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Biochem Sem 3 > MCQs > Flashcards

MCQs Flashcards

1
Q

Xenobiotic mechanism

A
  1. Hydrolysis, reduction, oxidation occur at phase 1
  2. Cytochrome P450 is involved in phase 1
  3. Conjugation occurs at phase 2
  4. Some drugs came directly go to phase 2
  5. Excretion is facilitated by phase 1
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2
Q

Cytochrome P450 enzymes

A
  1. Uses NADPH
  2. Inducible (xenobiotics can increase production of enzymes)
  3. Various isoforms present (superfamily = cyt. P450 enzymes)
  4. Haem proteins, haem as prosthetic group
  5. Present in SER (liver & most other tissues)
  6. Present in mitochondria + ER in adrenals
  7. Acst on steroid hormones
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3
Q

Postnatal growth

A
  1. GH promotes linear growth
  2. IGF-1 are involved
  3. Thyroxine is important in duration of infancy
  4. Insulin is a major determinant of fetal growth
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4
Q

Serum total alkaline phosphatase level is increased in

A
  1. Fractures
  2. Bone metastasis
  3. Osteomalacia
  4. Hyperparathyroidism
  5. Paget’s disease
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5
Q

Thyroid gland

A
  1. Iodine is absorbed by Na+/I- symporter & Na+/K+ ATPase
  2. Removal leads to hypercholesterolemia
  3. Contains thyroid peroxidase which is responsible for oxidation, iodination, coupling
  4. Secretes higher concentration of T4 than T3
  5. Increases in size if iodine is deficient
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6
Q

Adrenal medullary hormones

A
  1. Has 4 corresponding receptors at the nucleus
  2. Shows different affinities to different receptor subtypes
  3. Involved in vasoconstriction
  4. Increases glycogenolysis in skeletal muscle + liver
  5. Increases lipolysis
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7
Q

Pancreatic polypeptide

A
  1. Secreted by F cells of pancreatic islets
  2. Regulates pancreatic exocrine secretions
  3. Regulates pancreatic endocrine secretions
  4. Stimulated by exercise and fasting
  5. Inhibits gallbladder contraction
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8
Q

Insulin resistance leads to

A
  1. Uncontrolled haptic glucose production
  2. Decreased glucose uptake by adipose tissue
  3. Increased insulin level in circulation
  4. Excessive lipolysis
  5. Hypertriglyceridemia
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9
Q

Consequences of hyperglycemia

A
  1. Increased plasma osmolarity
  2. Polyuria
  3. Loss of calories
  4. Foot ulcer
  5. Glomerular dysfunction
  6. Non-enzymatic glycosylation of protein
  7. LDL oxidation (atherosclerosis)
  8. Sorbitol synthesis (cataracts)
  9. Protein kinase C activity
  10. Decreased myoinositol synthesis
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10
Q

Apo-lipoproteins

A
  1. Cofactors
  2. Ligands
  3. Co-enzymes
  4. Structural components of lipoproteins
  5. Antioxidants
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11
Q

Brown adipose tissue

A
  1. Secretes leptin (mostly from WAT)
  2. Both store triglycerides
  3. Contains large number of mitochondria
  4. Produces heat
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12
Q

Eukaryotic DNA replication

A
  1. Produces 2 identical DNA molecules
  2. Occurs @ S phase by mitosis
  3. Forms multiple replication bubbles at one end
  4. Shows polarity
  5. Forms Okazaki fragments
  6. Multiple sites of replication in one chromosome
  7. DNA polymerase needs an RNA primer
  8. Follows Watson-Crick model base complementary rules
  9. Daughter strand synthesis is from 5’ to 3’
  10. Mutations are repaired immediately
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13
Q

Eukaryotic gene expression

A
  1. Monocystronic
  2. Includes tRNA synthesis
  3. Not regulated by operons
  4. Regulated at the post transcriptional level
  5. Regulated by polypeptide hormone
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14
Q

Carcinogenesis

A
  1. Decreased P53 activity
  2. Decreased PDH complex activity
  3. Increased GF concentration
  4. Increase glucose uptake
  5. Increased biosynthetic activity
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15
Q

Blood brain barrier

A
  1. Endothelial cells are interconnected through tight junctions
  2. Active transport contributes to its function
  3. Permeable to immunoglobulin
  4. Dopamine cannot enter but L-dopa can
  5. Regulates transportation of many cancer therapy drugs
  6. Transports water through specific carrier protein
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16
Q

Southern blotting

A
  1. Technique used to analyze DNA
  2. Involves alkaline denaturation & transfer
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17
Q

Requirements of PCR

A
  1. Target DNA
  2. Heat stable DNA polymerase
  3. dNTPs
  4. Buffers
  5. Oligonucleotide primers
  6. Reverse transcriptase
18
Q

Neurotransmitter concentration at synaptic cleft depends on

A
  1. Synthesis of the neurotransmitter at the presynaptic neuron
  2. Re-uptake by presynaptic neuron
  3. Degradation in synaptic cleft
  4. Uptake by postsynaptic nerve
19
Q

RFLP

A
  1. Needs southern blotting
  2. Influenced by restriction endonuclease
  3. Involves chromatography
  4. Used in crime investigations
  5. Used in diagnosis of dengue
20
Q

