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Medical Sciences > Lecture 1-Exam 1 > Flashcards

Lecture 1-Exam 1 Flashcards

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USMLE® Step 1 flashcards
1
Q

How many genes are believed to inhabit the human genome in the early 2000s?

A

30,000 and 35,000

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2
Q

Recent studies T2T consortium (telomere to telomere) has identified what?

A

Even more genes 60k+ genes

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3
Q

What types of protein genes are there?

A

Protein coding vs non protein coding

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4
Q

How does genomics relate?

A
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5
Q

Why do we care about the genes?

A

Many of those genes are dysregulated in more than one disease, just as many disease are associated with the dysregulation of more than one gene

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6
Q

Examples of gene mutations

A
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7
Q

Phosphorylated sugars are what?

A

Chemical reactions and enzymes that convert glucose to pyruvate (glycolysis) to ethanol and CO2 (fermentation)

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8
Q

What was identified in the 1930s? What was also revealed?

A
  • 1930s identified the intermediates of the citric acid cycle and of urea biosynthesis
  • Revealed the essential roles of certain vitamin-derived cofactors or “coenzymes” - thiamine pyrophosphate, riboflavin, and ultimately coenzyme A, coenzyme Q, and cobamide coenzyme
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9
Q

1950s revealed what?

A

how complex carbohydrates are synthesized from, and broken down into simple sugars

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10
Q

The two major concerns for health care professionals? What subject impacts these

A
  1. Understanding and maintenance of health
  2. Effective treatment of disease
  • Biochemistry impacts both of these fundamental concerns
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11
Q

Interrelationship of biochemistry and medicine is what?

A

Wide, two-way street

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12
Q

What is metabolism? What does an average metabolic process involve?

A
  • All chemical processes that occur in an organism
  • An average metabolic process involves 20-100 molecules
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13
Q

What are some example of metabolism?

A
  • Glucose homeostasis- glycolytic enzymes, glucose transporters, glycogen synthetases, disaccharidases, gluconeogenic enzymes, etc.
  • DNA replication, RNA splicing, etc
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14
Q

How do you have a spectrum of error severity for each step in metabolism?

A
  • Gene deletions
  • Frameshifts
  • Sequence mutations
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15
Q

What are inborn errors of metabolism?

A

inherited or congenital disorders that are due to a defective enzyme causing a disruption in a specific metabolic pathway, the way that DNA or the genes communicate

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16
Q

What is central dogma of biology?

A
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17
Q

What do defective enzymes come from?

A

DNA mutations due to the central dogma of biology: DNA-> RNA-> protein

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18
Q

Sickle cell anemia:
* What type of inheritance?
* Heterozygous individuals exhibit what?
* What is the single nulcetide mutation?
* Mutated gene is what? where?

A
  • Autosomal recessive Homozygous for the disease gene
  • Heterozygous individuals exhibit the usually asymptomatic condition of sickle cell trait
  • Single nucleotide mutation: glutamic acid codon (GAG) to a valine codon (GTG)
  • Mutated gene hemoglobin beta (HBB), located on chromosome 11
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19
Q

What does the mutated gene hemoglobin beta on chromosoeme 11 cause?

A

Causes the body to produce a new form of hemoglobin called HbS, which behaves very differently to regular hemoglobin (HbA).

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20
Q

What is familial hypercholesterolemia?

A

specifically very high levels of low-density lipoprotein (LDL, “bad cholesterol”)

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21
Q

Familial hypercholesterolemia:
* How many people have this condition?
* Heterozygotes?
* Homozygotes?

A
  • 1 in 100 to 200 people have mutations in the LDLR gene that encodes the LDL receptor protein - removes LDL from the circulation, recognizes apolipoprotein B (ApoB) (which may also have mutations)
  • Heterozygotes for LDLR gene may develop cardiovascular disease prematurely at the age of 30 to 40.
  • Homozygotes may cause severe cardiovascular disease in childhood – may have heart attack or death by 30
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22
Q

How is familial hypercholesterolemia diagnosed with?

A
  • Diagnosed with blood tests, genetic testing and presence of xanthomas (waxy build up) – treatment is statins but may require surgical intervention in more severe cases
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23
Q

What is cancer and what are components

A
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24
Q

What monitors integrity of DNA? ⭐️

A

p53 protein

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25
Q

What is the purpose of p53 protein?

