Nutrition and Metabolism

Question 1

What is a nutrient?

Answer 1

Nutrient: a substance in food that promotes normal growth, maintenance, and repair of cells

Question 2

Some nutrients include…

Answer 2

Nutrients include carbohydrates, lipids, proteins, vitamins, minerals (and water)

Question 3

What is an essential nutrient?

Answer 3

A nutrient that cannot be synthesized by the body, and thus must be obtained from a dietary source

Question 4

What is a calorie?

Answer 4

The calorie (cal) is the amount of energy needed to raise the temperature of one gram of water by one degree Celsius

Question 5

What is a food calorie?

Answer 5

The food calorie (Cal) is defined in terms of the kilogram rather than the gram. It is equal to 1000 calories (kcal)

Question 6

Why are carbohydrates important?

Answer 6

a. Glucose is the fuel used by cells to make ATP
i. Neurons and RBCs rely almost entirely upon glucose
ii. Excess glucose is converted and stored as glycogen or fat

Question 7

What are sugars?

Answer 7

a. Sugars (simple carbohydrates – usually mono- or disacharides)
b. Sugar, jams, fruit drinks, honey, etc

Question 8

What is starch?

Answer 8

a. Starch (complex carbohydrates)

b. Green vegetables, grains, starchy vegetables, beans, lentils

Question 9

What are two types of fibers?

Answer 9

a. Insoluble fiber: cellulose in vegetables; provides roughage
b. Soluble fiber: pectin in apples and citrus fruits; reduces blood cholesterol levels

Question 10

What are lipids? Name and describe three types.

Answer 10

a. Triglycerides and fatty acids
b. Saturated fatty acids found in meat, dairy foods, and tropical oils (coconut, palm kernel or palm oils)
c. Unsaturated fats found in seeds, nuts, olive oil, and most vegetable oils (corn, peanut, soybean or sunflower oils)
d. Essential fatty acids
i. Linoleic and linolenic acid, found in most vegetable oils
ii. Must be ingested in diet

Question 11

What is the importance of lipids?

Answer 11

a. Help absorb fat-soluble vitamins
b. Major fuel of hepatocytes and skeletal muscle
c. Phospholipids are essential in myelin sheaths and all cell membranes
d. Adipose tissue
i. Protective cushions around body organs
ii. Insulating layer beneath the skin
iii. Concentrated source of energy
e. Prostaglandins
i. Control of blood pressure
ii. Inflammation
f. Cholesterol – found in egg yolk, meats, organ meats, shellfish, and milk products
i. Stabilizes membranes
ii. Precursor of bile salts and all steroid hormones

Question 12

How is cholesterol transported?

Answer 12

Cholesterol cannot dissolve in the watery blood plasma, so it must be carried around the body by transport proteins called lipoproteins.

Question 13

Which cholesterol is considered good and bad? Why

Answer 13

a. Low density lipoprotein (LDL) is considered bad because it gets stuck in arteries
b. High density lipoprotein (HDL) is considered good because it doesn’t get stuck

Question 14

How many proteins are there? How many are essential and nonessential?

Answer 14

a. 20 amino acids

b. 9 essential, 11 nonessential

Question 15

What are complete proteins?

Answer 15

Complete proteins are those that contain all 9 essential amino acids in sufficient quantity – these are typically animal-based proteins

Question 16

What are incomplete proteins?

Answer 16

Incomplete proteins are those that don’t contain all 9 essential amino acids, or don’t have sufficient quantities of them to meet the body’s needs, and must be supplemented with other proteins.

Question 17

Describe the use of amino acids in the body (all or none rule, caloric intake)

Answer 17

a. All-or-none rule- All amino acids needed must be present for protein synthesis to occur
b. Adequacy of caloric intake- Protein will be used as fuel if there is insufficient carbohydrate or fat available

Question 18

What is the importance of protein? (don’t memorize)

Answer 18

a. Structural materials: keratin, collagen, elastin, actin, myosin, microtubules, cilia, flagella, centrioles, etc.
b. Most are functional molecules: enzymes, receptors, transporter proteins, hemoglobin, antibodies, some hormones, transcription factors, etc.

Question 19

What are vitamins and what is their function?

Answer 19

a. Organic molecules

b. Most function as coenzymes, making metabolism more efficient

Question 20

What are the two types of soluble vitamins?

Answer 20

a. Water-soluble vitamins
i. B complex and C are absorbed with water
ii. B12 absorption requires intrinsic factor
iii. Not stored in the body
b. Fat-soluble vitamins
i. A, D, E, and K are absorbed with lipid digestion products
ii. Stored in the body, except for vitamin K

Question 21

What are the seven essential minerals?

Answer 21

a. Calcium, phosphorus, potassium, sulfur, sodium, chloride, and magnesium
b. Others required in trace amounts

Question 22

What do minerals do?

Answer 22

Work with nutrients to ensure proper body functioning

Question 23

What is metabolism?

Answer 23

biochemical reactions inside cells involving nutrients

Question 24

What are two type of metabolic reactions?

Answer 24

a. Anabolism: synthesis of large molecules from small ones

b. Catabolism: hydrolysis of complex structures to simpler ones

Question 25

What is cellular respiration?

