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BIOCHEMISTRY (CHEM 212) EXAM 3-STUDY GUIDE 2025-2026. ACTUAL EXAM QUESTIONS WITH ANSWERS, Exams of Chemistry

BIOCHEMISTRY (CHEM 212) EXAM 3-STUDY GUIDE 2025-2026. ACTUAL EXAM QUESTIONS WITH CORRECT DETAILED ANSWERS/PORTAGE LEARNING

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Available from 04/16/2025

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BIOCHEMISTRY (CHEM 212) EXAM 3-STUDY GUIDE
2025-2026. ACTUAL EXAM QUESTIONS WITH CORRECT
DETAILED ANSWERS/PORTAGE LEARNING
Origins of energy
From the sun
Have to use plants as an intermediary attempt
Creates carbohydrates that we can get energy
-
Glucose, use oxygen to help conbust
In plants: photosynthesis
In human bodies: cellular respiration
-
Opposite reactions
Energy Requirements For Life
Energy must be released from food gradually
Energy must be stored in a readily accessible form
Release of energy from storage must be finely controlled so that it is available exactly
when and where it is needed
Just enough energy must be released to maintain body temperature
Energy in a form other than heat must be available to drive chemical reaction that are
not favorable at body repretures
Metabolism
Metabolism: All chemical reactions that take place in an organism
Catabolism: process that breakdown food (lipids, carbohydrates and proteins) to produce
energy
Anabolic: process that requires energy to build molecules from small ones
Yellow is catabolic, blue is anabolic
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Download BIOCHEMISTRY (CHEM 212) EXAM 3-STUDY GUIDE 2025-2026. ACTUAL EXAM QUESTIONS WITH ANSWERS and more Exams Chemistry in PDF only on Docsity!

BIOCHEMISTRY (CHEM 212) EXAM 3 - STUDY GUIDE

2025 - 2026. ACTUAL EXAM QUESTIONS WITH CORRECT

DETAILED ANSWERS/PORTAGE LEARNING

Origins of energy

● From the sun ● Have to use plants as an intermediary attempt ● Creates carbohydrates that we can get energy

  • Glucose, use oxygen to help conbust ● In plants: photosynthesis ● In human bodies: cellular respiration
  • Opposite reactions

Energy Requirements For Life

● Energy must be released from food gradually ● Energy must be stored in a readily accessible form ● Release of energy from storage must be finely controlled so that it is available exactly when and where it is needed ● Just enough energy must be released to maintain body temperature ● Energy in a form other than heat must be available to drive chemical reaction that are not favorable at body repretures

Metabolism

● Metabolism: All chemical reactions that take place in an organism ● Catabolism: process that breakdown food (lipids, carbohydrates and proteins) to produce energy ● Anabolic: process that requires energy to build molecules from small ones ● Yellow is catabolic, blue is anabolic

● Stages of catabolism:

  • DIgestion of macromolecules into subunits ❖ Lipids into fatty acids and glycerol ❖ Carbohydrates into glucose and other sugars ❖ Proteins into amino acids

● TCA

● 6 dif enzymes,

Spiral Sequence

● One enzyme or group of enzymes breakdown a polymer one moner at a time ●

High energy Molecules

● Coenzymes

  • Acetyl-SCoA: high energy form ❖ Coenzyme A ❖ Function as carrier of acetyl groups (2 carbon groups into TCA cycle) ❖ Vitamin: Pantothenic Acid
  • NADH ❖ NAPPH is a derivative, has addition of PH ❖ Derived from Niacin ❖ NAD+ and NADP+ is low energy form ❖ NADH and NADPH high energy form ❖ Used in redox reactions
  • FADH ❖ ADAH2 is high energy form ❖ FAD is low energy form, oxidized ❖ Vitamin: riboflavin ❖ Used in redox reactions
  • An organic compound that is required for catalysis
  • Derived from water soluble vitamins ● ATP
  • Energy currency of cell
  • Delta g is 7.3 kcal/mol
  • Considered an energy store
  • Stable at ph 7
  • Requires an enzyme for hydrolysis: other anhydrides break down in water
  • Easy bond to leave: negative charge on O repel each other so bonds are strained
  • Precursor for other high energy molecules
  • Uniersial energy works in all cells
  • People typically generate and consume 3 moles of ATP/hr ● Endergonic reaction coupled with exergonic reaction to achieve a total free energy charge that is negative

