BIOCHEM UW: METABOLISM/ Nucleotides, CARBS & LIPIDS

Question 1

Draw the Citric Acid cycle

Answer 1

Question 2

Fermentation

Answer 2

• is the reduction of pyruvate to generate NAD+ for continued glycolysis under anaerobic conditions
• in mammals, fermentation is carried out by the conversion of pyruvate ——->lactate

Question 3

Glycolysis

Answer 3

• is the conversion of glucose—->pyruvate

Question 4

Glycogenolysis

Answer 4

• is the degradation of glycogen for use in other metabolic pathways

Question 5

Convert Glycogen to lactate

Answer 5

• glycogen is a form of energy storage
• when energy is needed, individual glucose units may be removed from glycogen through glycogenolysis
• The glucose-6-phosphate generated by glycogenolysis may then enter other metabolic pathways, including glycolysis & fermentation

Question 6

Glial Cells

Answer 6

Question 7

What is glycogen composed of?

Whata re the linkages?

what is phosphorylysis

Answer 7

• Glycogen is primarily composed of several glucose subunits bound together by α-1,4 glycosidic linkages.
  
  • Glycogen is cleaved into glucose-1-phosphate subunits by glycogen phosphorylase in a reaction called phosphorolysis.
    
    • Phosphorolysis breaks bonds by adding an inorganic phosphate group across them.

Question 8

Hydrolysis

Answer 8

Question 9

How can we provide evidence that a metabolic pathway worksby a proposed mechanism?

Answer 9

• a critical component of that mechanism should be inhibited & the effects observed
• the blocked component must be unique to the proposed mechanism to ensure that the observed effect is not due to a seperate pathway

Question 10

in the mitochondria, pyruvate undergoes_________________ as it is converted to _______________ & enters the citric acid cycle

What happens to the carbon atoms in pyruvate precursors?

Answer 10

• 3 decarboxylation reactions
• acetyl-CoA
• will be released as CO2

Question 11

what is the reaction that releases carbon atoms as CO2?

Answer 11

Question 12

Peptide (amide) bond condensation

Answer 12

Question 13

GLycosidic bond condensation

Answer 13

Question 14

_______________ reactions produce chiral molecules in a specific arrangment

The citric acid cycle produces only 2 intermedicates with chiral centers, which are?

Answer 14

• Stereospecif reactions
• isocitrate (converted from citrate by aconitase) & malate (transformation of fumarate by fumarase)

Question 15

Nucleotide structure

Which has the OH on the 2’ sugar? Ribose or deoxyribose?

Answer 15

• A nucleoside is a pentose (five-carbon) sugar linked to a nitrogenous base on the 1′ carbon by a covalent glycosidic bond.
• Nucleotides consist of a nucleoside attached to one or more phosphate groups by a phosphoester bond.
• If the pentose has a hydroxyl group at the 2′ carbon, it is ribose; if a hydrogen is present at the same position, it is deoxyribose.

Question 16

Watson-Crick base pairing

How mancy donors & acceptors does each pair have?

Answer 16

• Hydrogen bond acceptors are electronegative atoms (nitrogen or oxygen) that have at least one lone pair of electrons, and hydrogen bond donors are hydrogen atoms bound to electronegative atoms.

Question 17

DNA proofreading

exonuclease & endonucleases

Answer 17

• DNA polymerase I proofreads DNA and normally has exonuclease activity in the 5′-3′ as well as the 3′-5′ direction that allows it to remove primers and damaged or incorrect bases at the ends of the strand.
• It cannot fix mistakes in the middle of a strand; instead, base excision repair and nucleotide excision enzymes have endonuclease (mismatch repair enzyme, base excision repair) activity to remove damaged bases and mismatched nucleotides from the middle of a DNA strand, respectively.
• if an enzyme does not have a 5’-3’ exonuclease activity, thus can only proofread DNA in the 3’-5’ direction on the template strand, so only erros at the 3’ end of the growing strand can be repaired

Question 18

Effect of hydrogen bonding on DNA melting temperature (T_m)

Answer 18

• The melting temperature T_m of DNA is the temoerature at which 50% of the double helices in solution have been seperted into snigle strands
• it is determined by the strength of intermolecular forces holding the strands together
• an inc in IMF=inc Tm bc more nergy is rquired to disrupt them
• DNA molecules with high GC content have higher melting temperatures than those with low GC content.

