Chapter 3 Proteins & enzymes Flashcards
(119 cards)
1
Q
What elements are found in proteins?
A
C, H, O, N, and sometimes S
2
Q
What is the monomer of proteins?
A
Amino acid (αα)
3
Q
How is each amino acid coded?
A
By 3 DNA bases in a gene
4
Q
What are the three main groups in the structure of an amino acid?
A
- Amine group
- Carboxylic acid group
- Residual group
5
Q
What is the R group in amino acids?
A
A group of atoms that changes between each of the 20 naturally occurring amino acids
6
Q
What is the R group of glycine?
A
H
7
Q
What is the R group of cysteine?
A
SH
8
Q
What does it mean for amino acids to be amphoteric/zwitterionic?
A
They can donate H+ ions (acidic) and accept H+ ions (basic)
9
Q
List the functions of proteins represented by the acronym ‘THAMES’.
A
- Transport role
- Hormones
- Antibodies
- Membranes
- Enzymes
- Structural role
10
Q
What type of reaction joins two amino acids together?
A
Condensation reaction
11
Q
What is formed as a by-product of a condensation reaction between amino acids?
A
Water
12
Q
What is the covalent bond formed between amino acids called?
A
Peptide bond
13
Q
What type of reaction breaks a dipeptide into amino acids?
A
Hydrolysis reaction
14
Q
What is the primary structure of a protein?
A
Number and sequence of amino acids within the polypeptide chain
15
Q
What types of bonds are present in the secondary structure of proteins?
A
Peptide and hydrogen bonds
16
Q
What are the two formations of secondary protein structure?
A
- Alpha helices
- Beta pleated sheets
17
Q
What bonds are involved in tertiary protein structure?
A
- Peptide
- Hydrogen
- Ionic
- Disulfide
- Hydrophobic interactions
18
Q
What is the quaternary structure of a protein?
A
Interactions and bonds between R groups of amino acids on different polypeptides
19
Q
What are the types of bonds involved in protein structure, listed from weakest to strongest?
A
- Hydrogen
- Ionic
- Disulfide
20
Q
What is the stationary phase in chromatography?
A
Paper, silica gel, or column
21
Q
What is the mobile phase in chromatography?
A
Liquid or gas
22
Q
What is the purpose of ninhydrin in chromatography?
A
To identify amino acids by forming a blue-violet compound
23
Q
What is the retention factor (Rf) formula?
A
Rf = Distance travelled by the amino acid / Distance travelled by the solvent
24
Q
What are the minimum and maximum Rf values?
A
Minimum = 0; Maximum = 1
25
What is the role of cofactors in enzymatic activity?
They are additional molecules needed for enzyme function
26
What are the two general types of reactions enzymes catalyze?
* Catabolic reactions
* Anabolic reactions
27
What is the role of enzymes as biological catalysts?
Speed up the rate of reaction and lower activation energy
28
What is an inactive enzyme called?
Apoenzyme
29
What is a coenzyme?
An organic molecule that acts as a cofactor
30
What is the effect of enzyme concentration on enzyme action?
Must keep temperature, substrate concentration, pH, and inhibitor concentration constant
31
What type of bonds do proteases hydrolyze?
Peptide bonds
32
What are the properties of enzymes?
* Specificity
* Reversibility
* High turnover rate
33
How do enzymes lower activation energy?
They provide an alternative pathway and hold reactants close together
34
What is the turnover rate of an enzyme?
Maximum number of chemical conversions of substrate molecules per second
35
What can affect the activity of enzymes?
Environmental conditions such as pH and temperature
36
What must be done to a protein before running a chromatogram to identify amino acids?
Hydrolyze peptide bonds using hot acid
37
What is the purpose of drawing the baseline on chromatography paper?
To enable calculation of Rf
38
What happens if the solvent depth exceeds the height of the origin mark in chromatography?
Amino acids would dissolve in the solvent and not run up the chromatogram correctly
39
What do proteases do?
Hydrolyse peptide bonds to break proteins down into smaller peptides and/or amino acids
40
What is the function of lipases?
Hydrolyse ester bonds to break lipids (triglycerides) down into 3 fatty acids & glycerol
41
What role do carbohydrases play in biological processes?
Hydrolyse glycosidic bonds to break saccharides down into shorter saccharides / disaccharides and/or monosaccharides
42
What factors must be kept constant when investigating the effect of enzyme concentration on enzyme action?
* Temperature
* Substrate concentration [S]
* pH
* Inhibitor concentration [I]
43
Describe the trend in reaction rate (RoR) as enzyme concentration increases.
As [E] increases, the RoR increases showing a positive correlation with a linear relationship
44
What occurs at low enzyme concentration regarding the rate of reaction?
