Class Notes (836,562)
Canada (509,854)
BISC 110 (14)

Week 1

14 Pages
Unlock Document

Biological Sciences
BISC 110
Derek Bingham

Week 1 Biochemistry and Nutrition 1 DIGESTION The process of breaking food into (1) smaller pieces for enzymes, and (2) smaller molecules for absorption 1. Ingest food 2. Mechanically digest into smaller pieces 3. Those smaller pieces then get chemically digested into small nutrient molecules 4. Those nutrient molecules get absorbed through the gut 5. Undigested material is defecated CARBOHYDRATES Equal amounts of C and O, with more H (e.g., C H O ); 55% complex carbohydrates per day 6 12 6 TYPES OF CARBOHYDRATES MONOSACCHARIDES  Building blocks of carbohydrates (“monomers”) with 3 to 9 carbons  e.g., glucose, ribose, galactose, fructose Common Types: 1. Pentose sugars (5 C) – ribose and deoxyribose 2. Hexose sugars (6 C) – glucose, galactose, mannose, fructose Two Subtypes: 1. Aldoses – double bond at the end of the carbon chain – ribose, glucose, galactose 2. Ketoses – double bond at the center of the carbon chain – ribulose, fructose DISACCHARIDES  Two monosaccharides linked via dehydration synthesis  e.g, sucrose (glucose + fructose), maltose (glucose + glucose), lactose (galactose + glucose) POLYSACCHARIDES  Hundreds of monosaccharides linked together  Starch – stored form of glucose in plants, main nutritional carbohydrate  Glycogen – stored form of glucose in animals, stored in muscles and liver  Cellulose – plant’s cell walls; indigestible by humans because the bonds between glucose are different CARBOHYDRATES AS STRUCTURAL COMPONENTS  Synovial fluid contains long-chained glycosaminoglycans (GAG’s)  Main type is hyaluronic acid (“hyaluronan”)  In hyaline cartilage: hyaluronan combines with chondroitin sulfate to form a brush-like “sponge” that produces a springy/slippery surface FUNCTIONS OF CARBOHYDRATES 1. Energy source – glucose 2. Energy store – glycogen in muscles and liver Week 1 Biochemistry and Nutrition 2 3.Structural – chondroitin sulfate in cartilage, hyaluronic acid in synovial fluid 4.Other molecular components – ribose in RNA and deoxyribose in DNA 5.Cell recognition – glycoproteins and glycolipids of the glycocalyx (e.g., ABO antigens) CARBOHYDRATE DIGESTION 1 Oral Polysaccharides (starch/glycogen) are broken cavity down into smaller Disaccharides are not digested polysaccharides and maltose via yet , salivary amylase pharyn 2 No carbohydrate digestion because amylase cannot function in the acidic Stomac pH of the stomach! h 3 Lumen Polysaccharides break down of the into maltose and other disaccharides via pancreatic small amylase intest 4 Brush border Disaccharides are broken down into monosaccharides via of brush border enzymes like lactase, maltase, and sucrase small intesti 5 Absorption of monosaccharides into intestinal cells and into the blood for Villi transportation to liver and muscles Week 1 Biochemistry and Nutrition 3 MEMBRANE TRANSPORT MECHANISMS IN MONOSACCHARIDE ABSORPTION 1. Facilitated diffusion 2. Secondary active transport SIMPLE DIFFUSION – the passive movement of molecules from areas of high to low concentration; no energy FACILITATED DIFFUSION – the passive movement of molecules from areas of high to low concentration with the help of channel or transporter proteins ACTIVE TRANSPORT – the ATP-requiring movement of a substance across a cell membrane, against its concentration gradient (low to high concentration) SECONDARY ACTIVE TRANSPORT – a form of active transport across a membrane in which a transporter protein couples the movement of an ion down its electrochemical gradient to the uphill movement of another molecule against its concentration gradient  Energy is “stored” in the electrochemical gradient of the ion +  Example: Na ions are used to “drag” a glucose molecule against its concentration gradient and across the membrane CARBOHYDRATE ABSORPTION Monosaccharides cross two epithelial cell surfaces of the small intestinal villi to reach the blood capillaries: apical and basolateral. Secondary active transport ensures that glucose transport is a one-way process. If it wasn’t a one-way process, energy stores would quickly be depleted. Week 1 Biochemistry and Nutrition 4 LIPIDS  Very little O with amounts of C and H being similar  Generally insoluble in water because lipids are nonpolar and water is polar. FATTY ACIDS  Carboxylic acid with a long carbon chain SATURATED  Completely “filled” with H  No double bonds in the carbon chain UNSATURATED  Some H are missing  Some double bonds are present in the carbon chain POLYUNSATURATED  More H missing  More than 1 double bond in the carbon chain TRIGLYCERIDES  Glycerol backbone with three fatty acids PHOSPHOLIPIDS  Two fatty acids (nonpolar) linked to a glycerol molecule  The remaining carbon on the glycerol molecule is linked to a phosphate group/head (polar) STEROIDS  Four fused carbon rings with a carbon tail OTHERS  Glycolipids and prostaglandins (hormone-like fatty acids) FUNCTIONS OF LIPIDS 1. Energy stores – triglycerides in the liver and adipose tissue 2. Components of cellular membranes – phospholipids and cholesterol 3. Hormone precursors Week 1 Biochemistry and Nutrition 5 LIPID DIGESTION Triglycerides are broken down into fatty acids and monoglycerides Stomac via lingual and gastric lipases 1 h (Only accounts for 20% of lipid digestion) These fat globules are broken down (emulsified) into smaller fat 2 droplets via bile salts Lumen of 3 The small fat droplets are easily broken down into glycerol, fatty acids, and monoglycerides via pancreatic lipase small intest ine Bile salts then improve the solubility of lipids by surrounding them and forming tiny spheres called MICELLES. 