BIOL 204 Exam 4

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what is nutrition?

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1

what is nutrition?

the process of providing or obtaining the food necessary for health and growth

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2

what is digestion?

it is the catabolic process that breaks down large food molecules to monomers (chemical building blocks)

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3

what is hydrolysis?

the enzymatic breakdown of any food molecule; it involves adding a water molecule to each molecular bond to be broken (lysed)

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4

what are the monomers of carbohydrates, proteins, lipids, and nucleic acids?

monosaccharides; amino acids; fatty acids; nucleotides

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5

what is absorption?

the process of moving substances from the lumen of the gut into the body

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6

what is metabolism?

the sum of all biochemical reactions in the body

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7

what is the main difference between catabolism and anabolism?

anabolism includes reactions that build larger molecules from smaller ones and catabolism is the breakdown of complex structures to simpler ones

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8

what is a nutrient?

a substance in food the body uses to promote normal growth, maintenance, and repair

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9

what is an essential nutrient?

those that are inadequately synthesized by body cells and must be ingested in the diet

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10

what are the six nutrient categories?

carbohydrates, protein, fats, water, vitamins, and minerals

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11

what are the four macronutrients?

carbohydrates, protein, fats, and water

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12

what are the two micronutrients?

vitamins and minerals

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13

what is the difference between macronutrients and micronutrients?

macronutrients must be consumed in relatively large quantities and micronutrients require small quantities of consumption

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14

what is meant by percent of daily caloric intake?

the recommended proportion of energy supply

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15

what percentage of your daily caloric intake should carbohydrates, proteins, and fats make up?

carbohydrates: 45-65%

proteins: 10-35%

fats 20-35% (<10% should be saturated)

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16

what macronutrient should we eat most as a percentage of total calories?

carbohydrates

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17

what are calories?

the amount of heat (energy) needed to raise the temperature of 1 gram of water 1 degree Celsius

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18

what is the difference between calories, Calories, and kilocalories?

1000 calories = 1 Calorie = 1 kilocalorie

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19

what do Calories represent?

the ability of food to be converted by the body into energy

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20

what are the three energy-yielding nutrients?

carbohydrates, proteins, and fat

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21

how many calories are produced when one gram of carbohydrates, fats, and proteins are fully oxidized in our body?

carbohydrates/ proteins: 4 kcal/g

fats: 9 kcal/g

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22

what is an empty calorie?

calories that contribute to your total caloric intake but supply little or no nutritional value

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23

why is alcohol not a class of nutrients despite is high-calorie content?

alcohol provides “empty calories”- it suppresses appetite but fails to provide other nutrients

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24

which of the following vitamins are water-soluble or lipid-soluble: A,B,C,D,E,K?

water-soluble: B, C

fat soluble: A,D,E,K

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25

which of the two vitamin groups, water-soluble or lipid-soluble, has a higher risk of accumulating in your body until reaching toxic levels? Why?

fat-soluble vitamins because they are stored in the body

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26

How are water-soluble vitamins absorbed and excreted from the body?

water-soluble vitamins are absorbed with water by simple diffusion and excreted in urine

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27

how is vitamin B12 absorbed from the intestines?

vitamin B12 binds to the intrinsic factor, which is secreted by the stomach’s parietal cells

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28

Is ferrous (Fe2+) iron or ferric (Fe3+) iron more absorbable?

ferrous (Fe2+) iron

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29

what is the function of ferroportin (FPN)?

FPN transports iron into the bloodstream

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30

where can you find ferroportin?

basolateral membranes of intestinal epithelia

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31

what is the function of transferrin?

transports iron all over the body

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32

what happens to iron released by macrophage degradation of senescent red blood cells?

it is recycled

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33

why does transferrin transport iron to bones and muscles?

myoglobin synthesis

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34

what is ferritin?

iron storage protein

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35

which organ represents the primary storage site for iron?

the liver

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36

what is hepcidin? what is its main goal, increase or decreased blood levels of iron? How does it achieve this?

iron absorption and mobilization are regulated by hepcidin; it decreases blood levels of iron by binding to ferroportin

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37

will an increase in blood iron increase or decrease the production of hepcidin by the liver?

increase

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38

will an increase in red blood cells increase or decrease the hepcidin production by the liver?

decrease

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39

In which two main organs does digestion of carbohydrates take place?

oral cavity and small intestine

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40

where does the digestion of carbohydrates start?

in the oral cavity

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41

what is a polysaccharide?

polymer of carbohydrates

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42

what enzyme is in saliva that digests polysaccharides?

salivary amylase

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43

why does the digestion of carbohydrates not continue in your stomach if the bolus from your mouth also carries some salivary amylase?

the acidic pH of the stomach inactivates amylase

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44

where does the amylase in your small intestine come from?

the pancreas

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45

which two brush border enzymes act on oligosaccharides composed of more than three simple sugars?

dextrinase and glucoamylase

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46

what are disaccharides? give three examples.

disaccharides are two units of carbohydrates; maltose, sucrose, and lactose

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47

where can you find disaccharides in the digestive system?

in the small intestine

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48

where are monosaccharides absorbed?

small intestine

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49

are monosaccharides absorbed into the blood or lymph?

blood

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50

what is the primary purpose of cellular respiration?

generate ATP in the presence of oxygen

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51

what is the equation for aerobic respiration of glucose?

