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Enzymes
Replication
Transcription
the Genetic Code
Translation
100
Of the 4 types of macromolecules that we studied earlier in the year, what type is an enzyme?
What is a polypeptide (or protein)
100
Which enzyme "upzips" the double helix?
What is helicase?
100
What is the name of the enzyme that assembles the RNA transcript?
What is RNA polymerase?
100
What is a codon?
What is 3 nucleotides on the mRNA that codes for a particular amino acid.
100
Where does translation occur in the cell?
Where is in the cytoplasm of the cell.
200
What is the active site of an enzyme?
What is the site where the substrate(s) fits
200
What is meant by the statement that DNA replication is semiconservative?
What is the each newly-replicated double helix contains an older template strand and a new strand complementary to it.
200
What direction does transcription occur?
What is it follows the DNA template in the 3' to 5' direction and assembles the RNA in the 5' to 3' direction.
200
What is the anticodon of GAC?
What is CUG?
200
How do the ribosomal subunits bind to the RNA?
What is the small subunit attaches first with the help of the 5' cap, then the tRNA with methionine comes to the start codon (AUG) and the large ribosomal subunit clamps down on top.
300
Describe the effect of substrate concentration on enzyme activity (when there is a constant amount of enzyme).
What is the enzyme activity gradually rises until it plateaus. The cause for the plateau is that the active sites of the enzyme are all occupied, so the rate stays constant.
300
Where are the hydrogen bonds in the DNA double helix?
What is between complementary nitrogenous bases.
300
How is RNA different from DNA?
What is it is single-stranded as opposed to double-stranded, it has a ribose sugar instead of deoxyribose, and it has the base, uracil, instead of thymine.
300
The start codon also codes for which amino acid?
What is methionine (Met)?
300
What are the 3 sites of the ribosomal complex and what order do the tRNA's move through them.
What is tRNA's attach first to the A (aminoacyl) site, then go to the P (peptidyl) site, and finally to the E (exit) site.
400
Explain what is meant by enzyme-substrate specificity.
What is the shape of a substrate is specific to the shape of a particular enzyme's active site. For the most part, enzymes work only on a particular substrate, although there are some exceptions. For example, competitive inhibitors can have slightly different shapes, but can still fit in the active site. Also, many enzymes exhibit "induced fit", which means they can rearrange slightly after binding to fit different substrates.
400
What is the role of DNA polymerase I?
What is it removes RNA primer and replaces it with DNA.
400
How does the sense strand of DNA compare to the RNA transcript?
What is the sequence of nucleotides is the same, except that uracil is replaced by thymine.
400
What 2 types of genetic mutations do you have if you remove 2 nucleotides from the code?
What are "deletion" and "frameshift". Could also end up with a missense mutation and a nonsense mutation.
400
What happens at termination of translation?
What is one of the STOP codons is reached and a water molecule is attached to the end of the polypeptide. This causes the polypeptide to break away from the mRNA and ribosome immediately.
500
Distinguish between competitive and noncompetitive inhibitors and give an example of one.
What is competitive inhibitors stop the action of enzymes by blocking the active site (they have similar shapes to the substrate). Noncompetitive inhibitors bind at a different site from the active site (an allosteric site) and change the shape of the active site.
500
What are Okazaki fragments?
What are short sections of DNA formed during DNA replication on the lagging strand.
500
What are they 3 stages of transcription and what happens at each?
What is it begins with initiation, in which the RNA polymerase attaches to DNA at the promoter, followed by elongation, in which the RNA transcript grows 1 nucleotide at a time 5' to 3'. The nucleotides are complementary to the DNA template and uracil is used instead of thymine. Finally, termination occurs when a terminator is passed. The transcript is cut and the RNA polymerase continues for a bit longer.
500
What is meant by the statement "the genetic code is redundant but unambiguous."
What is the genetic code is redundant because there are multiple codons coding for most amino acids, but it is unambiguous because any given codon codes for only one amino acid. In other words, there are multiple ways to code for the same polypeptide, but any given genetic code has only one resultant amino acid sequence.
500
What is the function of aminoacyl synthetases?
What is they hook up the tRNA's with their proper amino acids. There are 20 of these enzymes in the cytoplasm. This is called "charging" the tRNA.