3 - Energy and Proteins Flashcards
What part of an amino acid makes it unique?
What is the constant part?
The R group makes it unique
Constant is a central carbon, a hydrogen, an acid group (COOH) and an amine group (NH2)
Which 2 amino acids contain sulfur?
Cysteine and methionine
A) How many essential amino acids are there?
B) how are nonessentials made?
C) what are conditionally essential amino acids and give some examples
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
Draw an example of transamination
Lecture slide
Give 4 examples of essential amino acids
Any of : Lysine, leucine, valine, phenylalanine, histidine, isoleucine, methionine, threonine, tryptophan
Draw an example of 2 amino acids forming a dipeptide bond
Lecture slide ( O=C-N-H)
What products are synthesised from an amino acid pool?
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
What are the 4 stages of protein structure?
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
Half of proteins in the body are only 4 different proteins. What are they?
Collagen
Haemoglobin
Myosin
Actin
What are the 4 main functions of proteins?
Structural, protective, transport/communication, enzymatic
How to proteins contribute to maintaining fluid balance?
They cause fluid to be drawn back into capillaries allowing a healthy fluid balance
What is the role of proteins in electrolyte balance?
Acts as a transport protein for sodium and potassium to cross the cell membrane
What is the RDA for protein intake?
0.8g per kg of body weight per day. 10-35% of total energy intake
When is nitrogen consumption > nitrogen excretion needed?
Periods of growth, pregnancy, illness recovery, protein deficiency
How can protein deficiency occur? What are the two severe forms of protein-energy malnutrition?
Increase in demand, increase in loss, failure in he conservation systems
Marasmus, grossly inadequate intake
Kwashiorkor, disease from low protein
How can too much protein be harmful?
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
What food is
a) limited in
b) high in
methionine and cysteine
Limited = Legumes and vegetables High = Grains/nuts and seeds
What food is
a) limited in
b) high in
lysine
Limited = Grains
High in = Legumes
What food is
a) limited in
b) high in
lysine and isoleucine
Limited = nuts and seeds High = Legumes
What food is limited in lysine, methionine and cysteine
Vegetables
What food is high in methionine and cystine
Nuts and seeds
What breaks proteins into single amino acids and small polypeptides in the stomach?
Pepsin
What digests polypeptides into smaller units in the small intestine?
Proteases
What is a negative nitrogen balance?
Nitrogen consumption < Nitrogen excretion
results from starvation, dieting, illness, infections e.c.t
What are 3 disorders related to problems with protein caused by defective DNA?
> 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)