Question 19

Polysaccharide Chain

Know the carbs orientation (D or L)

Fischer projections

Answer 19

• Fischer projections help distinguish anomers, epimers, and enantiomers.
• Enantiomers are compounds with the same chemical formula that differ at every stereocenter
• Epimers and anomers (are diastereomers) differ at only one stereocenter.
• Anomers can exist only in cyclized sugars (furanose or pyranose) and differ at the anomeric carbon.

Question 20

Descrube how OAA is synthesized by 3 reactions? in a single step!

Answer 20

• via (citric acid cycle) malate, (gluconeogenesis,) pyruvate, and (aa degradation) aspartate to glutamate to OAA

Question 21

how is pyruvate converted to OAA?

Answer 21

• Alanine can be deaminated to yield pyruvate, which can then be converted to oxaloacetate by pyruvate carboxylase.
  
  • This process requires two enzymatic steps instead of one.

Question 22

When different molecules enter the citric acid cycle at different points, the cycle will oxidize these molecules to produce the ______________

Answer 22

• the reduced electron carriers NADH & FADH₂
• the number of electron carries produced depends on the number of oxidative steps remaining int he cycle at the point of entry
  
  • example: methionine

Question 23

Fermentation

higher eukaryotes: fermentation occurs_______________

Bacteria & lower eukaryotes (yeast) fermentation occurs by: ____________

Answer 23

• reduction of pyruvate to lactate
• decarboxylation of pyruvate to form acetladehyde, followed by reducation of acetaldehyde to form ethanol
  
  • ​inc in partial pressure, yeast cells would exhibit INC function of the ETC & the need for fermentation to regenerate NAD+ would decrease
  • Becuase fermentation in yeast generates ethanol, increased partial pressure of oxygen (& decreased fermentation) would most likely result in reduced ethanol production

Question 24

Structural Lipids

Steps of cholecsterol synthesis?

Answer 24

• Steroid hormones are derived from cholesterol.
• Cholesterol has a characteristic four-ring backbone, which is synthesized from five-carbon subunits called isoprenes.
• Two isoprenes joined together form a monoterpene, and six isoprenes can join to form a triterpene called squalene, which then cyclizes and, after several steps, forms cholesterol.

Question 25

Fat-Soluble Vitamins

Answer 25

* Certain biomolecules such as vitamins and the essential amino and fatty acids cannot be synthesized in the human body and must be **obtained through the diet.** * **Water-soluble vitamins** (B series, C) are excreted in the urine whereas **fat-soluble vitamins (A, D, E, and K)** are stored in adipose and other fatty tissues.

Question 26

Steroid hormones & Peptide Hormones

Answer 26

* **Steroid hormones** are produced primarily in the adrenal cortex and the gonads from cholesterol and other precursors. * They are not required in the diet and do not generally accumulate in adipose tissue. * **Peptide hormones** are readily synthesized by the body, and are not required in the diet. * They are generally soluble in water, and are not stored in adipose tissue.

Question 27

***_Example of Semiconservative DNA replication:_*** Escherichia coli bacteria containing only 15N-labeled DNA were grown in media containing only 14N nucleotides. What percentage of double helices would be composed of one 15N strand and one 14N strand after three generations?

Answer 27

* **DNA replication is a semiconservative process** that results in each double helix containing one parental strand and one newly synthesized daughter strand. * **DNA polymerase synthesizes** each new daughter strand by using a parental strand as a template. * **Answer to question & explained: 25%****​** * In the experiment described, Escherichia coli bacteria initially have the heavy isotope 15N in their DNA. Once the bacteria are transferred to 14N media and allowed to replicate, newly synthesized strands will contain 14N. * In Generation 1, all new strands will be paired with parental strands that contain 15N. Therefore, 100% of double helices produced in Generation 1 will have one 15N strand and one 14N strand * In generation 2, both the 15N and 14N strands from Generation 1 are used as templates for the synthesis of new 14N strands. In the DNA that used a 14N strand as a template, both parental and daughter strands will contain 14N nucleotides. In DNA that used a 15N strand as a template, the parental strand will contain 15N and the daughter strand will contain 14N. Because half of the parental strands are 15N and half are 14N, 50% of the Generation 2 double helices will contain one 15N strand and one 14N strand. The other 50% will contain two 14N strands. * In generation 3, the percentage of double helices containing one 15N strand and one 14N strand will be half the percentage of the previous generation. Therefore, **in Generation 3, 25% of double helices will contain a 15N strand and a 14N strand.**

