MCS Revision Practice Q's

What neurotransmitter and hormone is tyrosine the precursor ? - Dopamine - Adrenaline What part of the protein does Biuret reagent react with ? Peptide bonds What is the Michaelis constant? Km = the substrate concentration where half of the Vmax is observed. The lower the Km, the higher the affinity the enzyme has for the substrate What are the x and y intercept of the Eadie-Hofstee plot ? Vmax/Km and Vmax How is urea cycle linked to the Krebs cycle ? - Fumarate formed in the urea cycle is converted to malate - Malate is converted to oxaloacetate that reacts with acetyl CoA to form citrate What enzyme catalyses transcription and what are the key steps in the process ? RNA Polymerase - Initiation, Elongation, Termination What part of cardiac muscle is responsible for rapid propagation of electrical impulses that force blood out of the heart ventricles and into the lungs and body? His-Purkinje network At which phase of the cardiac action potential does the Na+/K+ ATPase pump create a negative (resting) intracellular potential? Phase 4 Which leukocyte contains granules that contain histamine and heparin? Basophil Which plasma proteins are present at increased circulating levels during acute inflammation? C-reactive protein Fibrinogen What are the regulatory proteins that turn prevent and permit muscle contraction? - Troponin - Tropomyosin 1/6 - Adenosine triphosphate binds to myosin cross bridge and is hydrolysed to adenosine diphosphate + phosphate - this remains attached to myosin head until Ca2+ - the myosin cross bridge can bind with an actin molecule How is adenosine triphosphate used during muscle contraction? How is the cardiac action potential differPlateau phase after partial repolarisation ent from the neuron action potential? Which type of signal transmission at neuron synapses is able to synchronise groups of neurons? - Ionic Signals What are the predominant hormones present during the pre-ovulatory phase ? Oestrogen + Luteinising hormone What are the predominant hormones present during the post-ovulatory phase ? Progesterone + Oestrogen Which set of amino acids are the essential amino acids that must be sourced Arg, His, Ile, Leu, Lys, Met, Phe, Thr, Trp, from the diet by adults and growing in- and Val fants? What Amino acids are polar ? Serine, Threonine, Cysteine, Tyrosine, Asparagine, Glutamine What type of bonds are in Primary proteins ? Peptide bonds What type of bonds are in Secondary proteins ? Hydrogen bonds What type of bonds are in Tertiary proteins ? - Hydrogen bonds - Ionic bonds - Hydrophobic bonds - Van der waals - Disulphide bonds What type of bonds are in Quaternary proteins ? 2/6 - Ionic bonds - Hydrophobic bonds - Van der waals Which equation defines the Lineweaver-Burk plot? 1/v = Km/Vmax x 1/[S] + 1/Vmax - Km increase = slope on graph increases = x-axis intercept increases in the presence of the inhibitor How do the Vmax and Km values for enzyme activity change in the presence of a competitive inhibitor? - No effect on Vmax = intercept on the y-axis of the plot of 1/V versus 1/[S] is the same - Km remains the same = X-axis intercept stays the same How do the Vmax and Km values for enzyme activity change in the presence of a non-competitive inhibitor? - Lower Vmax = intercept on y-axis decreases Which organ produces ketone bodies but cannot use this as an energy source? Liver What is the net gain of ATP molecules during substrate level phosphorylation? 2 What is the composition of a Nucleoside ? Nucleobase + Pentose sugar What is the basic repeating unit of the chromatin 'beads on a string' component of the DNA structure? Nucleosome During which phase of the cell cycle does DNA replication occur ? S phase Describe the double strand breaks in DNA ? - It can lead to loss of genetic information - Involved in homologous recombination - Associated with a heterodimer in mammals - Can lead to mutations or improper regulation of gene expression 3/6 What is the function of kinetochore microtubules during mitosis? The alignment of chromosomes in one plane halfway between spindle poles. At which stage of mitosis does the nucleus that disappears during prophase, reappear? Telophase What would be the consequence of reCell would not have enough time to doumoving the G1 and G2 phases from the ble its mass before it divided. cell cycle? Which are the two key families of proteins that control the cell cycle? Cyclin dependent kinases and Cyclins What are the functions of blood ? Acid- base regulation Respiration Regulation of body heat Water balance Which component of blood is differentiated from megakaryocytes ? Platelets What type of drug for treating hypertension alleviates the symptoms of this con- Angiotensin Converting Enzyme (ACE) dition by causing natriuresis and diure- inhibitors sis? Which equation can be used to calculate the equilibrium potential for an ion and the membrane potential at which an ion cannot flow across a membrane? E (ion) = 61.5 / z x (log10 C0 / Ci) Which of the following cell types are located in the epidermis? Keratinocytes Melanocytes Langerhans cells Merkel cells A man presents with a yellowish colour to his skin and the whites of his eyes. What Bilirubin present in blood due to liver disis the most likely diagnosis for the man's ease condition ? What proteins in muscle function to allow alignment, elasticity and extensibility? 4/6 Titin Myomesin Nebulin Dystrophin - Macrophage activation - Eosinophil activation - Mast cell degranulation - Arteriolar vasodilation - Increased Capillary permeability - Mucus secretion into airway - Increased airways resistance - Response lasts up to 20h Define the key features of the late phases of an asthmatic response? What is the mechanism of the ²2agonist Bronchodilation - Myosin light-chain kiadministered to an individual suffering nase inhibition that leads to smooth musfrom an asthma attack ? cle relaxation. What is the role of the Kidney in acid/base balance ? Nephron can make H2CO3, excrete H+, reabsorb HCO3-, and balance body pH . What amino acid is the precursor of melatonin ? Tryptophan The Michaelis constants for enzyme A and enzyme B are 0.1 and 10 mM, respectively. From this it follows that ? Enzyme A has a higher affinity for its substrates What cellular compartment is the glycolytic pathway located in ? Cytoplasm What are the components of DNA ? Ribose group = deoxyribose, Phosphate group Nitrogenous bases = Adenine What is used to treat Glaucoma ? What order does Mitosis occurs in ? 1. Prophase 2. Prometaphase 3. Metaphase 4. Anaphase 5. Telophase 6. Cytokinesis The HPA axis responds to stress by sending which molecule below from the hypothalamus to the anterior pituitary? Corticotropin releasing hormone 5/6 What is the best way to describe the general anatomy of the integuments ? - Composed of 4 tissue types - 22 square feet - 1-2 mm thick - 10 lbs weight From the outside inwards, which is the correct histological order of the alimentary canal wall? - Serosa - Muscularis externa - Submucosa - Mucosa - Lumen What is the sequence of blood pressure ? Arteries = 80 to 120 mmHg Capillaries = 16 to 35 mmHg Veins = 4 to 7 mmHg Why are Salbutamol and Ipratropium Salbutamol is a B2 agonist bromide are effective in the treatment of Ipratropium bromide is a Muscarinic anasthma ? tagonist Where does the causative organism for bubonic plague Yersinia pestis multiplies and forms the characteristic buboes ? The lymph nodes what does the malarial parasite Plasmodium do after it enters the human body through the bite of the female Anopheles mosquito? - Spreads through the blood to the hepatocytes What organism produces the antibiotic Streptomycin ? Streptomyces griseus What enzyme involved in cross linking the rows and layers of peptidoglycan to make a strong cell wall in bacteria? Transpeptidase 6/6