A
  • If DNA damaged, cell division halted and repair enzymes
    stimulated
  • If DNA damage is irreparable, p53 directs cell to kill itself
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26
Q

What must happen to a tumor suppressor gene for cancerous phenotype to develop?

A

Both copies of a tumor-suppressor gene must lose function for the cancerous phenotype to develop

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27
Q
  • p53 is absent or damage?
  • What was the first tumor suppressor identified?
A

present in many canerous cells

First tumor-suppressor identified was the retinoblastoma susceptibility gene (Rb)
* Predisposes individuals for a rare form of cancer that affects the retina of the eye

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28
Q

What are proto-oncogenes?

A

Normal cellular genes that become oncogenes when mutated
* Oncogenes can cause cancer

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29
Q

What do some proto-oncogenes encode for? What happens if receptor is mutated ?

A
  • Some encode receptors for growth factors
  • If receptor is mutated in “on,” cell no longer depends on growth factors
  • Some encode signal transduction proteins
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30
Q

Do you need one or multiple copies of proto-oncogene to have uncontrolled divison?

A

Only one copy of a proto-oncogene needs to undergo this mutation for uncontrolled division to take place

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31
Q

Many diseases are manifestations of abnormalities in what?

A

genes, proteins, chemical reactions, or biochemical processes

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32
Q

Examples of Biochemical processes involved in disease are what?

A

electrolyte imbalance, defective nutrient ingestion or
absorption, hormonal imbalances, toxic chemicals or biologic agents, and DNA-based genetic disorders

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33
Q

What is anabolism and catabolism?

A
  • Anabolism - building substances (molecules)
  • Catabolism – breaking substances (molecules)
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34
Q

What do enzymes serve as?

A

Enzymes serve as catalysts to speed up these reactions
* Conversion of metabolites

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35
Q

Anabolic reaction do what with energy? What is that considered? What do they do in this reaction?

A

Anabolic reactions use up energy. They are endergonic. In an anabolic reaction small molecules join to make larger ones.

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36
Q

What are examples of anabolic reactions?

A
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37
Q

Catabolic reaction do what with energy? What is that considered? What do they do in this reaction?

A

Catabolic reactions release energy = exergonic. Large molecules are broken down into smaller ones.

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38
Q

What are example of catabolic reactions?

A
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39
Q

What is the predominant chemical component of living organisms

A

water

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40
Q

Your body consists of 80% of what? What are the Physical properties?n

A
  • Water
  • excellent solvent of organic and inorganic molecules
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41
Q

What is water considered? Due to water’s dipolat structure and exceptional capacity for forming hydrogen bonds?

A

Water is electrically neutral, but the asymmetry of the
molecule (hydrogen with two electropositive H+ and oxygen with an electronegative) makes it a polar molecule (like a small magnet)
* Due to water’s dipolar structure and exceptional capacity for forming hydrogen bonds.

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42
Q

What polar molecules can do what?

A

dissolve in water (hydrophilic) and
form aqueous solutions

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43
Q

non polar molecules fail to do what? What is an example?

A
  • Non polar molecules fail to dissolve in water (hydrophobic)
  • Example: kerosene (hydrocarbon) does not form hydrogen bonds and can only dissolve when mixed with other hydrophobic molecules such as lipids
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44
Q

Medical example of hyprophilic and hypropobic

A

Waste products from the digestion of nonpolar (fatty) food
tends to be excreted via bile (oily), where polar (hydrophilic) waste is excreted in urine

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45
Q

What is an acid? When is it stronger?

A

– Any substance that dissociates in water to increase the [H+] (and lower the pH)
– The stronger an acid is, the more hydrogen ions it produces and the lowers its pH

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46
Q

Base is what?

A

Substance that combines with H+ dissolved in water, and thus lowers the [H+]

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47
Q

Water dissociates into what?

A

dissociates into hydroxide ions, extra proton (-) and hydrogen ions, proton donor (+)

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48
Q

Concentration of hydroxine ions (protons) in a solution (acidity) generally reported using what?

A

Logarithmic pH scale

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49
Q

Bicarbonate and other buffers normally maintain the pH of extracellular fluid between what ? (human body)

A

7.35-7.45

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50
Q

Suspected disturbances of acid-base balance are verified by what?

A

measuring the pH of arterial blood and the CO2 content of venous blood

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51
Q

Causes of acidosis includes what? What about alkalosis?

A
  • Acidosis (blood pH <7.35) include diabetic ketosis and lactic acidosis. Alkalosis (pH >7.45) may follow vomiting of acidic gastric contents
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52
Q

What does the carbonic anhydrases (enzyme) do?

