Biological Compounds - AP Bio

polymer, lipids, nucleic acids, carbs, proteins. Sources OpenStax. Biology 2e — Biological macromolecules, Carbohydrates, Lipids, Proteins, and Nucleic acids. OpenStax +4 MedlinePlus, U.S. National Library of Medicine — Dietary fats and Cholesterol. MedlinePlus +1

What is a polymer?

A large molecule made of smaller repeating units called monomers, joined by covalent bonds.

Why are carbohydrates, lipids, and proteins called macromolecules?

Carbohydrates, lipids, and proteins are called macromolecules because they are large, complex biological molecules. However, carbohydrates and proteins can form polymers, while lipids are not true polymers. Lipids are made of smaller molecules rather than monomers.

How many calories per gram does each provide?

Carbohydrates: 4 calories/g

Proteins: 4 calories/g

Lipids: 9 calories/g

What do our bodies use carbohydrates for?

They provide the body's main readily available energy source. Excess glucose can be stored as glycogen in the liver and muscles.

What is the molecular formula for glucose?

C₆H₁₂O₆

Similarities and differences between monosaccharides, disaccharides, and polysaccharides.

All are carbohydrates made of carbon, hydrogen, and oxygen, but monosaccharides have one sugar unit, disaccharides have two, and polysaccharides have many.

Give an example of monosaccharides, disaccharides, and polysaccharides and their biological importance.

Monosaccharide: Glucose — provides energy for cellular respiration.

Disaccharide: Sucrose — provides energy when broken down into glucose and fructose.

Polysaccharide: Glycogen — stores glucose for later energy use.

Diagram: dehydration synthesis vs. hydrolysis

Dehydration synthesis (builds)

Monomer + Monomer → Larger molecule + H₂O

Water is removed to form a bond.

Hydrolysis (breaks down)

Larger molecule + H₂O → Monomer + Monomer

Water is added to break a bond.

Dehydration synthesis joins smaller molecules by removing water, while hydrolysis uses water to break their bonds.

How can marathon runners prevent hitting the wall?

Eat enough carbohydrates before the race to build glycogen stores, consume carbohydrates during the race, and stay hydrated. This helps delay glycogen depletion and maintain energy.

Why is a no-fat or extremely low-fat diet a bad idea?

Lipids store energy, form cell membranes, and insulate the body. Dietary fats also help absorb vitamins A, D, E, and K and provide essential fatty acids.

Why are fats suited for long-term energy storage?

Fats provide 9 calories per gram, storing more energy per gram than carbohydrates or proteins. They are also insoluble in water, allowing energy to be stored without drawing in large amounts of water.

What molecules make a triglyceride?

One glycerol molecule and three fatty acid molecules join to form a triglyceride, releasing three water molecules.

What is cholesterol, why is it important, and why can too much be harmful?

Cholesterol is a lipid used to build cell membranes and make steroid hormones, vitamin D, and bile acids. Your body makes all the cholesterol it needs, so dietary cholesterol is not essential; high LDL cholesterol can contribute to artery plaque and increase heart disease risk.

What is the monomer of proteins? What makes up proteins?

Amino acids are the monomers that make up proteins. They join through peptide bonds to form polypeptide chains that fold into functional proteins.

Why are proteins important to cell structure and function?

Proteins provide structural support, transport substances, and help cells communicate and carry out chemical reactions. Some proteins act as enzymes, while others support movement and defence.

What is the relationship between a peptide bond and a polypeptide?

A peptide bond is the covalent bond joining two amino acids. A polypeptide is a chain of many amino acids connected by peptide bonds.

Describe the four levels of protein structure and give an example of quaternary structure.

Primary: The sequence of amino acids.

Secondary: Local folding into alpha helices or beta sheets.

Tertiary: The overall three-dimensional shape of one polypeptide.

Quaternary: Two or more polypeptide chains joined into one functional protein.

Example: Hemoglobin has four polypeptide subunits and transports oxygen in red blood cells.

Give three examples of important nucleotides and their functions.

ATP: Transfers usable energy for cellular activities.

GTP: Supplies energy for protein synthesis and other cellular processes.

cAMP: Acts as a second messenger, relaying signals inside cells.

Similarities and differences between DNA and RNA.

Both are nucleic acids made of nucleotide chains. DNA is usually double-stranded, and stores genetic instructions; RNA is usually single-stranded, and helps use genetic instructions to make proteins.