Biochemistry Review Flashcards
Metabolism
The sum of all biochemical reactions that take place in an organism
Carbohydrates
C6H12O6
Monosaccharides
- glucose, fructose, galactose
- ribose
Disaccharides
-sucrose, lactose, maltose
Oligosaccharides
-a few linked monosaccharides
Polysaccharides
- many linked monosaccharides
- glycogen, starch
Monosaccharides
D and L structure, D structure most common in nature
Aldehyde- glucose and galactose
Ketone- fructose
*anomeric carbon is the one attached to these functional groups
Disaccharides
Maltose- glucose + glucose
- α-1,4 glycosidic bond
- can be either α or β depending on free anomeric C
Lactose- galactose + glucose
-β-1,4 glycosidic bond
Sucrose- glucose + fructose
-can’t be designated α or β
Polysaccharides
Starch (amylose)- polymer of glucose
- Linear (unbranched)
- α-1,4
Amylopectin- polymer of glucose
- Branched
- branches occur at α-1,6
Cellulose- polymer of glucose
- β-1,4
- Indigestible (stereospecificity of α-amylase)
- Bulking agent, energy for intestinal bacteria
Amino acids
Contain a carboxyl group, amino group, and the R side chain which is what differentiates them
Simplest
- Glycine- R = H
- Alanine- R = CH3
Branched chain
-Valine, leucine, and isoleucine
Sidechains containing -OH groups
-Serine and Threonine
Sidechains containing S atoms
-Cysteine and Methionine
Sidechains containing aromatic rings
-Phenylalanine, Tyrosine, and Tryptophan
Essential amino acids
Phenylalanine
Valine
Threonine
Tryptophan
Isoleucine
Methionine
Histidine*
Arginine*
Leucine
Lysine
*conditionally essential
Proteins
Functional categories
- Enzymes
- Hormones
- Structural Proteins
- Immune proteins
- Transport Proteins
Enzymes
Oxidoreductases- redox reactions Transferases- functional group transfer Hydrolases- cleavage of bonds with water Lyases- formation of double bonds Isomerases- yield isomers Ligases- formation of bonds
Prosthetic group
A coenzyme or cofactor that is tightly bound (sometimes covalently) to an enzyme and is necessary for its function
Holoenzyme
a complete, catalytically active enzyme together with its bound coenzyme and/or metal ions
Reversible enzyme inhibition
Competitive inhibition
- competes with the substrate for the active site
- sufficiently high [S] will always displace the competitive inhibitor
Noncompetitive (uncompetitive) inhibition
- binds to free enzyme or ES at a site distinct from the substrate active site, allosteric site
- cannot be overcome by increasing [S]
Irreversible enzyme inhibition
Inhibitors that bind covalently with or destroy a functional group on an enzyme that is essential for catalytic activity
Enzyme regulation
Regulatory enzyme
Allosteric enzymes
Feedback inhibition- end product binds to the enzyme
Proteolytic cleavage- zymogens (inactive precursor to the functional enzyme)
