MCAT Biology Practice Questions
the chemical reaction that breaks down all the major macro-molecules - CORRECT
ANSWER-Hydrolysis
What is the strongest type of INTER-molecular bonds? - CORRECT
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? - CORRECT ANSWER-Hydrogen
bonding bonds the water molocules closer together.
What is an ampipathic molecule? give an Example. - CORRECT ANSWER-A
molecule with both hydrophobic and hydrophilic regions.
Example: PhoshpoLipid (Phospho=philic,lipid= phobic)
What is a lipid? - CORRECT 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? - CORRECT 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? - CORRECT 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? - CORRECT 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? - CORRECT 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? - CORRECT ANSWER-Shorter chain
fatty acids are slightly water soluble.
explain what is so special about Saturated Fatty Acids........Also, explain the melting
point. - CORRECT 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. - CORRECT 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? -
CORRECT 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? - CORRECT 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. - CORRECT 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? - CORRECT ANSWER-Slightly amphipathic 4 ring
structures
lipids are insoluble. So how do they move through the blood? - CORRECT
ANSWER-They are usually carried by lipoproteins, like HDL or LDL.
What are the major classes of lipoproteins? - CORRECT 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? - CORRECT ANSWER-one or more chains of amino
acids, perhaps in a crazy ass arrangement.
,describe amino acid structure. - CORRECT 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? - CORRECT ANSWER-Hal
Histidine
Arginine
Lysine
What are the acidic amino acids? - CORRECT ANSWER-Aspartic acid and Glutamic
acid
What are the nonpolar amino acids? - CORRECT 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? - CORRECT ANSWER-Sequence of
amino acids and
Location of disulfide bonds between cistine residues
What is the secondary structure of a protein? - CORRECT ANSWER-1) Twisting of
the alpha helix
2) Beta sheets
What is the tertiary structure of a protein? - CORRECT ANSWER-3D structure
including bending
What is the quaternary structure of a protein? - CORRECT ANSWER-Multiple
proteins in formation
What are the five forces that create tertiary structure? - CORRECT 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? - CORRECT
ANSWER-Secondary - quaternary
What is the difference between a proteoglycan and a glycoprotein? - CORRECT
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? - CORRECT ANSWER-CH2O
Describe the chemical structure of glucose - CORRECT 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
Where is glucose stored in alpha linkages? - CORRECT ANSWER-Animals
(glycogen) and plants (starch)
Who stores glucose with beta linkages? - CORRECT ANSWER-beta linkages are in
Plant cell walls. Cellulose.
What molecule is added to glycogen, starch, and cellulose to break off individual
glucose molecules? - CORRECT ANSWER-Water
Hydrolysis reaction.
and enzymes like amylase speed it up.
What are the four macromolecules? - CORRECT ANSWER-Protein
Lipids
Carbohydrates
Nucleic acids
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