The enzyme concentration [E] is the limiting factor due to insufficient active sites
45
What happens when all active sites of the enzyme are occupied?
The substrate concentration [S] becomes the limiting factor, and additional enzyme does not increase the RoR
46
What factors must be kept constant when investigating the effect of substrate concentration on enzyme action?
* Temperature
* Enzyme concentration [E]
* pH
* Inhibitor concentration [I]
47
Describe the trend in oxygen production over time during an enzyme reaction.
As time increases, the volume of oxygen produced increases, initially sharply, then reaches a plateau
48
When does the volume of oxygen produced reach a plateau?
When all the substrate [S] has been broken down
49
What is the relationship between substrate concentration and rate of reaction?
As [S] increases, the rate of reaction (RoR) increases until it reaches a plateau
50
What happens at point (b) on the substrate concentration graph?
The increase in RoR begins to decrease as the number of substrate molecules available decreases
51
What is pH a measure of?
The number of protons (H+) in a solution
52
What does a change in pH value of 1 indicate?
A tenfold difference in the number of protons present in the solution
53
What is denaturation in the context of enzymes?
The loss in shape of the active site due to changes in pH or temperature affecting the enzyme's structure
54
Describe how temperature affects enzyme action.
As temperature increases, the RoR increases, showing a doubling of rate for each 10°C rise up to the optimum temperature
55
What happens to an enzyme at temperatures above its optimum?
The enzyme denatures, distorting the active site and preventing substrate binding
56
Define competitive inhibition.
Inhibition where the inhibitor resembles the substrate and competes for the active site
57
What is non-competitive inhibition?
Inhibition where the inhibitor binds to an allosteric site, altering the enzyme's shape and preventing substrate binding
58
What is the effect of increasing substrate concentration on competitive inhibition?
Increasing substrate concentration can overcome inhibition as substrate molecules can displace the inhibitor
59
What occurs with non-competitive inhibition regardless of substrate concentration?
Some inhibition remains at high substrate concentration as the inhibitor affects the enzyme's shape
60
What is coagulation necessary for?
* Preventing entry of pathogens
* Preventing excessive blood loss (haemostasis)
* Aiding maintenance of blood volume
61
What triggers the stimulation of blood clotting?
Damage to blood vessel walls exposing collagen fibers
62
What role does thromboplastin play in blood clotting?
Converts inactive prothrombin into active thrombin in the presence of Ca2+ ions
63
What is the result of thrombin acting on fibrinogen?
Converts fibrinogen into insoluble fibrin, forming a fibrous mesh over the wound
64
What is the difference between controlled and uncontrolled blood clotting?
Controlled clotting dissolves naturally after healing; uncontrolled clotting does not dissolve and can cause complications
65
What is the initial rate of reaction (iRoR) used for?
To allow a valid comparison of the activities of enzymes and is the fastest rate of reaction
66
What must be quoted when answering data questions on enzymes?
At least 2 sets of data accurately, along with units
67
What is the initial form of a clot?
A gel that contains fluid (serum) squeezed out onto the skin surface.
68
What happens to a clot when it dries?
It shrinks and pulls the fibrin threads closer together.
69
What is the dried, shrunken clot called?
A scab.
70
What occurs under the scab during healing?
Cells at the edge of the wound divide by mitosis and new tissue develops.
71
What happens to the scab once the wound is healed?
It falls away or is dissolved by the enzyme plasmin.
72
What is hypovolemic shock?
Shock caused by excessive blood loss and fluid loss.
73
What percentage of blood volume loss is associated with hypovolemic shock?
1/5th or more.
74
What are the consequences of hypovolemic shock?
Insufficient blood is pumped around the body, leading to organ failure.
75
What are common causes of hypovolemic shock?
Ruptured spleen, severe burns, diarrhea, excessive perspiration, excessive vomiting.
76
What is the first step in first aid for severe blood loss?
Send for help.
77
What does the primary survey in first aid include?
* Danger
* Response
* Airway
* Breathing
78
What should you do if a casualty is not breathing?
Begin CPR.
79
What is the proper depth for chest compressions during CPR?
About 5-6 cm.
80
What is the role of a defibrillator in first aid?
To restore circulation and breathing.
81
What should be done if a casualty has an embedded object in a wound?
Press the sides of the wound together but do not remove the object.
82
What is the function of antithrombin?
To inhibit thrombin and prevent excessive clotting.
83
What role does heparin play in thrombin inhibition?
It acts as a cofactor for antithrombin.
84
What is serum amylase used to diagnose?
Pancreatic disorders such as alcoholism, gallstones, and pancreatitis.
85
What does elevated serum amylase indicate?
Possible acute pancreatitis (AP).
86
What is lactic acid dehydrogenase (LDH) a marker for?
