OAT Booster Biology Set #1

1 Biochemistry 2 Cells and Organelles

What are the three main components of atoms?

Neutrons, protons, and electrons.

What defines a molecule?

Groups of 2 or more atoms held together by chemical bonds due to electron interactions.

What are macromolecules?

Large molecules (polymers) formed from bonding of smaller molecules (monomers).

What is an ionic bond?

Transfer of electrons from one atom to another with very different electronegativity.

Describe a covalent bond.

Sharing of electrons between atoms of similar electronegativities.

What is the difference between nonpolar and polar covalent bonds?

Nonpolar: equal sharing of electrons.

Polar: unequal sharing forming a dipole.

What is a hydrogen bond?

A weak bond between a hydrogen atom and an electronegative atom (O, F, or N) that gives water unique properties.

What occurs in a dehydration reaction?

Monomers link to form polymers, releasing H₂O in the process.

What is hydrolysis?

The use of H₂O to break polymers into monomers.

What is the monomer of proteins?

Amino acid.

What type of bonds link amino acids in proteins?

Peptide bonds.

What are the primary functions of proteins?

Structure, transport, defense, storage, enzymes. (TEDSS)

What are the protein structure levels and what are they composed of (like slpha helix , beta sheet etc)?

Primary (linear sequence), Secondary (α-helix/β-pleated sheets), Tertiary (3D shape), Quaternary (aggregation of polypeptide chains).

What is the monomer of carbohydrates?

Monosaccharide (single sugar molecule).

What types of carbohydrates exist and what are they composed of?

Monosaccharides, Disaccharides (2 sugar molecules), Polysaccharides (polymers of sugars like starch, glycogen, cellulose).

What is the linkage type in carbohydrates?

Glycosidic.

What is the main function of carbohydrates?

Store energy.

Are lipids polar or nonpolar?

Nonpolar, hydrophobic molecules.

What are the monomers of lipids?

Hydrocarbons.

What bonds link lipids?

Covalent carbon-carbon bonds.

What are three major types of lipids?

Triglycerides, Phospholipids, Steroids.

What defines triglycerides (structure) ?

Glycerol + 3 fatty acids, with saturated (single bonds) or unsaturated (double bonds) fatty acids.

What are phospholipids composed of?

2 fatty acids + phosphate group attached to glycerol backbone.

What structural feature is specific for steroids?

Three 6-membered rings + one 5-membered ring.

What is the monomer of nucleic acids?

Nucleotide.

What type of bonds link nucleotides?

• Phosphodiester bonds.

What are the main functions of nucleic acids?

Encode, express, and store genetic information.

What composes a nucleotide?

Nitrogenous base + 5' sugar + phosphate group.

What are the nitrogenous bases in DNA?

Adenine (A), Thymine (T), Cytosine (C), Guanine (G).

What nitrogenous base replaces something in RNA? What does it replace?

Uracil (U) replaces Thymine (T)

What pairs with Adenine in DNA? and with how many H bonds

• Thymine via 2 H-bonds.

What pairs with Guanine in DNA?

Cytosine via 3 H-bonds.

What rule describes the base pairing ratios in DNA?

• Chargaff's Rule: A & T and G & C present in equal amounts.

What bases are found in RNA?

A, U, C, G; RNA is single stranded.

How are porphyrins structured?

Four joined pyrrole rings with a metal center atom.

Give examples of important molecules that contain a porphyrin ring.

Chlorophyll and hemoglobin.

Are porphyrins lipids or non-lipids?

Non-lipids, but they are commonly associated with lipid membranes.

What is the basic unit of life?

The cell

What organelle contains the cell's DNA and coordinates activities such as protein synthesis and reproduction?

Nucleus

What does the nucleus do?

Contains the cell's DNA and coordinates activities such as protein synthesis and reproduction

What region in prokaryotes contains genetic material but is not membrane-bound?

Nucleoid region

What is the site of ribosome (rRNA) synthesis in the nucleus?

Nucleolus

What does the nucleolus do?

Its the site of ribosome (rRNA) synthesis in the nucleus

What organelle has ribosomes attached to its membrane and synthesizes and stores proteins?

Rough Endoplasmic Reticulum (RER)

What organelle synthesizes lipids and steroid hormones, detoxifies drugs, and stores Ca²⁺?

Smooth Endoplasmic Reticulum (SER)

Which organelle modifies and packages proteins such as glycosylated polypeptides?

Golgi apparatus

What organelle is double layered, makes ATP, and contains its own circular DNA?

Mitochondria

Which organelles contain digestive enzymes and break down bacteria, cell debris, and nutrients?

Lysosomes

Which organelle breaks down peroxides (H₂O₂) into water?

Peroxisomes

What is the function of ribosomes?

Make proteins; found in both prokaryotes and eukaryotes

What type of molecules does the cell membrane allow to freely pass through?

Small, uncharged, hydrophobic molecules

How does the membrane cholesterol content affect fluidity?

Unsaturated fatty acids ↑ membrane fluidity; saturated fatty acids ↓ fluidity

What are the functions of channel proteins?

Passage of water-soluble, polar, and charged substances; includes ion channels and pumps

What is the function of carrier proteins?

Pass specific molecules/ions across cell membranes after binding and changing shape

What is the role of transport proteins?

Use ATP to actively transport materials across the membrane

What is passive transport? What types do they include?

Movement of molecules without ATP; includes diffusion, osmosis, dialysis, plasmolysis, and facilitated diffusion

What does active transport require and what does it move?

Requires ATP; moves solutes like small ions, amino acids, and monosaccharides against their gradient

What is endocytosis?

Plasma membrane invaginates to engulf material; includes phagocytosis (solid) and pinocytosis (liquid)

What is exocytosis?

Membrane vesicles exit large molecules (e.g., receptors) by membrane pinching outward

What is the primary role of the cytoskeleton?

Maintain cell shape and movement

What are microtubules composed of and what are their functions?

Composed of tubulin; involved in spindle fiber formation, cilia (short hair-like extensions), and flagella (long thread-like extensions)

What are intermediate filaments composed of and their function?

Composed of keratin; maintain cell shape

What are microfilaments composed of and their functions?

Composed of actin; used for cell shape and division

What is the function of the extracellular matrix? What is the most abundant?

Provides mechanical support and helps connect adjacent cells; collagen is most abundant

What structures are found in plant cells?

Cell walls, plastids (e.g., chloroplasts), vacuoles

Name some key traits of prokaryotes:

• No nucleus (nucleoid)

• Single, circular, naked, double-stranded DNA

• Ribosomes (50S + 30S = 70S)

• Bacteria have peptidoglycan cell walls; Archaea have polysaccharides and sticky capsules

• Flagella are made of flagellin, not microtubules

What happens to a cell in a hypertonic solution?

Higher solute outside; water flows out, causing cell shrinkage

What happens in hypotonic solution?

Lower solute outside; water flows into cell, causing swelling

What happens in isotonic solution?

Equal solute concentration inside and outside; no net water flow

What does an anchoring junction do?

Includes desmosomes; connects cells in sheets

What is the function of a tight junction?

Encircles each cell; prevents passage of materials between cells; found in digestive tract

What does a gap junction allow?

Narrow tunnels enabling passage of ions and small molecules between animal cells

What are the three types of cell junctions and their functions?

• Anchoring junctions: Connect cells with desmosomes

• Tight junctions: Seal cells to prevent passage of materials (in digestive tract)

• Gap junctions: Allow passage of ions & small molecules between animal cells