydrogen bonding creates a strong surface layer, allowing small organisms to walk on water.

Ice Floating: Water expands when frozen, making ice less dense than liquid water, which insulates aquatic ecosystems.

High Specific Heat Capacity: Water absorbs and retains heat, stabilizing temperatures in organisms and ecosystems.

2. Polymer Formation (Dehydration Synthesis & Hydrolysis)

Dehydration Synthesis: Monomers bond to form polymers by removing water.

Hydrolysis: Polymers break down into monomers by adding water.

3. Biological Macromolecules

4. Protein Structure & Function

Primary Structure: Sequence of amino acids.

Secondary Structure: Alpha helices & beta sheets (formed by hydrogen bonds).

Tertiary Structure: 3D folding due to R-group interactions (hydrophobic, hydrophilic, ionic, disulfide bridges).

• Quaternary Structure: Multiple polypeptides interacting (e.g., hemoglobin).

• Denaturation: Loss of shape (due to pH, temperature, etc.), leading to loss of function.

Unit 2: Cell Structure & Function

1. Common Features of All Cells

Plasma membrane, cytoplasm, ribosomes, DNA.

2. Prokaryotic vs. Eukaryotic Cells

3. Protein Pathway (Gene to Excretion)

1. Nucleus: DNA transcribed into mRNA.

2. Ribosomes: mRNA translated into proteins.

3. Rough ER: Modifies & folds proteins.

4. Golgi Apparatus: Packages proteins into vesicles.

5. Plasma Membrane: Vesicles fuse, proteins are secreted.

4. Organelle Functions

Nucleus: Stores genetic material, site of transcription.

Ribosomes: Protein synthesis.

Smooth ER: Lipid synthesis, detoxification.

Rough ER: Protein synthesis & processing.

Golgi Apparatus: Modifies, sorts, and ships proteins.

Lysosomes: Digestive enzymes for waste breakdown.

Central Vacuole (plants): Stores water & nutrients.

Mitochondria: Produces ATP via cellular respiration.

Chloroplasts (plants): Site of photosynthesis.

Unit 2: Energetics

1. Compartmentalization & Organelle Function

Golgi Apparatus: Isolates modifications of proteins.

Mitochondria: Separates metabolic reactions for ATP production.

Chloroplasts: Compartmentalizes photosynthesis.

2. Surface Area-to-Volume Ratio (SA/V)

Smaller cells have a higher SA/V, increasing efficiency in nutrient exchange.

3. Plasma Membrane Structure & Transport

Fluid Mosaic Model: Phospholipid bilayer with embedded proteins.

Transport Mechanisms:

Passive Transport (no energy): Diffusion, osmosis.

Facilitated Diffusion: Uses transport proteins.

Active Transport (requires ATP): Pumps, endocytosis, exocytosis.

Unit 3: Cellular Metabolism

1. Enzyme Function

Lower activation energy for reactions.

Affected by:

pH (enzymes denature at extreme pH).

Temperature (high temps denature proteins).

Substrate & enzyme concentration (affects reaction rate).

2. Photosynthesis

Equation:

Stages:

Light Reactions: Convert light to ATP & NADPH (in thylakoid membrane).

Calvin Cycle: Uses ATP & NADPH to synthesize glucose (in stroma).

3. Cellular Respiration

Equation:

Stages:

1. Glycolysis (cytoplasm)

2. Krebs Cycle (mitochondria)

3. Electron Transport Chain (mitochondria)

Unit 4: Information Storage & Transmission

1. Feedback Loops

Negative Feedback: Maintains homeostasis (e.g., body temp regulation).

Positive Feedback: Amplifies response (e.g., childbirth contractions).

2. Types of Cell Communication

Direct Contact: Gap junctions (animal cells) & plasmodesmata (plant cells).

Local Signaling: Paracrine signaling (short-distance).

Long-Distance Signaling: Hormones via the bloodstream.

3. Cell Cycle & Checkpoints

Phases:

Checkpoints:

G1 Checkpoint: Cell size & DNA damage check.

G2 Checkpoint: Ensures DNA replication is complete.

M Checkpoint: Ensures spindle attachment before mitosis.