Chap 6

PKU is the best known of the amino acid inborn errors

**True False

People afflicted with tyrosinemia type II require treatment with both phenylalanine- and tyrosine-restricted diet.

**True False

Proline and hydroxyproline are the most common amino acids in collagen and elastin.

**True False

Pyridoxal phosphate is needed in transamination reactions.

**True False

The amount of protein (or nitrogen) required by a human is called nitrogen balance.

**True False

The inability to metabolize amino acid is often due to a defect in a rate-limiting enzyme that is critical for the disposal of the amino acid.

**True False

The main polypeptide chain of a protein is called the primary structure.

**True False

The nitrogen balance method historically used to determine protein requirements is believed to underestimate protein requirements.

**True False

The protein efficiency ratio monitors the weight gain of a growing animal in relationship to its protein intake when energy is ample and the protein source is fed at an adequate level.

**True False

The ratio of the conversion of tryptophan to niacin is about 60 to 1.

**True False

The urea cycle consists of five reactions that convert ammonia, carbon dioxide and the alpha-amino nitrogen of aspartate into urea.

**True False

There are several inherited diseases that pertain to the inability to properly metabolize certain amino acids.

**True False

There is a growing consensus that measuring nitrogen balance may not be the best method to determine protein requirement.

**True False

When an essential amino acid is present in an inadequate amount, protein synthesis ceases.

**True False

Which of the following amino acids is eventually converted to melatonin?

**Tryptophan Tyrosine Phenylalanine Methionine

Which of the following methods can be used to determine total nitrogen requirements?

Factorial method Nitrogen balance method Indicator amino acid oxidation method **All of these are correct.

The amino acid score is perhaps the simplest method of determining protein quality.

True **False

The biological value (BV) of a protein represents the percentage of dietary protein retained.

True **False

The main polypeptide chain is termed the secondary structure of a protein.

True **False

Threonine, cysteine, and methionine are sulfur-containing amino acids.

True **False

Using the IAAO (Indicator Amino Acid Oxidation) method the EAR (Estimated Average Requirement) and RDA (Recommended Daily Allowance) for protein are much lower then using the nitrogen balance method.

True **False

What imparts the character to an amino acid or the structure of protein?

**The side chains The sulfur content The nitrogen content The number of amino acids that are replicated within the protein molecule

An indicator of protein quality that assesses the percentage of the nitrogen retained as a result of consuming a particular protein is referred to as:

**biological value. protein digestibility corrected amino acid score. net protein utilization. the amino acid score.

All enzymes are proteins and function to catalyze biochemical reactions by _______ the energy requirements

**lowering raising maintaining raising and then lowering

There is some evidence that leucine can activate a key signaling pathway ............... that leads to protein production in muscle and other body tissues.

**mTOR BCAA PKU kTOR

Amino acids are different from other energy nutrients in that they contain the element

**nitrogen iron sodium potassium

Glutaric aciduria type 1 is a disoder of ............................ metabolism.

**tryptophan glycine lysine threonine

Serotonin and melatonin are derived from:

**tryptophan. tyrosine. histidine. leucine.

Most studies suggest that the United States, as nation, consumes ............ the required levels of dietary protein.

**twice three times four times six times

Intake of branched-chain amino acids has been linked to weight gain.

True **False

Kwashiorkor is results of lack of ....................... in the diet.

fat carbohydrate **total protein esential fatty acids

A protein efficiency ratio of 2.7 determined in an experiment with young growing rats means that:

for every 2.7 grams of protein consumed, there is an increase in body weight of 1 gram. the protein is 2.7 times as efficient as or better than the reference protein casein. the protein is of poor quality. **for every gram of protein consumed, there is a body weight gain of 2.7 grams.

The compound carbamoyl phosphate is used:

for transamination and deamination reactions for amino acids. in the synthesis of purines and pyrimidine nucleotide bases. **in the urea cycle. in the alanine-glucose cycle.

Leucine is a(n) ________ amino acid.

glucogenic All of these are correct. aminogenic **ketogenic

Recent studies have reported that increased intake of ...................... can increase lean body mass.

methionine **leucine glycine tryptophan

Amino acids are absorbed by ________ in enterocytes.

passive diffusion osmosis **active transport facilitated diffusion

A newer method of determining protein quality is referred to as the digestible indispensable amino acid score.