A
  • catalyze the bidirectional conversion of carbon dioxide (CO2) and
    water (H2O) into bicarbonate (HCO3-) and protons (H+)
  • impact numerous physiological processes that occur within and across the many compartments in the body.
  • promote rapid H+ buffering and thus the stability of pH-sensitive
    processes.
  • promote movements of H+, CO2, HCO3-, whose traffic is central to respiration, digestion, and whole-body/cellular pH regulation
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53
Q

What is buffering? Many metabolic rxn are accompanied by what?

A
  • Buffering = resist a change in pH following addition of strong acid or base
  • Many metabolic reactions are accompanied by the release or uptake of protons
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54
Q

What does oxidative metabolism produce what? What would this produce?

A

CO2, the anhydride of carbonic acid, which if not buffered would produce severe acidosis

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55
Q

Biologic maintenance of a constant pH involves what?

A

involves buffering by phosphate, bicarbonate, and proteins, which accept or release protons to resist a change in pH.

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56
Q

What are the normal ranges for arterial blood gas?

A
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57
Q

What parts of our body works to keep your acid-base balance normal?

A

your lungs and your kidneys

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58
Q

What is O2 saturation? Partial pressure of oxygen (PaO2)?

A
  • Oxygen saturation (O2Sat). This measures how much oxygen your red blood cells are carrying
  • Partial pressure of oxygen (PaO2). This measures the pressure of oxygen that’s dissolved in your blood. It helps show how well oxygen moves from your lungs to your bloodstream.
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59
Q

What does partial pressure of carbon dioxide (PaCO2) measure? Acid-base balance (pH level)?

A
  • Partial pressure of carbon dioxide (PaCO2). This measures the amount of carbon dioxide in your blood. It also shows how easily carbon dioxide can move out of your body.
  • Acid-base balance (pH level). This measures the acidity of your blood. Too much acid is called acidosis. Too much base (alkaline) is called alkalosis. These conditions are symptoms of other problems that upset the acid-base balance in your body.
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60
Q

What are the results of ABG’s?

A

Results: metabolic alkalosis or acidosis, respiratory alkalosis or acidosis. Compensated vs uncompensated

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61
Q

What is metabolic acidosis and alkalosis?

A
  • Metabolic acidosis – pH<7.35, respiratory CO2 normal, bicarb low (<24mEq/L), split into anion and non anion gap
  • Metabolic alkalosis – pH >7.45, respiratory CO2 normal, bicarb level high
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62
Q

What is respiratory acidosis? When does this happen and how?

A

pH <7.35, CO2 elevated >45, elevated HCO3 (bicarb)
* Respiratory acidosis is a state in which there is usually a failure of ventilation and an accumulation of carbon dioxide. The primary disturbance of elevated arterial PCO2 is the decreased ratio of arterial bicarbonate to arterial PCO2, which leads to a lowering of the pH. In the presence of alveolar hypoventilation, 2 features commonly are seen are respiratory acidosis and hypercapnia. To compensate for the disturbance in the balance between carbon dioxide and bicarbonate (HCO3-), the kidneys begin to excrete more acid in the forms of hydrogen and ammonium and reabsorb more base in the form of bicarbonate

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63
Q

What is respiratory alkalosis? What are examples?

A

Respiratory alkalosis – pH >7.45, respiratory CO2 <35
* Example: hyperventilation (blowing off CO2) due to fever, pain, or anxiety

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64
Q
A
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65
Q

What are the steps for evaluating an ABG?

A

Step 1: pH, determine if the acid-base status is acidemia or alkalemia
* Blood pH is maintained within a narrow range for optimization of physiological functions. Acid-base equilibrium is achieved within a pH range of 7.35 to 7.45. Blood pH distinguishes between acidemia (pH less than 7.35) and alkalemia (pH greater than 7.45)

Step 2: CO2, determine if the disturbance is metabolic or respiratory
* The pCO2 determines whether an acidosis is respiratory or metabolic in origin. For a respiratory acidosis, the pCO2 is greater than 40 to 45 due to decreased ventilation. Metabolic acidosis is due to alterations in bicarbonate, so the pCO2 is less than 40 since it is not the cause of the primary acid- base disturbance. In metabolic acidosis, the distinguishing lab value is a decreased bicarbonate

Step 3: Determine if there is anion gap or non-anion gap metabolic acidosis
Step 4: CO2, assess if respiratory compensation is appropriate
Step 5: Evaluate for additional metabolic disturbances

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66
Q

Human diets must include waht?

