question Of Protein كتاب الطويل Flashcards
(256 cards)
1
Q
How many amino acids occur in nature?
A
About 300 amino acids occur in nature
Only 20 of these amino acids are found in proteins.
2
Q
What are the four groups or atoms attached to the alpha carbon of an amino acid?
A
- Amino group (NH2)
- Carboxyl group (COOH)
- Hydrogen atom (H)
- Side chain or radical group (R)
These groups define the structure of amino acids.
3
Q
What characterizes all α-amino acids?
A
The amino group is attached to the second carbon next to the carboxyl group
This is a defining feature of α-amino acids.
4
Q
What is the configuration of L-amino acids?
A
The α-amino group is on the left side configuration
This configuration is important for biological functionality.
5
Q
Name the classifications of amino acids based on their side chains.
A
- Chemical
- Nutritional
- Metabolic
Each classification has subcategories that further describe the amino acids.
6
Q
What are the subcategories of chemical classification of amino acids?
A
- Fatty acids
- Polarity of -R
- Aromatic, heterocyclic, & aliphatic
- Neutral, acidic & basic
- Branched or not
- Amino and imino
- Sulfur and hydroxy
These characteristics determine the chemical behavior of amino acids.
7
Q
What are the two main categories of nutritional classification of amino acids?
A
- Essential
- Non-essential
Essential amino acids must be obtained from the diet, while non-essential amino acids can be synthesized by the body.
8
Q
What are the three metabolic classifications of amino acids?
A
- Glucogenic
- Ketogenic
- Glucogenic & Ketogenic
These classifications indicate how amino acids are metabolized in the body.
9
Q
Fill in the blank: Amino acids are combined in _______ linkages.
A
peptide
Peptide linkages are the bonds that form between amino acids in proteins.
10
Q
True or False: All amino acids are identical in structure.
A
False
While all amino acids share a common structure, their side chains (R groups) vary, leading to different properties.
11
Q
What is the chemical classification of amino acids based on the fatty acids they are derived from?
A
Amino acids can be classified according to the fatty acids they are derived from, such as acetic, propionic, butyric, valeric, isovaleric, caproic, isocaproic, and succinic acids.
Each fatty acid contributes to the structure of specific amino acids.
12
Q
Which amino acid is derived from acetic acid?
A
Glycine
Glycine is also known as alpha amino acetic acid.
13
Q
Which amino acids are derived from propionic acid?
A
- Alanine
- Serine
- Cysteine
- Phenylalanine
- Tyrosine
- Tryptophan
- Histidine
These amino acids have various functional groups that distinguish them.
14
Q
What is the structure of alanine?
A
Alanine is alpha amino propionic acid.
It consists of an amino group, a carboxylic acid group, and a side chain that is a methyl group.
15
Q
Fill in the blank: Cysteine is derived from _______.
A
Propionic acid
16
Q
Which amino acid is known as alpha amino beta hydroxy propionic acid?
A
Serine
Serine contains a hydroxyl group that contributes to its reactivity.
17
Q
True or False: Tryptophan is derived from butyric acid.
A
False
Tryptophan is derived from propionic acid.
18
Q
Which amino acids are derived from butyric acid?
A
- Threonine
- Methionine
Both amino acids have unique side chains that serve various biological functions.
19
Q
What is the amino acid structure of isoleucine?
A
Isoleucine is derived from valeric acid, specifically alpha amino beta methyl valeric acid.
Isoleucine is essential for protein synthesis.
20
Q
Which amino acid is derived from isovaleric acid?
A
Valine
Valine is essential and important for muscle metabolism.
21
Q
Fill in the blank: Lysine is derived from _______.
A
Caproic acid
22
Q
Which amino acids are derived from succinic acid?
A
- Aspartate
- Asparagine
Aspartate is involved in the urea cycle, while asparagine plays a role in protein synthesis.
23
Q
What distinguishes histidine among the amino acids derived from propionic acid?
A
Histidine is characterized by its imidazole side chain.
This side chain plays a crucial role in enzyme catalysis.
24
Q
True or False: Tyrosine is derived from phenyl propionic acid.
A
True
Tyrosine is a precursor to neurotransmitters and hormones.
25
What is glutaric acid?
A 5-carbon dicarboxylic acid
## Footnote
Glutaric acid is an organic compound with two carboxylic acid groups.
26
What is the structure of glutamate?
Alpha amino glutaric acid
## Footnote
Glutamate is a key amino acid in metabolism and neurotransmission.
27
What is the structure of glutamine?
Alpha amino glutaric acid amide
## Footnote
Glutamine plays a critical role in many metabolic processes.
28
What is proline?
An amino acid with a pyrrolidine ring
## Footnote
Proline is unique among amino acids due to its cyclic structure.
29
Name an example of an acidic amino acid.
Aspartate
## Footnote
Acidic amino acids contain more than one -COOH group.
30
Name an example of a basic amino acid.