* Haemolysis
* Myocardial infarction
* Muscle trauma
* Bone fractures
* Anaemia
* Pre-eclampsia
* Certain infections
87
What are LDH isoenzymes?
Enzymes that differ in amino acid sequence but catalyse the same reaction.
88
What is the main function of aspirin?
To act as an anti-prostaglandin agent and anti-platelet agent.
89
How does aspirin inhibit COX?
By adding an acetyl group to serine near the active site.
90
What does warfarin inhibit?
The production of vitamin K-dependent clotting factors.
91
What is the role of streptokinase in thrombolytic therapy?
To dissolve blood clots by converting plasminogen to plasmin.
92
What is the universal blood donor group?
Blood group O.
93
What are the eight blood groups determined by?
The presence or absence of antigens A, B, and the Rhesus antigen (D).
94
What must be matched to prevent agglutination during transfusions?
Antibodies present in the recipient and antigens present in the donor.
95
What is the shelf life of whole blood?
Up to 24 hours.
96
What should a donor do before attending a blood donation session?
Eat regular meals and drink plenty of non-alcoholic fluids.
97
What is a cold chain in blood storage?
A temperature-controlled supply chain for transporting blood and blood products.
98
What is an indicator of acute pancreatitis?
Elevated serum amylase, urine amylase, and serum lipase.
99
What is the shelf life of whole blood?
Up to 24 h
## Footnote
Whole blood is very rarely used nowadays and is only utilized in cases of severe blood loss.
100
What is leuco-depleted blood used for?
For patients who receive regular transfusions
## Footnote
Leuco-depleted blood consists of plasma, erythrocytes, platelets, and clotting factors.
101
What is packed red blood cells mainly composed of?
Only erythrocytes diluted with SAGM (Sodium chloride, Adenine, Glucose, Mannitol)
## Footnote
SAGM helps in reducing damage and providing necessary substrates for RBCs.
102
What are the uses of packed red blood cells?
To treat severe anaemia, replace blood loss after childbirth, replace blood loss after surgery, after major blood loss e.g. trauma
## Footnote
Shelf life is up to 35 days.
103
What is the shelf life of platelets?
Up to 7 days
## Footnote
Platelets are used to treat bone marrow failure patients and following various treatments.
104
What are clotting factors used for?
Various CF disorders, e.g. Factor V: Leiden thrombophilia
## Footnote
The shelf life is variable.
105
What is plasma used for?
Restores blood volume, cardiac surgery, excessive blood loss during childbirth, replace clotting factors, liver failure, stem cell transfusion, reverse anticoagulants
## Footnote
Plasma has a shelf life of 1 year.
106
What is serum?
Plasma with clotting factors removed
## Footnote
Used for snake bites and as a source of antibodies with a shelf life of 1 week.
107
Why is sodium chloride added to packed red blood cells?
Reduces viscosity to allow RBC to flow easier
## Footnote
This helps reduce damage to the cell membrane of RBCs.
108
What function does adenine serve in packed red blood cells?
Prevents clotting
## Footnote
Adenine is crucial for maintaining the functionality of red blood cells.
109
What is the purpose of glucose in packed red blood cells?
Provides respiratory substrate for RBC glycolysis and ATP production
## Footnote
This is essential for the energy needs of the red blood cells.
110
What is mannitol used for in packed red blood cells?
Free-radical scavenger to stabilize the cell membrane of the RBC
## Footnote
This helps in preserving the integrity of the RBC during storage.
111
What is the storage temperature for whole blood?
4°C
## Footnote
This temperature prevents ice crystals from forming and preserves the quality of the blood.
112
What is the role of a chelating agent like citrate in blood storage?
Prevents blood clotting
## Footnote
Chelating agents bind calcium ions which are necessary for the clotting process.
113
What is necessary for blood screening?
To ensure no diseases are transmitted to the recipient
## Footnote
Screening tests are mandatory and conducted using automated machines.
114
What infection does the test for Treponema pallidum detect?
Syphilis
## Footnote
A positive result indicates either a current or previous infection, rendering the blood unusable.
115
What does the hepatitis virus test determine?
Presence of surface antigens or viral nucleic acid
## Footnote
Different types of hepatitis (B or C) can cause liver inflammation and damage.
116
What does a positive HIV test trigger?
Further testing to confirm HIV infection
## Footnote
Antibodies to HIV do not protect against the virus.
117
What is West Nile Virus transmitted by?
Mosquito bites
## Footnote
It can cause mild flu-like symptoms or more serious illness, especially in vulnerable populations.
118
What does the malaria test determine?
Presence of antibodies to malaria parasites
## Footnote
A positive result indicates past infection, not necessarily active malaria.
119
What parasite causes Chagas disease?
Trypanosoma cruzi
## Footnote
This can cause damage to the heart and intestines and is transmitted through various means including blood transfusion.
