Unit 1 Biochemistry

What are the four macromolecules?

Carbohydrates, Lipids, Proteins, Nucleic Acids

What elements make up each macromolecule?

• Carbohydrates: C, H, O

• Lipids: C, H, O (sometimes P)

• Proteins: C, H, O, N (sometimes S)

• Nucleic Acids: C, H, O, N, P

What are the monomers of each macromolecule?

• Carbohydrates: Monosaccharides

• Lipids: Glycerol + Fatty Acids

• Proteins: Amino Acids

• Nucleic Acids: Nucleotides

What are the functions of carbohydrates?

• Quick energy source

• Structural support (cellulose in plants, chitin in fungi/insects)

What are the three types of carbohydrates?

• Monosaccharides (single sugar, e.g., glucose, fructose)

• Disaccharides (two sugars, e.g., sucrose, lactose)

• Polysaccharides (many sugars, e.g., starch, glycogen, cellulose)

How do dehydration synthesis and hydrolysis affect carbohydrates?

• Dehydration Synthesis: Forms disaccharides and polysaccharides by removing water

• Hydrolysis: Breaks down polysaccharides into monomers by adding water

What are the functions of lipids?

• Long-term energy storage

• Cell membrane structure (phospholipids)

• Insulation and protection

• Hormone production (steroids, e.g., testosterone, estrogen)

What are the types of lipids?

• Triglycerides (fats and oils, made of glycerol + 3 fatty acids)

• Phospholipids (make up cell membranes)

• Steroids (cholesterol, hormones)

What is the difference between saturated and unsaturated fats?

• Saturated fats: No double bonds, solid at room temperature (e.g., butter)

• Unsaturated fats: Double bonds, liquid at room temperature (e.g., olive oil)

What are the functions of proteins?

• Enzymes (speed up chemical reactions)

• Structure (muscles, skin, hair)

• Transport (hemoglobin in blood)

• Defense (antibodies in immune system)

• Signaling (hormones like insulin)

What are the four levels of protein structure?

• Primary: Amino acid sequence

• Secondary: Alpha-helix and beta-sheet (due to hydrogen bonding)

• Tertiary: 3D shape due to interactions between R-groups

• Quaternary: Multiple polypeptides combined

What is denaturation?

• Denaturation is the loss of a protein’s shape due to heat, pH, or chemicals.

• If the shape is lost, the protein can no longer function.

What are the functions of nucleic acids?

• Store and transmit genetic information

What are the two types of nucleic acids?

• DNA (Deoxyribonucleic Acid) – Stores genetic info

• RNA (Ribonucleic Acid) – Helps make proteins

What are the three parts of a nucleotide?

• Sugar (deoxyribose in DNA, ribose in RNA)

• Phosphate group

• Nitrogenous base (A, T, G, C in DNA; A, U, G, C in RNA)

How do DNA and RNA differ?

• DNA: Double-stranded, contains thymine (T), stores genetic info

• RNA: Single-stranded, contains uracil (U) instead of thymine, helps in protein synthesis

What are enzymes?

Proteins that act as biological catalysts (speed up chemical reactions)

How do enzymes work?

• Lower activation energy needed for a reaction

• Bind to a substrate at the active site

• Form enzyme-substrate complex, catalyzing reaction

What affects enzyme activity?

• Temperature: Too hot = denaturation

• pH: Too acidic or too basic = enzyme loses function

• Substrate concentration: More substrate = faster reaction until enzyme is saturated

What is the "lock and key" model vs. "induced fit" model?

• Lock and Key Model: Enzyme’s active site is a perfect fit for the substrate

• Induced Fit Model: Active site changes shape slightly to fit substrate better

Why is water important in biochemistry?

• Universal solvent (dissolves many substances)

• High heat capacity (absorbs heat, stabilizes temperature)

• Cohesion (water molecules stick to each other, surface tension)

• Adhesion (water sticks to other surfaces, capillary action)

What are hydrogen bonds?

Weak bonds between water molecules due to polarity

What is pH?

• pH measures how acidic or basic a solution is (0-14 scale)

• Acidic (0-6), Neutral (7), Basic (8-14)

What are buffers?

• Substances that resist pH changes by absorbing or releasing H+ ions

• Help maintain homeostasis in cells

How can we test for macromolecules?

• Benedict’s Test: Tests for simple sugars (turns orange if positive)

• Iodine Test: Tests for starch (turns blue-black if positive)

• Biuret Test: Tests for proteins (turns purple if positive)

• Sudan III Test: Tests for lipids (red layer appears if positive)

What is the role of ATP in biochemical reactions?

ATP (Adenosine Triphosphate) provides energy for cellular processes by breaking its phosphate bonds.

What is the difference between competitive and non-competitive enzyme inhibitors?

• Competitive: Inhibitor binds to the active site, blocking the substrate.

• Non-competitive: Inhibitor binds elsewhere, changing the enzyme’s shape.

What are purines and pyrimidines?

• Purines: Adenine (A), Guanine (G) (double-ring)

• Pyrimidines: Cytosine (C), Thymine (T), Uracil (U) (single-ring)

What are coenzymes and cofactors?

• Coenzymes: Organic molecules that help enzymes (e.g., vitamins)

• Cofactors: Inorganic substances that help enzymes (e.g., metal ions like Mg²⁺)

What is the difference between essential and non-essential amino acids?

• Essential: Must be obtained from diet (body cannot make them)

• Non-essential: Body can synthesize them

What is an amphipathic molecule?

A molecule with both hydrophilic and hydrophobic parts (e.g., phospholipids)

What type of bond forms between amino acids to create proteins?

Peptide bond (formed through dehydration synthesis)

What is the difference between an anabolic and a catabolic reaction?

• Anabolic: Builds larger molecules (requires energy, e.g., protein synthesis)

• Catabolic: Breaks down molecules (releases energy, e.g., cellular respiration)

What is an allosteric site on an enzyme?

A site other than the active site where molecules can bind to regulate enzyme activity.

What is the function of disulfide bonds in proteins?

They provide structural stability by forming strong covalent links between cysteine residues in a protein.

What are coenzymes and cofactors?

• Coenzymes: Organic molecules that help enzymes (e.g., vitamins)

• Cofactors: Inorganic substances that help enzymes (e.g., metal ions like Mg²⁺)

What is an example of a protein with quaternary structure?

Hemoglobin: Made up of 4 polypeptide chains.