Question 28

**describes the ribose component of a nucleotide triphosphate?**

Answer 28

* **_pentofuranose_** * Ribonucleotide triphosphates contain a nitrogenous base, ribose, and a triphosphate group linked to the 5′ carbon of ribose. * *Ribose is a five-carbon sugar (pentose) that must adopt the furanose form to be incorporated into the nucleotide triphosphates.* In this form, it can be classified as a **pentofuranose.**

Question 29

Difference in Furnose & pyranose forms of ribose

Answer 29

Question 30

Apoptosis is induced by \_\_\_\_\_\_\_\_\_\_\_\_

Answer 30

* **oxidative stress**

Question 31

ATP yeild calculation

Answer 31

* **1 NADH=** 2.5 ATP * **1 FADH₂=**1.5 ATP * **1 glucose=**32 ATP

Question 32

**_Complex V of ETC_**

Answer 32

* **Complex V** activity depends on proton availability. * Proton concentration in the intermembrane space can be increased by increasing the number of NADH molecules that enter the electron transport chain. * *NADH from glycolysis can indirectly enter the mitochondrial matrix by first passing its electrons to oxaloacetate, forming malate _(via malate-aspartate shuttle)_*

Question 33

Glycerol 3-Phosphate

Answer 33

* converts cytocolic NADH to mitochondrial **FADH₂** by **OXIDIZING** glycerol 3-phosphate to DHAP

Question 34

how to calculate rate of chemical output

Answer 34

* by dividing the total output by the time it takes to achieve that output

Question 35

When one chemical process provides the energy for another, the processes are said to be \_\_\_\_\_\_\_\_\_\_\_\_.

Answer 35

* **_Coupled_** * When two processes that are normally coupled become **decoupled**, *the process that provides the energy continues but the process driven by that energy slows or stops, as the two have become disconnected.*

Question 36

Regulation of glycolysis & gluconeogenesis by **insulin in the fed state** Question: Which of the following regulatory mechanisms helps increase net glucose catabolism in the liver after a meal?

Answer 36

* **Insulin** stimulates glycolysis by activating the enzyme **PFK-2,** which synthesizes fructose-2,6-bisphosphate. * **Fructose-2,6-bisphosphate** allosterically activates **PFK-1** and inhibits fructose-1,6-bisphosphatase, which **_stimulates glycolysis and reduces gluconeogenesis._** * **Answer: allosteric inhibition of fructose-1,6-bisphosphatase catalysis**

Question 37

Insulin & glucagon signaling

Answer 37

Question 38

a **deficiency in the pyruvate dehydrogenase complex (PDHC**) activity causes *lactic acid build up*, what can be indicated by this?

Answer 38

* **_impaired ability to synthesize lipoic acid_** * The pyruvate dehydrogenase complex (PDHC) is an enzyme composed of three subunits (E1, E2, and E3). * It catalyzes the **oxidative decarboxylation of pyruvate to form acetyl-CoA, along with the reduction of NAD+ to form NADH.** * During this process, electrons are passed from one subunit in the complex to the next until they can be transferred to NAD+. ***This transfer is facilitated in part by the cofactor lipoic acid.***

Question 39

*Fatty Acid Oxidation/Saturated/Unsaturated FA* * Fatty acids can be oxidized to form\_\_\_\_\_\_\_\_\_, and those with an **even number** of carbons produce half as many ____________ molecules as they have carbons. * Fatty acids with an **odd number** of carbons produce \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ * \_\_\_\_\_\_\_\_\_\_\_\_require isomerization reactions to convert cis-bonds to trans-bonds whereas ___________ do not.

