Amino Acids And Proteins Flashcards
1
Q
What are amino acids?
A
Amino acids ares organic compounds that contain an amino group (NH2) and a carboxyl group (COOH)
2
Q
What makes each amino acid unique?
A
Their side chains.
3
Q
True or false. Essential amino acids can be synthesized in the body.
A
False.
4
Q
How does the body obtain essential amino acids?
A
The body supplements essential amino acids through dietary intake since it can’t be synthesized in the body.
5
Q
Why are amino acids and proteins considered amphoteric molecules?
A
Because amino acids have coexisting positive and negative charges at an isoelectric point.
6
Q
At what pH does the blood normally remain?
A
7.35-7.45
7
Q
What are amphoteric molecules?
A
Molecules that are able to react both as an acid and a base.
8
Q
What is physiological pH?
A
7.35-7.45
9
Q
What happens to an amino acid at physiological pH?
A
The amino group is protonated, while the carboxyl group is dissociated.
NH3 +
COO -
10
Q
What is an amino acid’s form at lower pH?
A
At lower pH, an amino acid is cationic, that is, has a positive charge. Both amino group and carboxyl group are protonated.
NH3 +
COOH
11
Q
What is an amino acid’s form at higher pH?
A
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 -
12
Q
What is the isoelectric point? pI
A
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.
13
Q
What charge will an AA or protein have if pH > pI?
A
Negative charge, anion.
14
Q
What charge will an AA or protein have if pH < pI?
A
A positive charge, cationic.
15
Q
What type of linkage binds amino acids together?
A
Covalent linkages.
16
Q
How are the covalent linkages binding amino acids together called?
A
Peptide bonds.
17
Q
What are peptide bonds?
A
Peptide bonds are covalent linkages binding amino acids to each other.
18
Q
What is the product of peptide bonds between amino acids?
A
Proteins.
19
Q
What parts of one amino acids are linked together when they link covalently?
A
The linkage occurs between the -COOH group of one amino acid and the -NH2 group of another amino acid forming a peptide bond.
20
Q
What is the product of two amino acid reagents?
A
A dipeptide and water.
21
Q
Where does absorption of proteins occur?
A
In the GI tract.
22
Q
Where are proteins broken down into amino acids?
A
In the GI tract.
23
Q
True or false. Amino acids are re-used in protein synthesis.
A
True
24
Q
What is transamination?
A
Transamination is the transfer of an amino group to a keto acid in order to create new amino acids.
25
Via what substances do transamination processes occur?
Via aminotransferase enzymes, that is AST & ALT
26
What is a keto acid?
A keto acid is a molecule that contains a carboxyl group (-COOH) and a ketone group (-CO)
27
What structure filters amino acids?
The glomerulus.
28
What structure reabsorbs amino acids?
Renal tubules.
29
So, in what part of the body are amino acids filtered and reabsorbed?
In the kidneys.
30
If amino acids are not filtered and reabsorbed by the glomerulus and renal tubules respectively, what might occur?
Aminoacuduria
31
What is aminoaciduria?
Unusual amount of amino acids in urine.
32
What does aminoaciduria usually results to?
Renal tubular dysfunction.
33
What are proteins?
Proteins are polymers made of many amino acids covalently linked together by peptide bonds.
34
What are the 2 particularities of proteins?
Their different solubilities and electric charge.
35
Why do proteins have different solubilities and electric charges?
Because they have different amino acid compositions.
36
Name the type of protein structures.
Fibrous
| Globular
37
Give examples of fibrous proteins.
Fibrinogen
Collagen
Troponin
38
Give examples of globular proteins.
Hemoglobin
Enzymes
Plasma proteins
39
What four types of protein structure exist?
Primary
Secondary
Tertiary
Quaternary proteins.
40
What does the primary protein structure consist of?
A sequence of a chain of amino acids. Polypeptide chain (many peptide bonds)
41
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.
42
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.
43
What is the quaternary protein structure?
The association of more than one amino acid chain or subunits.
44
What are the four hemoglobin subunits?
Alpha chain
Beta chain
Heme chain
Iron chain (Fe+)
45
Define prosthetic groups?
They are non amino acid components that are attached to proteins.
46
What is another name for prosthetic groups?
Cofactors
| Moiety
47
What are examples of prosthetic groups we encounter attached to proteins?
Lipids
Carbohydrates
Phosphates
Metals
48
True or false. Prosthetic groups are not essential for protein function, but instead hinder their good functioning.
False.
49
How can the term apoprotein be defined?
The protein portion with removed prosthetic group.
50
What are conjugated proteins?
Protein plus a prosthetic group.
51
Give and example of a conjugated protein.
A glycoprotein.
| Protein (protein) + sugar (prosthetic groups)
52
What are the main properties of proteins?
Molecular size (large)
Different solubilities in different solutions
Electric charge
Binding qualities
53
What are protein properties useful for?
For separation, identification and other assays.
54
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.
