BIO 160 – Exam 1 Preview

A set of question-and-answer flashcards covering key topics for BIO 160 Exam 1, including cell organelles, membrane transport, thermodynamics, macromolecules, chemical bonds, and enzyme function.

What are the two broad categories of membrane transport?

Passive transport and active transport.

Which organelle is the primary site of protein synthesis in a cell?

The Rough Endoplasmic Reticulum (Rough ER).

Which organelle is known as the "powerhouse" of the cell because it produces most cellular ATP?

The mitochondrion.

Which cellular structure sorts and packages proteins and lipids received from the ER?

The Golgi apparatus.

Name three factors that influence membrane fluidity.

Cholesterol content, the saturation level of fatty acids, and temperature.

State the First Law of Thermodynamics.

Energy cannot be created or destroyed; the total energy of the universe is constant.

State the Second Law of Thermodynamics.

Every energy transformation increases the entropy (disorder) of the universe.

Why do saturated fatty acids generally have higher melting points than unsaturated fatty acids?

Their straight chains pack tightly, requiring more energy (heat) to separate them.

Which type of reaction releases energy, endergonic or exergonic?

Exergonic reactions release energy.

Which polysaccharide serves primarily as energy storage in plants?

Starch.

Which polysaccharide is the main structural component of plant cell walls?

Cellulose.

Give one key structural difference between a triglyceride and a phospholipid.

A triglyceride has three fatty-acid tails, whereas a phospholipid has two fatty-acid tails and a phosphate-containing head.

What is the chemical difference between ribose and deoxyribose?

Deoxyribose lacks one oxygen atom at the 2' carbon that ribose possesses (deoxyribose has H, ribose has OH).

List the three subatomic particles that make up an atom.

Protons, neutrons, and electrons.

Where are peripheral proteins typically located in relation to the membrane?

They are attached to the membrane surface, often bound to integral proteins.

What happens to a red blood cell placed in a hypotonic solution?

It swells and may burst (lyse).

What happens to a red blood cell placed in a hypertonic solution?

It shrinks (crenates).

What distinguishes isotopes of the same element?

They have the same number of protons but different numbers of neutrons, giving different atomic masses.

Give two essential roles of microtubules in eukaryotic cells.

They form tracks for vesicle/organelle transport and make up the mitotic spindle for chromosome separation (also cilia/flagella structure).

How do allosteric regulators modify enzyme activity?

They bind to a site other than the active site, inducing a conformational change that alters activity.

Define atomic number.

The number of protons in the nucleus of an atom.

Which property of water is chiefly responsible for surface tension?

Cohesion due to hydrogen bonding between water molecules.

Animal cells contain but lack .

Lysosomes; chloroplasts.

How many valence electrons does carbon have?

Four.

When electrons are shared equally between two atoms, what type of bond forms?

A non-polar covalent bond.

Why do lipids not dissolve in water?

They are hydrophobic (nonpolar) and therefore insoluble in polar solvents like water.

What type of bond typically forms between atoms with very large differences in electronegativity?

An ionic bond.

A peptide bond forms between the group of one amino acid and the group of another.

Amino; carboxyl.

What combined forces allow water to move upward through plant xylem against gravity?

Cohesion between water molecules and adhesion to xylem walls (capillary action).

The backbone linkage between nucleotides in nucleic acids is a _ bond.

Phosphodiester bond.

The base pairs in double-stranded DNA are held together by _ bonds.

Hydrogen bonds.

Why can small non-polar molecules cross the cell membrane easily?

They can diffuse through the hydrophobic lipid bilayer.

Distinguish passive transport from active transport.

Passive transport requires no energy input; active transport requires ATP (energy).

What are the four major classes of biological macromolecules?

Proteins, lipids, carbohydrates, and nucleic acids.

List the four levels of protein structure in order.

Primary, secondary, tertiary, and quaternary.

Where on an enzyme does substrate binding and catalysis occur?

At the active site.

Which structural feature of DNA ensures accurate replication?

Its double-helix with complementary base pairing.