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Transcript of Acid – substance that increases conc. of H + in water solution Base – substance that decreases...
Ch. 2 Some Basic Chemistry
Acid – substance that increases conc. of H+ in water solution
Base – substance that decreases conc. of H+
pH scale measures acidity or alkalinity (basicity) of solutions (Fig. 2-5)◦ 0 (most acidic) to 14 (most basic)◦ 7 = neutral ◦ < 7 = acidic◦ > 7 = basic (alkaline)
Acids, Bases, pH
Acidic – higher conc. of H+
Basic – higher conc. of OH-
Change of one pH unit is a 10-fold change in H+ concentration [H+]
Cells, internal fluids have a pH close to 7◦ Intracellular fluid = 6.8◦ Blood = 7.35 to 7.45 (critical range)
Acids, Bases, pH (cont.)
Chemical or pair of chemicals ◦ Minimize(s) pH change by reacting with strong
acids (SA) or strong bases (SB)
Buffer Systems
All contain covalently bonded C,H atoms 4 major groups
◦ Carbohydrates◦ Proteins◦ Lipids◦ Nucleic acids
Organic Compounds of Importance
Serve as sources of energy in cell respiration
Contain C, H, O Classified as:
◦ Monosaccharides◦ Disaccharides◦ Oligosaccharides◦ Polysaccharides
Carbohydrates
Simple sugars Glucose
◦ Hexose (6-C sugar)◦ Fructose, galactose have same formula, but
different atom arrangement Pentose (5-C sugar)
◦ Structural components of nucleic acids DNA (deoxyribose) RNA (ribose)
Monosaccharides
Double sugars◦ 2 monosaccharides linked by covalent bond◦ Sucrose = glucose + fructose◦ Lactose = glucose + galactose◦ Maltose = glucose + glucose◦ Broken down into monosaccharides & used for
energy production
Disaccharides
3 to 20 monosaccharides Found on outer surface of cell membranes Serve as antigens
◦ chemical markers that identify cells
Oligosaccharides
Thousands of glucose molecules Starches
◦ energy storage by plant cells Glycogen
◦ energy storage by animal cells
Polysaccharides
Nearly straight chain of glucose produced by plant cells as part of cell walls
We have no enzymes to digest cellulose◦ Serve as fiber to promote peristalsis (contraction)
of undigested food thru the colon
Cellulose
Contain C, H, O◦ Some contain P
3 types◦ True fats◦ Phospholipids◦ Steroids (Fig. 2-7)
Lipids
Made of 1 glycerol molecule and 1, 2, or 3 fatty acid (f.a.) molecules
Triglyceride◦ 3 f.a. bonded to a glycerol
Diglyceride◦ 2 f.a. bonded to a glycerol
Monoglyceride◦ 1 f.a. bonded to a glycerol
True fats (neutral fats)
Fatty acids may be saturated or unsaturated (Fig. 2-7)
Saturated◦ Only single bonds between its C atoms◦ Usually solid at room temp.◦ beef, pork, eggs, cheese
Unsaturated◦ At least 1 double bond between C atoms◦ Often liquid at room temp.◦ Corn/sunflower/safflower oil; some fish oils
True fats (cont.)
Trans fats◦ Unsaturated fats changed to saturated fats ◦ Hydrogen has been added◦ Gives a more pleasant texture or taste◦ Provides longer shelf life◦ Contribute to atherosclerosis
Abnormal cholesterol deposits clog arteries Triglycerides
◦ Storage form for excess food Potential energy
True fats (cont.)
Diglycerides with a phosphate (PO4) group in the third bonding site of glycerol
Structural components of cells Myelin
◦ Forms myelin sheath around nerve cells◦ Provides insulation for nerve impulse transmission
Phospholipids
Cholesterol◦ Made of 4 rings of C, H (Fig. 2-7)◦ Component of cell membranes◦ Precursor for making other steroids
estrogen or testosterone◦ Cholesterol in skin converts to vitamin D upon
sunlight exposure◦ Liver cells use cholesterol to synthesize bile salts◦ See Table 2-4
Steroids
Made of subunits called amino acids (AA)◦ Contain C, H, O, N◦ Some AA contain S for building disulfide bonds◦ 20 AA make up human proteins (Fig. 2-8)◦ Each AA has a central C bonded to a H atom, an
amino (NH2) group, and a carboxyl (COOH) group◦ A variable R group is found at the 4th bond of the
central carbon◦ Peptide bond – bond between 2 AA◦ Polypeptide – short chain of AA linked by a
peptide bond
Proteins
Consists of 50 to 1000s of AA Primary structure
◦ Sequence of AA is specific to each protein Secondary structure
◦ Protein is folded into a helix (coil) or pleated sheet Tertiary structure
◦ Protein folds into a globular structure (Fig. 2-8) Quaternary structure
◦ Some proteins consist of more than one AA chain Hemoglobin has 4 AA chains
Proteins
Some require trace elements (Fe, Zn) to complete their structure & function properly
Functions (Table 2-5) Excess AA will be converted to
carbohydrates or fat to be stored as potential energy
Proteins
Type of protein that catalyzes reactions◦ Catalyst – speed up chemical rxns
Most human enzymes function in normal range of body temp. (97 to 99°F)
At 106°F, enzymes can lose their shape (denature)◦ Unable to function as catalyst◦ May cause brain damage or death because
enzymes are permanently denatured
Enzymes
Deoxyribonucleic acid (DNA) Ribonucleic acid (RNA) Made of subunits called nucleotides
consisting of:◦ Pentose sugar◦ Phosphate group◦ Nitrogenous base
Nucleic Acids
Nucleotide◦ Pentose sugar – deoxyribose◦ Nitrogenous bases – adenine (A), guanine (G),
cytosine (C), and thymine (T) A:T; C:G
◦ Fig. 2-10 Looks like a ladder 2 strands of nucleotides called a double helix
◦ Alternating P and sugars form the uprights and pairs of N-bases form the rungs
DNA
Makes up the chromosomes of cells◦ The genetic code for hereditary characteristics
Gene ◦ Sequence of bases for one protein
DNA
Nucleotides◦ Pentose sugar – ribose◦ Nitrogenous bases – A, G, C, uracil (U)
A:U; C:G◦ Single strand of nucleotides (Fig. 2-10)◦ Synthesized from DNA in cell’s nucleus◦ Carries out function in the cytoplasm
Protein synthesis
RNA
Adenosine triphosphate◦ Specialized nucleotide consisting of A, ribose
sugar, 3 phosphate groups◦ Product of cell respiration◦ Energy transfer molecule
Transfers potential energy in food to cell processes◦ See Table 2-6
ATP