Answer 39

* **acetyl-CoA, acetyl-CoA** * **propionyl-CoA in addition to acetyl-CoA.** (# of Acetyl-CoA produced=total carbons-3/2) * **Unsaturated fatty acids** (they have at least 1 double bond) * **Saturated fatty acids** (no isomerization) *if we have a final product of 9 acetyl coA, know that the state point is 18 carbons*

Question 40

*Fatty Acid Oxidation* **Entry into the mitochondrial matrix is tightly regulated by transport proteins in the\_\_\_\_\_\_\_\_\_\_\_\_\_\_ membrane.** Fatty acids must be activated with ___________ followed by _________________ to enter the mitochondrial matrix. Activation requires \_\_\_\_\_\_\_\_\_\_\_\_\_\_.

Answer 40

* **inner mitochondrial membrane** * **coenzyme A** * **carnitine** * **ATP hydrolysis** *note that FA are not recognized by any transport proteins; they must be modified or "activated" to enter the matrix* (like what is said on top and shown in the attached pic)

Question 41

Oxaloacetate is an intermediate in the \_\_\_\_\_\_\_\_\_\_&\_\_\_\_\_\_\_\_\_\_\_\_&\_\_\_\_\_\_\_\_\_\_\_\_\_\_:

Answer 41

* citric acid cycle, gluconeogenesis, & transport of acetyl-CoA **_FROM the mitochondria INTO the cytosol for fatty acid synthesis_** * *NOTE: IT IS NOT INVOLED IN THE TRANSPORT OF FATTY ACIDS FROM CYTOSOL INTO THE MITOCHONDIRA*

Question 42

***_CORI CYCLE_***

Answer 42

* During **anaerobic** exercise, **pyruvate is reduced to lactate to regenerate NAD+**. * Lactate that builds up in muscles is sent to the liver, where it is **converted back to glucose (gluconeogenesis)** and returned to muscles. * *The process of carrying lactate from the muscle to the liver and moving regenerated glucose from the liver back to muscles is called the **_Cori cycle, which connects gluconeogenesis and glycolysis._***

Question 43

*_Pentose Phosphate pathway_* The pentose phosphate pathway generates \_\_\_\_\_\_\_\_\_&\_\_\_\_\_\_\_\_\_\_\_. The NADPH is generated by reduction of \_\_\_\_\_\_\_\_\_\_\_\_, which is catalyzed by the **_oxidoreductases_** \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_&\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Answer 43

* *ribose 5-phosphate and NADPH* * *NADP+* * *glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase.*

Question 44

**_Catabolic vs. Anabolic_**

Answer 44

Question 45

* Citric Acid Cycle:* * is **allosterically regulated** at the **irreversible steps** catalyzed by \_\_\_\_\_\_\_\_\_\_\_&\_\_\_\_\_\_\_\_\_\_\_\_\_\_&\_\_\_\_\_\_\_\_\_\_\_\_\_\_. The enzymes are inhibited by\_\_\_\_\_\_\_\_\_\_\_&\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_&\_\_\_\_\_\_\_\_\_\_\_\_\_\_, and are activated by \_\_\_\_\_\_\_\_&\_\_\_\_\_\_\_\_\_\_\_\_. The Krebs cycle enzymes are not under\_\_\_\_\_\_\_\_\_\_\_\_\_control.*

Answer 45

* ​Citrate synthase, isocitrate dehydrogenase, and α-ketoglutarate dehydrogenase. * NADH, ATP, citrate, and succinyl-CoA * ADP and calcium * hormonal control

Question 46

*_Electron Transport Chain_* *In the electron transport chain, four electrons are required to fully reduce one O2 molecule to two H2O molecules.* **_Given this information, how many NADH molecules are required?_**

Answer 46

* **_Answer: 2_** * Electron donors and acceptors in the ETC have different carrying capacities. Full reduction of oxygen to water requires four electrons, so two copies of a two-electron carrier such as NADH would be required to fully reduce oxygen. Four copies of a one-electron carrier, such as reduced cytochrome C, are required.

Question 47

*Anobolic processes* * Anabolic processes require **\_\_\_\_\_\_\_\_\_\_**, which is typically provided by \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ * These cleavage events either release the γ-phosphate as **inorganic phosphate (Pi)** or they release the **γ- and β-phosphates as pyrophosphate.** The α-phosphate remains attached to the NTP.

