Usuhs - Biochem I

Front 1

Chap 1-1: Identify the major body fuels according to name and structure.

Back 1

carbohydrates - starch, sucrose, lactose, fructose, and glucose (monosaccharide).

protein - amino acids.

fats - lipids composed of triacylglycerols containing 3 fatty acids esterified to 1 glycerol moiety.

Front 2

Chap 1-2: Describe the ATP-ADP cycle. Discuss its significance with regard to fuel metabolism.

Back 2

Electrons lost from fuels during oxidative reactions are transferred to oxygen by a series of proteins in the electron transport chain.

Electron transfer used to convert ADP and inorganic phosphate to ATP by oxidative phosphorylation.

As processes use energy, ATP converted back to ADP and inorganic phosphate.

Front 3

Chap 1-3: Define food calorie and recall the calorie content of carbohydrates, fats, proteins, and alcohol. Use these numbers to calculate the energy content of a meal.

Back 3

Energy content in food is expressed as a Calorie (= 1 kilocalorie) or in joules.

Carbohydrate = 4 kcal/g.
Fat = 9 kcal/g.
Protein = 4 kcal/g.
Alcohol = 7 kcal/g.

Example. If a person ate 100 g carbs, 20 g protein, and 15 g fat, how many calories?
(100*4) + (20*4) + (15*9) = 615 kcal

Front 4

Chap 1-4: Define basal metabolic rate and resting metabolic rate. Give an approximate value for these numbers. Recall the approximate Calories per hour expended in various common activities. Recall the approximate daily energy expenditures for a sedentary and active person.

Back 4

Basal metabolic rate (BMR) is defined as the energy expenditure of a person mentally and bodily at rest in a thermoneutral environment 12-18 hours after a meal.

Resting metabolic rate (RMR) is a measure of the energy required to maintain life (i.e. functioning of lungs, kidneys, and brain).

BMR and RMR are used interchangeably.

Multiply 24 kcal/kg-day by body weight to approximate BMR (or RMR).

Approximate DEE for a sedentary person is 1.3*RMR
DEE for active person is 2*RMR

Front 5

Chap 1-5: Define diet-induced thermogenesis.

Back 5

Related to intake of food.
Energy required to process the types and quantities of food in the typical diet is probably equal to approximately 10% of kilocalories ingested.

Often ignored since it is roughly equivalent to error involved in rounding off caloric content of fuels.

Front 6

Chap 1-6: Define BMI and discuss its clinical significance.

Back 6

Body mass index is defined as weight/height^2.

IN general, adults with BMIs below 18.5 are considered underweight; 18.5~24.9 are considered healthy; 25~29.9 are overweight or preobese, and above 30 are obese.

Front 7

Chap 1-7: Outline the requirements for a healthy diet in terms of macronutrients and micronutrients.

Back 7

No specific carbs have been identified as dietary requirements.

Essential fatty acids are α-linoleic and α-linolenic acid supplied by dietary plant oils; eicosapentaenoic acid and docosahexaenoic acid are supplied in fish oils.

RDA for protein is approximately 0.8 g high-quality protein (animal origin) per kilogram of ideal body weight (approx. 60 g/day for men and 50 g/day for women).

Vitamins (see Table 1.7, p. 14)

Required minerals are divided into 4 classes: electrolytes, minerals, trace minerals, and ultratrace (see Table 1.8, p. 15).

Front 8

Chap 2-1: Sketch the "Fed" state from memory and describe what is happening in each tissue during the absorptive state.

Back 8

Hint 8

1) Insulin: increases glycogen formation, decreases blood glucose levels
Glucagon: breaks down glycogen, increases glucose levels in blood
2) Glucose first obtained from glycogen breakdown.
3) Glucose transported to brain where it’s converted to acetyl CoA, which undergoes the TCA cycle to produce CO2 and ATP.
4) Glucose that goes to the RBCs is converted to lactate by glycolysis.
5) Triacylglycerides are converted to FAs and glycerol by lipolysis.
6) In muscle, FAs are oxidized to acetyl CoA, which enters the TCA cycle to yield
CO2 and ATP.
7) In liver, FAs are oxidized to yield KBs via the process:

8) Muscle tissue further oxidizes KBs to acetyl CoA which enters the TCA cycle to
yield CO2 and ATP.
9) When no more glucose can be obtained from glycogenolysis, gluconeogenesis
occurs in liver. This uses lactate, glycerol, and amino acids to synthesize glucose.
10) Amino acids (AAs) come from protein breakdown. The AAs’ nitrogen is
converted to urea and released from the body by the kidneys.
11) Lactate comes from glycolysis in RBCs.
12) Glycerol comes from lipolysis.