Lysine
## Footnote
Basic amino acids contain more than one -NH2 group.
31
What are neutral amino acids characterized by?
One -COOH and one -NH2 group
## Footnote
Examples include glycine and alanine.
32
What distinguishes polar amino acids from non-polar amino acids?
The polarity of the radical (R)
## Footnote
Polar amino acids have side chains that can form hydrogen bonds.
33
What are aromatic amino acids?
Amino acids containing a phenyl or phenol ring
## Footnote
Examples include phenylalanine and tyrosine.
34
Name a heterocyclic amino acid.
Tryptophan
## Footnote
Heterocyclic amino acids contain rings that include atoms other than carbon.
35
What are branched amino acids?
Amino acids like alanine, leucine, and isoleucine
## Footnote
Branched amino acids have side chains that are branched.
36
True or False: All amino acids are either branched or non-branched.
True
## Footnote
This classification helps in understanding amino acid structure.
37
What are imino acids?
Proline and hydroxyproline
## Footnote
Imino acids are a specific type of amino acid that contain an imino group.
38
What are the main sulfur-containing amino acids?
* Cysteine
* Cystine
* Methionine
## Footnote
These amino acids contain sulfur in their structure.
39
What are the main hydroxyl-containing amino acids?
* Serine
* Threonine
## Footnote
Hydroxyl-containing amino acids have hydroxyl groups (-OH) in their side chains.
40
How are amino acids classified nutritionally?
* Essential
* Semi-essential
* Non-essential
## Footnote
Nutritional classification helps determine the body's need for amino acids.
41
What is the definition of essential amino acids?
Amino acids that cannot be formed in the body
## Footnote
Essential amino acids must be obtained from the diet.
42
List the essential amino acids.
* Isoleucine
* Leucine
* Histidine
* Tryptophan
* Arginine
* Methionine
* Valine
* Threonine
* Lysine
* Phenylalanine
## Footnote
Essential amino acids are crucial for growth and maintenance.
43
What are semi-essential amino acids?
Amino acids formed in the body in amounts enough for adults, but not for growing children
## Footnote
Arginine is commonly recognized as a semi-essential amino acid.
44
What are the metabolic classifications of amino acids?
* Glucogenic
* Ketogenic
## Footnote
Metabolic classification helps in understanding how amino acids are utilized in metabolism.
45
What are glucogenic amino acids?
Amino acids that can be converted into glucose
## Footnote
This classification includes non-essential amino acids.
46
List some glucogenic amino acids.
* Alanine
* Arginine
* Aspartate
* Asparagine
* Glycine
* Glutamate
* Glutamine
* Cysteine
* Serine
* Tyrosine
## Footnote
Glucogenic amino acids are important for energy production.
47
What are ketogenic amino acids?
* Leucine
* Lysine
* Phenylalanine
* Tyrosine
* Tryptophan
## Footnote
Ketogenic amino acids can be converted into ketone bodies.
48
Fill in the blank: The rest of the amino acids are classified as _______.
Non-essential
## Footnote
Non-essential amino acids can be synthesized by the body.
49
What is B-Alanine and its significance?
A non-alpha amino acid that enters the structure of pantothenic acid
## Footnote
Pantothenic acid is a vitamin essential for the synthesis of coenzyme A.
50
What role does Gamma amino butyric acid (GABA) play in the body?
It is a neurotransmitter formed from glutamate in brain tissue
## Footnote
GABA is crucial for regulating neuronal excitability throughout the nervous system.
51
What is Taurine and where is it commonly found?
An amino acid that occurs in bile combined with bile acids
## Footnote
Taurine is important for bile salt formation and has various physiological roles.
52
Name the amino acids that participate in the urea cycle.
* Arginine
* Ornithine
* Citrulline
## Footnote
These amino acids are critical for the detoxification of ammonia in the liver.
53
What is the structure of Arginine?
Alpha-amino S-guanido valeric acid
## Footnote
Arginine is a semi-essential amino acid involved in protein synthesis and various metabolic processes.
54
What are the amino acids involved in intermediary metabolism?
* Homoserine
* Homocysteine
## Footnote
These amino acids play roles in various metabolic pathways, including the synthesis of other amino acids.
55
Which amino acids are precursors of thyroid hormones?
* Monoiodotyrosine
* Diiodotyrosine
* Triiodotyrosine (T3)
* Tetraiodotyrosine (T4)
## Footnote
These compounds are vital for the production of thyroid hormones, which regulate metabolism.
56
What is dicysteine and its importance?
Two molecules of cysteine united by removal of hydrogen from -SH groups
## Footnote
Dicysteine is important for the stability and structure of proteins.
57
What is the structural function of amino acids?
They enter the structure of body peptides and proteins, hormones, and amines
## Footnote
For example, some amino acids serve as precursors to neurotransmitters and hormones.
58
How do amino acids function as neurotransmitters?
Some amino acids like glycine and glutamate act as neurotransmitters
## Footnote
They are involved in transmitting signals in the nervous system.
