Biochem Block 2 Week 2

Front 1

What does it mean that Hb is cooperative?

Back 1

-Meaning that binding of each O2 molecule to the tetramer increases the affinity with which the next O2 can bind.
-Likewise, with each removal, the affinity decreases. This is important deep in tissues where Hb has the ability to release O2.

Front 2

1. How does lower pH affect Hb O2 affinity?
2. CO2?
3. 2,3-Diphosphoglycerate (DPG)?

Back 2

1. low pH decreases Hb affinity for O2
2. CO2 decreases affinity for O2 (makes sense, in tissues where CO2 is high, you want O2 coming off Hb)
3. DPG allows Hb to adapt to hypoxia by releasing O2 more easily.

Front 3

Describe the mutation that causes sickle cell disease. What does this do phenotypically?

Back 3

A mutation in the B-globin gene causing a change from Glu to Val at position 6 on Chromosome 11. Presence of Val at position 6 allows deoxyHbS to polymerize into microfibrils that distort RBC shape and cause both hemolysis and vaso-occulsive disease.

Front 4

What chromosome is Alpha-globin and Beta-globin on?

Back 4

1. Alpha-globin: Chromosome 16
2. B-Globin: Chromosome 11

Front 5

Describe embryonic a-globin's expression through the life cycle. What is the Greek letter assigned to this?

Back 5

It occurs only briefly during development (0-6 wks) and then adult form dominates through fetal growth and into adulthood. Greek = Zeta

Front 6

How many alpha-globin genes do most people have? How many are active?

Back 6

Four - two on each chromosome 16. They're all active each contributing about 1/4 of the total alpha expression.

Front 7

Describe embryonic B-globin's expression through the life cycle. What is the Greek letter assigned to this?

Back 7

Similar to Zeta - it drops off quickly between 0-6 weeks as it is replaced by gamma--globin which doesn't disappear until after birth. Greek = Epsilon

Front 8

How many forms of adult Hb are there? What are they and describe relative percentages.

Back 8

HbA (alpha2beta2) and HbA2 (alpha2gamma2). HbA2 accounts for only a few percent of adult Hb

Front 9

Of the alpha and beta globins, which is more likely to cause clinical problems?

Back 9

Beta globins because each chromosome 11 has only one functional B-globin gene.

Front 10

RBCs contain an enzyme to help get rid of CO2 - what is it and what does it do?

Back 10

Carbonic Anhydrase. Hydrates CO2 to carbonic acid (H2CO3). This spontaneously dissociates to bicarbonate HCO3- and H+ - both of which are highly soluble in plasma.

Front 11

Iron exists in hemoglobin as two forms - which can/cannot bind O2?

Back 11

Ferrous form (Fe2+) can bind O2 and Ferric (Fe3+) cannot. Ferric iron is found in an inactive form of hemoglobin called "methemoglobin"

Front 12

What is P50?

Back 12

It is the partial pressure of oxygen yielding 50% saturation of binding

Front 13

In regard to the partial pressure curves of Hb and Mb, describe their overall shape. Which one gives up O2 less easily?

Back 13

Hb is sigmoidal and Mb is hyperoblic. Myoglobin gives up O2 much less easily.

Front 14

Hb has a P50 at around a pO2 of 25mmHg. Why is that good?

Back 14

25mmHg is roughly the pO2 of resting/working tissues. At this point, Hb readily gives up its oxygen.

Front 15

Discuss how the affinity for Hb changes depending on the subunit composition and what this means for fetal Hb

Back 15

Fetal Hb (alpha2-gamma2) has a higher affinity for O2 than adult Hb - that means the fetus' circulation can draw O2 from maternal blood at the low pO2 of the placenta.

Front 16

Hemoglobin exhibits sequential co-operativity for oxygen binding. Define.

Back 16

Binding of oxygen to one subunit induces a conformational change that is partially transmitted to adjacent subunits. The transmission of the partial conformational change induces an increased affinity for oxygen by these adjacent subunits.

Front 17

Describe the Taut of Hb

Back 17

Taut Hb the DEOXY form and has constrained movement of its polypeptide chains that inhibits O2 from entering and binding complex. It thus has a low affinity for O2 and more likely to give it up than the Relaxed form.

Front 18

Describe the Relaxed form of Hb.

Back 18

Relaxed Hb is the result of oxygen binding that causes rupture of some of the iconic and hydrogen bonds giving Hb more freedom of movement. This form has a high affinity for O2 and less likely to give it up than Taut.

