Amino Acids And Proteins Flashcards
What are amino acids?
Amino acids ares organic compounds that contain an amino group (NH2) and a carboxyl group (COOH)
What makes each amino acid unique?
Their side chains.
True or false. Essential amino acids can be synthesized in the body.
False.
How does the body obtain essential amino acids?
The body supplements essential amino acids through dietary intake since it can’t be synthesized in the body.
Why are amino acids and proteins considered amphoteric molecules?
Because amino acids have coexisting positive and negative charges at an isoelectric point.
At what pH does the blood normally remain?
7.35-7.45
What are amphoteric molecules?
Molecules that are able to react both as an acid and a base.
What is physiological pH?
7.35-7.45
What happens to an amino acid at physiological pH?
The amino group is protonated, while the carboxyl group is dissociated.
NH3 +
COO -
What is an amino acid’s form at lower pH?
At lower pH, an amino acid is cationic, that is, has a positive charge. Both amino group and carboxyl group are protonated.
NH3 +
COOH
What is an amino acid’s form at higher pH?
At night pH, an amino acid is anionic, that is, it has a negative charge. Both the carboxyl and amino group are deprotonated.
NH2
COO -
What is the isoelectric point? pI
It is the pH at which the protein or amino acid has no net charge. That is, it is neither an anion nor a cation.
What charge will an AA or protein have if pH > pI?
Negative charge, anion.
What charge will an AA or protein have if pH < pI?
A positive charge, cationic.
What type of linkage binds amino acids together?
Covalent linkages.
How are the covalent linkages binding amino acids together called?
Peptide bonds.
What are peptide bonds?
Peptide bonds are covalent linkages binding amino acids to each other.
What is the product of peptide bonds between amino acids?
Proteins.
What parts of one amino acids are linked together when they link covalently?
The linkage occurs between the -COOH group of one amino acid and the -NH2 group of another amino acid forming a peptide bond.
What is the product of two amino acid reagents?
A dipeptide and water.
Where does absorption of proteins occur?
In the GI tract.
Where are proteins broken down into amino acids?
In the GI tract.
True or false. Amino acids are re-used in protein synthesis.
True
What is transamination?
Transamination is the transfer of an amino group to a keto acid in order to create new amino acids.
Via what substances do transamination processes occur?
Via aminotransferase enzymes, that is AST & ALT
What is a keto acid?
A keto acid is a molecule that contains a carboxyl group (-COOH) and a ketone group (-CO)
What structure filters amino acids?
The glomerulus.
What structure reabsorbs amino acids?
Renal tubules.
So, in what part of the body are amino acids filtered and reabsorbed?
In the kidneys.
If amino acids are not filtered and reabsorbed by the glomerulus and renal tubules respectively, what might occur?
Aminoacuduria
What is aminoaciduria?
Unusual amount of amino acids in urine.
What does aminoaciduria usually results to?
Renal tubular dysfunction.
What are proteins?
Proteins are polymers made of many amino acids covalently linked together by peptide bonds.
What are the 2 particularities of proteins?
Their different solubilities and electric charge.
Why do proteins have different solubilities and electric charges?
Because they have different amino acid compositions.
Name the type of protein structures.
Fibrous
Globular
Give examples of fibrous proteins.
Fibrinogen
Collagen
Troponin
Give examples of globular proteins.
Hemoglobin
Enzymes
Plasma proteins
What four types of protein structure exist?
Primary
Secondary
Tertiary
Quaternary proteins.
What does the primary protein structure consist of?
A sequence of a chain of amino acids. Polypeptide chain (many peptide bonds)
What causes the pleated sheet or alpha helix of the secondary protein structure?
Hydrogen bonding of the peptide backbone causes amino acids to fold into a repeating pattern.
Describe the tertiary protein structure.
It is a three-dimensional folding pattern of a protein due to side chain interactions. That is, consists of folded pleated sheet or alpha helix.
What is the quaternary protein structure?
The association of more than one amino acid chain or subunits.
What are the four hemoglobin subunits?
Alpha chain
Beta chain
Heme chain
Iron chain (Fe+)
Define prosthetic groups?
They are non amino acid components that are attached to proteins.
What is another name for prosthetic groups?
Cofactors
Moiety
What are examples of prosthetic groups we encounter attached to proteins?
Lipids
Carbohydrates
Phosphates
Metals
True or false. Prosthetic groups are not essential for protein function, but instead hinder their good functioning.
False.
How can the term apoprotein be defined?
The protein portion with removed prosthetic group.
What are conjugated proteins?
Protein plus a prosthetic group.
Give and example of a conjugated protein.
A glycoprotein.
Protein (protein) + sugar (prosthetic groups)
What are the main properties of proteins?
Molecular size (large)
Different solubilities in different solutions
Electric charge
Binding qualities
What are protein properties useful for?
For separation, identification and other assays.
List the 6 main functions of proteins.
Tissue nuitrition Water distribution Transport Act as a buffer (preventing huge pH swings). Structural support Act as enzyme, Ab, coags, hormones.
Where does protein synthesis occur?
Mainly in the liver cells or lymphocytes.
What determines the synthesis of specific proteins?
DNA coding