59
What role do amino acids play in detoxication?
Some amino acids are used in detoxication reactions
## Footnote
This function is crucial for the removal of toxic substances from the body.
60
What is the solubility of amino acids?
Amino acids may be soluble in water and dilute acids.
61
Which amino acid is not optically active?
Glycine
## Footnote
All other amino acids are optically active due to the presence of an asymmetric carbon atom.
62
What is the melting point characteristic of amino acids?
Amino acids have high melting points above 200°C due to high ionic forces in their crystalline structure.
63
What are the amphoteric properties of amino acids?
They have both basic (-NH2) and acidic (-COOH) groups.
64
What is a zwitter ion?
It is an amino acid that carries both positive and negative charges, making it electrically neutral.
65
What is the isoelectric point (pI) of an amino acid?
The pH at which the zwitter ion is formed, midway between the pK values of the carboxyl and amino groups.
66
What happens to alanine at strongly acidic pH?
Alanine is present mainly as a positively charged molecule.
67
What is the pK1 value for alanine?
2.34
68
What occurs when NaOH is added to alanine?
The carboxyl group loses a proton, forming a zwitter ion.
69
What is the pK2 value for alanine?
9.69
70
What reaction does ninhydrin have with amino acids?
Ninhydrin reacts with amino acids to give CO2, ammonia, and aldehyde.
71
What color does ninhydrin produce when reacting with liberated ammonia?
Blue
72
What does the intensity of the blue color from ninhydrin indicate?
The quantity of amino acids present.
73
How does ninhydrin react with proline and hydroxyproline?
It gives a yellow color.
74
What is the reaction of fluorescamine with amino acids?
Fluorescamine forms a blue complex with amino acids and is more sensitive than ninhydrin.
75
What color does tyrosine produce in Millon's reaction?
Red
76
What color does tryptophan produce in Rosenheim's reaction?
Purple
77
What color does phenylalanine and tyrosine produce in Xanthoproteic reaction?
Orange
78
What is formed during peptide bond formation?
A covalent bond between amino acids.
79
What is the absorption spectrum characteristic of amino acids?
Amino acids are colorless and do not absorb visible light.
80
Which amino acid absorbs ultraviolet light, particularly at 250-290 nm?
Tryptophan
81
What are peptides?
Compounds formed of less than 50 amino acids linked together by peptide bonds
## Footnote
Peptides can vary in size and complexity, influencing their biological function.
82
What is a dipeptide?
A peptide consisting of 2 amino acids and 1 peptide bond
## Footnote
Dipeptides are the simplest form of peptides.
83
Define tripeptide.
A peptide consisting of 3 amino acids and 2 peptide bonds
## Footnote
Tripeptides are formed by the linkage of three amino acids.
84
What is an oligopeptide?
A peptide consisting of 3-10 amino acids
## Footnote
Oligopeptides are larger than dipeptides but smaller than polypeptides.
85
What is a polypeptide?
A peptide consisting of 10-50 amino acids
## Footnote
Polypeptides can fold into functional proteins.
86
What is a peptide bond?
A covalent bond formed between the carboxyl group of one amino acid and the amino group of another
## Footnote
Peptide bonds are crucial for the formation of peptide chains.
87
How is a peptide bond formed?
By the removal of water
## Footnote
This process is known as a dehydration or condensation reaction.
88
What energy source is required for peptide formation?
Hydrolysis of ATP
## Footnote
ATP (adenosine triphosphate) provides the energy needed for this process.
89
What characterizes a peptide bond?
It is a semi-rigid bond with no free rotation around the bond axis
## Footnote
This rigidity is important for the structure of proteins.
90
What is the primary structure of peptides?
The arrangement of amino acids in a polypeptide chain
## Footnote
This structure determines the peptide's identity and function.
91
What is the position of the N-terminal amino acid in a polypeptide chain?
Always to the left side
## Footnote
The N-terminal contains a free amino group.
92
Where is the C-terminal amino acid located in a polypeptide chain?
Always to the right side
## Footnote
The C-terminal contains a free carboxyl group.
93
What techniques can be used for the separation of peptides?
* Electrophoresis
* Exchange chromatography technique
## Footnote
These techniques help in analyzing and purifying peptides.
94
What is glutathione?
A tripeptide formed of glutamate, cysteine, and glycine
## Footnote
Glutathione plays a crucial role in cellular functions.
95
What is the abbreviation for glutathione?
G-SH
## Footnote
The '-SH' indicates the sulfhydryl group of cysteine.
96
What are the functions of glutathione? (List at least two)
* Defense mechanism against toxic compounds
* Absorption of amino acids
## Footnote
Glutathione has multiple roles that are vital for cell health.
97
True or False: Glutathione protects against cell damage and hemolysis of RBCs.
True
## Footnote
Glutathione helps to break down harmful substances like hydrogen peroxide.
98
Fill in the blank: Glutathione is involved in the activation of _______.