A

9 essential amino acids that cannot be synthesized

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67
Q

Amino acids:

  • Kidney filter over how much a.a.?
  • What is found in urine?
  • A.a are almost totally what?
A
  • Kidneys filter over 50 g of free amino acids from the arterial renal blood
  • Only traces of free amino acids found in urine
  • Amino acids are almost totally reabsorbed in the proximal tubule, conserving them for protein synthesis and other vital functions
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68
Q

What are amino acids molecules shaped like and what do they exhibit?

A
  • Amino acids are asymmetric molecules that exhibit chirality or handedness
  • Determines the lock and key substrate specificity of their 3D structure
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69
Q

Virtually all natural proteins are what?

A

Left handed, s-enantiomers

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70
Q

Drugs such as propranolol, ibuprofen, warfarin, verapamil, terbutaline contain mixtures of what?

A

left and right
* These racemic mixtures are implicated in the pathogenesis of therapeutic side effects

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71
Q

What are the essential acids?

A
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72
Q

Amino acid enantiomer

What is thalidomide?

A
  • contains teratogenic S-enantiomer in addition to the therapeutic
    (anti-morning sickness) R-enantiomer
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73
Q

Amino acid enantiomet?

What is warfarin?

A
  • The S-enantiomer is five times more potent than the R-enantiomer
74
Q

Amino acid anantiomer

What is Ibuprofen?

A
  • S-enantiomer three times more potent than the other
75
Q
  • Proteins adopt their final 3D configuration within what?
  • What are serveral events occurring parallel?
A
  • 300ms of translational termination
  • Several events occurring parallel: hydrophobic collapse, compaction into a molten globule, acquisition of hydrogen-bonded secondary structure
76
Q

Protein folding can start on what?

A

polypeptide chain and continue after translation, time can vary
* Ex: immunoglobins (immune system) can take up to 10 minutes to fold correctly
* Will aggregate if folded too quickly

77
Q

Extended polypeptide chains cross the ER membranes more readily than what?

A

than folded proteins – so transport can be made more efficient by delaying folding

78
Q

Protein binding polypeptides called molecular chaperones do what?

A

stabilize unfolded protein intermediates
* Prevents aggregation and facilitates trafficking of newly formed proteins

79
Q

What are the different shapes of amino acids?

A
80
Q

Proteins yell directions at?

A

DNA -> DNA reads its genetic script back to protein

81
Q
  • Human genes go through what?
  • Proteins originate from what?
A
  • Human genes are transcribed and translated to form proteins
  • Proteins originate from a ribosome which got its instruction
    from tRNA->mRNA and DNA
    * They are basically configurations of amino acids
    * An average protein contains about 400 amino acids
82
Q

How are proteins classified?

A

Classified by size
* Fewer than 50 amino acids = peptide
* More than 50 amino acids = polypeptide

83
Q

Proteins can be what?

A

structural molecules or functional molecules

84
Q

What are structural molecules? What does it lack?

A
  • ex:collagen, keratin
  • Lack catalytic activity, but can still signal
  • Example: collagen acts as an extracellular activating ligand for cell surface adhesion molecules
85
Q

What are Functional molescules

A
  • Enzymes (proteases, glycosylases)
  • Signaling molecules (transcription factors and receptors)
  • Transport/storage molecules (transferrin, ferritin, hemoglobin)
  • Antibodies (IgG,IgM)
86
Q

Hydrophobic amino acids are what?

A
  • Valine, leucine, isoleucine, tryptophan, phenylalanine
87
Q

Hydrophilic (water-soluble) amino acids are what?

A

Glutamate & aspartate (Acidic) lysine & arginine (basic)

88
Q

What is the hydrophobic effect?

A

The influence of hydrophilic and hydrophobic interactions on structure of proteins

89
Q

Hydrophobic residues embed themselves where? Mutations can what?

A

in the interior of large proteins
– mutations that eliminate the hydrophobicity of key amino acids may create destabilizing cavities within the protein

90
Q

Hydrophilic residues stud themselves where? What do they do?

A

Hydrophilic residues stud themselves around the exterior of the protein where they provide interaction sites for proteins involved in cell signaling

91
Q

What is a missense mutation?

