Biological Molecules Quiz

Biological Molecules

• Biomolecules are the molecular players, structures, and organelles of the cell.
• They have distinct structures and biochemical properties.
• Most biomolecules are polymers, made of repeating subunits called monomers.
• Examples of polymers are nucleic acids, proteins, and carbohydrates.
• Lipids are not polymers.

Condensation & Hydrolysis Reactions

• Polymers are composed of smaller repeating subunits called monomers.
• Polymers are formed from monomers through condensation (dehydration) reactions.
• Condensation reactions join monomers together by covalent bonds while removing a water molecule.
• Energy is added during condensation reactions.
• Polymers are broken down into monomers through hydrolysis reactions.
• Hydrolysis reactions break covalent bonds by adding a water molecule.
• Energy is released during hydrolysis reactions.

Lipids

• Lipids are a diverse group of fatty, water-insoluble compounds.
• Lipids are composed Primarily of C, H, and O, but with fewer oxygen atoms compared to carbohydrates.
• Lipids function as energy storage, components of cellular membranes, and hormones.
• Types of lipids include:
  • Acylglycerides (neutral fats)
  • Phospholipids
  • Steroids
  • Waxes
  • Eicosanoids

Lipids: Triacylglycerides

• Triacylglycerides (triglycerides) are fats or oils.
• They are composed of glycerol and three fatty acids.
• Fatty acids vary in length (14–20 carbons) and in the number of double bonds.
  • Saturated fatty acids have no double bonds.
  • Unsaturated fatty acids have one or more double bonds.
• Triacylglycerides function as long-term energy storage, structural support, and insulation.
• Lipogenesis creates triglycerides from glycerol and fatty acids.
• Lipolysis breaks down triglycerides into glycerol and fatty acids.

Lipids: Phospholipids

• Phospholipids are modified triglycerides.
• Phospholipids have a polar (hydrophilic) head and nonpolar (hydrophobic) tails.
• They arrange themselves in an aqueous environment to form a lipid bilayer, a crucial component of cell membranes.

Lipids: Steroids

• Steroids are flat molecules with four interlocking hydrocarbon rings, with cholesterol as their basic backbone.
• They are synthesized in the liver and absorbed from the diet (milk, eggs, animal fats).
• Steroids are necessary for hormone production and are found in cell membranes.

Lipids: Eicosanoids

• Eicosanoids are a diverse family of 20-carbon fatty acids.
• They are derived from arachidonic acid.
• Eicosanoids include prostaglandins, prostacyclins, thromboxanes, and leukotrienes.
• They function as signaling molecules in inflammation, blood clotting, and labor contractions.

Lipids: Waxes

• Waxes are composed of a fatty acid and a long-chain alcohol linked by an ester bond.
• Waxes function as protective barriers, such as in cerumen (earwax).

Carbohydrates

• Carbohydrates are simple sugars and sugar polymers.
• They are classified by size:
  • Monosaccharides: Simple sugars
  • Disaccharides: Two simple sugars linked by covalent bonds. - Polysaccharides: Many monosaccharides.
• Carbohydrates contain C, H, and O in a fixed ratio (CH₂O)n.
• Most have 3 to 7 carbons.
• They are formed by condensation reactions & useful for "food" (energy) storage and as structural molecules.

Nucleic Acids

• Nucleic acids are the largest molecules in the body, which store and transfer genetic information within cells.
• Two major classes:
  • DNA (deoxyribonucleic acid).
  • RNA (ribonucleic acid).
• Nucleic acids are polymers of nucleotides.
• Nucleotides have three components:
  • A pentose sugar (ribose or deoxyribose). - A phosphate group
  • A nitrogenous base.
• Covalent linkages between nucleotides are phosphodiester bonds. - DNA is a double helix, with strands running antiparallel, and bases pairing (A with T, and C with G).
• RNA is usually single-stranded.

ATP: The Battery of the Cell

• ATP (adenosine triphosphate) is a molecule that stores chemical energy for cellular purposes.
• ATP has an adenine, ribose sugar, and three phosphate groups.
• Energy is stored in the bonds between phosphate groups.
• ATP is an unstable molecule because the phosphate groups repel each other.

DNA

• DNA is a long, double-stranded polymer.
• DNA's backbone consists of alternating sugar and phosphate molecules.
• The two strands run antiparallel and are held together by hydrogen bonds between complementary base pairs (A with T, and C with G).

RNA

• RNA is a single-stranded chain of nucleotides.
• RNA's structure is often more complex than DNA's.
• RNA has uracil (U) in place of thymine (T).
• RNA plays various roles in protein synthesis.

Central Dogma of Genetics

• DNA encodes the information that programs all cellular activities (genes).
• RNA is the specific instruction (information from a gene) to create a specific protein.
• Proteins are the tools (or machinery) of cellular function.

Proteins

• Proteins are the basic structural material of the body built from long chains of amino acids.
• Proteins play vital roles in cell function.
• Protein classes and functions include: -Structural -Enzymatic -Regulatory -Motile -Transport -Storage -Defensive

Amino Acids

• Amino acids are the building blocks of proteins.
• Twenty common amino acids.
• Each amino acid has a central carbon atom bonded to an amino group (-NH₂), a carboxyl group (-COOH), and a variable R group.
• The R group makes each amino acid unique.

Peptide Bonds

• The linking of two amino acids between the amine and carboxyl group.
• This linking is a condensation reaction.
• The resulting polypeptide chain is like a sentence.

Chaperone Proteins

• Chaperone proteins assist in protein folding helping proteins to achieve their functional 3D structure - and prevent accidental, premature, or incorrect folding..

Structure Levels of Proteins

• Primary structure: The linear sequence of amino acids
• Secondary structure: Polypeptide segments exhibiting structural patterns, such as alpha-helices and beta-sheets, based on interactions between R groups.
• Tertiary structure: The sum total of the secondary structures, providing the protein's final 3-dimensional shape with multiple bonds maintaining the structure.
• Quaternary structure: Aggregate of two or more polypeptide chains, maintained by interactions between subunits (hydrophobic interactions, van der Waals forces, ionic bonds, hydrogen bonds).

Denaturation

• Denaturation is a process that causes proteins to unfold and lose their shape.
• It can occur due to changes in pH, increases in temperature, and high concentrations of polar substances.
• Denaturation is frequently irreversible.

Enzymes

• Enzymes are biological catalysts that speed up chemical reactions, but are not consumed by those reactions.
• Enzymes are highly specific for a particular reaction.
• Most enzymes are proteins, but some are RNA (ribozymes).
• Enzymes function via an active site, a region where a substrate molecule binds.
• Binding modifies the enzyme slightly leading to induced fit between enzyme and substrate.
• Enzymes act by reducing the activation energy and enhancing reaction rates.
• Enzyme activity is influenced by factors such as substrate concentration, temperature, and pH.

Mechanism of Enzyme Actions

• Enzymes facilitate reactions by forming an enzyme-substrate complex
• The enzyme-substrate complex is stabilized by various interactions, and then undergoes an induced fit to modify the bonds in the substrate, and facilitate the breaking of bonds, and rearrangement of atoms to form products.
• The enzyme and products dissociate, enzyme remains unchanged.