Front 19

Discuss the equilibrium between T and R states.

Back 19

With no O2 bound, the T state is favored. Once O2 starts binding, the equilibrium begins to shift toward favoring R. When 2 O2 are bound, T and R are in equilibrium. Once 3 and 4 O2 are bound, R state is heavily favored.

Front 20

In essence, what does cooperative binding accomplish?

Back 20

It increases Hb binding of O2 in O2-rich areas (i.e. lungs) while increasing the release of O2 in deoxy areas where it is needed most (i.e. deep tissues).

Front 21

How does O2 binding change the conformation of the Hb subunit?

Back 21

Without O2 bound, heme Fe2+ is pulled away from the plane of porphyrin ring. When O2 is bound, it pulls Fe2+ back into the plane of the ring, causing other Hb subunits to shift relative to one another into an arrangement that favors the R-conformation.

Front 22

Define allosteric regulator or effector. What are allosteric regulators for Hb? How do they affect affinity for O2?

Back 22

A molecule that can bind to a protein and induce a conformational change that alters the affinity for substrate at some other site. Hb allosteric regulators are CO2, DPG, and H+. They all bind to Hb and reduce its affinity for O2.

Front 23

Including DPG, H+, and CO2, summarize the allosteric regulation in hemoglobin.

Back 23

DPG--HHb--CO2 +O2 <---> HbO2 + CO2 + DPG + H+

Front 24

Describe how the equilibrium of the allosteric regulation of Hb shifts according to where it's at in the body.

Back 24

In lungs where O2 is abundant, equil is shifted to the right where HCO3+ is converted to CO2 and DPG is released. In tissues, where CO2 and H+ is high and O2 is low, the eq is shifted to the left, causing O2 to be released from Hb and CO2 and H+ bind and removed from tissue.

Front 25

How does decreasing the pH affect the pO2 of Hb? Figure it out using the HbO2 equilibrium equation and plotting a graph % Saturation vs pO2. Do the same for CO2.

Back 25

See pg 22 lecture.

Front 26

H+ and CO2 are Heterotropic Negative Allosteric effectors. Why are they: 1) Heterotropic 2) Negative 3) Allosteric? 4) What would O2 be classified as?

Back 26

1. Heter bc they are not O2
2. Negative bc they decrease the affinity for O2
3. Allosteric bc they bind to a site other than the O2 sites.
4. Is a Positive Homotropic Allosteric effector.

Front 27

Describe the regulatory classification of O2 in regard to H+ and CO2 binding to Hb

Back 27

O2 is a negative allosteric effector of H+ and CO2.

Front 28

Where does DPG bind in Hb and is it a positive or negative effector? Binding is through...?

Back 28

It binds in a central cavity between the B subunits. It is a negative allosteric effector. Binds through ionic interactions.

Front 29

What does DPG essentially do? Why is this important?

Back 29

It fine-tunes the affinity of Hb for O2 in response to changes in metabolism and environment. DPG obviates the need for RBC to synthesize different isoforms of Hb - especially since it doesn't have that ability.

Front 30

In terms of T and R states, what does DPG do? And therefore what affect does it have on Hb's affinity for O2?

Back 30

It stabilizes the T state and therefore decreases Hb's affinity for O2.

Front 31

What would you regarding DPG concentration in RBC between an high altitude dweller vs low? Why?

Back 31

High altitude dweller would have higher DPG concentration. DPG stabilizes the T form Hb letting O2 release easier in the low O2 enviro of high altitudes.

Front 32

How would the Bohr effect shift with higher temp? How is this useful physiologically?

Back 32

It would shift to the right. Useful during elevated metabolic rates associated with fever.

Front 33

What is the genetic inheritability of SCD? What causes it?

Back 33

1. Homozygous recessive. 2. Caused by point mutation in the adult B-globin gene that causes substitution of Valine for Glutamic Acid at amino acid 6.

Front 34

What is HbS?

Back 34

It is the SC variant where the Hb contains two normal alpha su's and two defective adult beta-globulin su's.

Front 35

How does the sickle cell shape form?

Back 35

Normally, Glu is a hydrophilic residue on the water surface of a B-chain. Val is a hydrophobic residue that creates a sticky patch on the globin when it is substituted. This leads to polymerization of Hb tetramers into long chains - causing the sickle cell shape and reduced deformability of the RBCs.