Answer 47

* **energy input** * **cleaving phosphodiester bonds in nucleotide triphosphates (NTPs) such as ATP, GTP, or UTP.**

Question 48

**_During prolonged fasting, which of the following liver enzymes has upregulated activity?_** During periods of fasting, the liver helps maintain \_\_\_\_\_\_\_\_\_\_\_\_\_. The liver initially synthesizes glucose by degrading \_\_\_\_\_\_\_\_\_\_\_\_. However, after glycogen stores are depleted in prolonged fasting, _____________ is upregulated, increasing the synthesis of glucose from precursors such as \_\_\_\_\_\_\_\_\_\_\_\_. _**In the fasting state, the liver downregulates key enzymes of ______________ and upregulates enzymes of \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_.**_

Answer 48

* **Pyruvate carboxylase** * blood glucose levels * glycogen * gluconeogenesis * pyruvate * **_glycolysis_** * **_gluconeogenesis_**

Question 49

These decrease DNA stability when denaturation occurs

Answer 49

* **_hydrogen bonding are disrupted_** * **dec base stacking** (Stacking interactions, which are due to hydrophobic effects and nonpolar van der Waals forces between the bases, are primarily responsible for the stability of the double helix structure.) * **hydrophobic effects dec** (Hydrophobic effects decrease during the melting step because hydrophobic bases are exposed to water. In aqueous solution, hydrophobic effects force hydrophobic bases toward the double helix interior and away from the polar solvent (water))

Question 50

**_Nucleaotide Bases_**

Answer 50

Question 52

*_Sugar Cyclization_* ## Footnote **Pyranose** **Furanose** **Hemiacetal & hemiketal**

Answer 52

* In their linear form, monosaccharides contain **multiple alcohol groups and one carbonyl group.** * For **aldoses**, the **carbonyl is an aldehyde**, whereas for **ketoses the carbonyl is a ketone.** * ***All** monosaccharides contain at least **one primary alcohol,** and **most** contain **at least one secondary alcohol.***

Question 53

Hydrolyzable lipids

Answer 53

* Those with sphingosine backbones are **sphingolipids**; those with glycerol backbones are **glycerolipids**; phosphate modifications yield **phospholipids**; and carbohydrate modifications yield **glycolipids**. * Complex lipids may involve a combination of these characteristics and are named accordingly (ie, *glycosphingolipid, glycerophospholipid)*. * ***hydrolyzable linakges contain esters or amides***

Question 54

Nonhydrlyzable lipids

Answer 54

Question 55

Example of **Glycosphingolipid**

Answer 55

Question 56

Mutarotation

Answer 56

Question 57

**_Anomeric Carbon & glycosidic bonds_**

Answer 57

* A **glycosidic bond** is a bond between the anomeric carbon of a carbohydrate and any other biomolecule. * *A single carbohydrate may participate in many glycosidic bonds by linking to the anomeric carbons of other carbohydrates, allowing a high level of diversity among carbohydrate chains.*

Question 58

Example of glycosidic bond

Answer 58

Question 59

***Sphingolipids are strucural lipids*** Sphingolipids are structural lipids that help influence the \_\_\_\_\_\_\_\_\_\_\_&\_\_\_\_\_\_\_\_\_\_\_\_of biological membranes. The long hydrocarbon chain of the sphingosine head group cannot be readily \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_, and sphingolipids are not a primary means of \_\_\_\_\_\_\_\_\_\_\_\_\_

Answer 59

* fluidity and curvature * CANNOT hydrolyze * energy storage * *sphingolipids produce **_one fatty acid upon hydrolysis_***

Question 60

**_Membrane Fluidity_** fluidity of a cell membrane is largely dependent on the ___________________ in the bilayer and on the ____________ in each tail. ________________ **yield the highest fluidity because they participate in the**\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Answer 60

* lengths of the fatty acyl tails * number of double bonds * Short chains with double bonds * fewest hydrophobic interactions with neighboring lipids

Question 61

***_Nucleotide bases:_*** Thymine and adenine have _________ donor and ________ acceptor each, whereas guanine has _________ acceptor and ________ donors and cytosine has ________ acceptors and \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Answer 61

* 1 donor & 1 acceptor * 1 acceptor & 2 donors * two acceptors & 1 donor

Question 62

Enzyme Cooperativity *sigmoidal (S-shaped)* activity curves, indicating that both enzymes are \_\_\_\_\_\_\_\_\_\_\_\_\_. When does this ^^ occur?

