MCAT Biology Practice Exam Questions
And Correct Answers
The chemical reaction that breaks down all the major macro-molecules - answer✔✔Hydrolysis
What is the strongest type of INTER-molecular bonds? - answer✔✔Hydrogen bonds are the
strongest intermolecular bonds....
diople-dipole bonds are weaker. . . Vander wall bonds are the weakest.
Why is water a liquid at high temperatures? - answer✔✔Hydrogen bonding bonds the water
molocules closer together.
What is an ampipathic molecule? give an Example. - answer✔✔A molecule with both
hydrophobic and hydrophilic regions.
Example: PhoshpoLipid (Phospho=philic,lipid= phobic)
What is a lipid? - answer✔✔A lipid is a biological molecule with low solubility in water.
Lipid means fat. Liposuction is fat removal.
Peptides are NOT lipids.
What are the 6 major groups of lipids? - answer✔✔1) fatty acids...
the next 3 have a 3 carbon back bone:
2) Tri-glyceride
3) Phospholipids
4) Glycolipids
5) Steroids
6) Terpenes - A large class of organic compounds. examples: smelly pine oils, beer hops aroma
and vitamin A.
What is the structure of a Tri-glyceride? - answer✔✔triglicerides are esters. Composed from 3
carbon glycerol backbone and 3 fatty acid chains dangling. Each carbon chain is attached by an
ester bond.
What happens if you add water to an ester group in a Tri-glyceride? How is this reaction rate
increased? - answer✔✔Water cleaves the ester bond into an alcohol and a carboxylic/ fatty acid.
LIPASES speed are the enzyme that speed this reaction.
in terms of water solubility, What is important to know about the longer the carbon chain in a
Tri-glyceride when broken down? - answer✔✔longer carbon chains are less water soluble.
In longer chains the polar carboxylic acid are less significant.
How soluble is a Shorter chain fatty acids? - answer✔✔Shorter chain fatty acids are slightly
water soluble.
explain what is so special about Saturated Fatty Acids........Also, explain the melting point. -
answer✔✔saturated fatty acids have only single, alkane bonds along the carbon chain. They
have a straighter chain and have more van der wall forces, and therefor a higher melting point.
explain what is so special about Unsaturated Fatty Acid.... Also, explain the melting point. -
answer✔✔Unsaturated fatty acids have at least one double bond. They are not saturated with
Hydrogen. they have a LOWER melting point.
At room temperatures unsaturated fatty acids may be oily, like Healthy peanut butter.
explain the phospho-lipids structure. Where are phoshpo lipids common? -
answer✔✔Phospholipids are also built on a 3 Carbon backbone.
One of the carbon has a Phosphate PO4 group. the other 2 carbons have carbon chains attached
by a ester bond.
This is the lollypop of the cell membrane. Esters have 2 oxygens.
What regions are poplar nonpolar in a membrane? - answer✔✔1)the phosphates are Polar, water
lovin, hydro philic regions that face the outside.
2) Nonpolar, hydro phobic carbon chain regions face the inside.
Explain glycolipids structure. - answer✔✔glycolipids have 3 carbon backbone with
2 Carbon chains attached by an ester group.
THe third carbon has a carbohydrate
What do steroids look like? - answer✔✔Slightly amphipathic 4 ring structures
lipids are insoluble. So how do they move through the blood? - answer✔✔They are usually
carried by lipoproteins, like HDL or LDL.
What are the major classes of lipoproteins? - answer✔✔1) Chylomicrons which are the largest
2) VLDLs these are low denstiy, but large.
3) LDLs
4) HDLs. these high density lipids are the smallest, and called good proteins.
What are proteins made up of? - answer✔✔one or more chains of amino acids, perhaps in a
crazy ass arrangement.
describe amino acid structure. - answer✔✔Amino acids have 4 parts attached to the alpha
carbon.
1. the amino group, which is NH2
2. the R group, which is one of 20 choices
3. the Carboxylic acid or C O O
the last thing attached to the Carbon is the Hydrogen.
What are the basic amino acids? - answer✔✔Hal
Histidine
Arginine
Lysine
What are the acidic amino acids? - answer✔✔Aspartic acid and Glutamic acid
What are the nonpolar amino acids? - answer✔✔Poor LTMG Is Venezuelan At Parties
1) Phenylalanine
2) Leucine
3) Tryptophan
4) Methionine
5) Glycine
6) Isoleucine
7) Valine
8) Alanine
9) Proline
What is the primary structure of a protein? - answer✔✔Sequence of amino acids and
Location of disulfide bonds between cistine residues
What is the secondary structure of a protein? - answer✔✔1) Twisting of the alpha helix
What is the tertiary structure of a protein? - answer✔✔3D structure including bending
What is the quaternary structure of a protein? - answer✔✔Multiple proteins in formation
What are the five forces that create tertiary structure? - answer✔✔1) Covalent
2) Disulfide bonding between cysteine residues (Bond itself creates tertiary structure)
3) H bonds
4) HPhob away from cytosol and Hphil interactions towards cytosol
5) Van Der Waals (dipoles, instantaneous dipoles)
What levels of structure are disrupted during the denaturation process? - answer✔✔Secondary -
quaternary
What is the difference between a proteoglycan and a glycoprotein? - answer✔✔Glycoproteins:
1) Made of protein and carbohydrate
2) More stable than proteins
3) Often used in IS to bridge the cellular membrane.
4) Ratio - have more proteins
Proteoglycans:
1) Special class of glycoprotein
2) Contain extra carbohydrates
3) Structure = protein with one or more glycosaminoglycan chains.
4) Ratio - have more carbs
What is the empirical formula for any carbohydrate? - answer✔✔CH2O
Describe the chemical structure of glucose - answer✔✔1) Aldehyde
2) Has 4 chiral carbons
3) Fischer - R, L, R, R
4) 6 membered ring where one of the ring members is oxygen
5) C1 - anomeric carbon
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