biochemistry HIDDEN QUIZ Flashcards
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Characteristics of Proteins
> Most often, carbohydrates and lipids do not contain N.
The average nitrogen content of proteins is around 15.4% by mass. Other elements, such as phosphorous and iron, are essential constituents of certain specialized proteins.
Casein, the main protein of milk, contains phosphorous, an element that is very important in the diet of infants and children.
Hemoglobin, the oxygen-transporting protein of blood, contains iron.
Are organic compounds of high molecular weight made up ofα–amino acids joined by means of peptide linkage?
PROTEINS
They are the most important biological substances and are the fundamental constituents of cell protoplasm.
PROTEINS
Unlike carbohydrates and fats, ______ amount of protein is temporarily stored in the body
small
It has a molecular weight ranging from _______ to _________
5,000 to 8,000,000
The protein molecule is composed of ________ or even __________ of amino acids linked by peptide bonds.
hundreds or even thousands
The basic structure of an amino acid
Google it, I can’t add pictures
There are __ different groups attached to the alpha carbon atom in all of the standard amino acids
4
______, where the R group is a hydrogen atom.
glycine
With few exceptions (in some bacteria), the amino acids found in nature and proteins are __________.
L-isomers
Fischer projection formulas of amino acids:
Google it, I can’t add pictures
Classification of Amino acids:
A. According to Polarity (based on the side present)
1. Non-polar amino acids
2. Polar Neutral/Uncharged amino acids
3. Polar-acidic
4. Polar–basic
B.According to Essentiality
A complete dietary protein
An incomplete dietary protein
Complementary dietary proteins
(from the German term meaning “double ion”)
Zwitterions
It is a molecule that has a positive charge (+) charge on one atom and a negative charge (-) on another atom but has no net charge.
Zwitterions
Note that the net charge on zwitterions is ______ even though parts of the molecule carry charges.
zero
In solution and also in the solid state, ____ -______ ______ exist as zwitterions.
alpha-amino acids
It is the pH at which an amino acid exists primarily in its zwitterion form.
Isoelectric point/pH
a ) The pH is ______ (acidic)-by adding an acid such as HCl.
LOWERED
b ) The pH becomes ________ (basic) by adding a base such as NaOH.
higher
It is an amino acid that contains one amino group, one carboxyl group, and a non-polar side chain.
Non-polar amino acids
When Non-polar amino acids are incorporated into a protein, such as amino acids, they are _________
hydrophobic
They are generally found in the interior part of proteins, where there is little contact with water.
Non-polar amino acids
There are eight non-polar amino acids.
alanine, valine, leucine, proline, methionine, tryptophan, glycine, isoleucine, and phenylalanine
(GOOGLE THEIR STRUCTURES I CAN’T ADD PICTURES)
It is an amino acid that contains one amino group, one carboxyl group, and a side chain that is polar but neutral.
Polar Neutral/Uncharged amino acids
There are 7 polar neutral amino acids.
Threonine, serine, cysteine, tyrosine, glutamine, and asparagine.
(GOOGLE THEIR STRUCTURES I CAN’T ADD PICTURES)
Polar Neutral/Uncharged amino acids are ________, unlike non-polar amino acids
Hydrophilic
In solution, the Polar Neutral/Uncharged amino acids are neither ______ nor ______, and the side chain is at physiological pH.
acidic nor basic
It is an amino acid that contains one amino group and two carboxyl groups, the second of which is part of the side chain.
Polar-acidic
There are 2 polar acidic amino acids.
Glutamic acid, aspartic acid
(GOOGLE THEIR STRUCTURES I CAN’T ADD PICTURES)
In solution at physiological pH, the side chain bears a _______ charge; the side chain carboxyl group( COO—) has lost its acidic hydrogen atom.
negative charge
It is an amino acid that contains two amino groups, one carboxyl group, in which the second amino group is part of the side chain.
Polar–basic
In solution at physiological pH, the side chain bears a _________ charge;
Positive charge
There are 3 basic amino acids.
arginine (Arg), lysine (Lys), and histidine (His)
(GOOGLE THEIR STRUCTURES I CAN’T ADD PICTURES)
It is a protein that contains all of the essential amino acids in the same relative amounts in which the body needs them.
A complete dietary protein
It may or may not contain all of the non-essential amino acids
A complete dietary protein
Does not contain adequate amounts relative to the body’s needs.
An incomplete dietary protein
These are two or more incomplete dietary proteins that when combined, provide an adequate amount of all essential amino acids relative to the body’s needs.
Complementary dietary proteins
The pH at which amino acids are neutral; there will be an equal number of ________ and _________ charges.
positive (+) and negative (-)
Every amino acid has a different _________ ___.
isoelectric pH
mother of all amino acids
Alanine ( ala )
Clinical significance: it is a substrate of SGPT and SGO
SGPT- serum glutamic acid pyruvate transamylase
SGOT- serum glutamic acid oxalo transamylase
The amino acids that are associated with digestive enzymes.
Leucine ( leu ) and Isoleucine ( Ile )