Proteins Flashcards
(160 cards)
1
Q
What are the four levels of protein structure?
A
Primary, secondary, tertiary, and quaternary.
2
Q
True or False: The primary structure of a protein is its sequence of amino acids.
A
True.
3
Q
Which type of bond is primarily responsible for the secondary structure of proteins?
A
Hydrogen bonds.
4
Q
Fill in the blank: The structure of a ________ protein refers to its 3D shape of a single polypeptide chain
A
tertiary
5
Q
What is the main characteristic of the quaternary structure of proteins?
A
It involves the assembly of multiple polypeptide chains.
6
Q
Which amino acid contains sulfur and can form disulfide bonds?
A
Cysteine.
7
Q
True or False: All proteins have a quaternary structure.
A
False.
8
Q
What is the role of chaperone proteins?
A
To assist in the proper folding of other proteins.
9
Q
Which structure is stabilized by ionic bonds and hydrophobic interactions?
A
Tertiary structure.
10
Q
What is the significance of the protein folding process?
A
It determines the protein’s function.
11
Q
What type of interactions are crucial for maintaining a protein’s tertiary structure?
A
Hydrophobic interactions, hydrogen bonds, ionic bonds, and disulfide bridges.
12
Q
Fill in the blank: Proteins that are composed of more than one polypeptide chain exhibit _______ structure.
A
quaternary
13
Q
True or False: The sequence of amino acids in a protein does not affect its function.
A
False.
14
Q
What are the two types of secondary protein structures?
A
Alpha helices and beta sheets.
15
Q
What is denaturation in the context of proteins?
A
The process where proteins lose their structure and function due to external stress or conditions.
16
Q
Fill in the blank: The _______ structure is stabilized by peptide bonds.
A
primary
17
Q
Multiple Choice: Which structure is primarily determined by interactions among R groups?
A
Tertiary structure.
18
Q
What is a polypeptide?
A
A chain of amino acids linked by peptide bonds.
19
Q
Fill in the blank: The _______ structure of proteins can involve multiple subunits.
A
quaternary
20
Q
True or False: Protein function is always independent of its structure.
A
False.
21
Q
Fill in the blank: Proteins can be classified as _______ or _______ based on their structure.
A
fibrous, globular
22
Q
True or False: Denaturation is always a reversible process.
A
False
only reversible when solvents are used
23
Q
Which of the following is NOT a common cause of protein denaturation? A) Heat B) Cold C) pH changes D) Chemicals
A
B) Cold
24
Q
What is the primary consequence of denaturation on protein function?
A
the loss of biological activity or function of the protein.
25
What are non-enzymatic proteins?
Proteins that do not catalyze biochemical reactions.
26
True or False: Non-enzymatic proteins can still have regulatory functions.
True
27
Fill in the blank: Non-enzymatic proteins include _____ and structural proteins.
transport
28
What is the primary function of structural non-enzymatic proteins?
To provide support and shape to cells and tissues.
29
Which of the following is a type of non-enzymatic protein? A) Enzyme B) Hemoglobin C) Lipase
B) Hemoglobin
30
What role do transport proteins play?
They carry substances across cell membranes or within the bloodstream.
31
True or False: All proteins in the body are enzymatic.
False
32
What is the function of albumin?
To maintain osmotic pressure and transport various substances in the blood.
33
Fill in the blank: Collagen is a major _____ protein in the body.
structural
34
What is the significance of antibodies?
They are non-enzymatic proteins that help in immune response by recognizing and neutralizing pathogens.
35
Which non-enzymatic protein is crucial for oxygen transport in the blood?
Hemoglobin
36
True or False: Non-enzymatic proteins can be involved in signaling pathways.
True
37
What type of protein is fibrinogen?
A non-enzymatic protein involved in blood clotting.
38
Fill in the blank: Myoglobin is a non-enzymatic protein that stores _____ in muscle cells.
oxygen
39
What is the role of keratin in the body?
To provide structural support in hair, nails, and skin.
40
Which of the following is NOT a non-enzymatic protein? A) Insulin B) Collagen C) Actin
A) Insulin
41
What is the main function of casein?
To serve as a major protein in milk and provide amino acids.