[some enzymes]
## Footnote
Enzymatic activation is one of the critical roles of glutathione.
99
What is one role of glutathione regarding insulin?
Inactivation of insulin hormone
## Footnote
This function is important for regulating insulin levels in the body.
100
What hormones are produced by the pancreas?
Insulin and glucagon
## Footnote
These hormones regulate blood sugar levels.
101
Which hormones are secreted by the posterior pituitary gland?
Vasopressin and oxytocin
## Footnote
Vasopressin regulates water retention; oxytocin is involved in childbirth and social bonding.
102
What is ACTH and where is it produced?
Adrenocorticotropic hormone; produced by the anterior pituitary gland
## Footnote
ACTH stimulates the adrenal glands to release cortisol.
103
What is B-Lipotropin and what does it precede?
A polypeptide produced by the anterior pituitary; precursor of ß-endorphin
## Footnote
ß-endorphin acts as a neurotransmitter and has analgesic properties.
104
What is the analgesic effect of B-endorphin compared to morphine?
18-30 times more powerful
## Footnote
This makes it a significant endorphin in pain management.
105
What is Bradykinin and how is it produced?
A peptide released from specific plasma proteins by proteolytic enzymes
## Footnote
It acts as a potent smooth muscle relaxant.
106
What effects does Bradykinin have on the body?
Produces vasodilation and hypotension
## Footnote
It helps regulate blood pressure and blood flow.
107
Give an example of an antibiotic mentioned.
Valinomycin
## Footnote
Valinomycin is a potassium ionophore that disrupts ion gradients.
108
What is bleomycin used for?
As an antitumor agent
## Footnote
Bleomycin is used in chemotherapy for various cancers.
109
What is Aspartame and what are its components?
A dipeptide composed of aspartic acid and phenylalanine
## Footnote
It is commonly used as a sugar substitute.
110
What is the function of Atrial Natriuretic Peptide?
Produced by specialized cells in the heart; increases urine production
## Footnote
It helps lower blood pressure by promoting the excretion of sodium and water.
111
What are proteins made of?
Proteins are macromolecules formed of amino acids united together by peptide bonds.
## Footnote
Amino acids are the building blocks of proteins and are linked by peptide bonds to form polypeptide chains.
112
What is the term used for molecules containing less than 50 amino acids?
Peptides.
## Footnote
Proteins are defined as molecules greater than 50 amino acids.
113
What is the molecular weight range of proteins?
Proteins have a very high molecular weight, ranging from 5,000 to several millions.
## Footnote
This range indicates the complexity and size variability of proteins.
114
List three functions of proteins.
* Enzymes
* Transport
* Structural elements
## Footnote
Proteins play various roles in biological systems, including serving as enzymes, transporting molecules, and providing structural support.
115
What is the role of hemoglobin?
Hemoglobin is a carrier for oxygen.
## Footnote
Hemoglobin is a protein that facilitates oxygen transport in the blood.
116
What are glycoproteins and where are they found?
Glycoproteins are proteins found in the cell membrane.
## Footnote
These proteins play a role in cell recognition and signaling.
117
What is the primary structure of a protein?
The arrangement of amino acids in the polypeptide chain.
## Footnote
The primary structure is determined by the sequence of amino acids linked by peptide bonds.
118
What bonds are responsible for the primary structure of proteins?
Peptide bonds (covalent).
## Footnote
Peptide bonds link amino acids together to form polypeptide chains.
119
Fill in the blank: The first amino acid in a polypeptide chain is termed the _______.
N-terminal.
## Footnote
The N-terminal refers to the end of the amino acid chain that has a free amino group.
120
What is the C-terminal in a polypeptide chain?
The C-terminal is the last amino acid in the chain, characterized by a free carboxyl group.
## Footnote
This designation helps in understanding the directionality of the polypeptide chain.
121
True or False: Some hormones are proteins.
True.
## Footnote
Examples include growth hormone, which is protein in nature.
122
What role do antibodies play in the body?
Antibodies are proteins that function in the defense mechanism.
## Footnote
They help identify and neutralize foreign objects like bacteria and viruses.
123
Name a protein that acts as a storage form of iron.
Ferritin.
## Footnote
Ferritin is crucial for maintaining iron homeostasis in the body.
124
What are coagulation factors?
Coagulation factors are proteins involved in blood clotting.
## Footnote
They play a critical role in the hemostatic process.
125
List two structural proteins mentioned in the text.
* Collagen
* Keratin
## Footnote
Collagen provides structural support in skin and bones, while keratin protects against injury.
126
How do proteins influence genetic expression?
Many regulators of genes are protein in nature.
## Footnote
Proteins can act as transcription factors that regulate the expression of genes.
127
What are the remaining amino acids in the chains called?
Amino acid residues
128
What determines the types and arrangement of amino acids in each protein?
Genetic information present in DNA
129
What is the primary structure of a protein?