Answer 62

* **_cooperative_** * Cooperativity occurs when the binding of a *substrate to one active site increases the affinity of other active sites for the substrate*. Therefore, by definition, **_cooperative enzymes must have multiple active sites._**

Question 63

**Metabolic pathways and their allosteric activators & inhibitors**

Answer 63

Question 64

Cori Cycle: * one glucose molecule is converted to __________ pyruvate molecules in the muscle, which are then sent to the liver (as \_\_\_\_\_\_\_\_\_\_\_\_), where they are converted back to glucose. * Because gluconeogenesis consumes \_\_\_\_\_\_\_\_\_equivalents and glycolysis produces __________ equivalents, a net total of \_\_\_\_\_\_\_\_\_\_equivalents are consumed in one round of the cycle.

Answer 64

* **_two_** * **_lactate_** * **_6 net ATP_** * **_2 net ATP_** * **_4 ATP_**

Question 65

Gluconeogenesis is an _________ process that requires energy input from ATP equivalents. The necessary energy is provided by catabolic processes, most commonly by \_\_\_\_\_\_\_\_\_\_\_\_\_\_

Answer 65

* **anabolic** * **fatty acid oxidation** ## Footnote ***_if a reaction is anabolic, the energy required is provided by a catabolic reaction_***

Question 66

Iglycogenolysis produces glucose, so when glycogen is PRESENT, ___________________ IS NOT REQUIRED.

Answer 66

* **GLUCONEOGENESIS** * *gluconeogenesis generally occurs AFTER glycogen stores have been depleted*

Question 67

The rate of glycolysis is controlled by ___________ which is stimulated by the allosteric effector\_\_\_\_\_\_\_\_\_\_\_.

Answer 67

* PFK-1 * F2,6BP ## Footnote *When glycolysis is active, F2,6BP synthesis is also most likely active.*

Question 68

insulin and glucagon regulate blood glucose levels. When blood glucose is high, the pancreas releases \_\_\_\_\_\_\_\_\_\_, which upregulates uptake\_\_\_\_\_\_\_\_\_\_\_&\_\_\_\_\_\_\_\_\_\_\_ When blood glucose is low, the pancreas releases \_\_\_\_\_\_\_\_\_\_, which stimulates __________ and ___________ to release glucose from the liver into the bloodstream.

Answer 68

* insulin, glucose uptake (glycolysis) & glycogen synthesis * glucagon, gluconeogenesis, and glycogenolysis

Question 69

**Active transport processes** * Uniport* * Antiport* * Symport*

Answer 69

Question 70

How do fatty acids enter the mitochondria?

Answer 70

* **_via L-Carnitine_** * B-oxidation occurs in the mitochondria and produces **acetyl-CoA** * **_palmitate_** is an example of fatty acids

Question 71

*ATP Synthase* **Aerobic organisms primarily generate ATP using energy provided by the electron transport chain (ETC).** The final step in the chain is \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_, and the rate of oxygen consumption can be used \_\_\_\_\_\_\_\_\_\_\_\_\_\_. **_Higher ETC activity corresponds to a _________ ATP/ADP ratio or a _________ ADP/ATP ratio._**

Answer 71

* **reduction of oxygen to water** * as a measure of ETC activity * **_higher_** * **_lower_**

Question 72

* Inhibiting FA synthesis, might result in an increase in what? * What are the reactants needed to generate FA chains during lipid synthesis?

Answer 72

* **NADPH** *(conversion of NADPH to NADP+ will occur less frequently) thus, cystolic NADPH will build up* * pentose phosphate pathwat generated the NADPH needed to reduce the carbonly groups from each molecule of acetyl-CoA * acetyl coA will most likely increase * **Acetyl-CoA, NADPH, ATP**

Question 73

The pyruvate dehydrogenase complex catalyzes the decarboxylation reaction that converts **pyruvate into acetyl-CoA.** This reaction requires \_\_\_\_\_\_\_\_&\_\_\_\_\_\_\_\_\_\_\_&\_\_\_\_\_\_\_\_\_\_\_&\_\_\_\_\_\_\_\_\_\_\_ and links\_\_\_\_\_\_\_\_\_\_\_\_\_\_ to the citric acid cycle. These pathways are essential for maximal \_\_\_\_\_\_\_\_\_