Classification of Carbohydrates

● Carbohydrate

  • A member of a large class of naturally occurring polyhydroxy ketones and aldehydes ● Monosaccharide (simple sugar)
  • A carbohydrate that cannot be chemically broken down into a smaller sugar by hydrolysis with aqueous ……. ● Disaccharide
  • A charboydiriate composed of two monosaccharides
  • covalent bonds ● Polysaccharide (complex carbohydrate)
  • A carbohydrate which is a polymer of monosaccharides ● Aldose
  • A monosaccharide that contains an aldehyde group
  • Ends in alcohol group
  • Glucose: blood sugar ● Ketose
  • A monosaccharides that contains a ketone group
  • Ends in alcohol group
  • Fructose: fruit sugar ● Names ending in - ose indicates a carbohydrate

Isomers of Carbohydrates

● Isomers are compound with the same molecular formula but different 3D structure ● D and L isomers (enantiomers)

  • Monosaccharides that are mirror images of one another
  • D form of all monosaccharides is the most prevalent in nature
  • D: OH group on last chiral carbon is on the right side
  • L: OH group is on the left side ● Diastereomers
  • Diastereomers: stereoisomers but not mirror images of one another
  • of isomers is 2 to the n

  • Whatever carbon is bonded to the Oh group on fisher projection, is the anomeric carbon...determines where the hhh gets trapped ❖ Alpha vs beta form
  • Hemiacetal: a carbon atom bonded to both and OH and OR group ● Anomers
  • A monosaccharide has alpha and beta isomers that occur in different ratios in nature. The beta form of glucose is most prevalent in nature Reactions of Carbohydrates

● Can be a possible receptor ● Will either bind to a Asn or Ser or Thr residue ● Carbohydrates determine blood type

  • Will bind in certain configuration that makes the different blood groups
  • They have different groups which explain the inability to transfuse different blood groups
  • AB is the universal recipient

Cellulose

● Most abundant polysaccharide in the world ● Beta-d-glucose units linked by b1,4 glycosidic bonds ● Fibrous substances that provides structure in plants ● Humans do not have enzymes that is necessary to hydrolyze cellulose ● Buct can be digestible as indigestible fiber ● Als used to make material for houses, paper, cardboard

Plants starches

● Amylose:

  • 20% of plant starch
  • Polymer of a-1,4 D-glucose
  • Fully digestible polymers of glucose
  • Present only in plants ● Amylopectin
  • 80% of plant starch
  • Energy storage in seeds
  • Polymer of a-1,4 D-glucose with branches at a-1,6 D glucose

Glycogen

● Found in animals ● energy storage (liver and muscles) ● Similar to amylopectin found in plants ● But it has more branches and is much larger

Carbohydrate digestion

● In second section, a pancreatic a-amylase is produced ● In third section, absorption and through small intestine ● Glycolysis: conversion of glucose to pyruvate ● Gluconeogenesis: synthesis of glucose from amino acids, pyruvate, and non-carbohydrates ● Glycogenesis: synthesis of glycogen from glucose ● Glycogenolysis: breakdown of glycogen to glucose ● Pentose phosphate Pathway: conversion of glucose to five carbon sugar phosphates ●

Glycolysis

● Energy investment phase (steps 1 - 5)

  • Investing 2 molecules of ATP getting out 4 molecules of ATP ● Energy generation phase (6-10)
  • Generation of a super-high=energy compound Production of 2 ATPs
  • Pathway for synthesis of glycogen
  • Occurs when there's excess amount of glucose 6 phosphate ● Glycogenolysis
  • The pathway for breakdown of glycogen to free glucose
  • Occurs in muscle cells when there is an immediate need for energy
  • Occurs in the liver when blood glucose levels are low