The sequence of amino acids in a polypeptide chain
130
Define secondary structure in proteins
The spatial relationship of adjacent amino acid residues
131
What type of bond is responsible for the secondary structure?
Hydrogen bond
132
What does the hydrogen bond in secondary structure connect?
The hydrogen of -NH group of one amino acid and the carbonyl oxygen (C=O) of the fourth amino acid
133
What are the two main forms of secondary structure?
* α-helix
* β-pleated sheets
134
Describe the shape and formation of the α-helix
Rod-like structure formed by hydrogen bonds between amino acids
135
What is the formation process of β-pleated sheets?
Formed between two or more separate polypeptide chains or segments of the same chain
136
How does hydrogen bonding occur in β-pleated sheets?
Between the (-NH) group of one chain and the (C=O) of adjacent chain
137
What are the two types of β-sheets?
* Parallel β-sheets
* Antiparallel β-sheets
138
In parallel β-sheets, how do the polypeptide chains run?
In the same direction
139
In antiparallel β-sheets, how do the polypeptide chains run?
In opposite directions
140
How many amino acids are in each complete turn of the α-helix?
3.6 amino acid residues
141
What is the complete turn distance of the α-helix?
54 hm
142
What is the final arrangement of a single polypeptide chain called?
Tertiary structure
## Footnote
Tertiary structure results from the spatial relationship of more distant amino acid residues.
143
What are the two forms of tertiary structures?
* Fibrous
* Globular
## Footnote
Fibrous structures are extended forms like keratin, while globular structures are compact forms like myoglobin.
144
What type of bond is primarily responsible for the fibrous structure of proteins?
Hydrogen bonds
## Footnote
Hydrogen bonds can occur within the chain or between chains.
145
What are the types of bonds that contribute to tertiary protein structure?
* Hydrogen bonds
* Hydrophobic bonds
* Electrostatic bonds
* Disulfide bonds
## Footnote
These bonds involve interactions between amino acid side chains and contribute to the overall stability of the protein structure.
146
What is an example of a fibrous protein?
Keratin
## Footnote
Keratin is a key structural protein found in hair, nails, and skin.
147
What is an example of a globular protein?
Myoglobin
## Footnote
Myoglobin is a globular protein that serves as an oxygen storage molecule in muscle tissue.
148
Fill in the blank: The compact form of tertiary structure that results from folding of the polypeptide chain is known as _______.
Globular
## Footnote
Globular proteins are typically soluble in water and perform various functions in biological systems.
149
True or False: Disulfide bonds are formed between oppositely charged groups in the side chains of amino acids.
False
## Footnote
Disulfide bonds are formed between residues within the chain, specifically between cysteine residues.
150
What type of bond involves interactions between nonpolar side chains of neutral amino acids?
Hydrophobic bonds
## Footnote
Hydrophobic bonds help stabilize the protein structure by minimizing exposure of nonpolar side chains to water.
151
What are the components of quaternary structure in proteins?
Many proteins are composed of several polypeptide chains called subunits
## Footnote
Each subunit has its own primary, secondary, and tertiary structure.
152
What types of bonds are responsible for the quaternary structure of proteins?
* Hydrogen bond
* Hydrophobic bond
* Electrostatic bond
## Footnote
These bonds help stabilize the quaternary structure formed by multiple subunits.
153
Name an example of a protein that has a quaternary structure with 2 subunits.
Insulin
## Footnote
Insulin is a well-known example of a protein with quaternary structure.
154
Name an example of a protein that has a quaternary structure with 4 subunits.
* Lactate dehydrogenase enzyme
* Globin of hemoglobin
## Footnote
Both are examples of proteins that consist of four subunits.
155
What is denaturation in the context of proteins?
Unfolding and loss of secondary, tertiary, and quaternary structure
## Footnote
Denaturation does not affect the primary structure.
156
Does denaturation affect the primary structure of proteins?
No, it does not affect the primary structure
## Footnote
Denaturation is not accompanied by hydrolysis of peptide bonds.
157
What are the effects of protein denaturation?
* Loss of biological activity
* Insolubility of denatured proteins
* Easier precipitation of denatured proteins
## Footnote
For example, insulin loses its activity after denaturation.
158
What is a common factor that causes protein denaturation?
* Heat
* Organic solvents
* Detergents
## Footnote
These factors interfere with the stabilizing interactions within the protein.
159
How does heat contribute to protein denaturation?
Causes coagulation and precipitation of certain proteins like albumin
## Footnote
Heat can disrupt the bonds that maintain protein structure.
160
What role do organic solvents play in protein denaturation?
They interfere with hydrophobic bonds of proteins
## Footnote
Organic solvents can disrupt the interactions that help maintain protein structure.
161
What are detergents classified as in relation to protein denaturation?
Amphipathic
## Footnote
Detergents contain both hydrophobic and hydrophilic groups, allowing them to interfere with protein bonds.
162
What effect do strong acids or bases have on polypeptide chains?