Front 36

Besides the vaso-occlusive manifestations of sickle cell disease, what are two other sxs of SCD?

Back 36

Shorter erythrocyte half-life and chronic hemolytic anemia.

Front 37

What four independent factors affect the rate and extend of polymer formation in circulating SS RBCs?

Back 37

1. Degree of deoxygenation (affected by changes in pH, ionic strength, and temp)
2. Intracellular hemoglobin concentration.
3. Relative amount of HbF present - it prevents polymerization
4. Hydration - scRBC tend to be dehydrated which increases sickle cell shape and stickiness.

Front 38

What is the most common therapy for SC? How does the drug work?

Back 38

Hydroxyurea - an antitumor drug. It increases the percentage of HbF and therefore decreases sickling.

Front 39

Based on charge, what is more negative - Hb or HbS?

Back 39

Hb - the mutation substitutes Glu to Val. Glu is neg charged and Val is neutral. Thus, wt has more negative charge.

Front 40

How is RFLP used to diagnose SC?

Back 40

DNA is restricted and run on a gel. MstII enzyme specifically cuts at CCTNAGG - however, in SS pts, the sequence CCTNTGG is no longer recognized. This results in a longer fragment of DNA compared to wt that runs slowly on a gel.

Front 41

Name the embryonic, fetal and adult Alpha-globulins

Back 41

Embryonic: Zeta
Fetal: Alpha
Adult: Alpha

Front 42

Name the embryonic, fetal and adult Alpha-globulins

Back 42

Embryonic: Epsilon
Fetal: Gamma
Adult: Sigma and Delta

Front 43

Where does heme Fe2+ get all six of its protons to satisfy its electron requirements?

Back 43

4 from the Nitrogens in the protoporphyrin ring. 1 from a His residue that's part of the protein and 1 from the Oxygen

Front 44

What is the primary role of myoglobin?

Back 44

As a store for O2. Also, in muscle, it may facilitate diffusion of O2 down concentration gradient.

Front 45

What has greater affinity for Hb - O2 or CO? What is the consequence of this in terms of T and R states and re O2 delivery?

Back 45

CO. CO "locks" Hb in R state. Even if just one CO is bound, the other 3 O2 on Hb cannot be released to tissues.

Front 46

Define the Bohr effect.

Back 46

The ability of protons to modulate Hb's affinity for oxygen. See p. 23 lecture notes.

Front 47

What is the problem in Thalassemia?

Back 47

Failure to produce a B- and/or A-globulin. I.e. there's an imbalance between a- and b-chains.

Front 48

Sickle cell pts are most susceptible when?

Back 48

Whenever they're Hb is deoxygenated (exercise, fever, COPD). Deoxygenated Hb is what polymerizes.

Front 49

Which Thalassemia is more common? Why?

Back 49

Beta. Bc there are two alpha genes / chromosome vs one beta gene / chromosome. Having two messed up alpha genes is less likely.

Front 50

What is the difference between B-zero and B-plus thalassemia?

Back 50

B-zero makes no B-globin and therefore no functional RBCs.
B-plus makes chain but it is dysfunctional - it's not as severe as B-zero.

Front 51

What happens in hereditary persistence of fetal hemoglobin?

Back 51

For unknown reasons, large deletions in gamma and beta genes result in turning on of fetal genes. Pt usually doesn't realize they have it - favorable consequence for high altitude dwellers.

Front 52

What is HbC? What are the clinical consequences of this? How does it affect people who are heterozygous for HbS (i.e. they're Hb SC)

Back 52

It a mutation Glu --> Lys where a neg charge is substituted for a pos charged residue. It's not as severe as the Val substitution but it still doesn't function properly. It's a less severe form of Thalassemia and if complexed with HbS, then a mild form of sickle cell.

Front 53

What is HbA1c and what is its clinical consequence?

Back 53

Hemoglobin is often glycosylated permanently throughout its 120 day life cycle. Normally, a low amount is glycosylated but if unregulated blood sugar levels, as in diabetics, this is higher. A good way to evaluate the long term control of blood glucose levels.

Front 54

Specifically, what do enzymes do? What do they don't do?

Back 54

They reduce the free energy of activation of the reaction. THEY DO NOT CHANGE Keq!

Front 55

What is Keq? Define it relative to product A and product B. Can a catalyst affect it?