A

Replacement of a hydrophobic by a hydrophilic amino acid or vice versa

92
Q

Examples of major amino acid alterations

A
  • A valine for glutamine (GUG-GAG) substitution in the 6th amino acid of beta globulin underlies sickle cell anemia
    * The mutation causes a pathologic hydrophobic area on the surface of the hemoglobin molecule, favoring it to collapse (sickling)
  • Deletion of hydrophobic phenylalanine residue at position 508 of the cystic fibrosis transmembrane conductance regulator is responsible for 70% of CF cases
93
Q

What are nonsense mutations?

A

stop codons that result in chain termination – severity depends on the extent of protein truncation

94
Q
  • What are catalytic subunits?
  • The active site binds where? Energy?
A

Enzymes contain chemically reactive sites termed catalytic subunits
* The active site binds to a substrate and catalyzes its transformation in an energy dependent reaction

95
Q

Many drugs act by targeting (usually inhibiting) cellular enzymes, list the examples (4)

A
  • ASA- inhibits cyclooxygenase
  • ACEI- inhibits angiotensin-converting enzyme
  • Pravastatin- inhibits hydroxymethylglutaryl (HMG) CoA reductase * Omeprazole – inhibits gastric H+/K+ ATPase pump
96
Q

Careful control of the activities of these enzymes is required to do what?

A

ensure that they act only at appropriate times - Many diseases may be tied to defective enzymes

97
Q

What is allosteric regulation?

A
98
Q
  • The site to which the effector binds is termed the allosteric site or _ _
  • allosteric sites allows what?
  • Effectors that enhance the protein’s activity are referred to as _ _, whereas those that decrease the protein’s activity are called _ _
A
  • Regulatory site
  • Allow effectors to bind to the protein, often resulting in a conformational change and/or a change in protein dynamics
  • Effectors that enhance the protein’s activity are referred to as allosteric activators, whereas those that decrease the protein’s activity are called allosteric inhibitors
99
Q

Explain a catabolic enzyme reaction

A

.

100
Q

Explain a anabolic enzyme reaction

A
101
Q

Explain how a feedback loops for enzymes?

A
102
Q
  • Best enzyme for regulatory intervention is what?
  • Decreasing the efficiency or the amount of this enzyme is called what? What will it do?
A
  • Best enzyme for regulatory intervention is one whose reaction is slow relative to all others in the pathway.
  • Decreasing the efficiency or the amount of this enzyme (“bottleneck” or rate- limiting reaction) will immediately reduce metabolite flux through the entire pathway
103
Q

What is an example of rate limiting reactions?

A
  • Example: “statin” drugs used for lowering cholesterol work by inhibiting HMG-CoA reductase, catalyst of the rate-limiting reaction of cholesterogenesis
104
Q

What is a zymogen?

A

enzyme that acts as a proteases that is activated by the complement cascade (an initial signal is serially amplified).

105
Q

What do zymogens include?

A
  • Coagulation factors- fibrinogen, prothrombin, protein C, plasminogen
  • Digestive enzymes- trypsinogen, pepsinogen
  • Blood pressure regulators- prorenin, angiotensin converting enzyme
106
Q

What is the advanage of zymogens?

A
  • enzymes remain inactive until the appropriate tissues destination is reached-> Pepsinogen activates itself – intragastric acidity (pH <3) partly denatures the peptide exposing the enzymes active site leading to its cleavage, which activates the enzyme
  • Zymogen activation also offers clinical opportunity for detection assays->During initial phases of trypsin activation in acute pancreatitis, the release from trypsinogen of its cleavage product trypsinogen activation peptide (TAP) provides a sensitive diagnostic predictor
107
Q

ZYMOGEN BP REGULATORS: RENIN-ANGIOTENSIN SYSTEM

A
108
Q

How can enzymes aid in diagnosis?

A
  • Several enzymes are released into plasma following cell death or injury and can be used as biomarkers
  • plasma concentration of an enzyme or other protein released consequent to injury may rise early or late, and may decline rapidly or slowly
109
Q

What are the first enzymes used to dianose MI?

A

aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH)

110
Q

Creatine kinase (CK) has three tissue-specific isozymes, what are they?

A

CK-MM (skeletal muscle), CK-BB (brain), and CK-MB (heart and skeletal muscle)

111
Q

Plasma Troponin Constitutes what?

A

the Currently Preferred Diagnostic Marker for an MI
* Troponin levels rise for 2 to 6 hours after an MI, and remain elevated for 4 to 10 days

112
Q

Monosaccharides are what?