Answer 73

* **_CoA, thiamine pyrophosphate, lipoic acid, and NAD+_** * **_glycolysis_** * **_ATP synthesis_**

Question 74

* Insulin stimulates lipid synthesis by activating the majoy enzymes involved in fatty acid production: \_\_\_\_\_\_\_\_\_\_&\_\_\_\_\_\_\_\_\_\_&\_\_\_\_\_\_\_\_\_\_\_\_

Answer 74

* **_pyruvate dehydrogenase complex, acetyl-CoA carboxylase & fatty acid synthase_** * *PDH converts pyruvate produced from glucose into acetyl-CoA, which is transported to the cytoplasm for fatty acid synthesis*

Question 75

* Protein catabolism refers to the breakdown of polypeptide chains and proteins into\_\_\_\_\_\_\_\_\_\_\_\_\_ to produce\_\_\_\_\_\_&\_\_\_\_\_\_\_\_\_\_&\_\_\_\_\_\_\_\_\_\_\_ Transamination & deamination of amino acids?

Answer 75

* individual amino acids * ATP, glucose, or new proteins * **Transamination reactions generate α-keto acids** from amino acids by **transferring the NH3 group to α-ketoglutarate,** which is **converted to glutamate.**

Question 76

Protein metabolism

Answer 76

* **Glucogenic amino acids** are converted to pyruvate, which can be used to make glucose or citric acid cycle intermediates. * **Ketogenic amino acids** are converted directly to acetyl-CoA, which can enter the citric acid cycle or be used to form ketone bodies. * ***In the absence of oxygen, pyruvate is reduced to lactate to regenerate NAD+ during fermentation.***

Question 77

Reducing & Non-reducing sugars

Answer 77

* **Reducing sugars** contain free anomeric carbons that provide reducing power when they are oxidized. * In linear form the anomeric carbon is an aldehyde or a ketone, and in cyclic form reducing sugars have hemiacetal or hemiketal configurations. * **Nonreducing sugars** contain acetal or ketal structures in their cyclic forms.

Question 78

Sphingolipids are structural lipds

Answer 78

Question 79

Glycerophospholipds

Answer 79

Question 80

Triglycerides Structure

Answer 80

Question 81

Example of constituitonal isomers

Answer 81

same molecular formula but distanct arrangements

Question 82

Examples of Enantiomers

Answer 82

differ at all centers

Question 83

Gycosidic bonds and reducing sugars

Answer 83

**Glycosidic bond formation** requires a sugar with a free anomeric carbon, called a **reducing sugar.** * All free monosaccharides are reducing sugars whereas disaccharides are reducing only if one anomeric carbon does not participate in a glycosidic bond. * Sucrose is the most common nonreducing sugar.

Question 84

increase in acidity is ______________ in pH

Answer 84

a decrease in pH!!!

Question 85

glucose 6-phosphatase & the Cori cycle:

Answer 85

* Several biological processes, including gluconeogenesis, glycogenolysis, and the Cori cycle, help buffer blood glucose levels. All of these processes require glucose 6-phosphatase (G6Pase) to catalyze the final step to release free glucose. * The pentose phosphate pathway uses glucose 6-phosphate as a substrate, but does not produce free glucose or require dephosphorylation and is unaffected by changes in G6Pase activity.

Question 86

Inactivation of PEPCK:

Answer 86

catalyzes the second step in gluconeogenesis, the conversion of oxaloacetate to phosphoenolpyruvate, and its inactivation can indeed lead to both lactate buildup and glucose depletion in the blood

Question 87

Pyruvate decarboxylase

Answer 87

converts pyruvate to acetaldehyde as the first step in the production of ethanol by yeast

Question 88

Acyl-CoA Dehydrogensase

Answer 88

catalyzes the first step in fatty acid catabolism

Question 89

Hormones regulating glucose metabolism chart

Answer 89

Question 90

Genetic mutations that inhibit gluconeogenesis and glycogenolysis can prevent effective hormonal control of blood glucose levels, how can this be counteracted? like how can hypoglycemia be counteracted?