42
True or False: Non-enzymatic proteins can be involved in transport and storage.
True
43
What are the two main categories of non-enzymatic proteins?
Structural proteins and transport proteins.
44
What is the primary function of globulins?
To serve as transport proteins and antibodies.
45
Which non-enzymatic protein is important for the elasticity of connective tissues?
Elastin
46
What is the function of transferrin?
To transport iron in the bloodstream.
47
True or False: Non-enzymatic proteins can undergo post-translational modifications.
True
48
What is the role of immunoglobulins?
To act as antibodies in the immune response.
49
True or false: Actin and myosin are examples of transport proteins.
false
## Footnote
structural
50
Multiple choice: Which of the following is NOT a transport protein? A) Myoglobin B) Collagen C) Hemoglobin D) Serum albumin
B) Collagen.
51
What is the function of fibroin?
It serves as a structural protein in silk.
52
What is a transport protein involved in glucose transport?
GLUT (Glucose Transporter).
53
Fill in the blank: ______ is a structural protein that forms the framework of cells and tissues.
Cytoskeleton.
54
What type of protein is ferritin?
A transport protein that stores and releases iron.
55
True or False: Transport proteins can be specific to certain molecules.
True.
56
Fill in the blank: ______ proteins help maintain osmotic balance in the body.
Transport.
57
Which protein acts as a carrier for lipids in the bloodstream?
Lipoprotein.
58
What structural protein is found in connective tissues?
Elastin.
59
Multiple choice: Which of the following is a structural protein? A) Actin B) Insulin C) Enzyme D) Antibody
A) Actin.
60
True or False: Transport proteins can undergo conformational changes.
True.
61
True or false: Hemoglobin is a protein that functions both as a structural and transport protein.
false
## Footnote
Myoglobin
62
What is biosignaling?
the process by which cells communicate with each other using chemical signals.
63
True or False: Biosignaling only occurs between neurons.
False
64
Fill in the blank: The molecules that transmit signals in biosignaling are called __________.
ligands
65
What type of molecules can act as ligands in biosignaling?
Hormones, neurotransmitters, and cytokines can all act as ligands.
66
What is the primary function of receptors in biosignaling?
Receptors bind to ligands and initiate a response within the cell.
67
Multiple Choice: Which of the following is NOT a type of receptor involved in biosignaling? A) G protein-coupled receptors B) Ion channel receptors C) Enzyme-linked receptors D) Lipid carriers
D) Lipid carriers
68
What is signal transduction?
the process by which a cell responds to a signal, often involving a series of biochemical reactions.
69
True or False: Signal transduction can amplify the strength of a signal.
True
70
Fill in the blank: The process by which a single signal molecule can activate multiple downstream molecules is known as __________.
signal amplification
71
What is the role of second messengers in biosignaling?
relay signals from receptors to target molecules inside the cell.
72
Multiple Choice: Which of the following is a common second messenger? A) ATP B) cAMP C) DNA D) RNA
B) cAMP
73
What is the significance of feedback regulation in biosignaling?
Feedback regulation helps maintain homeostasis by modulating the signaling pathways.
74
True or False: Biosignaling pathways are static and do not change.
False
75
Fill in the blank: The term __________ refers to the ability of a cell to respond differently to the same signal under different conditions.
signal specificity
76
What is an example of a paracrine signaling mechanism?
The release of growth factors that act on nearby cells.
77
Multiple Choice: Which type of signaling involves hormones traveling through the bloodstream? A) Autocrine B) Juxtacrine C) Endocrine D) Paracrine
C) Endocrine
78
What is the difference between autocrine and paracrine signaling?
Autocrine signaling involves a cell responding to signals it produces itself, while paracrine signaling involves signals affecting nearby cells.
79
True or False: All biosignaling pathways lead to changes in gene expression.
False
80
Fill in the blank: __________ signaling involves direct contact between cells through gap junctions.
Juxtacrine
81
What is the role of protein kinases in biosignaling?
Protein kinases add phosphate groups to proteins, which can activate or deactivate signaling pathways.