4 This is due to the amphipathicity of bile salts: Hydrophilic regions associate with watery intestinal chyme. Week 1 Biochemistry and Nutrition 6 LIPID ABSORPTION Anything insoluble in water or blood (i.e., cholesterol) has to be delivered in a lipoprotein called a chylomicron—a “large” lipid/protein delivery vehicle that is sent out from the intestines to deliver dietary fat. The chylomicron is transported in lymph and drains into the circulatory system. Lipids are stored as triglycerides in the liver and adipose tissue. Week 1 Biochemistry and Nutrition 7 PROTEINS  Varying ratios of C, H, O, N, and sometimes sulfur  Monomer = amino acid  20 different kinds  Amino acids are linked via peptide bonds and dehydration synthesis  Dipeptide = two AA  Polypeptide = several AA  The sequence of AA is vital for the proper functioning of proteins FUNCTIONS OF PROTEINS 1. Structural – collagen, keratin 2. Regulatory – insulin, glucagon 3. Enzymes – speeds up cell reactions 4. Contractile – actin and myosin 5. Immunological – antibodies 6. Transport – hemoglobin 7. Protective – clotting Week 1 Biochemistry and Nutrition 8 PROTEIN DIGESTION 1 Stomac Proteins are broken down into small polypeptides via pepsin. h 2 Polypeptides are broken down into small polypeptides via pancreatic trypsin and Lumen chymotrypsin. of small intest These small polypeptides are ine broken down into amino acids via pancreatic carboxypeptidase. 3 Brush Small peptides are then reduced border to amino acids using three enzymes: of Dipeptidases – splits apart small dipeptides into two AA’s Carboxypeptidases – “eats” intest the carboxyl group of an AA Aminopeptidases – “eats” the ine amino group of an AA (epith Week 1 Biochemistry and Nutrition 9 ABSORPTION OF AMINO ACIDS  Half of the absorbed amino acids come from food, the other half are manufactured or come from dead cells sloughed off the intestines.  Proteins are transported as amino acids dissolved in blood plasma  No (“significant”) protein stores in the human body NUTRITION Kcal or Cal – approximates the energy needed to increase the temperature of 1 kilogram of water by 1 C  1 Kcal = 1000 cal = 4.2 kilojoules Nutrition – substances obtained from foods that are necessary for metabolism, growth, and development Nutrient – food substance that has the possibility to provide energy, serve as raw material to form new components, and/or assist in physiological processes Diet – all that a person eats and drinks in relation to nutritional value, composition, and physiological effects ENERGY STORES Fuel Reserves in a 70-kg male (Kcal) Organ Carbohydrates Lipids Proteins (Glucose or Glycogen) (Triglycerides) (Mobilizable Proteins) Blood 60 Kcal 45 Kcal 0 Kcal Liver 400 Kcal 450 Kcal 400 Kcal Brain 8 Kcal 0 Kcal 0 Kcal Muscle 1200 Kcal 450 Kcal 24,000 Kcal Adipose Tissue 80 Kcal 135,000 Kcal 40 Kcal 1% 77% 22% 4.2 Kcal/g 9.5 Kcal/g 4.2 Kcal/g BASAL METABOLIC RATE (BMR) Energy needed to perform the basic functions of a resting, awake, alert, and fasting person BMR ♂ (Kcal/hr) Weight (kg) BMR ♀ (Kcal/hr) Weight (kg) x 0.9 Week 1 Biochemistry and Nutrition 10 NUTRIENT USE IN RELATION TO FASTING/STARVATION Glycogen Glucose Brain 1 day Triglycerides Fatty acids Muscles Several days Proteins Amino acids Heart Example: If you have used up glycogen stores, your body switches to glucose. If you’ve used up proteins, switch to amino acids, etc. MAIN NUTRIENTS 1. Water – two liters per day 2. Carbohydrates – 55% of complex carbs per day 3. Lipids – 30% of unsaturated fats per day 4. Proteins – 15% of lean proteins per day 5. Minerals 6. Vitamins RECOMMENDED DAILY ALLOWANCE (RDA) FOOD SOURCES RDA FOR ADULTS PROBLEMS Carbohydrates EXCESSES DEFICITS Total digestible: 130 grams Complex (starches): bread, cereal, crackers, 45-65% of total caloric - Obesity flour, pasta, nuts, rice, intake - Nutritional deficits - Tissue wasting potatoes (extreme cases) Simple (sugars): - Dental cavities - Metabolic acidosis carbonated drinks, - Gastrointestinal resulting from irritation candy, fruit, ice cream, - Elevated triglycerides accelerated fat use for pudding, young energy vegetables in plasma Total fibre: 25-30 grams Week 1 Biochemistry a
More Less

Related notes for BISC 110

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.