A

are those sugars that cannot be hydrolyzed into simpler carbohydrates

113
Q

What are polyhydric alcohols?

A

Polyhydric alcohols (sugar alcohols or polyols), in which the aldehyde or ketone group has been reduced to an alcohol group, also occur naturally in foods. They are synthesized by reduction of monosaccharides for use in the manufacture of foods for weight reduction and for diabetics. They are poorly absorbed, and have about half the energy yield of sugars

114
Q

Polyhydric alcohols examples?

A

Examples: Xylitol and sorbitol
* Xylitol is generally well tolerated, but some people experience digestive side effects when they consume too much. The sugar alcohols can pull water into your intestine or get fermented by gut bacteria. This can lead to gas, bloating and diarrhea

115
Q

What are disaccharides?

A

are condensation products of two monosaccharide units, for example, lactose, maltose, isomaltose, sucrose, and trehalose.

116
Q

What are oligosaccharides? How are they beneficial?

A

Oligosaccharides are condensation products of 3 to 10 monosaccharides – indigestible (humans lack enzymes to break them down in the small intestine)
* They reach the large intestine, where beneficial colonic bacteria break them down (ferment) to absorbable nutrients, which provide some energy–about 2 Calories (kilocalories) per gram in average

117
Q

What is an example of oligosaccharides?

A

Raffinose can be hydrolyzed to D-galactose and sucrose by the enzyme α-GAL, an enzyme which in the lumen of the human digestive tract is only produced by bacteria in the large intestine

118
Q

Most oligosaccharides act as a soluble fiber, which may help what?

A

prevent constipation

119
Q

What is a Polysaccharide

A

> 10 sugars, starch molecules (rice, wheat, potatoes), such as glycogen

120
Q

What is an example of polysaccharide?

A

Glycogen

121
Q

Glycogen:
* Where is present?
* Muscle glycogen is what?
* In an average human being, what is present?

A
  • Glycogen is present in almost all the cells of the human body, however, its major stores are skeletal muscles (3/4 total body glycogen is in the muscle and liver)
  • Muscle glycogen is a readily available source for glycolysis (using the glycolysis pathway to create ATP). Liver glycogen uses glucose-6- phosphatase to release free glucose into the bloodstream to maintain blood glucose concentration in fasting state
  • In an average human being, 400 grams of glycogen are present in the skeletal muscles while the liver contains only 100 grams of glycogen in the well-fed state- makes around 10% of the total weight of the liver
122
Q

Polysaccharides combine and do what?

A

combine readily with nucleic acids, proteins, and fats to form the sugar-phosphate backbone of DNA, proteoglycans, and glycolipids

123
Q
A
124
Q

Sodium-glucose co-transporter- responsible for what? How?

A

Sodium-glucose co-transporter- responsible for transporting glucose and galactose (monosaccharides hydrolyzed from dietary polysaccharides) by ATP dependent active transport against a concentration gradient

125
Q

What is the downside and plus side of sodium glucose co-transporter?

A
  • Downside: missense mutations affecting the co-transporter may cause autosomal recessive glucose-galactose malabsorption
  • Plus side: oral rehydration therapy for diarrhea uses glucose solutions to activate the sodium-glucose co-transporter (SGLT1) thereby enhancing NA+/H2O absorption
126
Q

Glucose absorbed into the blood uses what?

A

use sfacilitated transport to get glucose into the extracellular space and across the cell membrane into the cytoplasm

127
Q

Uses glucose transporters (GLUTs) to enter the cytoplasm, explain the different GLUTs and thier locations

A
128
Q

What is glycogenesis and glycogenolysis?

A
129
Q

What is gluconeogensis and glycolysis?

A
130
Q

What is glycogenesis?

A

Glycogenesis is the process of forming
glycogen molecules from glucose in order to store it

131
Q

What is glyconeolysis? When does it occur? what is the main enzyme used? May be especially important in what?

A
132
Q

What is Gluconeogenesis

A

is the process of synthesizing glucose from non-carbohydrate precursors such as lactate, amino acids, and glycerol.

133
Q

Gluconeogeneis:
* Where does it occur mainly
* Cellular sites include what?
* What cannot participate in this and why?
* Begins when?

A

.

134
Q

?

What is glycolysis? What is released

A
135
Q
  • What is glucagon? Where is it made?
  • Glucagon signals via what?
  • Simulates what?
A
136
Q
  • Glucagon levels increase how much in response to what?
  • Where does production begin?
A

Glucagon levels increase two to three fold in response to hypoglycemia ,and the liver begins production of glucose from glycogen.