82
Multiple Choice: Which of the following is a key feature of G protein-coupled receptors? A) They are always active B) They undergo conformational changes upon ligand binding C) They do not require ligands D) They are only found in prokaryotes
B) They undergo conformational changes upon ligand binding
83
What is the function of phosphatases in biosignaling?
Phosphatases remove phosphate groups from proteins, often reversing the actions of kinases.
84
True or False: Biosignaling is only important for multicellular organisms.
False
85
Fill in the blank: The __________ is a network of signaling pathways that coordinate cellular responses to stimuli.
signal transduction network
86
What can dysregulation of biosignaling lead to?
Dysregulation can lead to diseases such as cancer, diabetes, and autoimmune disorders.
87
What type of channel is always open and contributes to the resting membrane potential?
Ungated channels
88
True or False: Voltage-gated channels open in response to changes in membrane potential.
True
89
Fill in the blank: ____________ channels open when a specific ligand binds to them.
Ligand-gated
90
Which type of channel is primarily responsible for the action potential in neurons?
Voltage-gated channels
91
Multiple Choice: What is the primary function of ungated channels? A) Signal transduction B) Maintaining resting potential C) Action potential generation D) Ligand binding
B) Maintaining resting potential
92
helicase is a ligand that can activate ligand-gated channels.
false
## Footnote
Acetylcholine
93
True or False: All ion channels can be classified into ungated, voltage-gated, or ligand-gated categories.
True
94
What triggers the opening of voltage-gated sodium channels during an action potential?
Depolarization of the membrane
95
Fill in the blank: Ligand-gated channels often play a crucial role in ____________ signaling.
Synaptic
96
Multiple Choice: Which type of channel does NOT require a change in voltage or binding of a ligand to open? A) Ungated B) Voltage-gated C) Ligand-gated D) All of the above
A) Ungated
97
What does RTK stand for?
Receptor Tyrosine Kinase
98
True or False: GPCRs are involved in mediating cellular responses to a variety of ligands.
True
99
Fill in the blank: RTKs typically become activated through ________.
dimerization
100
What is the primary function of GPCRs?
To transmit signals from outside the cell to the inside.
101
Which type of receptor is known for its role in cell growth and differentiation?
Receptor Tyrosine Kinase (RTK)
102
Multiple Choice: Which of the following is NOT a characteristic of GPCRs?
A) Seven transmembrane domains
B) Directly phosphorylates proteins
C) G-protein coupling
D) Ligand binding triggers a conformational change
B) Directly phosphorylates proteins
103
What type of signaling pathway do RTKs primarily activate?
Phosphoinositide 3-kinase (PI3K) and MAPK pathways
104
True or False: GPCRs can interact with multiple types of G-proteins.
True
105
Short Answer: What role do RTKs play in cancer?
They can become constitutively active, leading to uncontrolled cell proliferation.
106
Fill in the blank: The ligand for GPCRs is often a ________ molecule.
hormonal or neurotransmitter
107
What does G in G protein stand for?
Guanine nucleotide-binding
108
True or False: G proteins are only found in eukaryotic cells.
True
109
Fill in the blank: G proteins are classified into three main types: _____, _____, and _____.
Gs, Gi, Gq
110
Which type of G protein is primarily involved in stimulating adenylate cyclase?
Gs
111
What is the main function of Gi proteins?
Inhibit adenylate cyclase
112
Multiple Choice: Which G protein type activates phospholipase C? A) Gs B) Gi C) Gq
C) Gq
113
Short Answer: Name one effect of Gs protein activation.
Increased cyclic AMP levels
114
True or False: G proteins can exist in both active and inactive states.
True
115
What is the role of GTP in G protein function?
It activates the G protein.
116
Fill in the blank: The G protein family is part of a larger family known as _____ proteins.
GTP-binding
117
What is the primary purpose of the urea cycle?
To convert toxic ammonia into urea for excretion.
118
True or False: The urea cycle occurs in the cytoplasm of liver cells.
false
## Footnote
it occurs in the mitochondria and cytosol of liver cells.
119
Fill in the blank: The urea cycle begins with the combination of ammonia and _______.
carbon dioxide.
120
What is the first enzyme involved in the urea cycle?
Carbamoyl phosphate synthetase I.
