CELL BIO EXAM 1

What is cell biology?

The study of cells—their structure, function, and interactions—and how cellular components work together to maintain life.

Why are cells considered fundamental to life?

They are the basic structural and functional units of all living organisms.

What early limitations slowed progress in cell biology?

Poor microscopes, lack of methods to isolate cell components, and limited biochemical knowledge.

Why were early microscopes a barrier to scientific progress?

They couldn’t reveal fine cellular structures or allow accurate molecular analysis.

What are the three main principles of Cell Theory?

All organisms are made of cells; cells are the basic unit of life; all cells arise from pre‑existing cells.

What does a light microscope allow scientists to see?

Living cells and basic cellular structures.

What is the main advantage of electron microscopes?

High resolution that reveals organelles and molecular complexes.

What do fluorescence microscopes highlight?

Specific proteins or structures using fluorescent tags that bind to antigens.

What is centrifugation used for?

Separating cellular components based on density.

What does gel electrophoresis analyze?

DNA or proteins by separating them based on size and charge.

What is chromatography used for?

Purifying molecules such as proteins or nucleic acids.

What does sequencing allow scientists to determine?

The precise order of nucleotides in DNA.

Why are model organisms essential in cell biology?

They are easy to study, manipulate, and produce results that apply broadly across biology.

What do model organisms help scientists uncover?

Universal cellular mechanisms.

Name common model organisms.

E. coli, yeast, Drosophila, C. elegans, zebrafish, and mice.

What are proteins?

Large biological molecules made of amino acids linked together in specific sequences.

What are the four parts of an amino acid?

An amino group, carboxyl group, hydrogen, and an R‑group.

What makes amino acids different from one another?

The chemical properties of their R‑group.

What are the four stages of protein maturation?

Primary, secondary, tertiary, and quaternary structure.

What is protein denaturation?

Loss of protein shape due to heat, chemicals, or pH changes, causing loss of function.

What can protein misfolding lead to?

Loss of function or harmful aggregates linked to diseases like Alzheimer’s.

What are nucleic acids made of?

Monomers called nucleotides.

What are the two types of nucleic acids?

DNA and RNA.

How do DNA and RNA differ?

DNA stores long‑term genetic information; RNA helps express and translate genes.

What is the flow of genetic information called?

DNA → RNA → Protein, known as the central dogma.

What does a nucleotide consist of?

A phosphate group, a sugar, and a nitrogenous base.

How do nucleosides differ from nucleotides?

Nucleosides contain only a sugar and base; nucleotides also include a phosphate group.

What are purines?

double‑ring nitrogenous bases (A, G)

What are pyrimidines?

single‑ring bases (C, T, U)

How do purines and pyrimidines differ?

Purines have two rings; pyrimidines have one.

What is complementary base pairing?

Specific pairing where A bonds with T (or U) and G bonds with C.

What are the four classes of biological macromolecules?

Proteins, nucleic acids, carbohydrates, and lipids.

What are polymers?

Long chains of repeating monomers.

What are monomers?

Small building‑block molecules that form polymers.

What are enzymes?

Protein catalysts that speed up chemical reactions.

What occurs during dehydration synthesis?

Monomers join together by removing water to form covalent bonds.

What occurs during hydrolysis?

Water is added to break covalent bonds and split polymers into monomers.

What are carbohydrates and what are they used for in the cell?

Energy‑rich molecules used for fuel, structure, and cell recognition.

What are monosaccharides?

Single sugar units (e.g., glucose) that serve as basic energy sources.

What are disaccharides?

Two monosaccharides linked together (e.g., sucrose, lactose).

What are polysaccharides?

Long chains of monosaccharides used for storage or structural support.

What are examples of polysaccharides found in plants

Starch and cellulose.

What an example of a polysaccharide found in animals?

glycogen.

What is the most common monosaccharide?

Glucose.

Monosaccharides are classified by what?

The number of carbons and the type of carbonyl group (aldose or ketose).

What are fats composed of?

Glycerol attached to three fatty acids (a triglyceride).

What is a saturated fat?

Fats that have no double bonds and are solid at room temperature

What is a unsaturated fat?

Fats that have double bonds with kinks and are liquid at room temperature

What is a phospholipid and what do they form?

Two fatty acids and a phosphate head, they form the cell membrane bilayer.

What are steroids and provide an example.

Lipids with a four‑ring structure, an example is cholestrerol

What is a peptide bond?

A covalent bond linking amino acids together in proteins.

What is an ester linkage?

A bond formed between glycerol and fatty acids in lipids.

What is a glycosidic linkage?

A covalent bond connecting monosaccharides to form carbohydrates.

What is a phosphodiester bond?

A bond linking nucleotides together in nucleic acids (DNA and RNA).

What are hydrogen bonds used for in biology?

Weak interactions that stabilize structures like DNA base pairs and protein folding.