C6H12O6 + 6O2 → 6CO2 + 6H2O

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52

what are the three consecutive pathways of glucose aerobic respiration?

glycolysis, citric acid cycle, and electron transport chain

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53

what is the role of ATP?

energy carrying molecule that releases to fuel cell processes

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54

what is the role of NAD or FAD?

coenzymes that carry the extracted energy

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55

what molecules are the starting and end products of glycolysis?

converts glucose to pyruvic acid

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56

How is energy stored in the body?

energy is stored at carbohydrates and fats and converted into ATP when energy is needed

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57

how many pyruvates are obtained per molecule of glucose being oxidized in glycolysis?

two pyruvates

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58

what pathway does pyruvic acid enter in the absence of oxygen? and in the presence of oxygen?

in the absence of oxygen: pyruvate processing (pyruvic acid to lactic acid)

presence of oxygen: citric acid cycle

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59

what is pyruvate converted into to enter the citric acid cycle?

acetyl CoA

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60

is the citric acid cycle and Krebs cycle the same?

yes

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61

what is the final pathway to produce ATP in glucose metabolism?

electron transport chain/ oxidative phosphorylation

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62

what ion gradient is used to make ATP?

H+ (proton) gradient

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63

what is glycolysis?

conversion of glucose to pyruvic acid

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64

what is gluconeogenesis?

formation of glucose from noncarbohydrate precursors

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65

what is glycogenesis, and when does it occur?

polymerization of glucose to form glycogen; occurs when cellular ATP reserves are high

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66

what is glycogenolysis, and when does it occur?

hydrolyzation of glycogen to glucose monomers; occurs when blood glucose levels begin to fall

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67

what is the general name of enzymes that act on proteins?

peptidases

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68

what enzyme begins the digestion of proteins and where is it located?

pepsin; stomach

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69

what enzymes from the pancreas digest protein? which are zymogens?

trypsin, chymotrypsin, carboxypeptidase (zymogens) and elastase

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70

what three brush border enzymes digest proteins?

carboxypeptidase, aminopeptidase, and dipeptidase

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71

what is the function of dipeptidase?

split dipeptides into separate amino acids

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72

what is contact digestion?

action of brush border enzymes

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73

where are brush border enzymes located?

small intestine (simple cuboidal epithelium?)

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74

what is nitrogen balance?

state in which the rate of N ingestion = rate of N excretion

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75

how do you get nitrogen for your body?

via proteins

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76

what happens when you have too little nitrogen in your body (state of negative nitrogen balance)?

increase of nitrogenous wastes in urine; muscle atrophy; protein catabolism

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77

what can cause a state of negative nitrogen balance?

nitrogen excretion>ingestion

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78

what is positive nitrogen balance associated with?

periods of growth (during adolescence and pregnancy)

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79

what three steps comprise the amino acid catabolic pathway?

transamination, oxidative deamination, keto acid modification

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80

how does the body get rid of the amino group of amino acids?

transamination; the amino group is switched from an amino acid to a keto acid (glutamic acid)

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81

how is urea produced in the body?

oxidative deamination; the amine group of glutamic acid is removed as ammonia and combined with CO2 to form urea

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82

what happens during keto acid modification?

the keto acids formed during transamination are altered so they can easily enter the citric acid cycle

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83

can you obtain energy from proteins?

yes; 4 kcal/ g

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84

what is the name of this functional group: -NH2?

amine group

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85

what is bile made of?

95% water

5% solute

  • bile acids

  • lecithin

  • cholesterol

  • bilirubin

  • proteins

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86

what is the main component of bile?

water

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87

what are bile salts made of?

bile acids that are often bonded to glycine or taurine to increase water solubility (= conjugated bile acids)

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88

what is the role of bile salts in the digestive process

increase water solubility

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89

where is bile produced? from which molecule?

produced in the liver from cholesterol

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90

what are conjugated bile salts?

bile acids bonded to glycine or taurine

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91

what is the only way for the body to get rid of cholesterol?

in feces

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92

what percentage of bile salts are lost in the feces?

20%

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93

in what part of the intestine are bile salts recycled?

the ileum

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94

what is the role of emulsification?

bile salts in the duodenum break large fat globules into smaller fat droplets: increases surface area available to lipase enzymes

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95

what are miscelles?

aggregates of bile salts that forms a polar outer shell and a hydrophobic inner core

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96

what are triglycerides composed of?

three fatty acids and a glycerol

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97

which enzyme is mainly responsible for digesting triglycerides in the small intestine?

pancreatic lipase

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98

what is the function of micelles in the absorption of lipids?

since micelles are water-soluble, this allows for lipid digestion products to be transported into the small intestine

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99

why do lipids need to be transported in the core of the micelles to to enter the enterocytes?

lipids are not water-soluble and micelles are

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100

what happens to the fatty acids and monoglycerides once inside of the enterocytes?

the fatty acids and monoglycerides are converted into triglycerides

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