Chapter 13 Biochemistry: A Molecular View of Life

Chapter 152 Biochemistry Chemistry of living things and life processes Cell: structural unit for all living things –Cell membrane defines cell and lets material flow into and out of cell Plant cells: also have walls made of cellulose Animal cells: do not have cell walls

Chapter 153 Plant Cells

Chapter 154 Animal Cells

Chapter 155 Major Internal Structures Cell nucleus: contains material that controls heredity Ribosomes: carry out protein synthesis Mitochondria: produce energy Chloroplasts: only in plant cells –Convert solar energy into chemical energy

Chapter 156 Metabolism Series of coordinated reactions that keeps cells alive Catabolism: reactions that break down molecules for energy Anabolism: synthesize molecules of living systems

Chapter 157 Carbohydrates Sugars, starches, and cellulose General formula: C x (H 2 O) y Sugars: sweet tasting carbohydates –Aldoses: aldehyde functional group –Ketoses: ketone functional group Monosaccharides: simplest sugars

Chapter 158

9 Polysaccharides Contain two or more monosaccharides Main energy storage system: starch Plants use them for cell walls: cellulose Both are polymers of glucose –Difference in way they are linked together –Determines chemistry

Chapter 1510 Starch Two kinds in plants –Both made of glucose Amylose: straight chain Amylopectin: branched chain

Chapter 1511 Glycogen Another kind of starch found in animals Made of glucose - branched chain The structure of glycogen is similar to that of amylopectin, although the branches in glycogen tend to be shorter and more frequent Allows more ends to undergo a more rapid hydrolysis to release glucose for energy requirement

Chapter 1512 CELLULOSE A polymer of glucose molecules with beta linkage Beta linkage Does not allow for chain of molecules to coil Chains can align with one another to form fibers Fibers can lay down in a criss-cross pattern Hydrogen bonding Criss-cross pattern gives strength in many directions Cannot be digested by animals and therefore serves as dietary fiber to help regulate bowel movement

Chapter 1513 Lipids Defined by solubility –Insoluble in water Fats are largest subgroup of lipids –Made up of fatty acids and glycerol

Chapter 1514 Some Naturally Occurring Fatty Acids

Chapter 1515 Saturated vs. Unsaturated Fats Saturated fats have no C=C bonds –Saturated with hydrogen Unsaturated fats have C=C bonds –May have more than one double bond –Can add more hydrogen to fats –React readily with iodine, bromine, and chlorine

Chapter 1516 Iodine Number Iodine Number: number of grams of iodine consumed by 100 g of fat

Chapter 1517 Proteins Serve as structural material for animals Required in all living cells Composed of carbon, hydrogen, oxygen, and usually sulfur

Chapter 1518 Amino Acids Building blocks for polymers called proteins Contain an amino group, –NH 2, and a carboxylic acid, –COOH Can form zwitterions: have both positively charged and negatively charged groups on same molecule 20 required for humans

Chapter 1519

Chapter 1520

Chapter 1521 Peptide Bond Connect amino acids from carboxylic acid to amino group Produce amide linkage: -CONH- Holds all proteins together Indicate proteins by 3-letter abbreviation

Chapter 1522 Sequence of Amino Acids Amino acids need to be in correct order for protein to function correctly Similar to forming sentences out of words

Chapter 1523 Structure of Proteins Four organizational levels Primary structure: amino acid sequence Secondary structure: arrangement of chains around an axis –Pleated sheet –Alpha helix: right-handed helix

Chapter 1524 Pleated Sheets

Chapter 1525 Alpha Helix

Chapter 1526 Tertiary Structure Spatial relationships of amino acids relatively far apart in protein chain Globular proteins: compact spherical shape

Chapter 1527 Quaternary Structure Structure when two or more amino acid sequences are brought together Hemoglobin has four units arranged in a specific pattern

Chapter 1528 Intermolecular Forces in Proteins Hydrogen bonding Ionic bonds Disulfide linkages Dispersion forces

Chapter 1529 Enzymes Biological catalysts produced by cells Nearly all are proteins Enormous catalytic power –Reactions occur at lower temperatures and at higher rates Ordinarily highly specific

Chapter 1530 Induced-Fit Model of Enzymes Explains how enzyme works Substrate: reacting substance Active site: where chemical reaction takes place and where substrate fits

Chapter 1531 Cofactors Something other than polypeptide chain required by enzyme May be metal –Iron in hemoglobin May be organic cofactor –Coenzyme Apoenzyme: does not have cofactor

Chapter 1532 Inhibition of Enzymes Lets cell control when an enzyme works Inhibitor binds to allosteric site Prevents substrate from binding

Chapter 1533 Nucleic Acids Serve as information and control center of the cell Deoxyribonucleic acid (DNA) –Carries blueprint for proteins –Found in cell nucleus Ribonucleic acid (RNA) –Carries out protein assembly –Found in all parts of the cell

Chapter 1534 Nucleotides Three components Sugar –Either ribose or deoxyribose Phosphate unit Nucleic acid –Purines: two fused rings –Pyrimidines: one ring

Chapter 1535 Nucleotides Four bases in DNA Pair up in a specific pattern

Chapter 1536 DNA When all base pairs are paired up with second strand – form double helix Held together by hydrogen bonding

Chapter 1537 RNA Tends to form single strand May pair up with itself

Chapter 1538 Genetic Information Chromosomes: hereditary material, concentrated in long threadlike bodies –46 in humans –Made of protein and DNA Gene: basic unit of heredity –Section of DNA Genome is complete set of genes for an organism

Chapter 1539

Chapter 1540 Self-Replication Occurs every time a cell divides

Chapter 1541 Transcription Converts DNA code to RNA Must occur before protein synthesis Can make multiple copies to make multiple copies of the protein

Chapter 1542 Translation Converts code on RNA into protein Read using base triplet –Code for amino acids –Some redundancy

Chapter 1543

Chapter 1544 Polymerase Chain Reaction (PCR) Method to rapidly amplify any DNA present in sample –Can use very small amounts of DNA Allows for genetic testing –Cut DNA into relatively small sizes –Amplify it to see any pattern

Chapter 1545 Recombinant DNA Allows for addition of genes to organisms Make microorganisms produce useful drugs –All insulin is made this way Rapidly change genetics of plants Treat genetic disorders in humans

Chapter 1546

Chapter 1547 End of Chapter 15