Untitled Flashcards Set

CHEM 1204 Exam 2 Practice Problems ANSWER KEY 

1. Previously learned ochem

1. List the functional groups

Alkene, alkyne, aldehyde, carboxylic acid, ketone, ester, ether, amine, amide 

2. What are chiral atoms?

A carbon atom that is attached to four different groups or atoms

3. Which of the following molecules has a chiral center?

   1.  CH3-CH2-CH3

   2.  CH3-CH(Br)-CH2-CH3

   3. CH3-CH2-CH2-CH2OH

   4. CH3-CH2-COOH

4. What is the electron & molecular geometry of methane?

Electron: tetrahedral

Molecular: tetrahedral

5. What is the electron & molecular geometry of carbon dioxide?

Electron: linear

Molecular: linear

6. What is the electron & molecular geometry of water?

Electron: tetrahedral

Molecular: bent 

7. What would the bond angle be in a trigonal planar molecule? 

120

8. What would the bond angle be in a tetrahedral molecule?

109.5

2. Lipids

1. What are the general functions of lipids? (list as many as you can)

Energy storage, membrane structure, signaling

1. What functional groups are found in lipids

Carboxyl, ester 

2. What organic chem reactions can be done to these functional groups?

Esterification, hydrolysis, and hydrogenation

2. Which of the following would lipids be soluble in?

   1. Water

   2. Ethanol

   3. Hexane

   4. Acetic acid 

3. Explain the polarity and molecular interactions involved in the question above

Hexane is a nonpolar molecule, because it consists of only carbons and hydrogens. 

Since it lacks a F, O, N atom(s) and strongly electronegative molecules, it can’t have hydrogen bonding or dipole-dipole interactions. 

4. Identify the different classes of lipids

Fatty acids, triacylglycerides, phospholipids, steroids, waxes, eicosanoids, glycolipids, lipoproteins 

5. Which isomer is naturally occurring? 

cis

1. How is the other isomer made if its not natural?

Made via a hydrogenation reaction. This reaction forces the natural “bent” (cis) bond to straighten out → trans

6. Where is vitamin D synthesized and stored?

Made in the skin when exposed to sunlight (then sent to the liver to be converted into a form that the body can use). 

Stored in fat tissues and liver 

7. What factors affect melting point?

*stronger the force, higher the melting point

Ionic bonds > hydrogen bonding > dipole-dipole > london dispersion

Larger molecules have higher melting points (because of the increase in london dispersion forces)

Linear molecules have a higher melting point, because they can pack tightly

Polar molecules have higher melting points

8. Why do unsaturated lipids have lower melting points than saturated lipids?

Saturated fats have no double bonds; they are linear. The bends in the fatty acid chains of unsaturated lipids dont allow for close packing, and gives them a lower melting point

3. Steriods + others related 

1. Draw out a steroid backbone

2. Bile salts are derived from which lipid molecule?

Cholesterol 

3. What is the relationship between cholesterol and bile salts?

Bile salts are derived from cholesterol when the liver modifies its structure. 

Bile salts help emulsify fat and regulate cholesterol levels

Excreting bile salts is a way that the body removes excess cholesterol

4. Are bile salts soluble in water?

They are both hydrophilic and hydrophobic, making them partially soluble in water. 

5. What does cholesterol help with regarding cell membranes?

Maintains structure and function of cell

1. What are the functions of cholesterol?

Regulating membrane fluidity, providing structural support between the phospholipid bilayer, precursor to steroid hormones/vitamin D, needed for myelin sheath formation

6. Explain the storage and release of bile salts

Bile salts are made in the liver and stored/released from the gallbladder.

7. Roles of calcium

bone/teeth health, muscle function, nerve transmission, hormonal secretion, cellular functions

8. Roles of phosphorus

Energy metabolism, dna/rna synthesis, cell membrane, muscle function, bone remodeling and mineralization

9. Why is the liver important for the synthesis of vitamin D?

If the liver isn’t functioning properly, it would struggle to convert vitamin D into its active form, possibly leading to rickets 

10. What is the main function of glucocorticoids?

Regulate metabolism and help body’s response to stress 

11. What is the main function of mineral corticoids?

Ion balance, blood pressure

12. What is the primary glucocorticoid and what does it assist with?

Cortisol, commonly known as the “stress hormone” and helps the body respond to stress by increasing glucose levels & breakdown of fats/proteins

13. What is the primary mineral corticoid and what does it assist with?

Aldosterone, assists in maintaining electrolyte/fluid balance, and blood pressure 

14. List out the biochemical influences for sex hormones (estrogen, testosterone) and vitamin D 

Estrogen: regulation of menstrual cycles, reproductive tissue development, cognitive, bone, cardiovascular health

Testosterone: development of male reproductive tissues, muscle growth, fat distribution, bone health

Vitamin D: bone health, calcium & phosphate regulation, immune system activity, muscle function, 

15. List the water soluble & in-soluble vitamins

Water soluble: Vitamin C and B

Fat soluble: Vitamin A, D, E, and K

4. Bonds and reactions

1. What does a lipid lack if it cannot be hydrolyzed?

Lack an ester, amide, or glycosidic bond

2. List the hydrolyzable lipids

Triglycerides, phospholipids, glycolipids, sphingolipids, waxes

3. List the non-hydrolyzable lipids

Sterols, fat-soluble vitamins, lipid-soluble hormones

4. What is the structure of sphingomyelin composed of?

Sphingosine backbone, fatty acid, phosphate group, choline (*or other group) attached to phosphate 

5. List the hydrolyzable bond(s) on sphingomyelin

Amide, phosphodiester 

6. Whats the relationship between ceramide and sphingolipids?

Ceramide is a building block of sphingolipids, serves as a precursor

7. What would the product be if you hydrated ethene?

Ethanol 

8. What happens if you hydrogenate an unsaturated fatty acid?

You get a saturated fatty acid

9. Explain saponification

Chem reaction when a fat reacts with a strong base (such as NaOH), and the result is soap and glycerol

10. Explain what the saponification of vegetable oil would produce

Soap and glycerol

11. How do soap molecules emulsify oils?

Emulsify via their (both) hydrophobic and hydrophilic parts. The hydrophobic tails of soap molecules bind to oil, and the hydrophilic heads interact with water. This allowes the oil to be washed away from surfaces.

