Biology Week 4 Notes
Biology Week 4 Notes BY 101
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This 4 page Class Notes was uploaded by Alexandria Thomas on Thursday September 22, 2016. The Class Notes belongs to BY 101 at University of Alabama at Birmingham taught by Mickie L Powell in Fall 2016. Since its upload, it has received 5 views.
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Date Created: 09/22/16
Metabolism ● All of the chemical reactions occurring in the body Enzymes ● Catalyze(Speed up) reaction rates ● (can be proteins or RNA) ● Named for the reaction catalyzed ● End in suffix ase ● For Ex. sucrase breaks down sucrose Activation Energy ● Energy required to start a metabolic reaction Induced fit model ● Substrate: chemical being metabolized ● Active site: enzymes region where substrate binds, which stresses the substrate bonds Enzyme specificity ● Each enzyme catalyzes a particular reaction based on enzyme shape and active site shape ● Each enzyme is composed of varying sequences of amino acids ● Genes determine the specific enzyme protein Metabolic rates: the measure of a person’s energy ● Depends on speed and efficiency of different enzymes ● Changes according to activity levels Basal metabolic rate (BMR): the energy use of a resting, wakeful person ● Average BMR is 70 calories/hour or 1680 calories/days Metabolic rate is influenced by many factors: ● Exercise ● Time ● Intensity ● Biological Sex ● Males required more calories and energy ● Genetics ● Lower basal metabolic rates ● Differences in fat storage and utilization Cellular respiration: series of metabolic reactions converting food energy into a usable Adenosine Triphosphate (ATP) ● Consists of adenine, a ribose sugar, and 3 phosphate groups ● Energy stored in chemical bonds of ATP Phosphorylation ● Phosphate group is transferred from ATP to another molecule ● Energy is transferred ● ADP is produced ATP and cellular work ● Movement of cells ● Active transport of substances across membranes ● Making complex molecules Regenerating ATP ● Cellular respiration replenishes ATP when used in the cell Breathing and cellular respiration ● Breathing: inhalation of oxygen into lungs to be delivered to cell; exhalation of carbon dioxide ● Cellular respiration: the chemical process that generates most of the energy in the cell, supplying molecules needed to make the metabolic reactions of an organism run. Aerobic cellular respiration ● Occurs mostly in the mitochondria ● Requires oxygen ● Glucose (C6H12O6) + 6O2 > 6H2O +6CO2 Stages of cellular respiration ● Stage 1: Glycolysis ● Stage 2: Citric acid cycle ● Stage 3: Electronic transport chain and ATP synthesis Stage 1: Glycolysis ● 6carbon glucose molecule is broken down into two 3carbon pyruvic acid molecules ● Occurs in the cytosol ● Doesn’t require oxygen ● Produces 2 ATP Nicotinamide adenine dinucleotide (NAD+): taxicab for electrons ● Empty taxicab (NAD+) picks up electrons and hydrogen ions (H+) ● Becomes full taxicab that carries electrons to final destination After Glycolysis ● Pyruvic acid loses a carbon dioxide (Decarboxylated) ● 2carbon fragment is metabolized inside mitochondrion Stage 2: Citric and Cycle ● Series of enzymecatalyzed reactions in the mitochondrial matrix ● Produces 2 ATP ● Releases carbon dioxide and NADH Stage 3: Electron transport and ATP synthesis ● Electron transport chain: series of proteins in the mitochondrion acting like a conveyor belt for electrons Electron transport chain ● NADH drops off electrons and H+ ions ● Electrons move through the chain ● H+ concentration increases as the ions are moved into the intermembrane space ● Charged H+ ions can’t diffuse across the membrane ● Pass through ATP synthase protein channels ● Synthesize ATP molecules ● Electrons eventually combine with oxygen to produce water Metabolism of other nutrients ● If carbohydrates and fats are unavailable, proteins may be used ● Amino group is removed ● Other components enter the citric acid cycle ● If carbohydrates are unavailable, fats may be used ● Glycerol and fatty acids enter the citric acid cycle Cells can generate energy without oxygen through anaerobic respiration During intense exercise: ● Muscles run low on oxygen ● ATP comes from glycolysis only ● NAD+ levels decrease ● Muscle cells use fermentation to regenerate NAD+ Lactic acid ● Builds up due to fermentation in muscle cells ● Is transported back to the liver for conversion to pyruvic acid ● Oxygen debt needs to be restored for conversion Fermentation ● Microbes transform milk sugars into lactic acid ● Yogurt ● Sour cream ● Cheese ● Yeast cells convert glucose to ethyl alcohol Body mass index (BMI): uses height and weight to estimate weightrelated risk of illness and death Relative health risk and BMI ● Less than 18.5= underweight ● 18.524.9= normal weight ● 2529= overweight ● 3034.9= moderate obesity ● Greater than 35= severe obesity Body weight and health risks ● Underweight: at risk of anorexia ● Overweight: associated with less mortality than normal weight ● Obesity: health consequences usually begin ● Increased risk of heart disease, stroke, type 2 diabetes ● Obesity prevention is better than yoyo dieting ● Health choices for food and exercise Anorexia: selfstarvation ● Rampant on college campuses ● 1 in 5 college women ● 1 in 5 college men Bulimia: binge eating followed by purging Health consequences of anorexia ● Damaged heart muscles ● Lack of estrogen production (due to low body fat) ● Amenorrhea (cessation of menstruation) ● Osteoporosis lower bone density
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