Exam 3 Review
1. Chemical structure of protein- How is it different from CHO and Fats?
∙ Proteins contain nitrogen in addition to the same atoms as CHO and fats – carbon, hydrogen, and oxygen
∙ All amino acids have the same basic structure – a central carbon, with a hydrogen atom, an acid group (COOH), an amino group (NH3), and a side chain (unique to each individual amino acid)
2. Positive and negative nitrogen balance- what does it mean? Examples ∙ Nitrogen balance: amount of nitrogen consumed compared with the amount of nitrogen excreted over a period of time
o Positive nitrogen balance: when the body synthesizes more than it degrades and protein is added
Found in growing infants, children, adolescents, pregnant women, and people recovering from protein deficiency or illness
o Negative nitrogen balance: when the body degrades more than it synthesizes and protein is being lost
Found in people who are starving or suffering other severe stresses
such as burns, injuries, infections, and fever
3. Essential and non-essential amino acids- do not have to know the names. What are food sources of proteins?
∙ Essential amino acids – must be supplied by the diet b/c they either cannot be made by the body or are synthesized in the body in insufficient quantity
∙ Nonessential amino acids – can be synthesized by the body; protein foods can deliver these but it is not necessary that they do so
Don't forget about the age old question of What taxes are mandatory payroll deductions?
∙ Found in protein foods (7 g), milk and milk products (8 g), vegetables (2 g), grains (3 g)
4. What are the functions of proteins? Can they be used for energy?
∙ Used as (1) structural materials – form building blocks of muscles, bone, and blood and replace dead or damaged cells, (2) enzymes – facilitate chemical reactions by making or breaking down substances , (3) hormones – regulate body processes, (4) regulators of fluid balance, (5) acid-base regulators – maintain balance between acids and bases and help to maintain steady body pH levels, (6) transporters – carry materials and substances across cell membranes or to another organ or part of the body, (7) antibodies – protect against disease and injection, (8) a source of energy and glucose – are sacrificed to provide energy and glucose during times of starvation or insufficient carbohydrate intake
5. Be able to calculate protein requirements
∙ 10-35% of total energy intake
∙ Protein RDA for adults: 0.8 g/kg of body weight/day
6. Where are amino acids digested…? absorbed? What are the enzymes involved in protein digestion? We also discuss several other topics like What is friction's simple definition?
∙ Major protein digestion starts in the stomach
o Hydrochloric acid denatures the protein strands and converts pepsinogen to pepsin – cleaves large polypeptides into smaller polypeptides and some
∙ Small intestine
o Intestinal proteases hydrolyze polypeptides into short peptide chains
o Peptidase breaks down smaller peptide chains into single amino acids
∙ Enzymes involved:
o Hydrochloric acid – denatures proteins and creates pepsin
o Pepsin – breaks down large polypeptides into smaller polypeptides
o Proteases – break down smaller polypeptides into short peptide chains
o Peptidase – breaks down short peptide chains into single amino acids ∙ Absorption:
o Amino acids are transported into intestinal cells – are used for energy or to synthesize needed compounds
o Those not used by the intestinal cells are transported across the cell membrane into surrounding fluid and enter capillaries on their way to the liver Don't forget about the age old question of What is the meaning of grand strategy?
7. What is meant by limiting amino acids?
∙ Limiting Amino Acids: an essential amino acid supplied in less than the amount needed to support protein synthesis
o All or nothing law of protein synthesis
Diet must supply all essential amino acids in adequate amounts and be available simultaneously for protein synthesis to occur
o Most common: lysine, methionine, threonine, tryptophan
8. What are the characteristics of Kwashiorkor and marasmus?
∙ Kwashiorkor: inadequate protein but adequate food energy
o Reflects sudden and recent food deprivation
o Common in 18-month to 2-year olds
o Edema – bulging belly and thin face and limbs
o Loss of appetite
o Dry, brittle fair that loses color
o Sores that don’t heal If you want to learn more check out What is the definition of continuous development?
∙ Marasmus: inadequate protein and inadequate food energy
o Very thin – children look elderly
o Severe deprivation over a long period of time
o Most common in children 6-18 months old
o Muscles waste and weaken, impaired brain development, decreased body temperature, protein is used for brain, heart, lungs only
o GI tract atophies
9. What is BMR, RMR, TEF, PA?
∙ Basal Metabolic Rate (BMR): rate of energy use for metabolism under specified conditions: after a 12-hr fast and restful sleep, without physical activity or emotional excitement, and in a comfortable setting
o Expressed as kcal/kg of body weight/hr
∙ Resting Metabolic Rate (RMR): a measure of energy use for a person at rest in a comfortable setting, but with less stringent criteria for recent food intake and physical activity
o RMR is slightly higher than BMR
∙ Physical Activity (PA): voluntary movement of the skeletal muscles and support system We also discuss several other topics like What is the relation between cancer incidence and mortality?
o Most variable – has significant influence on weight gain and weight loss o The longer, more frequent, and more intense the activity is, the more kcals expended If you want to learn more check out What are the classifications of meat?
∙ Thermic Effect of Food (TEF): an estimation of the energy required to process food o Proportional to the food energy taken in
o Estimated at 10% of energy intake
10.Calculate and evaluate BMI. How many decimal points?