Enzymes used for recombinant proteins

A
  1. Reverse transcriptase
  2. DNA ligase
  3. RNA polymerase
21
Q

Estrogen synthesis

A
  1. Mainly depends on LDL as a source of cholesterol
  2. Influenced by cytochrome P450 SCC enzyme
  3. Increased by LH
  4. Occurs in both theca and granulosa cells
  5. Involves StAR protein
22
Q

Insulin receptors

A
  1. Has an intrinsic tyrosine kinase activity
  2. Phosphorylates insulin receptor substrates
  3. Increases translocation of GLUT4
  4. Synthesized as a single polypeptide
  5. Beta subunit spans plasma membrane
23
Q

Bile acid sequestrate

A
  1. Activates HMG CoA reductase
  2. Inhibits bile acid absorption
  3. Up-regulates 7 alpha hydroxylase
  4. Leads to decreased plasma cholesterol concentration
  5. Associated with vitamin K deficiency
24
Q

Addison’s disease

A
  1. Hyponatremia
  2. Hypokalemia
  3. Reduced extracellular fluid volume
  4. Hyperpigmentation
  5. Impairs gluconeogenesis between meals
25
Q

In aging general decline is seen in

A
  1. Bone mineral density
  2. Muscle mass
  3. Body water content
  4. Total energy expenditure
  5. Appetite
26
Q

Apoptosis

A
  1. Energy dependent
  2. Strictly regulated
  3. Helps maintain cell number
  4. Occurs in wound healing
  5. Used in cancer chemotherapy
  6. Occurs during embryogenesis
  7. Involved in capes cascade
  8. Results from DNA damage
  9. No inflammation
  10. Cancer cells do not show apoptosis
27
Q

Causes of hypoglycemia

A
  1. Ethanol
  2. Renal impairment
  3. Reduced food intake
  4. Diabetic ketoacidosis
  5. Irregular meals
  6. Overdose of insulin
  7. Alcohol consumption
  8. Hyperthyroidism
28
Q

Ammonia

A
  1. Produced by enteric bacteria
  2. High level causes neurotoxicity
  3. Symptoms are due to impaired TCA cycle
  4. Transferred in the form of glutamine
29
Q

Obesity

A
  1. Defined as BMI>30kg/m2
  2. Is a considerable feature in Cushing syndrome
  3. Risk factor for gallstones
  4. Feature of metabolic syndrome
  5. Can be treated by lifestyle modifications
30
Q

Acetylcholine esterase

A
  1. Inhibited by organophosphate
  2. Acetylcholine is degraded to inactive metabolites
  3. Essential for termination of skeletal muscle contraction
  4. Present in synaptic cleft
  5. Not inhibited by atropine
31
Q

Hormones and their second messenger system

A
  1. cAMP = epinephrine, norepinephrine, glucagon LH, FSH, TSH, calcitonin, PTH, ADH
  2. Tyrosine kinase = insulin, GH, prolactin, IGF, oxytocin
32
Q

Synthesis of catecholamines depend on

A
  1. Conc. of catecholamines
  2. Alpha-methyl tyrosine
  3. Glucocorticoids
33
Q

Epinephrine

A
  1. Synthesised by using tyrosine as a precursor
  2. Decreases insulin secretion + Increases blood glucose levels
  3. G protein coupled receptor pathway
  4. Act as a vasodilator
  5. Increases glycogenolysis in liver
34
Q

Synthesis of cortisol depends on

A
  1. Circulatory LDL level
  2. Adrenocorticotropic hormone
  3. Cholesterol desmolase
  4. Infection
35
Q

Tumor suppressor genes

A
  1. P53
  2. BRCA gene
  3. Mismatch repair gene
  4. Retinoblastoma gene
36
Q

Markers of bone resorption

A
  1. Hydroxylysine glycosides
  2. Pyridinaline cross links
37
Q

Familial hypercholesterolemia

A
  1. Autosomal dominant
  2. Found in 1 in 500 of a population
  3. Characterized by accumulation of excessive LDL
  4. Does not affect plasma triglyceride level
  5. Associated with cutaneous xanthomas
38
Q

Factors affecting intra-uterine growth

A
  1. Chromosomal abnormalities of the fetus
  2. Insulin levels of the fetus
  3. Placental function
  4. Height of parents
39
Q

Theories of cellular aging

A
  1. Somatic cells can undergo cell division only a limited number of genes
  2. Telomerase enzyme leads to regrowth of telomeres
  3. Modifications of histone proteins occur with aging
  4. Mitochondrial DNA is damaged by free radicals
  5. Advanced glycosylated end products can affect the protein function
40
Q

Somatostatin

A
  1. Inhibits GH
  2. Secreted by D cells
  3. Secreted in response to high amount of AAs in blood
  4. Inhibits synthesis of insulin & glucagon
  5. Decreases acid secretion of stomach
41
Q

Hormones in hunger & satiety

A
  1. Hunger = ghrelin, motilin, orexin, agouti
  2. Satiety = leptin, CCK, insulin, glucose, FAs, AAs, amylin, GIP, GLP
42
Q

Proto-oncogenes

A
  1. Epidermal growth factor gene
  2. Chromatin remodeler gene
  3. Beta-catenine gene

Biochem Sem 3 (2 decks)

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