Signalling cascade

  • Messenger moleuve or neurotransmitter
  • Binds to certain cell to turn it on and signal
  • Hormone binds to surface of the cell to signal a biochemical response
  • Inulin replenishes energy stores and glucagon breaks down energy stores to make new glucose
  • Glucose is gone so secrete glucagon
  • Pancreas: sensus blood glucose levels and releases according hormos
  • Liver: release or extracts glucose from the blood

Glucagon/epinephrine

● Hormone that when bound to receptors on the surface of cell cause activation of adenylate cyclase within the cell ● Glucagon is a peptide hormone whose main site of action is liver ● epinephrine/adrenaline is an amino acid derivative with receptors mainly on muscle ● Both signaling cause glycogen to breakdown, glucose to be synthesized and blood glucose levels to increase ● Accomplished by

  • Phosphorylated glycogen synthase to deactivate it (MAKES IT)
  • Phosphorylated glycogen phosphorylase to activate (BREAKS DOWN)

Insulin

● Insulin is a protein hormone whose receptor is a pryose kinase present in most cells ● It signaling causes glycogen to be synthesized and blood glucose levels to decrease ● Accomplished by

  • Phosphorylated glycogen synthase to activate
  • Dephosphorylation glycogen phosphate to deactivate it

Regulation of glycogen synthase

● Starts with hexokinase ● In liver NOT feedback inhibited by glucose - 6 - P ● Isomerase brings next step to compilation ● Regulation of glycogen synthase

  • Non hormonal: glucose- 6 - P is a positive allosteric regulator
  • Hormonal: epinephrine and glycogen inhibits glycogen synthesis
  • Insulin stimulates glycogen synthesis ● ● Glycogen storage diseases
  • Von gierke's disease: glucose - phosphate deficiency
  • Enlarged liver
  • Dangerously low blood sugar ● Mcardles
  • Muscle glycogen defincues
  • The normal pancreas in plasma lactate following exercise is absent
  • Muscles are damaged because of inadequate energy supplies and glycogen accumulation blood analysis shows increased levels of creatine phosphokinase, aldolase, myoglobin ● Pentose Phosphate Pathway ● AN alternate pathway for carbohydrate oxidation ● Anabolic role ● Primary functions is to provide NADPH for biosynthesis pathways
  • The provide ribose 5 - phosphate for nucleic acid biosynthesis
  • Occurs when cell is dividing
  • Metabolism of dietary pentose sugars ● Cori Cycle
  • On covering on fruits

● Chosestoreal

  • Ridged ring like structure ● Prostaglandin
  • 20 carbon unit
  • Contractions are due to type of prostaglandin Fatty Acids ● Saturated fatty acids
  • Long alkane
  • A Long chain carboxylic acids containing only C-C single bonds
  • Beta carbon will be catalyzed
  • Can pack together very densely
  • No double bonds
  • Chains pack together as a result of hydrophobic interactions and van der waal forces ● Unsaturated fats
  • A long chain carboxylic acid containing one or more C-C double bonds
  • Unsaturated fatty acids: one double bonds
  • Polyunsaturated fatty acids: have more than one c-c double bonds
  • Cis is naturally occuring unsatuated fatty acids
  • Because of kinks, cant pack together
  • Have low melting points
  • Linoleic are two essential unsaturated fatty acids ● What determines the melting temp
  • Chain length: the longer the carbon chain the higher the melting temp
  • Degree of saturation: the more double bonds the lower the melting temperature Fat vs. Oil ● Two types of TAG’s: fat and oil ● Non polar, hydroponic, non ironic ● Animal fat contains more saturated fats than plant oil ● Because of the high degree of saturation in animal fat, it is a solid at room temp

● Because of the higher content of unsaturated fatty acids in plant oil it is commonly liquid at room temperature ● Double bonds in naturally occurring fatty acids are always “cis” in configuration ● Form of the double bonds in unsaturated are CIS

Reactions with triglycerides

● Saponification: hydrolysis of fats and oils carried out by strong aqueous bases to form soaps