121
Multiple choice: Which molecule is formed when ammonia combines with carbon dioxide in the urea cycle?
Carbamoyl phosphate.
122
What is the second step of the urea cycle?
Formation of citrulline from carbamoyl phosphate and ornithine.
123
True or False: Aspartate is an important substrate in the urea cycle.
True.
124
Short answer: How many nitrogen atoms are incorporated into urea during the urea cycle?
Two nitrogen atoms.
125
Fill in the blank: Urea is excreted from the body primarily through _______.
urine.
126
What is the final product of the urea cycle?
Urea.
127
Multiple choice: Which amino acid is regenerated during the urea cycle?
Ornithine.
128
True or False: The urea cycle is regulated by the concentration of ammonia.
True.
129
What is the role of arginase in the urea cycle?
It catalyzes the conversion of arginine to urea and ornithine.
130
Fill in the blank: The urea cycle requires _______ as an energy source.
ATP.
131
Short answer: Where does the urea cycle primarily take place?
In the liver.
132
True or false: glucose, ammonia, and aspartate are the substrates of the urea cycle
false
## Footnote
bicarbonate, ammonia, and aspartate
133
True or False: The urea cycle is a linear metabolic pathway.
False
## Footnote
it is a cyclic pathway.
134
What is the role of citrulline in the urea cycle?
It is a key intermediate that combines with aspartate to form argininosuccinate.
135
Fill in the blank: The urea cycle converts _______ into urea.
ammonia.
136
Ornithine transcarbamylase deficiency is a disease associated with urea cycle dysfunction.
true
137
Which enzyme is responsible for converting citrulline and aspartate into argininosuccinate?
Argininosuccinate synthetase.
138
True or False: The urea cycle is essential for detoxifying nitrogen in the body.
True.
139
What is the significance of the urea cycle in protein metabolism?
It helps eliminate excess nitrogen from amino acid degradation.
140
Fill in the blank: The urea cycle is also known as the _______ cycle.
ornithine.
141
Short answer: How many steps are there in the urea cycle?
Five steps.
142
Multiple choice: Which of the following enzymes is involved in the final step of the urea cycle?
Arginase.
143
True or False: Urea is a more toxic compound than ammonia.
False
## Footnote
urea is less toxic than ammonia.
144
What is the function of ornithine transcarbamylase in the urea cycle?
It catalyzes the conversion of carbamoyl phosphate and ornithine into citrulline.
145
Fill in the blank: Urea produced in the liver is transported to the _______ for excretion.
kidneys.
146
Short answer: What is the role of aspartate in the urea cycle?
It provides one of the nitrogen atoms for urea synthesis.
147
What is hyperammonemia?
An elevated level of ammonia in the blood.
148
True or False: Hyperammonemia can be caused by liver dysfunction.
True
149
Fill in the blank: The normal blood ammonia level is typically less than _____ µmol/L.
50
150
What are common symptoms of hyperammonemia?
Confusion, lethargy, and seizures.
151
Which enzyme deficiency is often associated with hyperammonemia?
Urea cycle enzyme deficiency.
152
Multiple choice: Which of the following is NOT a potential cause of hyperammonemia? A) Liver failure B) Kidney disease C) High protein diet D) Diabetes
D) Diabetes
153
What is the primary treatment for acute hyperammonemia?
Lactulose and/or ammonia scavengers.
154
True or False: Hyperammonemia can lead to brain damage if left untreated.
True
155
What is the role of the liver in ammonia metabolism?
The liver converts ammonia into urea for excretion.
156
Fill in the blank: Chronic hyperammonemia can lead to _____ encephalopathy.
hepatic
157
What is ornithine transcarbamylase deficiency?
A genetic disorder that affects the urea cycle, leading to the accumulation of ammonia in the blood.
158
True or False: Ornithine transcarbamylase deficiency is an X-linked recessive condition.
True
159
Fill in the blank: The primary symptom of ornithine transcarbamylase deficiency is ________.
hyperammonemia
160
Multiple Choice: What is a common treatment for ornithine transcarbamylase deficiency? A) Liver transplant B) Chemotherapy C) Insulin therapy D) Antibiotics
A) Liver transplant