Back 55

It is the energy difference between the two - think of the free energy diagram. Catalysts cannot change Keq (draw the E diagram to prove it to yourself).

Front 56

What is the rate constant (Kr)? Can a catalyst affect it?

Back 56

Kr is the free energy required to activate a rxn to make products. Catalyst can lower the energy required.

Front 57

Know that there is a group commissioned to formally/systematically name enzymes. How many classes are there?

Back 57

6

Front 58

Before a reaction can happen, reactants A and B must diffuse into each other. They are typically surrounded by tightly bound water molecules...why is that?

Back 58

Because the functional groups are typically charged or polar.

Front 59

When reactants diffuse into each other, what happens in terms of the water molecules surrounding them and subsequent interactions?

Back 59

The water molecules form a cage where the molecules experience about 150 collisions before diffusing away (at RT).

Front 60

For a reaction to occur within the reaction sphere, what three things must occur?

Back 60

1. Reactants must collide with enough energy to exceed activation energy.
2. Reactants must collide with correct orientation.
3. During collision, water molecules within the hydration sphere must be physically moved away.

Front 61

What is the proximity effect of enzymes?

Back 61

It is the ability of enzymes to bring substrates together, line them up, and increase chances of right collision for rxn.

Front 62

In terms of transition state, how do enzymes increase the rate of rxn?

Back 62

Enzymes typically have a part of the rxn pocket that stabilizes the transition state. Usually it binds more tightly than the initial reactant. This has been useful for drug design - e.g. anti-HIV protease inhibitor.

Front 63

Possible exam Q: If you were to design a drug to inhibit a rxn, what would you target?

Back 63

Design a molecule that closely resembles the transition state molecule.

Front 64

What are the three most common aa found in active sites of enzymes? Why is that?

Back 64

Glutamate, Aspartate, Histidine. They can act as general acids/bases - i.e. proton donors or acceptors. Since physiological pH is very narrow, these aa provide the right proximal pH for rxns to occur.

Front 65

In terms of polarity, what is the microenvironment for enzymes at its active site? Why is this beneficial? What can the microenvironment do in terms of pKa?

Back 65

It is typically hydrophobic. It excludes solvent molecules from getting in the way, and if the transition state is less polar than the substrate or product, this microenvironment stabilizes it and lowers the energy of activation. In terms of pKa, it can alter the pKa's of aa to either more easily protonate or deprotonate. (see p34)

Front 66

Briefly discuss the example used re the two-step protease and peptidase catalysis rxns and their microenvironment. (see pg 35)

Back 66

Step 1: Polarization of peptide carboxyl group to form an oxyanion similar to transition state.
Step 2: proximity of a nucleophile to attack the carbonyl carbon - which ultimately removes peptide bond. This rxn requires a Zn2+ to create carboxy anion. (see pg 35)

Front 67

The example he used re Ribonuclease, demonstrates what? Particularly about His and its special ability. (p35)

Back 67

How enzymes can function as a general acid and/or base. Histidine can function as both an acid and a base in the same enzyme. (p35)

Front 68

Describe "induced fit". How does it reduce the energy required to cause a rxn?

Back 68

It is a conformation change that enzymes cause to distort the shape of a substrate into one that resembles the transition state. Bc the enzyme favorably binds to substrates this way, it reduces the amount of energy required to make this required conformational change.

Front 69

What? Review pg 37. 9/13 lecture at 58:00 and earlier.

Back 69

What? Review pg 37. 9/13 lecture at 58:00 and earlier.

Front 70

Know "catalytic triad" mechanism at 1:00:00 on 9/13

Back 70

Know "catalytic triad" mechanism at 1:00:00 on 9/13

Front 71

What is covalent catalysis?

Back 71

It is when a covalent enzyme-substrate intermediate is formed during the course of a rxn.

Front 72

What are the residues in the catalytic triad?

Back 72

Asp102, His 57, Ser195.

Front 73

What role does Asp102 in the triad?

Back 73

It forms a low-barrier H-bond with H57, turning it into a powerful base.

Front 74

What role does H57 have in the triad after it is converted to a base by Asp102? (see pg 37)

Back 74

His57 deprotonates Ser195

Front 75

What role does Ser195 play in triad once it has been deprotonated?

Back 75

It acts as a nucleophile and attacks the carbonyl carbon of the peptide - forming a covalent bond

Front 76

Catabolism vs Anabolism?

Back 76

Catabolism breaks down to yield energy. Anabolism takes in energy to build new molecules.

