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50 practice questions for chapters 23-25.
CHEM 108 SI
Session XXIII – 11/29/16
Exam Review IV
SI Leader: Cassidy Sloot
Final Exam Review Session
Thursday, December 8th
3-5pm @ Ag Engineering 100
End of semester evaluation
Like the Facebook page for updates: SDState CHEM 108 SI
What type of lipid is shown?
I have no idea!
What are the similarities and differences between these two lipids?
A: glycerol backbone vs. sphingosine backbone
Both contain a phosphate group (both are phospholipids)
One contains nitrogen in an amide bond
Two fatty acids vs. one fatty acid
Complete this portion of the flow chart.
Following absorption, how does the transport of lipids differ from that of carbohydrates? Why?
A: lipids must be packaged into transport molecules (lipoproteins) before entering the blood stream because they are not water-soluble. Glucose can directly enter the blood stream because it is water-soluble.
How many acetyl-CoA molecules will be produced from a fatty acid with 20 carbons?
Compare the main differences between passive and active transport. Why do we need both?
A: passive – no ATP required; moves molecules from high to low concentration
Active – ATP required; moves molecules from low to high concentration
Our body needs to move molecules in both directions in order to function properly.
Label the type of bonds indicated:
Phosphate diester bond
What sequence of amino acids will this mRNA code for? 5' UCA CAC UUG GGC CCA GUA AUG 3'
Ser His Leu Gly Pro Val Met
Met His Leu Gly Pro Val Met
Ser Leu Gly His Pro Val Met
His Ser Leu Gly Pro Val Met
Match the following processes with the correct nucleic acid involved in each:
2. mRNA, rRNA
replication - DNA
transcription - mRNA, rRNA
translation - tRNA
What kind of problems might a person who has had gastric bypass surgery have when digesting foods after their stomach has been bypassed straight to the small intestine? Why?
A: fats will enter the small intestine too quickly without the churning action of the stomach. Enzymes will not be able to break down lipids fast enough, resulting in steatorrhea (fatty diarrhea)… not pretty.
T/F: guanosine is a nucleoside.
What type of bond connects the sugar and base of a nucleoside?
Phosphate diester linkage
β -N- glycosidic
Is it healthier to have higher levels of HDL than LDL in the blood? Why or why not?
A: yes, HDL removes cholesterol from cells and returns it to the liver while LDL brings cholesterol to cells. High cholesterol levels in cells increases risk for heart disease.
Which lipoprotein transports dietary lipids following a meal?
All of the above
None of the above
What substance is responsible for emulsifying fats during digestion? What is this substance derived from?
A: bile salts, derived from sterol lipids.
Select all terms that apply to this fatty acid:
Trans fatty acid
Name a food that this fatty acid might be found in.
Answer: vegetable oil, olive oil, etc.
What are nucleotides composed of?
nucleoside + phosphate
sugar + base + nucleic acid
What are the three main functions of lipids? How does their polar/non-polar nature facilitate these functions?
A: 1. energy storage
2. cell membrane
their amphiphilic property allows them to separate compounds between environments that are chemically different.
Where do lipids first get hydrolyzed during digestion? Why?
A: small intestine; there are enzymes (lipases) present there.
More transport proteins are found on the surface of cells where glucose must be continually taken in. Why might this be?
A: There are more proteins present for active transport to occur when glucose must be taken in against its concentration gradient.
What must occur immediately before fatty acids can be oxidized?
Transport to the mitochondria
Activated to acetyl Co-A
Activated to acyl Co-A
Hydrolyzed to monoglycerides
What are the two fates of triglycerides following digestion? Under what condition would each occur?
Converted back to triglycerides for storage (excess energy is available in the body)
Converted to acetyl-CoA for generation of energy (body is in a low-energy state)
Label the eicosanoid structures correctly:
Which of the following steroids is involved in glucose metabolism and inflammation? Select all that apply.
List all lipoproteins that can transport cholesterol. Indicate the source of the cholesterol.
LDL – cholesterol synthesized in the liver
HDL – cholesterol from dead cells
Place a dot on the carbon where a phosphate group can attach to form a nucleotide:
What will this mRNA code for? 5' GUU CAA ACU AAC GUC 3'
Gln Thr Asn Val Val
Val Val Thr Asn Val
Val Gln Thr Asn Val
Thr Asn Val Gln Asn
Which of the following can be metabolized to provide energy?
B, C, & D only
What process of lipid metabolism will occur during starvation to provide the brain with energy? Summarize how this occurs.
Answer: ketogenesis; excess acetyl Co-A molecules pair up to form ketone bodies (alternative energy source during starvation).
What forces hold bases together in a DNA double helix?
All of the above
none of the above
Discuss the differences in the fats found in butter and margarine. Which is a healthier source of fat, and why?
A: butter – contains saturated fats
Margarine – contains trans fats
Both types of fats have negative health effects, although I would rather eat saturated fats than trans fats. (Any logical explanation will do for this).
How many steps are there in one cycle of beta oxidation and what is the overall purpose of this cycle?
A: 4 steps; fatty acids are broken down into 2-carbon segments (acetyl-CoA), which can enter the TCA cycle to be used for energy.
What type of lipid is characterized by four fuzed rings?
What pathway occurs when we have enough energy and need to store fat? Select all that apply.
Which of the following are derived from sterol lipids?
How many ATP molecules will this fatty acid produce after complete metabolic catabolism?
What form will the triglyceride be in at each of these locations during digestion?
Duodenum diglycerides, monoglycerides, & free fatty acids
Small intestine free fatty acids
Describe the similarities and differences between a micelle and a liposome, shown below.
A: Micelles form by the clustering of soap or detergent molecules after saponification of fats; hydrophobic inside, hydrophilic outside.
Liposomes form by the clustering of phospholipids into a bilayer; hydrophilic inside and outside.
Both form a spherical structure.
List the 4 lipoproteins in order of increasing density:
Answer: chylomicrons < VLDL < LDL < HDL
Which of the following processes will occur first in lipid digestion?
Activation to acyl Co-A
Transport to mitochondria
Which macromolecule will produce more ATP energy? Describe how you came to your conclusion.
Label each rxn as either hydrolysis or saponification. How is each catalyzed?
What process occurs during step two of beta oxidation, shown below?
A: hydration of the double bond
Is this nucleic acid DNA or RNA and why? What is its function?
A: DNA because it has deoxyribose sugar and ACGT bases; DNA is the nucleic acid that stores genetic information.
Which is a correct pairing of nitrogenous bases in DNA?
How do more double bonds in a fatty acid affect its melting point? Describe why you answered the way you did.
A: decreases melting point; more double bonds weaken the intermolecular forces between fatty acids.
Which of the following is/are contained in the cell membrane?
Why are lipids considered to be amphiphilic (both hydrophilic and hydrophobic)?
A: lipid molecules contain both polar (O, N, P, etc.) and non-polar (C, H) aspects in their structure.
Transport to mitochondri