∙ Body Mass Index: a measure of a person’s weight relative to their weight o Weight (lbs) / height (in) / height (in) x 703
o Healthy weight: 18.5-24.9
o Underweight: <18.5
o Overweight: >25
o Obese: >30
o One decimal place**
11.Anabolic and catabolic reactions
∙ Anabolic reactions require energy
o Glucose -- glycogen
o Glycerol + fatty acids -- triglycerides
o Amino acids -- protein
∙ Catabolic reactions release energy
o Glycogen -- glucose
o Triglycerides -- glycerol + fatty acids
o Protein -- amino acids
12.New G words to add to your list. Know what they are/what they mean: glycolysis, gluconeogenesis, glucogenic, glycerol
∙ Glycolysis: metabolic breakdown of glucose to pyruvate
o Doesn’t require oxygen (anaerobic)
∙ Gluconeogenesis: the making of glucose from a noncarbohydrate source such as amino acids or glycerol
∙ Glucogenic: amino acids that can be used to make glucose
∙ Glycerol: the 3-carbon backbone of triglycerides; can be converted to glucose or pyruvate
13.Where do AA/proteins enter the energy cycle?
∙ Some amino acids can be converted to pyruvate (glucogenic)
∙ Some amino acids can be converted to acetyl CoA (ketogenic)
∙ Some amino acids can enter the TCA cycle directly
14.What is the preferred source of energy initially if CHOS (carbohydrates) are not available? ∙ The body begins making glucose from the amino acids of protein through gluconeogenesis
15.Aerobic and anaerobic reactions- what kind of activity do we mean? ∙ Aerobic: requiring oxygen
o Produce energy more slowly and can be sustained for a longer period of time – greater total energy yield
o Ex) Pyruvate to Acetyl CoA
∙ Anaerobic: not requiring oxygen
o Yields energy quickly and cannot be sustained for long
o Ex) Pyruvate to Lactate
16.What is Lactic acid? Does it occur in anaerobic or aerobic metabolism; can it form glucose? ∙ A compound that is created from pyruvate that turns into lactate, which builds up in muscles and coincides with a drop in pH, burning pain, and fatigue
∙ Occurs in anaerobic metabolism
∙ Doesn’t form glucose
17.What happens if one consumes excess CHO/ pro /fat
∙ Excess Protein
o First replaces normal daily losses
o Then increases protein oxidation – uses some excess protein, but displaces fat in the fuel mix
o If excess is still available, amino acids are deaminated and remaining carbons are used to make fatty acids, which are stored as triglycerides in adipose tissue
∙ Excess Carbohydrate
o First is stored as glycogen until glycogen stores are full
o Can also be converted to fat but is energetically expensive
o Can also displace fat in the fuel mix
∙ Excess Fat
o Moves into body’s fat stores – almost all of the excess is stored
18.What happens if the diet is Insufficient in CHO/pro/ fat?
∙ Body will draw on reserves of CHO and fat and eventually protein tissues
∙ Body proteins are converted to glucose to supply brain and nerve cells ∙ Fat breakdown increases, but glycerol provides minimum amount of glucose ∙ Metabolism slows to conserve energy and body tissue
19.Ketones- what are they? When do they form? What do they show?
∙ Ketones are an alternate energy source when glucose is not available in low carb diets
o Can provide fuel for some brain cells
o Causes elevated blood pH levels and ketosis – changes in blood chemistry Acidic blood denatures proteins and causes them to stop functioning o Spills into blood and leaves breath with a fruity odor from acetone
20.What are the recommendations for healthy weight loss?
∙ Be realistic about energy intake
o Avoid rapid weight loss and restricted eating
o Goal is nutritional adequacy without excess
o Adequacy and variety, eat smaller portions, and eat more nutrient dense foods and lower energy dense foods
o Adequate water
∙ Physical Activity
o Choose moderate to vigorous physical activities
o Avoid inactivity
o Gradually increase frequency, intensity, and duration of activities
∙ Behavior and Attitude
o Become aware of behaviors, avoid tempting situations
o Change behaviors – set goals
o Consider support groups if necessary
21.Be able to calculate wt loss/timing
22.How do we determine IBW?
∙ Ideal body weight is not appearance based
o Perceived body images has less to do with body weight than actual body size o Is subjective
o Has little in common with health
23.What are Leptin and Ghrelin? How do they work?
∙ Leptin: a protein produced by fat cells under direction of the ob gene that decreases appetite and increases energy expenditure
o Maintains homeostasis by regulating food intake and energy expenditure in response to adipose tissue
∙ Ghrelin: a protein produced by the stomach cells that enhances appetite and decreases energy expenditure
o Promotes eating and weight gain by increasing smell sensitivity, stimulating appetite, and promoting efficient energy storage
o Triggers the desire to eat
24.Body fat distribution- how does this affect health?
∙ Visceral fat: fat stored in the abdominal cavity around the internal abdominal organs o Referred to central obesity (“apple shaped”) or upper-body fat
o More common among men and women after menopause
o Central obesity contributes to heart disease, cancers, diabetes, and related deaths
Is associated with chronic diseases
∙ Subcutaneous fat: fat stored under the skin
o Referred to as lower-body fat (“pear shaped”)
o Most common in women in their reproductive years
o Is associated with lower heart disease risks and not associated with chronic diseases