5. Fatty acids

1. Arachidonic acid is a carbon, omega- fatty acid

20, 6

2. What is arachidonic acid involved in?

Precursor to eicosanoids, inflammatory response

3. What food(s) have omega-3 fatty acids?

Fortified foods, fatty fish

4. Functions of omega-3 fatty acids

Reduce inflammation, improves heart health, brain function, eye health, skin

5. What food(s) have omega-6 fatty acids?

Vegatable oils, nuts, processed foods 

6. Functions of omega-6 fatty acids

Inflammatory response, brain function, skin health

7. List the common diseases linked to omega-3 & omega-6 fatty acid imbalance

Heart disease, inflammatory conditions, mental health disorders 

8. How are prostaglandins formed?

From arachidonic acid 

1. List the physiologic effects of prostaglandins

Inflammation, pain sensation, fever, clotting

9. What do all prostaglandins have in common with their structure?

All cyclic compounds with a 5-membered ring, derived from arachidonic acid, have a hydroxyl group attached to ring structure 

1. What determines their differences?

Functional groups, enzyme activity

2. Understand the Name format differences PGF2, PGE1 etc

P stands for prostaglandin

Letter refers to the specific type of prostaglandin

The number indicates the number of double bonds in the side chain

PGE indicates prostaglandins that have an alcohol group of carbon 15

PGF indicates prostaglandins that have a ketone group on carbon 9 

10. What is the relationship between aspirin and prostaglandins?

Aspirin inhibits the enzyme that is responsible for converting arachidonic acid innto prostaglandins 

11. What are waxes composed of? What is their structure?

Waxes are esters formed from the ration between a fatty acid and long-chain alcohol

Structure: ester bond between the carboxyl group of the fatty acid bonded to the hydroxyl group of the alcohol

12. Does wax have a high or low melting point? Why? 

High melting point, because they have long hydrocarbon chains with intermolecular forces

6. Membrane components 

1. Why are phospholipids an important characteristic of membranes?

Because they have both hydrophilic and hydrophobic regions, they are able to form a bilayer, which then allows the cell to be selective permeable

1. What lipid type has the largest % in a membrane?

Phospholipids

2. Why is cholesterol an important characteristic of membranes?

Membrane fluidity regulation, membrane integrity, 

3. List and explain the two types of membrane proteins 

Integral- embedded within bilayer

Peripheral- not embedded, rather attached to hydrophilic heads

4. Function of carbohydrates on membranes?

Cell recognition, protection, signal reception

5. What type of membrane transport do: glucose, amino acids, Na+, K+, and Ca2+ use? Why?

Glucose uses facilitated, because its too large and polar to freely diffuse, but transporters move glucose down concentration gradient 

Amino acids use active transport, because they are polar molecules

Na+, K+, Ca2+ use active transport, because these are kept in an imbalance (think about how the imbalance changes via action potential), and need to be moved against their concentration gradient.

6. What are chylomicrons and what do they do?

Chylomicrons are large lipoproteins that are responsible for transporting lipids from the intestine to various tissues.

7. What differentiates VLDL, LDL, and HDL from one another, and where does each transport to/from?

VDLD- delivers triglycerides from liver to tissues

LDL- transports cholesterol from liver to tissues –often contributing to plaque formation if too much-

HDL- removes excess cholesterol from tissues and returns it to liver for disposal

7. Medical associations

1. What lipids are associated with an increased risk for cardiovascular disease?

High levels of LDL, triglycerides, low levels of HDL

1. What 4 other conditions are associated with these lipids?

Metabolic syndrome, type 2 diabetes, hypertension, atherosclerosis

2. What is atherosclerosis?

Condition where fatty deposits, cholesterol, and other substances build up on inner walls of arteries causing them to become narrower that constricts blood flow.

3. Explain fatty liver disease

Buildup of fat in the liver cells from an imbalance between fat intake and fat breakdown in the liver, often leading to obesity, insulin resistance, etc..

4. How is insulin resistance (type 2 diabetes) relayed to triglycerides and cholesterol?

Insulin resistance is when the body’s cells become less responsive to the effects of insulin → often leads to type 2 diabetes with blood glucose levels abnormally high. 

Insulin resistance leads to increase in triglyceride levels (insulin helps ocntrol the breakdown of fats, but if body becomes resistant, fat metabolism is impaired).

Insulin resistance can also lead to formation of (small) LDL particles (resuling in more LDL and less HDL), which is a contributor to atherosclerosis and cardiovascular diseases.

5. List two neurological disorders that are related to lipids

Alzheimer’s disease- lipid metabolism (esp cholesterol) is disrupted → high cholesterol levels →  lipid abnormalities that affect brain’s ability to clear amyloid plaques → alzheimers disease

Multiple sclerosis (MS)- autoimmune disease wheere immune system attacks (the lipid-rich) myelin → impairs transmission of signals along nerve fibers → causing inflammation, damage, and poor nerve function.