Answer 90

* Dietary supplementation with a glucose source such as starch can help maintain glucose levels in these cases

Question 91

breaking bonds require:

Answer 91

* require energy * **energy is absorbed when phosphodiester bond is broken** and energy is released when new bonds form

Question 92

Acetylation of lysine residues in histones increases gene expression because:

Answer 92

* **_the salt bridges between charged amino acids and phsophate groups are disrupted_** * *Histones associate with DNA by forming salt bridges between their positively charged residues and negatively charged phosphate groups on DNA. Acetylation of histones involves the transfer of an acetyl group to positively charged amino groups on lysine or arginine residues, increasing gene expression by disrupting salt bridges between histones and DNA.*

Question 93

Complex II (succinate-ubiquinone reductase or succinate dehydrogenase)

Answer 93

* **Oxidizes succinate to fumarate and transfers electrons to Complex III.** * Electrons are transferred from flavin adenine dinucleotide (FAD) to iron-sulfur centers in Complex II, then to ubiquinone (coenzyme Q), which carries them to Complex III through the inner membrane.

Question 94

Complexes I, III, and IV

Answer 94

* **_pump protons into the intermembrane space against their concentration gradient,_** but Complex II does not pump protons against their gradient, and therefore does not contribute to the decrease in pH in the intermembrane space.

Question 95

redox potentials

Answer 95

In the electron transport chain, electrons are transferred to carriers with higher redox potentials at each step

Question 96

Cell communication

Answer 96

* *Cells communicate through chemical signals called hormones.* * **Hydrophilic hormones** such as peptide hormones cannot cross the cell membrane and require second messengers. * **Hydrophobic hormones** such as steroid hormones can cross the cell membrane and do not need second messengers.

Question 97

**_starvation response: lipid metabolism_**

Answer 97

* Triacylglycerols, also known as triglycerides, are storage lipids that consist of three fatty acid chains attached to a glycerol molecule. * During prolonged starvation, acetyl-CoA produced from fatty acid oxidation in the mitochondria is converted into alternative fuel molecules known as ketone bodies.

Question 98

phospholipids in cell membrane could be seperated by:

Answer 98

* Phospholipids are composed of a hydrophilic head group that contains a phosphate and a hydrophobic tail with one or two fatty acid chains. * Phospholipids have either a glycerol or a sphingosine backbone. * **The composition of the head groups and the length of the tails create lipids with distinct solubility (TLC), charge( HPLC), and mass (size-excluson chromatogrphy)**

Question 99

lipid processing & classification Emulsification & micelles

Answer 99

* Lipid processing begins in the small intestine (dduodenum), while bile salts break down lipid globules into smaller droplets in a process called **emulsuificaiton** * **Emulsification** increases the surface area of lipids by breaking down large globules into spherical structures called **micelles**. * **Micelles** have a hydrophobic core, which contains the nonpolar hydrocarbon tails of lipids, and an outer shell of polar head groups, which make contact with water. * Lipases can cleave the ester bonds in hydrolyzable lipids such as triglycerides, phospholipids, and waxes by adding a water molecule (hydrolysis).

Question 100

Catalysts (including enzymes)

Answer 100

* increase reaction rate constants by stabilizing transition states and decreasing activation energy. * *They do not affect the energy states of products or reactants, and therefore they do not affect the equilibrium positions of the reactions they catalyze.*

Question 101

branched alkyl chains

Answer 101

Question 102

Prostagladins

Answer 102

* Prostaglandins are nonhydrolyzable, 20-carbon (eicosanoid) lipids involved in autocrine and paracrine signaling. * They are derived from **arachidonic acid** and often help mediate localized inflammatory responses. * Nonsteroidal anti-inflammatory drugs (NSAIDs) such as aspirin and ibuprofen treat inflammation by inhibiting prostaglandin synthesis.

Question 103

Terpenes

Answer 103

* are precursors in the synthesis of cholesterol and steroid hormones. They are derived from isoprenes

Question 104

Ketone bodies

Answer 104

* are fuel sources that are produced under low glucose conditions. They are derived from acetyl-CoA

Question 105

Catecholamines

Answer 105

* such as epinephrine and norepinephrine are hormones derived from the amino acid tyrosine. * They can play a role in inflammatory responses but generally do so as endocrine signals (acting on cells that are distant from their origin).

Question 106

Chargaff's rules

Answer 106

* Chargaff's rules state that there is a 1:1 nucleotide mole ratio of pyrimidines to purines and that for any double-stranded DNA sample: A=T and G=C G+A = C+T