Carbohydrates Overview Quiz

Carbohydrates

• Carbohydrates are biological macromolecules essential for structural components, energy storage, and other biological processes.
• Three major classes of carbohydrates exist: monosaccharides, disaccharides, and polysaccharides.

Monosaccharides

• Monosaccharides, also known as simple sugars, are the fundamental building blocks of carbohydrates.
• Common examples include glucose, galactose, and fructose.
• These sugars can be used for fuel, converted into other organic molecules, or combined into polymers.

Disaccharides

• Disaccharides are formed when two monosaccharides are joined together by a dehydration reaction.
• They serve as building blocks and cellular fuels.
• Key disaccharides include:
  • Maltose: formed from two glucose molecules.
  • Sucrose: formed from glucose and fructose.
  • Lactose: formed from glucose and galactose.

Polysaccharides

• Polysaccharides are long chains of monosaccharides linked together, forming polymers with a few hundred to a few thousand monosaccharides.
• They play various roles in organisms.
  • Structural materials: cellulose and chitin provide structural support.
  • Storage materials: glycogen and starch store energy.

Storage Polysaccharides

• Starch is a polymer of glucose monomers found as granules within plastids, serving as the primary glucose storage form in plants.
• Glycogen is a glucose polymer that functions as the primary glucose storage form in animals.

Structural Polysaccharides

• Cellulose is a glucose polymer that forms the primary component of plant cell walls.
• Chitin is a carbohydrate used by arthropods (insects, spiders, crustaceans) to build their exoskeletons.

Lipids

• Lipids are a diverse group of hydrophobic molecules, meaning they repel water.
• Lipids have key biochemical functions, including:
  • Structural and storage functions.
  • Primary energy source for organisms.
  • Acting as metabolic regulators, such as hormones.

Types of Lipids

• Fats: Constructed from glycerol and fatty acids, responsible for storing large amounts of energy.
• Phospholipids: Essential for cell membrane structure, containing two fatty acid tails.
• Steroids: Important for various functions, including cell membrane components and precursors for hormones.
• Waxes: Hydrophobic compounds that provide protection and waterproofing.

Fats

• Fats are synthesized from glycerol and fatty acids.
• They store more than twice the energy per gram compared to polysaccharides.

Saturated Fatty Acids

• Saturated fatty acids contain the maximum number of hydrogen atoms possible.
• They lack carbon-carbon double bonds.
• Saturated fats, typically found in animal products, are solid at room temperature due to their tightly packed molecules.

Unsaturated Fatty Acids

• Unsaturated fatty acids contain one or more carbon-carbon double bonds.
• They tend to be liquid at room temperature and are commonly found in plant and fish oils.

Phospholipids

• Phospholipids have a hydrophilic (water-loving) head and hydrophobic (water-repelling) tails.
• This structure allows them to form bilayers that make up cell membranes.

Steroids

• Steroids include cholesterol and vertebrate sex hormones.
• Cholesterol is crucial for animal cells, acting as a membrane component and precursor for other steroids.
• Excessive blood cholesterol can contribute to atherosclerosis.

Proteins

• Proteins are complex macromolecules constructed from amino acids.
• They play diverse roles in organisms.
  • Structural: keratin and collagen provide structural support.
  • Transport: hemoglobin carries oxygen.
  • Enzymatic: pepsin aids in digestion.
  • Immunological: antibodies protect against pathogens.

Enzymes

• Enzymes are proteins that act as catalysts, accelerating chemical reactions.
• They have specific active sites that bind to substrates (reactants) and facilitate their conversion into products.

Amino Acids

• Amino acids are organic molecules containing both carboxyl and amino groups.
• They have unique properties due to their side chains, known as R groups.
• Twenty different amino acids are used to construct proteins.

Nucleic Acids

• Nucleic acids are macromolecules that store, transmit, and express hereditary information.
• They are polymers composed of monomers called nucleotides.
• Two primary types of nucleic acids:
  • Deoxyribonucleic acid (DNA)
  • Ribonucleic acid (RNA)

DNA

• DNA carries genetic information and directs its own replication.

• It governs protein synthesis through RNA.

• The entire process of DNA directing protein synthesis is called gene expression:

  • DNA -> RNA -> Protein

  Components of Nucleic Acids

• Each nucleotide is made up of three parts:

  • A nitrogenous base
  • A five-carbon sugar (pentose)
  • One or more phosphate groups.

• A nucleoside is a nucleotide lacking phosphate groups.

RNA

• RNA participates in protein synthesis.
• RNA differs from DNA in several key ways:
  • RNA is single-stranded.
  • RNA uses uracil (U) instead of thymine (T) as a nitrogenous base.
  • RNA contains ribose sugar instead of deoxyribose sugar.

Types of RNA

• Messenger RNA (mRNA): Carries genetic information from DNA to ribosomes in the cytoplasm.
• Ribosomal RNA (rRNA): Component of ribosomes, playing both catalytic and structural roles.
• Transfer RNA (tRNA): Delivers specific amino acids to ribosomes during protein synthesis based on the information coded in mRNA.

Test your knowledge on carbohydrates with this quiz. Explore the different types of carbohydrates, including monosaccharides, disaccharides, and polysaccharides. Understand their structures, functions, and examples as building blocks of life.