**True False

Active trypsin is responsible in activating in active procarboxylase A and B, trypsinogen, and chymotrypsinogen.

**True False

All enzymes are proteins.

**True False

Dietary protein needs are expressed in grams/kg/day.

**True False

HCl is important in protein digestion.

**True False

High-protein diets appear effective in promoting weight loss.

**True False

Humans require about eight to nine essential amino acids.

**True False

Individuals with marasmus are emaciated from excessive muscle wasting and minimal body fat reserves.

**True False

Infacts with Maple Syrup Urine Diseases (MSUD) have elevated plasma levels of Branched-chain Amino Acids (BCAAs).

**True False

In an experiment, suppose you determine that a meal contains 20 grams of nitrogen. How much protein does this correlate to?

75 grams None of these is correct. 200 grams **125 grams

How many amino acids are genetically coded via mRNA?

8 **20 25 over 100

What is the name of the key enzyme that begins the process of protein hydrolysis?

Bile Serotonin Gastrin **Pepsin

If a food item contains 8 grams of nitrogen, the total amount of protein is 90 grams.

True **False

Urea is produced as a by-product by which of the following reactions?

Citrulline + aspartate → arginosuccinate Ornithine→ citrulline **Arginine → ornithine Arginosuccinate → arginine

Tyrosine is a precursor for which of the following neurotransmitters?

DOPA Norepinephrine Dopamine **All of these are correct.

Lysine, arginine, ornithine, and cystine are considered basic amino acids.

True **False

Which of the following is true with regards to transamination reactions?

It is used for the urea cycle to produce urea. These reactions are only used during low-protein diets. **Vitamin B6 is a cofactor that is required for this reaction. Threonine is the only amino acid that undergoes transamination reactions.

Why is protein essential?

Its role as a methyl donor via methionine. Its role in maintaining fluid balance, often through its role in generating osmotic pressure Its role in the development of connective tissue such as collagen and elastin - PROBABLY All of these are correct. - NOT

Which of the following is essential in transamination reactions for amino acids?

Methyl donors Folic acid **Vitamin B6 Ammonia

Why is the 43S preinitiation complex important for protein synthesis?

NADH is an important methyl donor to generate initiation of protein synthesis - NOT None of these is correct. -NOT ATP stimulates the 40S ribosomal unit to block formation of the preinitiation complex. The 43S preinitiation complex is blocked when an essential amino acid is missing

Which of the following biochemical substances is used to synthesize amino acids?

Serotonin Carnitine Purine **All of these are correct.

Where is urea synthesized?

Stomach and duodenum Bones and joints **Liver and kidneys Brain and pancreas

PKU has many genetic variants and is most common in Asians.

True **False

mTOR metabolic pathway via a group of kinases is involved in ......................

cell growth survival proliferation protein transcription protein translation **all answers ar correct

Glutamine is used extensively by the mucosal cells of the intestine. It can..............

control appetite control muscle contraction control memory **stimulate cell proliferation

Leucine and other BCAAs appear to ............................. lean body mass.

decrease have no effect on **increase

If you determine protein quality by calculating the weight gain and dividing by the amount of protein consumed when energy is adequate, this is a measure of the protein quality referred to as the:

digestible indispensable amino acid score. chemical score. net protein utilization. **protein efficiency ratio.

Tyrosine is synthesized by hydroxylation of ....................

proline arginine **phenylalanine aspartate

Studies suggest that BCAAs and leucine can..............

reduce the potential for obesity resulting from a high-fat diet reduce high blood glucose levels reduce abnormal blood lipid levels **all answers are correct

Nitrogen can be removed from amino acids by ...............

saturation coagulation **deamination desaturation

Individual suffering from marasmus have ........................

swolen abdomens **minimal body fat fatty liver moon-face appearance

Marasmus victims display .........................

swolen ankles decreased ability to cry **excessive crying constant shaking

The standart treatment for PKU has been diet restricted in phenylalanine. This diet must be continued.................

till puberty **over lifetime during the first year of life only in infancy

All of the following are considered neutral amino acids, except:

tyrosine, tryptophan, and phenylalanine. methionine, histidine, glutamine, asparagine, and cysteine. **lysine, arginine, ornithine, and cysteine. valine, leucine, isoleucine, and glycine.