Answer 25

catabolism of food (& O2) fuels and capture of energy to form ATP in cells

Question 26

What is phosphorylation?

Answer 26

a. Enzymes shift high-energy phosphate groups of ATP to other molecules b. Phosphorylated molecules are activated to perform cellular functions

Question 27

Describe the oxidation-reduction (Redox) reactions (OIL, RIG)

Answer 27

a. Oxidized substances have lost electrons | b. Reduced substances have gained electrons

Question 28

What is dehydrogenation?

Answer 28

often times, during redox, a proton (H+) accompanies the electron

Question 29

What do coenzymes (carriers) act as? What are their specific names?

Answer 29

a. Act as hydrogen (or electron) acceptors b. Nicotinamide adenine dinucleotide (NAD+) c. Flavin adenine dinucleotide (FAD)

Question 30

Describe the two mechanisms of ATP synthesis

Answer 30

a. Substrate-level phosphorylation (one stop shopping) | b. Oxidative phosphorylation

Question 31

Describe substrate-level phosphorylation

Answer 31

a. High-energy phosphate groups directly transferred from phosphorylated substrates to ADP b. Occurs in glycolysis and the Krebs cycle

Question 32

Describe oxidative phosphorylation

Answer 32

a. Chemiosmosis- Couples the movement of hydrogen ions across mitochondrial membrane with phosphorylation of ADP to ATP b. In the mitochondria c. Carried out by electron transport proteins d. Nutrient energy is used to create H+ gradient across mitochondrial membrane e. Pairs of H+ flow through ATP synthase f. Energy is captured and attaches phosphate groups to ADP

Question 33

Oxidation of glucose will give you how many ATP?

Answer 33

38 ATP

Question 34

Glucose is catabolized in which three pathways?

Answer 34

a. Glycolysis b. (bridge) c. Krebs’ cycle d. Electron transport chain (ETC) and oxidative phosphorylation

Question 35

Where does glycolysis occur?

Answer 35

Cytoplasm of cell

Question 36

What are the steps of the glycolysis?

Answer 36

a. Sugar activation- Glucose is activated by phosphorylation and converted to 6-bisphosphate (2 ATP are lost) b. Cleavage- 6-bisphosphate is cleaved into two 3-carbon fragments (pyruvate) c. 4 ATP molecules are formed, and 2 NAD+ is reduced to 2 NADH + H+

Question 37

What are the final products of glycolysis?

Answer 37

a. 2 pyruvic acid i. Converted to lactic acid if O2 not readily available ii. Enter aerobic pathways if O2 is readily available b. 2 NADH + H+ (reduced NAD+) c. Net gain of 2 ATP

Question 38

Describe the transitional phase (bridge) to Kreb cycle

Answer 38

a. Each pyruvic acid is converted to acetyl CoA b. Decarboxylation: removal of 1 C to produce acetic acid and CO2 c. Oxidation: H+ is removed from acetic acid and picked up by NAD+ d. Acetic acid + coenzyme A forms acetyl CoA

Question 39

Where does the Krebs’ Cycle occur and what is it fueled by?

Answer 39

a. Occurs in mitochondrial matrix | b. Fueled by pyruvic acid and fatty acids

Question 40

Describe the Krebs Cycle

Answer 40

a. Coenzyme A shuttles acetic acid to an enzyme of the Krebs cycle b. Each acetic acid is decarboxylated and oxidized, generating: i. 3 NADH + H+ ii. 1 FADH2 iii. 2 CO2 iv. 1 ATP v. There are 2 acetic acids, so all of these are doubled

Question 41

What are 3 facts about the Krebs cycle?

Answer 41

a. Does not directly use O2 b. Breakdown products of fats and proteins can also enter the cycle c. Cycle intermediates may be used as building materials for anabolic reactions

Question 42

Describe the electron transport chain and oxidative phosphorylation

Answer 42

a. The only part of metabolism that directly uses oxygen b. Chain of proteins bound to metal cofactors on inner mitochondrial membrane c. Coenzymes NADH and FADH2 deliver electrons and protons (they now are oxidized) d. Electrons are shuttled along the inner mitochondrial membrane, losing energy at each step e. Released energy is used to pump H+ into the intermembrane space f. H+ diffuses back to the matrix in pairs via ATP synthase g. ATP synthase uses released energy to make ATP h. Electrons are delivered to O, forming O– i. O– attracts H+ to form H2O

Question 43

Describe electron transport chain and oxidative phosphorylation (last step of ETC)

Answer 43

a. Electrons are delivered to O, forming O– | b. O– attracts H+ to form H2O

Question 44

Describe the electron transport chain and oxidative phosphorylation

Answer 44

a. Transfer of energy from NADH + H+ and FADH2 to oxygen releases large amounts of energy b. This energy is released in a stepwise manner through the electron transport chain

Question 45

Describe the ATP synthase

Answer 45

a. Two major parts connected by a rod b. Rotor in the inner mitochondrial membrane c. Knob in the matrix d. Works like an ion pump in reverse

Question 46

How many ATP are produced by each metabolic step?

Answer 46

a. Glycolysis: Net +2 ATP b. Krebs Cycle: +2 ATP c. ETC: +34 ATP i. 10 NADH + H+ x 3 ATP= 30 ATP ii. 2 FADH2 x 2 ATP= 4 ATP