They lead to change in pH which affects the charges on polypeptide chains, disrupting hydrogen and electrostatic bonds.
## Footnote
This disruption can alter protein structure and function.
163
How do heavy metals like lead and mercury affect proteins?
They form ionic bonds with negatively charged ions in polypeptide chains and unite with -SH groups, causing denaturation.
## Footnote
Denaturation is the process where proteins lose their structure and function.
164
What are examples of enzymes mentioned in the text?
Digestive enzymes.
## Footnote
Enzymes are biological catalysts that speed up biochemical reactions.
165
What substances are known to cause precipitation of proteins?
Urea, ammonium sulfate, and sodium chloride.
## Footnote
Precipitation is a method used to separate proteins from a solution.
166
What is the effect of repeated freezing and thawing on proteins?
It causes disruption of hydrogen and other bonds.
## Footnote
This process can lead to protein denaturation.
167
What are the two main classifications of proteins?
Simple proteins and conjugated proteins.
## Footnote
Simple proteins consist solely of amino acids, while conjugated proteins contain additional non-amino acid components.
168
Give two examples of simple proteins.
Albumin and globulins.
## Footnote
Simple proteins are typically soluble and can be coagulated by heat.
169
What are the classifications of basic proteins?
Globins (histones) and protamines.
## Footnote
Basic proteins are characterized by a higher proportion of basic amino acids.
170
List two types of acidic proteins.
Gliadins and glutelins.
## Footnote
Acidic proteins often contain a higher number of acidic amino acids.
171
Name three examples of scleroproteins.
Keratins, collagen, and elastin.
## Footnote
Scleroproteins are structural proteins that provide support and strength.
172
What is the molecular weight of albumin?
68,000.
## Footnote
Molecular weight can affect a protein's solubility and biological function.
173
Fill in the blank: Serum albumin is coagulable by _______.
full saturated ammonium sulfate.
## Footnote
This technique is used to isolate proteins based on solubility.
174
What is the solubility characteristic of globulins?
Soluble in salt solution.
## Footnote
This solubility property is important for protein purification processes.
175
What is the molecular weight of serum globulins?
150,000.
## Footnote
The size of globulins can influence their roles in the immune response.
176
What are basic proteins rich in?
Basic amino acids
## Footnote
Examples include histones and protamines.
177
What type of basic amino acid is found in histones?
Histidine
## Footnote
Histones are basic proteins that play a role in DNA packaging.
178
Which basic amino acids are present in protamines?
Lysine and Arginine
## Footnote
Protamins are also basic proteins that are involved in sperm cell formation.
179
How do basic proteins behave in salt solution?
They are soluble
## Footnote
Basic proteins, like globins and histones, dissolve in salt solutions.
180
What is the solubility of basic proteins in 70% ethanol?
Insoluble
## Footnote
This property varies among different proteins.
181
What are gliadins and glutelins rich in?
Acidic amino acids
## Footnote
Specifically, they are rich in glutamic acid.
182
Where are gliadins and glutelins found?
Cereals
## Footnote
They are important proteins in wheat and other grains.
183
In which solutions are gliadins and glutelins soluble?
Diluted acids and alkalies
## Footnote
Gliadins are also soluble in 70% ethanol.
184
What are the major structural proteins found in connective tissue?
Keratin, collagen, elastin, and reticulin
## Footnote
These proteins provide structural support in various tissues.
185
Where are keratins found in the body?
Hair, nails, enamel of teeth, and outer layer of skin
## Footnote
Keratins are essential for the protective barriers in these structures.
186
What is the primary structure of keratins?
Alpha-helical polypeptide chains
## Footnote
The structure contributes to their strength and resilience.
187
Why are keratins insoluble in water?
High content of hydrophobic amino acids
## Footnote
This hydrophobicity prevents them from dissolving in aqueous environments.
188
What percentage of total body proteins does collagen make up?
About 30%
## Footnote
Collagen is the most abundant protein in the human body.
189
What is the most common type of collagen in the human body?
Type I collagen
## Footnote
This type accounts for approximately 90% of all collagen in the body.
190
What is collagen's role in the body?
Protein of connective tissue
## Footnote
It is present in skin, bones, tendons, and blood vessels.
191
What structure do collagen molecules form?
Triple helix molecule
## Footnote
This structure is crucial for the strength and stability of collagen.
192
What is the composition of collagen molecules?
Three polypeptide chains called alpha-chains
## Footnote
These chains twist around each other to form a stable structure.
193
What happens to collagen in the extracellular matrix?
It may be present as a gel
## Footnote
Collagen provides support and structure in the extracellular matrix.
194
Fill in the blank: Collagen is found in ______ in the eye.
vitreous humour
## Footnote
This gel-like substance helps maintain the shape of the eye.
195
What are the three polypeptide chains in collagen held together by?
Hydrogen bonds
196
What is the length and diameter of each collagen chain?
About 300 nm in length and 1.5 mm in diameter
197
How many amino acids are in each collagen chain?