Front 77

In what molecules is energy stored (5 - 3 of which are co-factors)

Back 77

ATP, GTP, NADPH, NADH, FADH2

Front 78

Which energy molecules are used to drive anabolic pathways?

Back 78

ATP and NADPH

Front 79

Define substrate level phosphorylation.

Back 79

The metabolic process that generates high energy molecules directly - either GTP or ATP

Front 80

Although you can get more energy out of splitting ATP at this P bond, it's irreversible. Bn which P bond is this? Bn which bond is it not irriversible?

Back 80

Between the alpha and beta. Between beta and gamma.

Front 81

Why is the hydrolysis of the pyrolphosphatase from ATP irriversible?

Back 81

B/c pyrophosphatse immediately cleaves pyrolphosphate.

Front 82

What is the role of phosphoreatine? What enzyme mediates the rxn?

Back 82

It stores a high energy phosphate bond that can be used to quickly convert ADP to ATP when the cells need a burst of energy. Creatine Kinase mediates this rxn.

Front 83

NADH is another way to store energy. How does it do it?

Back 83

NAD+ captures two high energy electrons in the form of hydride ion (H with 2e) to form NADH. Reoxidation by O2 in mitochondria yields 2.5 ATP.

Front 84

You know that NADH can accept a hydride ion to store energy - does NADP+ do the same?

Back 84

No. NADP+ accepts hydride ions to produce NADPH but it has biosynthetic and antioxidant defense system roles - not ATP synth role.

Front 85

On pg 44, note subtle difference between NAD+ and NADP+ - at the 'OR' group in the figure, R is either H or P

Back 85

On pg 44, note subtle difference between NAD+ and NADP+ - at the 'OR' group in the figure, R is either H or P

Front 86

Similar to NADH, how does FAD capture/release energy?

Back 86

It can capture two high energy electrons to form FADH or FADH2. It can be oxidized by O2 in mitochondria to yield 1.5 ATP.

Front 87

Prof wants use to know where "business end" of each energy storing molecule is. Review that:
Creatine: bottom right p 43
NADH: upper right p 44
FAD: bottom half p44

Back 87

Prof wants use to know where "business end" of each energy storing molecule is. Review that:
Creatine: bottom right p 43
NADH: upper right p 44
FAD: bottom half p44

Front 88

Note how Acetyl-CoA is a high energy species that can transfer acetyl groups to other bio molecules or water. p45

Back 88

Note how Acetyl-CoA is a high energy species that can transfer acetyl groups to other bio molecules or water. p45

Front 89

Name the four high energy storage molecules and the two low energy molecules.

Back 89

High energy: Creatine, FADH2, NADH, Acetyl-CoA.
Low energy: Glycogen, Triglyceride (Fat)

Front 90

When intake of energy exceeds needs, how does the body store it? Is there a storage means from protein?

Back 90

Glycogen and triglyceride are energy stores. No storage unit for protein - must degrade own tissues if necessary.

Front 91

Review general properties of metabolic pathways on pg 45

Back 91

Review general properties of metabolic pathways on pg 45

Front 92

How do you determine the reaction order?

Back 92

It's based on how many reactants there are. If there are two, it's 2nd order. If one, it's first order.

Front 93

What is usually the limiting step in enzyme mediated rxns? What is usually the fastest?

Back 93

The conversion to products is usually the slowest. Binding to the enzyme is usually the fastest. (Review graph on p51)

Front 94

What is the Michaelis-Menton Equation? What are the two assumptions here?

Back 94

vo = (vmax[s])/(Km + [s])
Assumptions:
1. [s] is equal to the initial amount added and there is no product yet
2. The concentration of [ES] is nearly constant as P is being formed.
(see p. 52)

Front 95

You know the Michaelis-Mention equation - but what does Vmax equate to? Knowing this, you should know what effect increasing the [E] should be on vo.

Back 95

Vmax = k2[E], so by increasing the [E], you'll increase the vo.

Front 96

What does Km equate to? It is defined as the substrate concentration at which the rxn rate is half of Vmax. However, remember that it defines the average K for the entire rxn and derivation involves using each K.

Back 96

Km = (k-1 + k2)/k1

Front 97

When considering the Michaelis-Menton equation, what does it reduce to when [S]<<Km or when [S]>>Km?

Back 97

1. [S]<<Km

Front 98

What is a competitive inhibitor?

