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Cell Biology: Macromolecules and Their Functions

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Termini in questo insieme (21)

  • What are the four major classes of macromolecules in cells?

    Proteins, nucleic acids, carbohydrates, and lipids are the four major classes of macromolecules essential for cell structure, function, and regulation.

  • What are proteins made of?

    Proteins are polymers of 20 standard amino acids, each with a central alpha carbon bonded to an amino group, carboxyl group, hydrogen atom, and a unique side chain (R group).

  • Name three functional categories of proteins.

    Examples include enzymes (catalyze reactions), structural proteins (support and shape), and transport proteins (move substances across membranes).

  • How are amino acids linked to form proteins?

    Amino acids are linked by peptide bonds formed through condensation (dehydration) reactions, releasing water and creating polypeptides.

  • What is the primary structure of a protein?

    The linear sequence of amino acids in a polypeptide chain, written from the N-terminus to the C-terminus, determines all higher levels of structure.

  • Describe the secondary structure of proteins.

    Regular folding patterns stabilized by hydrogen bonds, mainly alpha helices (right-handed coils) and beta sheets (extended strands).

  • What stabilizes the tertiary structure of a protein?

    Interactions among R groups such as hydrophobic interactions, hydrogen bonds, ionic bonds, and disulfide bridges stabilize the overall 3D shape.

  • What defines the quaternary structure of proteins?

    The association of multiple polypeptide subunits into a functional protein complex.

  • What causes protein denaturation?

    Changes in pH, temperature, or chemical environment can disrupt protein structure, causing loss of function.

  • What are nucleic acids composed of?

    Polymers of nucleotides, each containing a five-carbon sugar, phosphate group, and nitrogenous base.

  • What is the difference between DNA and RNA sugars?

    DNA contains deoxyribose, while RNA contains ribose as the five-carbon sugar.

  • How are nucleotides linked in nucleic acids?

    By 3',5'-phosphodiester bonds forming a sugar-phosphate backbone with directionality from 5' to 3'.

  • What base pairing rules apply in DNA?

    A pairs with T and G pairs with C via hydrogen bonds, forming the double helix structure.

  • How are carbohydrates classified?

    As monosaccharides (simple sugars), disaccharides (two monosaccharides), and polysaccharides (long chains).

  • What is a glycosidic bond?

    A covalent bond formed by condensation between two monosaccharides to create disaccharides or polysaccharides.

  • Name two storage polysaccharides and their sources.

    Starch in plants and glycogen in animals serve as energy storage polysaccharides.

  • What is the main structural polysaccharide in plants?

    Cellulose is a structural polysaccharide forming plant cell walls.

  • What are lipids and their main functions?

    Hydrophobic molecules including fats, phospholipids, and steroids; they function in energy storage, membrane structure, and signaling.

  • What composes fats (triacylglycerols)?

    One glycerol molecule bonded to three fatty acids, which can be saturated or unsaturated.

  • Describe the structure of phospholipids.

    Consist of two fatty acids, a glycerol, and a phosphate group; they are amphipathic and form cellular membranes as bilayers.

  • What is the characteristic structure of steroids?

    Steroids have a four-ring structure; cholesterol is a common steroid and precursor for hormones.