137
Q

What is the main mediator of glycogen breakdown in skeletal muscle?

A

Epinephrine

138
Q

During times of high blood glucose, glucagon is reduced to half of its normal level. Glucagon also stimulates what?

A

stimulates the release of insulin, thereby allowing insulin-sensitive cells to take up the released glucose. Glucagon secretion is also inhibited by insulin, amylin, and somatostatin

139
Q
  • Where is insulin produced? Where?
  • B-islet cells are what?
  • Increased blood glucose does what?
A
  • Insulin is produced by the β cells of the islets of Langerhans in the pancreas in response to hyperglycemia
  • β-islet cells are freely permeable to glucose via the GLUT 2 transporter, and the glucose is phosphorylated by glucokinase
  • Increased blood glucose increases glycolysis, the citric acid cycle, and the generation of ATP
140
Q

The increase in [ATP] inhibits what?

A

inhibits ATP-sensitive K+ channels, causing depolarization of the cell membrane, which increases Ca2+ influx via voltage-sensitive Ca2+ channels, stimulating exocytosis of insulin

141
Q

What is needed for muscle contraction?

A

Rapid increase in the rate of glycolysis
* At rest the rate of phosphofructokinase activity is some 10- fold higher than that of fructose 1,6-bisphosphatase

142
Q

What happen when in anticipation of muscle contraction?

A

In anticipation of muscle contraction, the activity of both enzymes increases, fructose 1,6-bisphosphatase 10 times more than phosphofructokinase, maintaining the same net rate of glycolysis

143
Q

At the start of muscle contraction, the activity does what?

A

the activity of phosphofructokinase increases and that of fructose 1,6- bisphosphatase falls, so increasing the net rate of glycolysis (and hence ATP formation) as much as a 1000-fold

144
Q

The concentration of blood glucose is maintained between what?
What happens after ingestion of carb meal? Starvation?

A
  • 4.5 and 5.5 mmol/L
  • It may rise to 6.5 to 7.2 mmol/L, and in starvation, it may fall to 3.3 to 3.9 mmol/L.
145
Q
  • A sudden decrease in blood glucose (eg, in response to insulin overdose) causes what?
  • much lower concentrations can be what?
A
  • A sudden decrease in blood glucose (eg, in response to insulin overdose) causes convulsions, because of the dependence of the brain on a supply of glucose.
  • However, much lower concentrations can be tolerated if hypoglycemia develops slowly enough for adaptation to occu
146
Q
  • Glucose can also be formed from two groups of compounds that undergo gluconeogenesis:
  • What are these processes known as?
A
147
Q

Ingesting carbohydrates causes what?

A

transient hyperglycemia

148
Q

What is secreted when glucose is present? What is it inhibited by?

A

Insulin is secreted when glucose is present. It is inhibited by
norepinephrine and glucagon (insulin antagonist)

149
Q

Liver responds to glucose by what?

A

removing plasma glucose for glycogenesis (glycogen formation) and or glycolysis (pyruvate generation)

150
Q

Carb absorption happens when?

A

Carb absorption happens for 1-6 hours after eating, then plasma insulin levels fall while glucagon levels rise

151
Q

Insulin is an anabolic stimulus, explain

A
  • When insulin and glucagon are co-expressed there is inhibition of gluconeogenic pathway
  • Lack of insulin leads to DM, carbohydrates fail to be directed to anabolic pathway and organ damage ensues due to default deposition of glycation products
152
Q

What is epinephrine and what is glucagon?

A
153
Q

Diabetes mellitu:
* How many people have it?
* Hallmark of disease?
* Directly and indirectly responsible for most what?
* In the absence of effective insulin signaling, glucose intolerance or frank hyperglycemia causes what?

A
154
Q

What is the different between type one and two?

A
155
Q

Essential fatty acids, fat-soluble vitamins are where?

A

are contained in the fat of natural foods

156
Q

Dietary supplementation withl ong-chain ω3 fatty acids is believed to have what?

A

beneficial effects: (chronic diseases) cardiovascular disease, rheumatoid arthritis, and dementia

157
Q
  • Where is fat stored and what is its purpose?
  • Lipid biochem is necessary for what?
A
158
Q

What are lipids?

A

Loosely defined group of molecules with one main chemical characteristic – they are insoluble in water, hydrophobic

159
Q

What are the types of lipids and facts about them?

