Biological Macromolecules.ppt

1、Biological Macromolecules,Carbohydrates Lipids Proteins Nucleic acids,A. Carbohydrates,General properties Composed mostly of carbon, hydrogen, and oxygen Large number of OH groups attached to the carbons Functions Energy source for living cells Certain structural components of cells,Monosaccharides

2、“Simple sugars” Monomer unit of carbohydrate group Examples: glucose, fructose Disaccharides Composed of two monosaccharide units joined together Examples: sucrose, lactose Polysaccharides Composed of multiple monosaccharide units (100s 1000s) Examples: starch, glycogen, cellulose,A. Carbohydrates,G

3、eneral properties Biological compounds with hydrophobic components in their molecular structures Functions Energy storage Structural components Glycerides A major class of lipid Composed of a glycerol molecule attached to one, two, or three fatty acid molecules,B. Lipids,Generalized structure of a t

4、riglyceride:,B. Lipids,B. Lipids,Fatty acid saturation Fatty acids with greater saturation have fewer C=C double bonds; Have higher melting points Fatty acids with less saturation have more C=C double bonds; Have lower melting points,B. Lipids,Phospholipids A lipid molecule (for example, a diglyceri

5、de) with a hydrophilic group attached via a phosphate linkage Found in membrane structure (details later in course) Other lipids Sterols: cholesterol and steroid hormones Waxes,General properties Composed of chains of amino acids There are 20 different amino acids, each with distinctive chemical pro

6、perties A protein molecule may contain several hundred amino acids Each different protein has its own order, or “sequence,” of amino acids The correct sequence of amino acids is essential for the proteins function,C. Proteins,Functions Enzymes: enzymes are biological catalysts that control almost ev

7、ery reaction in living systems Cellular recognition and communication Structural components of living cells,C. Proteins,Amino acid structure To the central carbon atom, four things are attached: Hydrogen atom Amino group Carboxylic acid group Side chain “R” group Twenty different “R” groups, with di

8、fferent chemical properties,C. Proteins,Peptides Chains of amino acids attached by peptide bonds May be named by number of amino acids: dipeptide, tripeptide, tetrapeptide, pentapeptide, etc.; Polypeptide,C. Proteins,Protein: A polypeptide chain with a specific biological function Most proteins have

9、 from about 50 up to several hundred amino acids in their structure,C. Proteins,Levels of protein structure Primary structure: amino acid sequence Secondary structure: localized folding of a chain into regions of helix or sheet structure Tertiary structure: folding of a single polypeptide chain into

10、 a three-dimensional structure Quaternary structure: only in proteins with more than one polypeptide chain; Folding of more than one chain together,C. Proteins,General properties Composed of chains of nucleotides There are 4 different nucleotides A nucleic acid molecule may contain several thousands

11、 or millions of nucleotides Each nucleic acid molecule has its own order, or “sequence,” of nucleotides The correct sequence of nucleotides is essential for the nucleic acids function,D. Nucleic Acids,Overall function. The sequence of nucleotides in a nucleic acid molecule serves as a blueprint to e

12、ncode the correct sequence of amino acids for a protein. The code for a specific protein is called a “gene.” Deoxyribonucleic acid (DNA): DNA molecules (chromosomes) serve as the “master blueprint” for all of the cells proteins. The DNA molecules are transmitted to offspring during reproduction. Rib

13、onucleic acid (RNA): RNA molecules serve as “working copies” of the genes for the proteins that the cell is making at any given time.,D. Nucleic Acids,Nucleotide structure A nucleotide consists of: Nitrogenous base Pentose sugar Phosphate group Nitrogenous bases: Purines: adenine & guanine Pyrimidines: cytosine, thymine (in DNA), & uracil (in RNA) Pentose sugars: Ribose (found in RNA) Deoxyribose (found in DNA),D. Nucleic Acids,