Midterm Section 3.3 - Protein/Body Comp

Question 1

main functions of protein/AA

Answer 1

maintenance and regulation of body functions
growth
repair and response to injury
energy (converted to glucose, converted to fat or burned as fuel)

Question 2

thyroid hormone requires which amino acid precursor?

Answer 2

tyrosine

Question 3

definition of an essential nutrient

Answer 3

performs an identifiable biological function
abnormality results from lack of consumption
body cannot make it, or cannot make enough to satisfy demand

Question 4

insulin peptides are held together with

Answer 4

disulfide bonds

Question 5

enzymes and chemicals that break down proteins

Answer 5

HCl denatures protein structures
activated pepsin hydrolyzes peptide bonds
pancreatic bicarbonate denatures pepsin
pancreatic peptidases hydrolyze peptide bonds
dipeptidases on brush border

Question 6

SNP

Answer 6

single nucleotide polymorphisms - single change of an amino acid in sequence can create disease state, such as sickle cell anemia
heterozygous genes for sickle cell have resistance to malaria

Question 7

PKU

Answer 7

phenylketonuria - change of phenylalanine hydroxylase, needed to create enzyme to break down phenylalanine

Question 8

nutritional genomics categories

Answer 8

nutritional genomics - interactions of food and genes, includes:
nutrigenetics - examines how genes influence activities of nutrients
nutrigenomics - include epigenetics, examines how nutrients affect expression of genes

Question 9

how nutrients can affect gene expression

Answer 9

nutrients can turn on or off genes, or interacting with intermediates
protein synthesis up or down regulated which directly affects disease progression or prevention

Question 10

protein turnover in a healthy adult

Answer 10

is in equilibrium: same amount synthesized, same amount broken down

Question 11

does increased protein intake alone drive increase muscle mass?

Answer 11

no, requires weight training or increased protein requirements due to illness/injury/stage of life/poor absorption
30g in one sitting required to trigger protein synthesis

Question 12

percent nitrogen in protein and nitrogen balance equation

Answer 12

16%
Nitrogen balance = N intake - N fecan - N urinary

Question 13

how ammonia is never free in the body

Answer 13

it is toxic, transferred from one amino acid to another in intermediate keto acid form
delivered to liver for urea cycle

Question 14

AA required for urea cycle

Answer 14

arginine, required for ammonia detoxification into urea

Question 15

nephron definition and numbers

Answer 15

working unit of the kidney
more than 1 million nephrons in one kidney

Question 16

nephron anatomy

Answer 16

blood flows into the glomerulus where fluid and substances are absorbed in the tubule
reabsorption of nutrients and fluid along the descending tubule

Question 17

adequacy of dietary protein (3)

Answer 17

1. adequate energy intake, otherwise amino acids will be catabolized
2. protein quantity: official RDA is .8g per kg/day, AMDR 10-35%
3. quality - having all EAA in relative amounts similar to need

Question 18

usual intake of protein vs. RDA
athletes recommendation
unofficial recommendation

Answer 18

100g/day vs .8g per kg/day (~56g)
1.2-2 g per kg/day, 1.7g per kg/day for female athletes
unofficial recommendation is 1.2g per kg/day

Question 19

what is a limiting amino acid

Answer 19

AA present in the lowest amount, relative to the body’s need for it
all others are comparatively present in excess and must be degraded

Question 20

DIAAS

Answer 20

Digestible Indispensable Amino Acid Score
expressed as a percent of dietary requirement relative to .66g (EAR protein) of the test protein
test protein is lowest DIAAS score
above 100 is considered excellent

Question 21

homeostasis defition

Answer 21

dynamic processes maintain constant internal environment despite changing external environment (often relies on negative feedback)

Question 22

in energy production pathways, which intermediates have a one way arrow between them? meaning?

Answer 22

pyruvate to acetyl coA, ketogenic amino acids to acetyl coA
this means that ketogenic amino acids cannot produce glucose and an excess of acetyl coA will become ketone bodies

Question 23

cellular respiration pathway (basic)
glucogenic AA pathway for energy

Answer 23

glucose (or glycogen) –> pyruvate by pyruvate decarboxylase –> acetyl coA –> krebs cycle and ATP
AA –> pyruvate –> lactase to leave cell –> back to liver to convert into glucose

Question 24

postprandial

Answer 24

fed state

Question 25

excess proteins are metabolized into:

Answer 25

carbon skeleton stored as fat or glycogen
nitrogen lost as urea

Question 26

short term fasting pathways

Answer 26

glycogen stores converted to glucose for energy
fatty acids broken down by hormone sensitive lipase and used as energy via beta oxidation (acetyl coA)

Question 27

long term fasting pathways

Answer 27

• body protein broken down into AA (glucogenic and ketogenic)
• fat broken down by hormone sensitive lipase and used as energy via beta oxidation (acetyl coA) or into ketone bodies from build up of acetyl coA
• Over time of continued fasting, the body adapts to reduce amino acid catabolism and increase fatty acid catabolism into ketones and ATP

Question 28

body mass index
BMI ranges

Answer 28

kg/m^2
healthy: 18.5-25
overweight: 25-30
obese: >30

Question 29

body composition analysis methods

Answer 29

1. Hydro densitometry - under water weighing, fat is lighter than water adipose is less dense than lean tissue)
2. Air displacement plethysmography
3. DEXA - x ray absorptiometry, can also be used to measure bone density
4. waist circumference (doesn’t differentiate visceral vs adipose)
   - >= 40” (M), 35” (F)
5. skinfold testing
6. BIA - bioelectrical impedance

Question 30

how to screen for visceral obesity

Answer 30

MRI, CT and waist circumference

Question 31

visceral adipose tissue metabolic activity

Answer 31

adipose tissue in the omentum that are metabolically active producing inflammatory signaling molecules
increases risk of type II

Question 32

BMI is

Answer 32

generalized screening tool to categorize people into weight related risk categories
Advantage: cheap, easy and available