Front 9

Chap 2-2: Explain the role of insulin and glucagon in general terms.

Back 9

Insulin secreted from pancreas carries message that dietary glucose is available and can be used and stored.

Glucagon is suppressed by glucose and insulin levels. Glucagon carries message that glucose must be generated from endogenous fuel stores.

Front 10

Chap 3-1: Sketch the "Basal State" from memory and describe what is happening in each tissue during an overnight fast.

Back 10

Hint 10

1) Person in basal state: serum insulin level is low and glucagon is rising. Insulin is a hormone that triggers the uptake of blood glucose by the cell and promotes storage of excess glucose in the form of glycogen. Glucagon is a hormone that triggers the breakdown of glycogen to obtain stored glucose for the cells, and is released when glucose levels in the blood are low.
2) After overnight fasting, glucose levels are low so glucagon is released to promote breakdown of glycogen (glycogenolysis). Breakdown of glycogen releases stored glucose in the liver.
3) Glucose is transported from the liver to glucose-dependent tissues including the brain and red blood cells (RBCs). In the brain, glucose is oxidized to acetyl CoA. This acetyl CoA then serves as a substrate for the tricarboxylic acid cycle (TCA cycle; also known as the citrate or citric acid cycle). In the TCA cycle, acetyl CoA is oxidized to CO2. NADH, FADH2, and GTP are also produced. NADH and FADH2 donate electrons to the electron transport chain during the oxidative phosphorylation process to yield ATP (cellular respiration). GTP, like ATP, is a source of a high energy phosphate bond that stores energy.
4) Glucose is necessary for RBCs, because they do not contain mitochondria and thus are unable to break down fatty acids (FA’s) for energy. Glucose undergoes glycolysis here to produce lactate (occurs in exercising muscle tissue too).
5) When insulin levels decrease and glucagon levels increase, triacylglycerides in adipose tissue are broken down by lipolysis, liberating FA’s and glycerol.
6) In muscle cells, FA’s are oxidized completely, yielding acetyl CoA, which enters the TCA cycle (yields CO2 and eventually ATP).
7) FA’s that enter the liver are partially oxidized to ketone bodies (liver lacks enzymes to further oxidize them). These FA’s are first converted to acetyl CoA (this produces ATP to drive these reactions). This acetyl CoA is converted into ketone bodies (KBs).
8) Muscle and other tissue (not the liver or RBCs) have enzymes to oxidize KBs to acetyl CoA. This acetyl CoA enters the TCA cycle to produce CO2 and ATP.
9) When glycogen stores are degraded, another source of glucose is needed. Gluconeogenesis occurs in the liver to produce glucose from lactate, glycerol, and amino acids.
10) Amino acids are produced from the breakdown of protein (mainly from muscle tissue). Nitrogen from amino acids can form ammonia (toxic to body), so liver converts the nitrogen to urea which is excreted by the kidneys.
11) When glucose undergoes glycolysis in the RBCs, lactate is formed. This lactate is a substrate in gluconeogenesis.
12) Glycerol is another substrate for gluconeogenesis. It is a product of lipolysis (breakdown of triacylglycerides in adipose tissue).

Front 11

Chap 3-2: Sketch the "Starved State" and describe what is happening in each tissue during starvation.

Back 11

Hint 11

1) Insulin: increases glycogen formation, decreases blood glucose levels
Glucagon: breaks down glycogen, increases glucose levels in blood
2) Glucose first obtained from glycogen breakdown.
3) Glucose transported to brain where it’s converted to acetyl CoA, which undergoes the TCA cycle to produce CO2 and ATP.
4) Glucose that goes to the RBCs is converted to lactate by glycolysis.
5) Triacylglycerides are converted to FAs and glycerol by lipolysis.
6) In muscle, FAs are oxidized to acetyl CoA, which enters the TCA cycle to yield
CO2 and ATP.
7) In liver, FAs are oxidized to yield KBs via the process:
FAs -> acetylCoA + ATP (used to drive reactions)
acetylCoA -> KBs
8) Muscle tissue further oxidizes KBs to acetyl CoA which enters the TCA cycle to
yield CO2 and ATP.
9) When no more glucose can be obtained from glycogenolysis, gluconeogenesis
occurs in liver. This uses lactate, glycerol, and amino acids to synthesize glucose.
10) Amino acids (AAs) come from protein breakdown. The AAs’ nitrogen is
converted to urea and released from the body by the kidneys.
11) Lactate comes from glycolysis in RBCs.
12) Glycerol comes from lipolysis.