```
55
Where does protein synthesis occur?
Mainly in the liver cells or lymphocytes.
56
What determines the synthesis of specific proteins?
DNA coding
57
Where does protein catabolism occurs?
In the GI tract, kidneys, and liver.
58
Identify the steps of protein breakdown.
Proteins - amino acids - keto acids - ammonia - urea.
59
What is the final product of protein catabolism?
Urea
60
What are acute phase reactant proteins (APR)?
APR proteins are particular proteins whose levels increase during acute inflammation.
61
How can acute inflammation be defined?
Acute inflammation refers to the the body’s process of fighting against things that harm it like infections, toxins, injuries, in a period of days.
62
In a defense mechanism of inflammation, what does the liver increase production of?
Acute phase reactant proteins.
63
What is the most commonly used APR by the body?
C-reactive proteins. (CRP)
64
What are negative APR?
Negative APR proteins are proteins whose levels decrease during inflammation.
65
What are examples of negative APRs?
Pre-albumin, albumin, transferrin.
66
Give examples of plasma proteins.
Pre-albumin, albumin, retinol-binding proteins, globulins.
67
What protein is the most abundant in the body?
Albumin
68
What percentage of albumin is there in the body?
About 40-60%
69
What are the main functions of albumin?
Maintaining plasma osmotic pressure
Transport
Source if amino acid
70
What is pre-albumin useful for?
Transport
| Carrying thyroid hormones.
71
What is the function of retinol-binding protein?
Transporting vitamin A
72
What plasma proteins are insoluble in water?
Globulins
73
Examples of globulins.
```
Alpha 1
Alpha 2
Beta
Gamma
Some Ig
```
74
What method is most common used in the lab for total protein analysis?
Biuret method
75
What does the biuret method consist of?
Biuret method uses chromogenic organic agent that contains copper sulfate which binds to peptide bonds.
76
What technique is used in lab analysis of albumin?
Dye-binding.
77
Why is the anionic dye-binding technique used for albumin analysis?
In an acidic solution, anionic dyes bind to albumin which is sufficiently cationic at a pH of 4.2 and has higher affinity to dye than other proteins.
78
What are used for lab globulin analysis?
Immunoassays: quantitative
| Protein electrophoresis: semi-quantitative
79
What are aminoacidopathies?
These are disorders of faulty amino acid metabolism which belong to a group of diseases called inborn errors of metabolism.
80
What are inborn errors of metabolism?
These are rare genetic disorders in which the body cannot properly turn food into energy.
81
How are inborn errors of metabolism contracted?
They are usually inherited as autosomal recessive disease.
82
What do these aminoacidopathy disorders likely have?
- Loss of specific metabolic enzyme activity
- Loss of cell membrane transport system.
- Lack if necessary AAs
- Accumulation of toxic products.
83
Give examples of inborn errors of metabolism.
Marble syrup urine disease
Phenylketonuria
Glycogen storage disease
84
What is MSUD?
This is a rare genetic and congenital disorder of enzyme complex deficiency in which the body can’t break down branched chain amino acids.
85
What is the landmark of MSUD?
Dark, sweet smelling urine.
86
What causes the dark sweet smelling urine in MSUD?
The branched chain amino acids pass through urine making it dark and sweet smelling.
87
What are some complications of MSUD?
The build up of AA and it’s toxic byproducts in MSUD cause organ and brain damage based on how much residual enzyme there is.
88
How is MSUD detected?
Through newborn screening at 1-2 days
89
How is MSUD cured or treated?
It has no cure so treated through avoidance of proteins, supplements without BCAA, careful monitoring of condition during metabolic crisis triggers such as illness, infection, surgery, fasting.
90
What is phenylketonuria?
It is a rare genetic disorder characterized by the inability of the body to breakdown the essential aa phenylalanine.
91
What does the essential aa phenylalanine do?
It is broken up by the tyrosine pathway to eventually help make thyroid hormone, neurotransmitter dopamine and melanin.
92
What leads to build up of Phenylalanine in PKU patients?
The deficiency or absence of phenylalanine hydroxylase leads to build up of Phe in blood and brain.
93
What brings about the mousy odor of urine in PKU patients?
Phe and it’s byproducts (phenylketones) are partially shed in urine giving it a mousy odor.
94
What will happen if PKU goes untreated?
It will lead to brain damage, seizures, and other abnormalities.
95
How is PKU detected?
Through crucial newborn screening at 1-3 days.
96
How is PKU cured or treated?
There is no cure so it is treated for life with reduced or special protein diets and crisis monitoring same way as MSUD patients.
97
List the quantitative detection methods of amino acid analysis.
Mass spectrometry
Chromatography
Molecular analysis
Immunoassay
98
What test is used to diagnose PKU?
The Guthrie test
99
How is the Guthrie test performed?
A filter paper containing blood spot is placed on agar mixed with B. subtilis and growth antagonist. Elatvated Phe level overcome antagonist and let bacterial growth around the filter paper. No bacterial growth occurs on normal patients.