1050 amino acids
198
What is the composition of amino acids in collagen?
* 33% glycine
* 10% proline
* 10% hydroxyproline
* 1% hydroxylysine
199
What is the repeating amino acid sequence in collagen's alpha chain?
Glycine-X-Y, where X is frequently proline and Y is often hydroxyproline or hydroxylysine
200
What is glycosylation in the context of collagen?
Collagens are present in the form of glycoprotein with glucose and galactose commonly attached
201
Why does collagen have a very firm structure?
* Each helical turn contains only 3 amino acids
* Glycine forms 33% of the total molecule
* High content of hydroxyproline and hydroxylysine increases hydrogen bonds
202
What type of cells are responsible for collagen synthesis?
Fibroblasts
203
What is required for the hydroxylation of proline and lysine residues in collagen synthesis?
O2 and vitamin C
204
What is the form of collagen before it is secreted from the cell?
Procollagen in the form of a triple helix
205
What happens to collagen when it is heated?
It loses its structure; the triple helix unwinds and chains separate
206
What is gelatin and how is it formed?
Gelatin is formed when denatured collagen cools and soaks up water; it is soluble in water and digestible
207
What condition is caused by a deficiency in vitamin C related to collagen?
Scurvy
208
Fill in the blank: Collagen is _______ in all solvents.
insoluble
209
True or False: Gelatin is given to patients during convalescence in the form of jelly.
True
210
What is elastin?
A connective tissue protein that is rubber-like and can be stretched to several times its normal length.
## Footnote
Elastin recoils to its original shape when the stretching force is removed.
211
Where is elastin primarily located in the body?
In the lungs, walls of large blood vessels, and elastic ligaments.
## Footnote
These locations highlight elastin's role in providing elasticity and flexibility.
212
What is the structural composition of elastin?
It is formed of 4 polypeptide chains that are interconnected through lysine residues.
## Footnote
Elastin is rich in glycine and proline but poor in hydroxyproline and hydroxylysine.
213
What is the role of a1-antitrypsin (a1-AT)?
It inhibits enzymes that destroy proteins, particularly elastin in the lungs.
## Footnote
a1-AT is mainly produced by the liver and also by monocytes and macrophages.
214
What happens to elastin in the lungs when a1-antitrypsin is deficient?
Destruction of connective tissue in alveolar walls by neutrophil elastase, leading to emphysema.
## Footnote
Emphysema is a lung disease characterized by the destruction of alveoli.
215
True or False: Elastin is similar to collagen in its amino acid composition.
True.
## Footnote
Both elastin and collagen are rich in glycine and proline.
216
Fill in the blank: Elastin can stretch to several times its normal length and _______ to its original shape.
recoil.
## Footnote
This property is essential for its function in elastic tissues.
217
What is the primary source of a1-antitrypsin?
The liver.
## Footnote
a1-AT is also produced by blood cells, including monocytes and macrophages.
218
List the characters of elastin.
* Connective tissue protein
* Rubber-like
* Can be stretched
* Recoils to original shape
## Footnote
These characteristics contribute to its functionality in various tissues.
219
What is the primary amino acid composition of collagen?
1/3 glycine, rich in proline, more hydroxyproline
## Footnote
Collagen is a fibrous protein that provides strength and structure to various tissues.
220
In what direction does collagen stretch?
One direction
## Footnote
This characteristic is crucial for its structural function in tissues.
221
What are the characteristics of elastin?
1/3 glycine, rich in proline, less hydroxyproline, free from hydroxylysine
## Footnote
Elastin allows tissues to return to their original shape after stretching.
222
Elastin has how many structural forms?
Fibrous in extended form, Globular in relaxed form
## Footnote
This dual structure is important for its function in elastic tissues.
223
What are conjugated proteins?
Proteins that yield a prosthetic group upon hydrolysis
## Footnote
They consist of an apoprotein part and a non-protein part.
224
What are phosphoproteins?
Proteins conjugated with phosphate groups
## Footnote
Phosphate is typically attached to the -OH group of serine or threonine.
225
Name two examples of phosphoproteins.
* Casein
* Vitellin
## Footnote
Casein is found in milk and vitellin in egg yolk.
226
What effect does phosphorylation have on enzymes?
It may activate or inactivate the enzyme according to its type
## Footnote
Phosphorylation is a common regulatory mechanism in biochemistry.
227
What are lipoproteins?
Proteins conjugated with lipids
## Footnote
They play key roles in transporting lipids in the bloodstream.
228
What are glycoproteins and proteoglycans?
Proteins conjugated with carbohydrates
## Footnote
They are involved in cell-cell recognition and signaling.
229
What are nucleoproteins?
Proteins conjugated with nucleic acids
## Footnote
They are found in ribosomes and chromatin.
230
What are chromoproteins?
Proteins conjugated with colored elements
## Footnote
They include metalochromoproteins and non-metalochromoproteins.
