EXAM 1 Flashcards
Lactose is a disaccharide where galactose is linked to glucose through a beta 1,4 glycosidic linkage from carbon 1 of galactose to carbon 4 of glucose. Galactose is a structural isomer of glucose and the only difference is in the orientation of the hydroxyl group on carbon 4. In the beta orientation, the hydroxyl on carbon 1 is in the upward position. Draw the structure of lactose.
The formula weight of glucose is 180. Because galactose is a structural isomer of glucose if formula weight is also 180. What is the formula weight of galactose.
342
Briefly explain what the endosymbiotic theory is, and describe some of the evidence that supports it.
It is the theory that eukaryotic cells were created by a pro-eukaryotic cell engulfing a prokaryote and that the structures we know as mitochondria and chloroplast underwent this to form. The evidence to support is that they each have their own DNA that is single stranded like prokaryotes and circular similar to some bacteria.
What is the pH of a solution that is 1 micromolar H+? How much more acidic would a 1 millimolar solution of H+ be?
- pH of 6
- 1000x more acidic
The nerve cell that extends from the tip of the big toe to the base of the spine in a very tall person is 1 meter long. A typical bacterial cell is one micrometer long. How many bacteria can fit along the length of this nerve cell?
1,000,000
Draw a dipeptide bond where serine is linked to alanine through a peptide bond. The R group on alanine is simply a methyl group. Remember to include all charges at pH 7.
Draw two cysteines joined by a disulfide bond. The R group on cysteine is similar to that of serine, but it has a sulfhydryl group instead of a hydroxyl group. Remember to include all charges at pH 7.
Suppose you discover a new drug that is effective at treating monkeypox. You call this drug poxivir and determine that it has a formula weight of 300. How much of this drug would you need to make 100 milliliters of a solution that is 100 millimolar poxivir?
3 grams
Briefly describe the two major types of secondary structure found in proteins.
alpha helices - polypeptide chains with amino acid side groups attached, coiled by hydrogen bonds
beta sheets - sheets of polypeptides that can be either parallel or antiparallel, they can be very rigid and are sometimes used as backbones
Explain why most catabolic reactions can proceed without an input of energy, while many anabolic (or biosynthetic) reactions require the input of energy.
- catabolic reactions are breaking things down and release energy so they do not need energy to start they are spontaneous
- anabolic reactions synthesize things from smaller things which requires energy
What kind of molecule is this? You do not have to give its specific name, just the general class of molecules it belongs to.
polypeptide
Consider the portion of protein shown here.
a. Circle all of the peptide bonds shown.
b. If this portion of the molecule was in alpha helical form, would it be part of the protein that spanned the cell membrane? Why or why not?
c. If this portion of the molecule was in a single strand beta strand, would it be part of the protein that spanned the cell membrane? Why or why not?
b. yes, if it was put in alpha helical form it could part of the protein that spanned the cell membrane, this is because R groups on the outside are non polar and the polar groups would be “hidden” inside
c. no, if this was a single beta strand it would not be part of the proteins that spanned the cell membrane, this is because the R groups are too polar
Suppose you discover a new compound that acts as a potent inhibitor of enzyme that is absolutely required for most bacteria to grow, but it is not present at all in eukaryotic cells. Such a compound could be a great antibiotic. How could you determine whether this new compound acted as a competitive inhibitor or a noncompetitive inhibitor? Feel free to use graphs to illustrate your answer.
You could collect data and compare it to the normal data and see which line it looks like.
Competitive inhibition acts by decreasing the number of enzyme molecules available to the substrate.
Noncompetitive inhibitors do not bind to the active site but change the conformation of the enzyme so it cannot make its product.
In this biochemical pathway, substrate A is transformed through various branches of the pathway to the end products D, J, and Z. Intermediate compounds and products are labeled with a letter, and enzymatic steps are indicated by numbered arrows.
a. Suppose product Z exerts feedback inhibition of this pathway to limit its production when concentration of Z are sufficient for cellular needs. b. b. Which enzymatic step ( give its number) is it most likely to affect in this way, and why?
Which enzymatic step would product J be most likely to affect by feedback inhibition, and why?
c. Which enzymatic step would product D be most likely to affect by feedback inhibition, and why?
a. It is most likely going to affect step 5 because it does not want to block production of product D or J
b. J would affect step 7
c. D would affect step 3
Define the following enzymatic terms as they relate to enzymatic reactions -
V max -
Km - Substrate - Action barrier - Allosteric Inhibition -
V max - max reached when the enzyme has been completely saturated
Km - substrate concentration at 1/2 V max
Substrate - solution, molecule, enzyme being catalyzed
Activation barrier - barrier that must be crossed in order for the activation of a reaction to occur
Allosteric Inhibition - a regulatory molecule binds to an enzyme (not at active site) and causes a conformational change that doesn’t allow it to work (involved in feedback regulation)
draw the structure of glucose in the alpha and beta conformations.