  • Fat → boil in presence of sodium hydroxide and makes glycerol and fatty acids salts
  • Laundry detergent is anionic
  • Non ionic - cold water/sanitizers/toilet bowl cleaners
  • Catonic is fabric softener ● Hydronigation
  • Unsaturated fatty acid to saturated fatty acid
  • Ionine number=the number of grams of iodine which will react with 100g of fat or oil
  • Higher the ionization number the more double bonds
  • Trans fats are byproducation of of trans fatty acids
  • Trans fatty acids do not exist in nature, increases LDL and decreases HDL and increases coronary heart disease

Cell membranes

● Phospholipids

  • Hydrophobic region and hydrophilic region
  • X can be replaced with choline, serine, and ethanolamine
  • Also can be replaced with sugar (inositol) ● Phospholipids congreates away from water

Cholesterol

● Four fused rings ● Our bodies can synthesize cholesterol ● Synthesized from acetyl CoA ● Precursor for steroid hormones, vitamin D, and bile ● 50% found in cell membranes Biosynthesis of fatty acid ● Link between carbohydrates, lipid, and protein metabolism

Lipid transport in the blood

● Lipoprotein: lipoprotein contains a core of neutral lipids, including triacylglycerols and cholesterol esters ● Starting the core is a layer of phospholipids in which the varying proportions of proteins and cholesterol are embedded ● ● Density and composition of lipoproteins: based on amount of proteins they have within them ● Chylomicrons: transports dietary lipids ● VLDL: transport of synthesized TAGS ● LDL: transport of endogenous lipids (cholesterol) to the tissues (receptor mediated) (bad)

● HDL: Transport of lipids and cholesterol from cells in the vasculature to liver (good) ● VLDL and LDL ---> atherogenic ● HDL is anti-atherogenic

TAG Metabolism

● Storage of TAGS is regulated by insulin and glucagon ● Storage and synthesis of TAGS: high levels of insulin stimulate TAG synthesis

  • Step 1: glycolysis produces DHAP
  • Mobilization (hydrolysis) of TAGS: low insulin levels and high glycogen levels simulate triacylglycerol lipase in adipocytes

Fate of Fatty Acid in Cell

● Activation of FA by the addition of CoA: energy cost 2 ATPs ● Can be converted into TAGS, cholesterol, or phospholipids ● Bnds to carnitine for transport into mitochondrial matrix via pore formed by large enzyme complex ● Oxidation of FA with even number of carbon to acetyl-SCoA ● ●

Ketone Bodies and Ketosis

● Increase in FA breakdown causes increase in Acetyl-SCoA, which overlaps the citric acid cycle causing the production of ketone bodies

● Thrombosis a blood clot that forms in blood vessel ● ● Prevention

  • Lower cholesterol: form diet and synthesis ❖ Cholesterol is only found in animal products
  • Increase HDL levels ❖ Aerobic exercise, women have high levels

❖ Lose weight ❖ One glass of alcohol/day ❖ Eat more unsaturated FA instead of saturated

Protein Metabolism

● Protein digestion

  • Comes from diet
  • Put into mouth and chew
  • In stomach, ph (2) of stomach breaks down covalent bonds and potent unfolds
  • Peptin brakes more bonds
  • Small intestine signals releases of protease, more bonds are chewed
  • Amino acids are released into bloodstream ● Proteins through digestion dn old proteins from cells are broken down into amino acids to form amino acid pool ● Pool amino acids can either got to cells to form new proteins of they are broken down into the following ● Fate of the amino group
  • Step 1: transamination ❖ Amine group is transferred to a-keto acid which is converted to a whole new amino acid ❖ Alpha-ketoglutarate (TCA cycle intermediate, product of step 3 in TCA cycle) ❖ Purpose it to remove the amino group format the amino acid ❖ Occurs in cytosol in cells ❖ Reversible
  • Step 2: oxidative deamination ❖ Purpose is to recycle glutamate in order to regenerate alpha- ❖ Result: amino group of an amino acid has been converted to ammonium ion
  • Urea cycle ❖ Purpose is to convert toxic NH4 (which converts to equally tocis ammonia) into non toxic urea that can be transport to kiddenu and excreted from body ❖ Combines the CO2 from TCA cly with NH4 to make urea in a four step cyclic metabolic pathway