Back 98

Binds to same enzyme form as the substrate.

Front 99

How is the Vmax affected by a competitive inhibitor?

Back 99

It is not. See p55.

Front 100

Go over the various inhibitors and their features:
1. Competitive
2. Non-competitive
3. Uncompetitive
4. Irreversible I
p 53-8

Back 100

Go over the various inhibitors and their features:
1. Competitive
2. Non-competitive
3. Uncompetitive
4. Irreversible I
p 53-8

Front 101

Recall how the activity of Phosphofructiokinase changes according to the presence of ATP and AMP and how this is typical of allosteric enyzmes. p58

Back 101

Recall how the activity of Phosphofructiokinase changes according to the presence of ATP and AMP and how this is typical of allosteric enyzmes. p58

Front 102

review how inactive/active enzyme equilibrium is dependent on concentration of inhibitor and/or substrate. p58.

Back 102

review how inactive/active enzyme equilibrium is dependent on concentration of inhibitor and/or substrate. p58.

Front 103

This is important for carbohydrate nomenclature: What is the most reduced carbo and what is the most oxidized?

Back 103

Most reduced: CH4
Most oxidized: CO2

Front 104

Monosaccharides can only be classified as two things...?

Back 104

aldose (has aldehyde group) and ketose (has ketone group)

Front 105

How do you determine the chirality of a CHO?

Back 105

You start with the chiral C furthest from the carbonyl end. and look at the OH. If it is on the left side, it is L- on the right side it is D-.

Front 106

What is the difference between isomers and epimers?

Back 106

Isomers have a chiral C and have groups that differ around that C. Epimers are sugars with more than one chiral carbon and differ only by the configuration about a single carbon. (Think about L- vs D- glucose. If you flip only one OH group, it's an epimer)

Front 107

What are the four most biologically important hexoses? And what is their relations to each other regarding epimers and isomers?

Back 107

A. Remember GalGMF
1. Galactose
2. Glucose
3. Mannose
4. Fructose
B. Draw out to help with relations:
1. Galactose and Glucose are C4-epimers
2. Glucose and Mannose are C2-epimers
3. Glucose and Fructose are isomers

Front 108

Isomers that exist as mirror image molecules are termed...?

Back 108

Enantiomers

Front 109

in bio systems, where are sugars oxidized?

Back 109

At C1 or C6

Front 110

Sugars (aldohexoses) oxidized at C6 have what suffix?
Sugars oxidized at C1 have what suffix?

Back 110

C6 = -uronic acid or uronate
C1 = -conic acid or conate

Front 111

What is common table sugar? It is composed of what two monosaccharides?

Back 111

Sucrose is F-ing Good:
Fructose
Glucose

Front 112

1. When hexose sugars cyclize, what is this rxn called? (there's two types).
2. When the new ring forms and the -OH is above the ring, it is a _a_? Below the ring it is _b_?

Back 112

1. hemiacetalisis or hemiketalisis
2. a. Above is Beta anomeric
b. Below is Alpha anomeric

Front 113

What are the subunits that make up lactose and maltose?

Back 113

Lactose: Galactose and Glucose
Maltose: 2x Glucose

Front 114

Know that: Humans can digest alpha 1,4 (amylose) and alpha 1,6 linkages (amylopectin, glycogen) but cannot digest beta 1,4 linkages (cellulose). p 68-9

Back 114

Humans can digest alpha 1,4 (amylose) and alpha 1,6 linkages (amylopectin, glycogen) but cannot digest beta 1,4 linkages (cellulose). p 68-9

Front 115

What is a Schiff base?

Back 115

A double bond between a N and C.

Front 116

Alpha-amylase is present in __a__ and __b__. It attacks the internal alpha 1,4 glycosidic bonds of __c__ and __d__.

Back 116

a. saliva
b. pancreatic juice
c. starch
d. glycogen

Front 117

Lactase is relatively non-abundant. How can lactose become a problem in the digestive system?

Back 117

If not digested, it remains a disaccharide and cannot be absorbed. In the large intestine, it functions as an osmotic molecule where it pulls water in and causes diarrhea. It can also be a food to microbes and cause cramping and gas.

Front 118

How can you ID the carina in a radiograph?

Back 118

Find the aortic knob...it's medial to the base of that.

Front 119

In radiograph, what forms the right side boarder of the heart? What about the left? Why is the right

Back 119

R = R atrium
L = L ventricle