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Membrane Proteins Overview
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Membrane Proteins Overview

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Questions and Answers

What happens to enzyme activity in neutral solutions?

  • Enzyme activity becomes erratic with significant fluctuations.
  • Enzyme activity remains unchanged despite variations in pH. (correct)
  • Enzyme activity can only decrease at very low or high pH levels.
  • Enzyme activity decreases significantly regardless of other factors.

    • How does temperature affect enzyme reactions outside their optimal range?

  • Temperature extremes can slow down reaction rates significantly. (correct)
  • Enzymes function best at any temperature, adjusting to conditions.
  • Cold temperatures always lead to denaturation of enzymes.
  • Higher temperatures enhance enzyme activity indefinitely.

    • What structural change in enzymes can lead to loss of function?

  • Addition of cofactors that stabilize the enzyme structure.
  • Denaturation of the enzyme's three-dimensional shape. (correct)
  • Modification of the enzyme's primary sequence.
  • Increasing the substrate concentration to excessive levels.

    • What is the effect of substrate concentration on the initial rate of reaction?

    <p>A plateau is reached when all enzymes are saturated with substrate.</p> Signup and view all the answers

    How is the enzyme active site's shape affected by pH changes?

    <p>Alterations in pH can change the active site's shape and decrease function.</p> Signup and view all the answers

    What is the main physiological process most affected in sickle cell disease?

    <p>Hemoglobin structure</p> Signup and view all the answers

    What describes the state of free enzyme availability in a saturation scenario?

    <p>All enzymes are either in a complex with substrate or leftover as free.</p> Signup and view all the answers

    Which amino acid is replaced in sickle cell disease due to a point mutation?

    <p>Glutamic acid</p> Signup and view all the answers

    What typically happens to enzymes at high temperatures?

    <p>They change shape and eventually denature.</p> Signup and view all the answers

    What specific genetic alteration causes sickle cell disease?

    <p>Single base-pair substitution</p> Signup and view all the answers

    Which of these results from the abnormal protein formation in sickle cell disease?

    <p>Formation of rigid red blood cells</p> Signup and view all the answers

    Which of the following correctly describes enzyme behavior at low pH?

    <p>Enzymes may undergo structural changes that affect activity.</p> Signup and view all the answers

    In sickle cell disease, which molecule would likely demonstrate abnormal behavior in response to stress?

    <p>Hemoglobin S</p> Signup and view all the answers

    What could be concluded from an arterial blood gas showing a pH of 7.39, PaCO2 of 27 mmHg, and HCO3 of 19 mmol/L?

    <p>Partially compensated metabolic acidosis</p> Signup and view all the answers

    How is the mutation in sickle cell disease commonly characterized?

    <p>Cytosine to thymine substitution</p> Signup and view all the answers

    In the context of the given pCO2 value of 68 mmHg, what pathology does this suggest?

    <p>Acute respiratory acidosis</p> Signup and view all the answers

    What does an HCO3 level of 28 mmol/L indicate in the context of acid-base balance?

    <p>Metabolic alkalosis</p> Signup and view all the answers

    What major symptom arises from the morphological changes in red blood cells in sickle cell disease?

    <p>Increased hemolysis</p> Signup and view all the answers

    Which of the following describes the relationship between sickle cell disease and specific genetic polymorphisms?

    <p>Identical mutations and identical phenotype</p> Signup and view all the answers

    How would a PaO2 of 65 mmHg be interpreted in an arterial blood gas analysis?

    <p>Mild hypoxemia</p> Signup and view all the answers

    For a patient whose NGT is draining coffee ground secretions post-abdominal surgery, what is the likely concern?

    <p>Metabolic acidosis due to gastrointestinal loss</p> Signup and view all the answers

    Which of the following parameters is primarily involved in diagnosing respiratory acidosis?

    <p>Decreased pH and elevated PaCO2</p> Signup and view all the answers

    What does a pH level of 7.3 indicate in terms of acid-base status?

    <p>Metabolic acidosis</p> Signup and view all the answers

    When assessing a patient with a pH of 7.45, what can be inferred regarding their acid-base status?

    <p>Fully compensated respiratory alkalosis</p> Signup and view all the answers

    What is the interpretation of a pH of 7.57 in terms of acid-base balance?

    <p>Alkalosis</p> Signup and view all the answers

    Given a PaO2 of 85 mmHg, how would the oxygenation status of the patient be classified?

    <p>Mild Hypoxemia</p> Signup and view all the answers

    What does a HCO3 value of 30 mmol/L suggest about the patient's acid-base status?