100
What is hypoproteinemia?
These are abnormally reduced blood protein levels.
101
What are the causes of hypoproteinemia?
- Hemodilution (increased plasma water volume), over hydration, edema
- Kindey disease that allows proteins lost in urine (hyperpermeability of membrane and/or tubular dysfunction)
- Malnutrition
- Severe liver disease (no protein synthesis by liver)
- Accelerated protein breakdown in burn or trauma patients,
102
What is hyperproteinemia?
These are abnormally high levels of blood protein.
103
What causes hyperproteinemia?
- Hemoconcentration(low plasma water volume)
- Dehydration; low water intake or heavy water loss from vomiting, diarrhea or sweating
- Increased protein intake
- Increased gamma globulin production in respond to infection, multiple myeloma, autoimmune disease
104
List specific plasma proteins and their classification.
- Albumin
- alpha 1-antitrypsin
- alpha 1-fetoprotein
- Haptoglobin
- Ceruloplasmin
- Transferin
- CRP
- Igs
105
What does decrease in albumin imply?
```
Liver disease
Loss in urine due to kidney disease
GI loss
Malnutrition
Burns
```
106
What does an increase in albumin imply?
Dehydration or improper specimen collection
107
What is A1AT?
This is an alpha 1 protein produced in the liver to counteract the strong elastase production by neutrophils usually in the lungs.
108
Why is strong elastase production by neutrophils in the lung bad?
It might cause emphysema. (Lung damage)
109
What will a genetic deficiency or deformation of A1AT cause?
No A1AT results in overload of elastase which destroys lung tissue (elastin) from neutrophils.
110
What disease can occur from a complete lack of A1AT?
Lung disease
111
Does misfolded A1AT. Abuse any damage?
Yes, presence if A1AT in the body without any action leads to lung and liver disease (cirrhosis)
112
What is AFP?
These are proteins produced by fetal liver cells, most abundant proteins in an embryo
113
During what is AFP levels elevated?
Pregnancy or twin pregnancy
114
What do abnormal increase in AFP during pregnancy indicate?
Neural tube defects (anencephaly) and fetal spina bifida.
115
What do increases in AFP levels without pregnancy indicate?
This is a cancer marker and may show liver cancer, testicular cancer, liver damage like cirrhosis or hepatitis.
116
What do decreases in AFP during pregnancy indicate?
Down syndrome
117
What type of proteins are A1AT and AFP?
Alpha 1 proteins
118
What is haptoglobin?
It is a protein made in the liver that binds free hemoglobin in the blood to take it to the spleen macrophages to be degraded.
119
Why does the body need haptoglobin to bind free hemoglobin?
Free hemoglobin is toxic especially to kidneys.
120
When are haptoglobin levels increased?
It is an ARO protein so during inflammation, burns, rheumatic diseases.
121
When are haptoglobin levels decreased?
- In intravascular hemolysis
- Transfusion reactions
- Hemolytic anemia
122
What is cerulosplasmin?
These are proteins that bind and transport copper in plasma.
123
How does the body obtain copper in plasma?
From dietary intake in liver, nuts some seafood, chocolate
124
Where does excess copper go to in the body L
Excess is excreted in the bile then to feces.
125
When are ceruloplasmin levels decreased?
In Wilson’s disease(genetic), malnutrition.
126
What happens if excess free copper builds up in the body?
It will affect the brain, liver, heart, kidneys, and bones (Kayser-Fleischer ring)
127
What type of proteins are haptoglobin and ceruloplasmin?
Alpha 2 proteins
128
What is transferrin?
This is a protein that binds and transport free irons in plasma.
129
When are transferrin levels increased?
In iron deficiency anemia.
130
When are transferrin levels decreased?
In iron overload disorders.
131
What type of protein is transferrin?
Beta plasma protein.
132
What is CRP?
This is the main APR protein that binds many compounds such as bacteria, fungi, histones, and activated the classic component pathway.
133
When are CRP levels increased?
Whenever there is any kind of inflammation in the body.
134
What type of disease is CRP a nonspecific indicator for?
Nonspecific indicator but steady predictor of heart disease (atherosclerosis) along with other analytes.
135
What are Ig?
These are ARP proteins produced by plasma cells which play an important role in humoral immunity.
136
When are Ig levels increased?
In infections, multiple myeloma, autoimmune disorders.
137
Examples of Igs
G, A, M, D, E
138
What type of proteins are CRP and Ig?
Gamma globulins.
139
List all the APR proteins.
Haptoglobin
CRP
Ig
140
What are methods used for protein lab analysis?
Protein electrophoresis
UV absorption
Color photometric
141
What test can be used to evaluate abnormalities in Ig levels?
Serum protein electrophoresis
142
What is the difference between monoclonal and polyclonal gammopathy?
Monoclonal gammopathy is the excess production of one type of Ig while in polyclonal gammopathy, the body produces two or more Ig in excess.
