Chapter 5 Flashcards
(10 cards)
What are macromolecules, and how are they formed?
Macromolecules are large, complex molecules that are essential for life, formed by linking smaller units called monomers.
The process of linking monomers to form polymers is called polymerization.
Dehydration synthesis (or condensation) links monomers by removing a water molecule.
Hydrolysis is the opposite process, where polymers are broken down into monomers by adding a water molecule.
What are the major types of macromolecules, and what are their monomers?
Carbohydrates: Monomers are monosaccharides (e.g., glucose, fructose).
Proteins: Monomers are amino acids.
Nucleic acids: Monomers are nucleotides (e.g., adenine, guanine).
Lipids: Monomers are fatty acids and glycerol (note: lipids are not true polymers).
What is the structure and function of carbohydrates?
Monosaccharides: Simple sugars that provide quick energy (e.g., glucose, fructose, galactose).
Disaccharides: Two monosaccharides joined by a glycosidic bond (e.g., sucrose, lactose).
Polysaccharides: Long chains of monosaccharides.
Starch: Energy storage in plants.
Glycogen: Energy storage in animals.
Cellulose: Structural support in plant cell walls.
Functions:
Immediate energy source (glucose).
Energy storage (starch, glycogen).
Structural support (cellulose in plants).
What are lipids and their functions?
Monomers: Fatty acids and glycerol.
Types of Lipids:
Fats: Composed of one glycerol molecule and three fatty acids.
Saturated fats: No double bonds, solid at room temperature (e.g., butter).
Unsaturated fats: One or more double bonds, liquid at room temperature (e.g., olive oil).
Phospholipids: Composed of two fatty acids, one glycerol molecule, and a phosphate group.
Steroids: Lipids with a four-ring structure (e.g., cholesterol, sex hormones).
Functions:
Energy storage (fats).
Structural components of cell membranes (phospholipids).
Hormonal signaling (steroids like cholesterol).
What is the structure and function of proteins?
Monomers: Amino acids, which consist of an amino group, a carboxyl group, and a side chain (R group).
Polymers: Polypeptides, which are chains of amino acids joined by peptide bonds.
Levels of Protein Structure:
Primary: Sequence of amino acids.
Secondary: Coiling into α-helix or β-pleated sheet.
Tertiary: Overall 3D shape formed by interactions between side chains.
Quaternary: Multiple polypeptides interacting (e.g., hemoglobin).
Functions:
Enzymatic catalysis: Enzymes speed up chemical reactions (e.g., amylase).
Structural support: Collagen provides strength in connective tissue.
Transport: Hemoglobin carries oxygen in blood.
Signaling: Hormones like insulin regulate metabolism.
Movement: Actin and myosin are involved in muscle contraction.
What are nucleic acids, and what are their functions?
Monomers: Nucleotides, each consisting of a sugar (ribose or deoxyribose), a phosphate group, and a nitrogenous base (adenine, guanine, cytosine, thymine/uracil).
Polymers:
DNA: Double-stranded helix; stores and transmits genetic information.
RNA: Single-stranded; involved in protein synthesis (transcription, translation).
Functions:
DNA: Stores genetic information in the form of genes.
RNA: Helps in protein synthesis by transferring genetic information from DNA to ribosomes.
What is the difference between DNA and RNA?
DNA:
Double-stranded.
Contains the sugar deoxyribose.
Contains the base thymine.
Stores genetic information.
RNA:
Single-stranded.
Contains the sugar ribose.
Contains the base uracil (instead of thymine).
Involved in protein synthesis.
What is the role of enzymes in proteins?
Back:
Answer:
Enzymes are proteins that act as biological catalysts, speeding up chemical reactions by lowering the activation energy.
Enzymes are highly specific to substrates and work through mechanisms such as the induced fit model, where the enzyme’s active site adjusts to fit the substrate.
Examples: Amylase (digests starch), DNA polymerase (replicates DNA).
How do lipids contribute to cell membrane structure?
Phospholipids are key components of cell membranes.
The hydrophilic (water-loving) head interacts with water, while the hydrophobic (water-fearing) tails face inward, away from water, forming a bilayer.
This structure creates a semi-permeable membrane, regulating the movement of molecules into and out of cells.
What is dehydration synthesis, and how does it relate to macromolecule formation?
Dehydration synthesis is a chemical reaction that links monomers to form polymers by removing a water molecule.
For example, when two amino acids form a peptide bond, a water molecule is released as a byproduct.
This process is crucial for forming all types of macromolecules, including proteins, carbohydrates, lipids, and nucleic acids.