A
160
Q

Lipid steroids are important for what?

A
  • bile acids, adrenocortical hormones, sex hormones, vitamin D and cardiac glycosides
  • Because of Asymmetry in the Steroid Molecule, Many Stereoisomers Are Possible
  • Cholesterol Is a Significant Constituent of Many Tissues
161
Q

_ _ provides large energy store for mobilization during fasting or exercise (but is slower process)

A

Adipose tissue

162
Q

What are varieties of fats?

A
  • Fatty acids (Mainly obtained from the diet)
  • Sphingolipids
  • Isoprenoids
  • Triacylglycerols (triglycerol)- Triacylglycerol is the major form of dietary lipid in fats and oils, whether derived from plants or animals
163
Q

Fatty acids are classified as what?

A

as either saturated (full of single bonds, carbon to carbon) or unsaturated (containing double or triple bonds )

164
Q

What is the difference between unsaturated and saturated fatty acids?

A
165
Q

What is hydrogenation? What is trans fat?

A
166
Q
A
167
Q
  • Examples of food products with “partially hydrogenated oils are what?
  • What do these food cause?
A
  • Commercial baked goods, such as cakes, cookies and pies, Shortening and margarine, Microwave popcorn, Frozen pizza, Refrigerated dough, such as biscuits and rolls, Fried foods, including french fries, doughnuts and fried chicken
  • Elevates LDL (low density lipoprotein) “bad cholesterol” and lowers HDL (high density lipoprotein) “good cholesterol”
168
Q

What is liplysis?

A
169
Q

The most important regulatory hormone in lipolysis is what?

A

insulin

170
Q

Fats (dietary) and lipids (synthesized by the liver and adipose tissue) need to be transported for use and storage. What is the problem? How do we fix this problem?

A
  • Problem - lipids are insoluble in water – how do we transport them in aqueous blood plasma
  • They get structured into micelles that transport the fatty acids and monoglycerides to the enterocytes in the intestines. They cross the membrane and form into triglycerides and then combine into a lipoprotein, specifically a chylomicron
171
Q

Lipoproteins (have a hydrophobic core) transport lipids how?

A

transport lipids from the intestines as chylomicrons—and from the liver as very-low-density lipoproteins (VLDL)—to most tissues for oxidation and to adipose tissues for storage. They transport triglycerides, cholesterol, and Vit A, D, E, and K

172
Q

What is the micelles?

A

Micelles–lipid molecule orient with polar (hydrophilic) head toward water and nonpolar (hydrophobic) tails away from water

173
Q

Four Major Lipid Classes Are Present in Lipoproteins?

A
    1. triacylglycerols (16%)
    1. phospholipids (30%)
    1. cholesterol (14%)
    1. cholesteryl esters (36%)
  • A much smaller fraction of unesterified long-chain fatty acids (or FFAs) (4%) which is metabolically the most active of the plasma lipids
174
Q

What are chylomicron?

A

chylomicrons, derived from intestinal absorption of triacylglycerol and other lipids

175
Q

What are VLDL?

A
  • VLDL, derived from the liver for the export of triacylglycerol
176
Q

What are LDL and HDL?

A
    1. low-density lipoproteins (LDL) - LDL has been associated with the progression of atherosclerosis and blockage of the artery lumen, because it can carry cholesterol into smaller vessels. But LDL is also essential for carrying lipids that keep the human body alive, including in those small vessels.
    1. high-density lipoproteins (HDL), involved in cholesterol transport-> absorbs cholesterol in the blood and carries it back to the liver. The liver then flushes it from the body. High levels of HDL cholesterol can lower your risk for heart disease and stroke.
177
Q

Triacylglycerol is what?

A

the predominant lipid in chylomicrons and VLDL, where as cholesterol and phospholipid are the predominant lipids in LDL and HDL

177
Q

Lipids mainly as triacylglycerol— can accumulate in what? What can it cause?

A
  • liver
  • Extensive accumulation causes fatty liver
178
Q

What is Nonalcoholic fatty liver disease (NAFLD)

A
  • Nonalcoholic fatty liver disease (NAFLD) is the most common liver disorder worldwide
  • Accumulation of lipid in the liver becomes chronic, inflammatory and fibrotic changes may develop
  • May lead to cirrhosis, hepatocarcinoma, and liver failure
179
Q
  • Two main etiologies of NAFLD?
A
180
Q

What is alcoholic fatty liver?

A

Medical Sciences (11 decks)

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