    <p>Metabolic alkalosis</p> Signup and view all the answers

    If the arterial blood gas shows pCO2 of 37 mmHg, what does this imply about the respiratory status?

    <p>Normal respiratory function</p> Signup and view all the answers

    What can be inferred from the values Na+ 140 mmol/L and Cl- 100 mmol/L?

    <p>Normal serum electrolyte levels</p> Signup and view all the answers

    If a patient has a pH of 7.38 and a PaCO2 of 41 mmHg, what could be the acid-base disturbance?

    <p>Respiratory acidosis</p> Signup and view all the answers

    Which equation represents the bicarbonate buffer system accurately?

    <p>pH = pKa + log([HCO3-]/[0.03×PCO2])</p> Signup and view all the answers

    Which condition is characterized by a pH less than 7.35?

    <p>Metabolic acidosis</p> Signup and view all the answers

    Which type of amino acids are primarily found in the intra-membrane domain of transmembrane proteins?

    <p>Hydrophobic amino acids</p> Signup and view all the answers

    Which of the following amino acids is likely to be found in the extracellular domain of plasma membrane proteins?

    <p>Lysine</p> Signup and view all the answers

    What feature distinguishes polar molecules from non-polar molecules?

    <p>Asymmetrical charge distribution</p> Signup and view all the answers

    Among the following bonds, which is known to be the least polar?

    <p>C-H</p> Signup and view all the answers

    Which amino acids are typically found in the cytosolic domain of membrane proteins?

    <p>Glutamic acid and aspartic acid</p> Signup and view all the answers

    What is a characteristic of hydrophobic amino acids in relation to the lipid bilayer?

    <p>They cluster together within the hydrophobic core</p> Signup and view all the answers

    In the context of hydrogen bonding, which type of bond would exhibit the highest polarity?

    <p>O-H</p> Signup and view all the answers

    What factor contributes most to the polarity of a covalent bond?

    <p>The electronegativity difference between atoms</p> Signup and view all the answers

    Study Notes

    Membrane Proteins

    • Membrane proteins have three domains: extracellular, intra-membrane, and cytosolic.
    • The intra-membrane domain consists of hydrophobic amino acid sequences within the lipid bilayer.
    • Extracellular and intracellular domains contain hydrophilic amino acids.

    Polar Covalent Bonds

    • The most polar covalent bonds involve H-O, N-H, O-H, or F-H due to high electronegativity differences.
    • A polar covalent bond exhibits a bond dipole, influencing molecular interactions.

    Sickle Cell Disease

    • Sickle cell disease (SCD) is caused by a single base-pair mutation in the β-globin gene.
    • This mutation replaces glutamic acid with valine in the β-globin chain, leading to abnormal hemoglobin formation.
    • Sickle cell anemia is one of the most common genetic disorders linked to hemoglobin.

    Enzyme Activity and pH

    • Enzyme activity is influenced by pH; deviations from optimal pH can change enzyme shape and function.
    • Hot temperatures can denature enzymes, leading to irreversible changes in the active site.

    Initial Reaction Rates

    • There is a positive correlation between substrate concentration and the initial reaction rate until saturation occurs.
    • Past a certain point, all enzyme active sites are occupied, decreasing the availability of free enzymes.

    Arterial Blood Gas Interpretation

    • Normal pH range is 7.35 – 7.45; values outside this indicate acidosis or alkalosis.
    • pCO2 levels determine respiratory status; elevated values suggest respiratory acidosis.
    • HCO3 values help assess metabolic status; levels outside the normal range indicate metabolic acidosis or alkalosis.

    Patient Case Studies

    • A case with irritability and diarrhea in an infant resulted in ABG results displaying partially compensated metabolic acidosis.
    • A patient with coffee-ground drainage post-surgery had ABG results indicating uncompensated metabolic alkalosis.

    Oxygenation Status

    • Oxygenation levels can be assessed through PaO2 measurements, indicating hypoxaemia at varying severities.

    ABG Measurements

    • ABG results showing pH, PaO2, HCO3, and PaCO2 provide insight into the acid-base status of the patient.
    • Bicarbonate buffering systems play a crucial role in maintaining acid-base balance, described by the equation: pH = pKa + log([HCO3-]/[0.03×PCO2]).

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    Description

    Explore the key concepts of membrane proteins, including their structure and the roles of various amino acids like alanine, valine, and phenylalanine. This quiz will help you understand the organization of transmembrane and cytosolic domains in relation to the lipid bilayer.

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