3 - Energy and Proteins

Question 0

What part of an amino acid makes it unique?

What is the constant part?

Answer 0

The R group makes it unique

Constant is a central carbon, a hydrogen, an acid group (COOH) and an amine group (NH2)

Question 1

Which 2 amino acids contain sulfur?

Answer 1

Cysteine and methionine

Question 2

A) How many essential amino acids are there?
B) how are nonessentials made?
C) what are conditionally essential amino acids and give some examples

Answer 2

A) 9
B) transferring the amino group from one amino acid to a different acid, and r group transamination
C) may need them at a certain period of life or you may have a medical condition such as PKU that prevents you from making them. E.g. Tyrosine, arginine, cysteine, glutamine

Question 3

Draw an example of transamination

Answer 3

Lecture slide

Question 4

Give 4 examples of essential amino acids

Answer 4

Any of : Lysine, leucine, valine, phenylalanine, histidine, isoleucine, methionine, threonine, tryptophan

Question 5

Draw an example of 2 amino acids forming a dipeptide bond

Answer 5

Lecture slide ( O=C-N-H)

Question 6

What products are synthesised from an amino acid pool?

Answer 6

1) non protein compounds that need N
2) body proteins e.g. Enzymes
3) fat/adipose tissue from amino acid carbon skeletons
4) glucose from amino acid carbon skeletons
5) urea in the liver from excess N

Question 7

What are the 4 stages of protein structure?

Answer 7

Primary - sequence of amino acids

Secondary - polypeptides form b pleated sheets or helices

Tertiary - 3D structure, peptides fold and cross links form to stabalise. Determines the function.

Quaternary - two or more polypeptides bond to form globular or fibrous proteins

Question 8

Half of proteins in the body are only 4 different proteins. What are they?

Answer 8

Collagen
Haemoglobin
Myosin
Actin

Question 9

What are the 4 main functions of proteins?

Answer 9

Structural, protective, transport/communication, enzymatic

Question 10

How to proteins contribute to maintaining fluid balance?

Answer 10

They cause fluid to be drawn back into capillaries allowing a healthy fluid balance

Question 11

What is the role of proteins in electrolyte balance?

Answer 11

Acts as a transport protein for sodium and potassium to cross the cell membrane

Question 12

What is the RDA for protein intake?

Answer 12

0.8g per kg of body weight per day. 10-35% of total energy intake

Question 13

When is nitrogen consumption > nitrogen excretion needed?

Answer 13

Periods of growth, pregnancy, illness recovery, protein deficiency

Question 14

How can protein deficiency occur? What are the two severe forms of protein-energy malnutrition?

Answer 14

Increase in demand, increase in loss, failure in he conservation systems

Marasmus, grossly inadequate intake
Kwashiorkor, disease from low protein

Question 15

How can too much protein be harmful?

Answer 15

When packaged with sat or trans fat, too much can lead to heart disease

Contribution to bone loss through increase in calcium excretion

Kidney disease among susceptible individuals

Question 16

What food is
a) limited in
b) high in
methionine and cysteine

Answer 16

Limited = Legumes and vegetables
High = Grains/nuts and seeds

Question 17

What food is
a) limited in
b) high in
lysine

Answer 17

Limited = Grains

High in = Legumes

Question 18

What food is
a) limited in
b) high in
lysine and isoleucine

Answer 18

Limited = nuts and seeds
High = Legumes

Question 19

What food is limited in lysine, methionine and cysteine

Answer 19

Vegetables

Question 20

What food is high in methionine and cystine

Answer 20

Nuts and seeds

Question 21

What breaks proteins into single amino acids and small polypeptides in the stomach?

Answer 21

Pepsin

Question 22

What digests polypeptides into smaller units in the small intestine?

Answer 22

Proteases

Question 23

What is a negative nitrogen balance?

Answer 23

Nitrogen consumption < Nitrogen excretion

results from starvation, dieting, illness, infections e.c.t

Question 24

What are 3 disorders related to problems with protein caused by defective DNA?

Answer 24

> Phenylketonuria (cannot break down phenylalanine to tyrosine)
Sickle cell anemia (change in amino acid sequence of hemoglobin)
Cystic fibrosis (abnormal transport protein, prevents Cl- transport)