1.
Select the CORRECT statement about DNA and RNA:
Correct Answer
D. Thymine is absent in RNA, but is present in DNA.
Explanation
This statement is accurate because DNA uses thymine as one of its four nitrogenous bases (along with adenine, cytosine, and guanine), whereas RNA uses uracil instead of thymine. This difference is key in distinguishing DNA's double-stranded structure from RNA's typically single-stranded form, affecting their respective functions in genetic coding and protein synthesis.
2.
The sequence of DNA 3'-ACCGTTACC-5' would be transcribed as follows:
Correct Answer
B. 5'-UGGCAAAUG-3'
Explanation
The given sequence of DNA, 3'-ACCGTTACC-5', would be transcribed into its complementary RNA sequence. In RNA, the base thymine (T) is replaced by uracil (U). Therefore, the complementary RNA sequence would be 5'-UGGCAAAUG-3'.
3.
5' and 3' refer to:
Correct Answer
B. The direction of the DNA strand.
Explanation
The terms "5'" and "3'" refer to the directionality of the DNA strand. DNA is made up of nucleotides, and each nucleotide has a sugar molecule with a phosphate group attached at the 5' carbon and a hydroxyl group attached at the 3' carbon. The numbering system is used to indicate the order in which the nucleotides are linked together in the DNA strand. The 5' end is where the phosphate group is located, and the 3' end is where the hydroxyl group is located. This directionality is important for DNA replication and transcription processes.
4.
Which enzyme is incorrectly paired with its function?
Correct Answer
D. RNA polymerase - adds RNA nucleosides to a growing rRNA strand
Explanation
mRNA strand, not rRNA.
5.
The leading strand and the lagging strand have roles in:
Correct Answer
C. DNA replication
Explanation
The leading strand and the lagging strand have roles in DNA replication. The leading strand is synthesized continuously in the 5' to 3' direction, while the lagging strand is synthesized discontinuously in short fragments called Okazaki fragments. These strands work together to replicate the DNA molecule during cell division.
6.
The molecule(s) that does not act to make a new DNA molecule is/are:
Correct Answer
A. RNA polymerase
Explanation
RNA polymerase is not involved in DNA replication. RNA polymerase is responsible for transcribing DNA into RNA during the process of transcription, not for making a new DNA molecule. DNA replication involves enzymes such as helicase, gyrase, SSBs, and primase, which are responsible for unwinding the DNA helix, relieving DNA supercoiling, stabilizing single-stranded DNA, and synthesizing RNA primers, respectively. Therefore, the correct answer is RNA polymerase.
7.
Using the enclosed table of messenger RNA codons, select the NUMBER of CORRECT statements about the following sequence of RNA bases:
AUG AAG AAA GGU UGA CAC UCU
(i) It is a normal polypeptide since it starts off with a methionine.
(ii) The polypeptide is six amino acids long.
(iii) The sequence of amino acids could be altered by a point mutation in the third codon, AAA, to AAG.
(iv) The sequence of amino acids shown above would constitute a large polypeptide.
(v) The polypeptide includes a molecule of lysine.
The number of correct statements above is:
Correct Answer
E. You have to look this up and figure out what the answer is!
Explanation
i) is true. ii) find the stop codon, then count how many amino acids would be made.
iii) Consult the code. If the mutation is silent (does not change the resulting amino acid), no change in the sequence will occur.
iv) false - this is a very short sequence, but most polypeptides are hundreds of amino acids long.
v) consult the code to figure out which amino acids will result.
8.
All the following are mutagens (can cause mutations), EXCEPT:
Correct Answer
C. Dideoxynucleotides
Explanation
Dideoxynucleotides are not mutagens because they are not capable of causing mutations. Dideoxynucleotides are modified versions of nucleotides that lack a 3' hydroxyl group, which is necessary for DNA chain elongation during DNA replication. These modified nucleotides are commonly used in DNA sequencing techniques, but they do not have the ability to induce mutations in DNA. Therefore, dideoxynucleotides do not belong to the category of mutagens.
9.
Select the INCORRECT statement about a eukaryotic DNA molecule:
Correct Answer
E. It is found associated with a protein, haptitone.
Explanation
It is associated with histone
10.
During translation, a transfer RNA (tRNA) molecule is associated with:
Correct Answer
B. An amino acid, a messenger RNA molecule and a ribosome.
Explanation
see protein synthesis, translation
11.
For which processes is RFLP required?
Correct Answer
D. Both a and c
Explanation
RFLP (Restriction Fragment Length Polymorphism) is a technique used in DNA fingerprinting and Sanger dideoxy sequencing. In DNA fingerprinting, RFLP helps to analyze and compare the unique patterns of DNA fragments, while in Sanger dideoxy sequencing, it is used to determine the sequence of nucleotides in a DNA fragment. Therefore, both processes require the use of RFLP. PCR (Polymerase Chain Reaction) is a different technique that amplifies specific DNA sequences and does not involve RFLP.
12.
Which biotechnology method most closely resembles natural DNA replication?
Correct Answer
D. PCR
Explanation
PCR (Polymerase Chain Reaction) is the biotechnology method that most closely resembles natural DNA replication. PCR is a technique used to amplify a specific segment of DNA, just like DNA replication in living cells. It involves the use of DNA polymerase enzyme to synthesize new strands of DNA using the existing DNA as a template. This process mimics the natural DNA replication process, where DNA polymerase replicates the DNA molecule by adding complementary nucleotides to the template strand. Therefore, PCR is the method that closely resembles natural DNA replication.
13.
Post transcriptional modificiations DO NOT include:
Correct Answer
F. More than one of these is a correct answer
Explanation
read each one carefully...make sure you know what introns and exons are, and to what end the methyl cap is being added.