231
What are metalochromoproteins?
Proteins that contain colored metals
## Footnote
They often play roles in electron transport and catalysis.
232
Give an example of a non-metalochromoprotein.
Flavin-containing proteins
## Footnote
These proteins are often involved in redox reactions.
233
What are melanoproteins?
Proteins that contain melanin pigments
## Footnote
They give color to hair and iris.
234
What are metalloproteins?
Proteins conjugated with metals
## Footnote
They are crucial for various biological functions, including enzyme activity.
235
What are metaloproteins?
Metaloproteins are proteins that contain metal ions as cofactors.
## Footnote
Examples include hemoglobin, myoglobin, and various enzymes.
236
Name the metals commonly associated with metaloproteins.
* Iron
* Copper
* Zinc
* Magnesium
* Selenium
## Footnote
These metals play crucial roles in biochemical processes.
237
What is heme iron?
Heme iron refers to the iron found in hemoproteins like hemoglobin and myoglobin.
## Footnote
Heme iron is more readily absorbed by the body compared to nonheme iron.
238
What are the main types of nonheme iron?
* Ferritin: storage form of iron
* Transferrin: iron carrier protein
* Hemosiderin: result of iron toxicity
## Footnote
Ferritin and transferrin play vital roles in iron metabolism.
239
Define hemoproteins.
Hemoproteins are conjugated proteins composed of a protein part (globin) and a nonprotein prosthetic part (heme).
## Footnote
They are involved in various biological functions, particularly in oxygen transport and storage.
240
List examples of hemoproteins.
* Hemoglobin: carries oxygen
* Myoglobin: stores oxygen in muscles
* Respiratory enzymes: utilize oxygen
## Footnote
These proteins are essential for respiratory and metabolic processes.
241
What is the structure of heme?
Heme consists of four pyrrole rings united to form protoporphyrin III with iron in the ferrous state (Fe²⁺) incorporated.
## Footnote
The unique structure allows heme to bind oxygen.
242
True or False: Hemoglobin is responsible for carbon dioxide transport.
True
## Footnote
Hemoglobin carries both oxygen and carbon dioxide in the blood.
243
Fill in the blank: _______ is the storage form of iron in the liver, spleen, and bone marrow.
Ferritin
## Footnote
Ferritin helps regulate iron availability in the body.
244
What role does ceruloplasmin play?
Ceruloplasmin is a copper-carrying protein involved in iron metabolism.
## Footnote
It also has antioxidant properties.
245
Name a function of glutathione peroxidase.
Glutathione peroxidase functions as an antioxidant enzyme.
## Footnote
It helps protect cells from oxidative damage.
246
What is hemoglobin?
A metalloprotein formed of heme and globin
## Footnote
Hemoglobin consists of globin (95% of the molecule) and heme, functioning primarily in oxygen transport.
247
What are the components of globin in hemoglobin?
2 alpha chains (each 141 amino acids) and 2 beta chains (each 146 amino acids)
## Footnote
Globin has a quaternary structure and is rich in histidine amino acids.
248
List the functions of hemoglobin.
* Carries O2 to tissues
* Removes CO2 from tissues to lungs
* Acts as blood buffer
* Synthesis of heme
* Forms hemoglobin derivatives
## Footnote
These functions are crucial for maintaining oxygen levels and acid-base balance in the blood.
249
Where is myoglobin found?
In the cytosol of red skeletal muscle and cardiac muscle
## Footnote
Myoglobin gives these tissues their characteristic red color.
250
How does myoglobin differ from hemoglobin in terms of oxygen affinity?
Myoglobin has a much higher affinity for oxygen than hemoglobin
## Footnote
Myoglobin releases oxygen only under very low oxygen tension.
251
What happens to myoglobin levels in the blood during myocardial infarction?
Myoglobin concentration increases in blood
## Footnote
However, serum myocardial enzymes provide a more sensitive index for myocardial infarction.
252
What is myoglobinuria?
The release of myoglobin from muscles after massive crush injury
## Footnote
Myoglobin excreted in urine can color it dark and may cause renal tubular obstruction and renal failure.
253
What is sickle cell anemia characterized by?
Abnormal hemoglobin called hemoglobin S (HbS)
## Footnote
HbS contains 2 normal alpha chains and 2 mutant beta chains, with glutamate at position six replaced by valine.
254
What are thalassemias?
Anemias characterized by reduced synthesis of either alpha chains (alpha-thalassemias) or beta chains (beta-thalassemias) of hemoglobin
## Footnote
Thalassemias affect hemoglobin production and can lead to various forms of anemia.
255
Fill in the blank: Hemoglobin is formed of _______ and globin.
heme
## Footnote
Heme is the iron-containing molecule that binds oxygen.
256
True or False: Myoglobin can release oxygen easily under normal conditions.
False
## Footnote
Myoglobin releases oxygen only under very low oxygen tension, making it less effective in oxygen delivery compared to hemoglobin.
