Learn: Biology Study Set

What determines how an atom forms chemical bonds?

Its valence electrons in the outermost energy level.

How does an ionic bond form?

Electrons are transferred, creating oppositely charged ions.

How does a covalent bond form?

Atoms share electrons to become more stable.

Why is water considered a polar molecule?

Uneven charge distribution makes oxygen slightly negative and hydrogen positive.

How do hydrogen bonds form between water molecules?

Slightly positive hydrogen attracts slightly negative oxygen.

What is high specific heat?

Water resists temperature changes because it takes high energy.

What is high heat of vaporization?

Water requires much energy to evaporate as hydrogen bonds break.

How do cohesion and adhesion help water transport?

Cohesion binds molecules together; adhesion sticks them to surfaces.

What is the difference between a solute and a solvent?

Solute dissolves; solvent does the dissolving.

What are the ions and pH of acids?

Release H+ ions and have a pH below 7.

What are the ions and pH of bases?

Release OH- or accept H+ and have a pH above 7.

What are the ions and pH of neutral solutions?

Equal H+ and OH- ions with a pH of 7.

What are the three main parts of an amino acid?

Amino group, carboxyl group, and R group.

What makes each amino acid different?

Its unique R group.

What happens when two amino acids join?

A peptide bond forms, releasing a water molecule.

What is the movement function of proteins?

Actin and myosin.

What is the enzyme function of proteins?

Lactase.

What is the transport function of proteins?

Hemoglobin.

What is the structure function of proteins?

Collagen.

What is the defense function of proteins?

Antibodies.

What is the signaling function of proteins?

Insulin.

What determines primary protein structure?

The specific sequence and number of amino acids.

What is secondary protein structure?

Folding into an alpha helix or beta sheet.

What is tertiary protein structure?

Further folding into a specific 3D shape.

What is quaternary protein structure?

Two or more polypeptide chains joined together.

What role do hydrogen bonds play in tertiary structure?

Weak attractions between polar groups.

What role do ionic bonds play in tertiary structure?

Attractions between charged particles.

What role do disulfide bridges play in tertiary structure?

Strong bonds between cysteine amino acids.

What role do hydrophobic and hydrophilic interactions play in tertiary structure?

They affect how amino acids arrange themselves.

How do hydrophobic amino acids affect protein folding?

They cluster toward the inside.

How can a change in amino acid sequence affect a protein?

It alters folding, shape, and proper function.

What is the difference between kinetic and potential energy?

Kinetic is movement energy; potential is stored energy.

What is the law of conservation of energy?

Energy cannot be created or destroyed, only transformed.

What is activation energy?

Minimum energy required to start a chemical reaction.

How do enzymes speed up chemical reactions?

They lower activation energy without being used up.

What is an enzyme?

A protein that speeds up a chemical reaction.

What is a substrate?

The reactant an enzyme acts on.

What is an active site?

The specific location where the substrate binds.

What is induced fit?

Enzymes slightly change shape to fit their substrates closely.

Why are enzymes specific to certain substrates?

Active sites have particular shapes matching specific substrates.

What happens when an enzyme is exposed to high temperatures?

It denatures, changing shape and losing function.

How do temperature and pH affect enzyme activity?

Extremes alter shape, reducing activity or causing denaturation.

What is the role of the phospholipid bilayer in the plasma membrane?

Forms the membrane structure.

What is the role of proteins in the plasma membrane?

Help move substances in and out.

What is the role of carbohydrate chains in the plasma membrane?

Attach to proteins and phospholipids.

What is the role of cholesterol in the plasma membrane?

Stabilizes membrane fluidity.

What is the difference between hydrophilic heads and hydrophobic tails?

Heads are attracted to water; tails repel water.

What is passive transport?

Movement across a membrane without energy, down concentration gradient.

What is diffusion?

Movement of solutes from high to low concentration without energy.

What happens at equilibrium during diffusion?

Particles move equally in both directions with no net concentration change.

What is facilitated diffusion?

Passive transport using channel or carrier proteins without energy.

What is the difference between channel and carrier proteins?

Channels provide passageways; carriers bind and change shape.

What is osmosis?

The movement of water across a selectively permeable membrane.

What is an isotonic solution?

Equal solute concentrations; no net water movement.

What is a hypertonic solution?

Higher outside solute concentration causing water to move out.

What is a hypotonic solution?

Lower outside solute concentration causing water to move in.

What happens to an animal cell in a hypertonic solution?

Water leaves, causing it to shrink.

What happens to an animal cell in a hypotonic solution?

Water enters, causing it to swell and burst.

What happens to a plant cell in a hypotonic solution?

Water enters, making it turgid due to the cell wall.

What is active transport?

Movement against concentration gradient, requiring energy.

What are protein pumps?

Membrane proteins using ATP to move substances against gradients.

What is endocytosis?

A vesicle brings substances into the cell.

What is exocytosis?

A vesicle releases substances outside the cell.