Chapter 2: Molecular Biology Flashcards
Why is carbon a key element in molecular biology?
It forms four covalent bonds, enabling a variety of stable compounds.
What are the four groups of carbon compounds in living organisms?
Carbohydrates, lipids, proteins, nucleic acids.
What is metabolism?
The web of all enzyme-catalyzed reactions in a cell or organism.
Define anabolism.
The synthesis of complex molecules from simpler ones by condensation reactions.
Define catabolism.
The breakdown of complex molecules into simpler ones by hydrolysis.
What role do enzymes play in metabolism?
They increase the rate of reactions by providing an active site for reactants.
What are examples of metabolic reactions in cells?
DNA replication, RNA synthesis, protein synthesis, cell respiration, photosynthesis.
Why is water essential in biological systems?
It acts as a polar solvent due to hydrogen bonding.
What are the key properties of water due to hydrogen bonding?
Cohesion, adhesion, thermal stability, and solvent properties.
cohesion -> surface tension
adhesion -> transpiration
What determines whether a substance is hydrophilic or hydrophobic?
Its polarity.
How are polysaccharides formed?
By condensation reactions linking monosaccharides with glycosidic bonds.
What is the general formula for carbohydrates?
Cx(H2O)y.
Give examples of hexose and pentose monosaccharides.
Hexose: glucose, fructose, galactose;
Pentose: ribose, deoxyribose.
What are the two main roles of monosaccharides in cells?
Energy source in respiration and building blocks for larger molecules.
energy released through respiration because contains many C-H bonds
What is the storage polysaccharide in plants?
Starch.
What is the structural polysaccharide in plants?
Cellulose.
What is glycogen, and where is it stored in animals?
A storage polysaccharide stored in liver and muscle cells.
What is the function of cellulose?
Provides structural support in plant cell walls.
What are triglycerides made of?
Three fatty acids and one glycerol via condensation.
What is a phospholipid, and what is its structure?
A lipid with a hydrophilic head and hydrophobic tails.
What is the role of phospholipids in the cell?
Form membranes with hydrophobic barriers and hydrophilic surfaces.
What are nucleic acids made of?
Polymers of nucleotides.
What are the structural differences between DNA and RNA?
DNA: two strands; RNA: one strand; differ in base composition and pentose sugar.
What is the structure of DNA?
A double helix with antiparallel strands joined by hydrogen bonds.