Quiz 4 molecular biology

Genes in eukaryotic cells often have intronic sequences coded for within the DNA. These sequences are ultimately not translated into proteins. Why?

Intronic sequences are removed from RNA molecues by the spicosome, which works in the nucleus.

Which of the following statements about prokaryotic mRNA molecules is false? A single prokaryotic mRNA molecule can be translated into several proteins. b. Ribosomes must bind to the 5′ cap before initiating translation. c. mRNAs are not polyadenylated. d. Ribosomes can start translating an mRNA molecule before transcription is complete.

Ribosomes must bind to the 5′ cap before initiating translation

If an mRNA codon reads 5' UAC 3', its complementary anticodon will be:

c- 5' GUA 3

RNA in cells differ from DNA in that...

it is single stranded and can fold up into variety of structures

What type of RNA molecules contains anti-codons?

tRNA

Which of the following statements is false? (a) A new RNA molecule can begin to be synthesized from a gene before the previous RNA molecule's synthesis is completed. (b) If two genes are to be expressed in a cell, these two genes can be transcribed with different efficiencies. (c) RNA polymerase is responsible for both unwinding the DNA helix and catalyzing the formation of the phosphodiester bonds between nucleotides. (d) Unlike DNA, RNA uses a uracil base and a deoxyribose sugar.

(d) Unlike DNA, RNA uses a uracil base and a deoxyribose sugar

You have a piece of DNA that includes the following sequence 5′-ATAGGCATTCGATCCGGATAGCAT-3′ 3′-TATCCGTAAGCTAGGCCTATCGTA-5′ What RNA molecule could be transcribed from this piece of DNA?

5′-AUAGGCAUUCGAUCCGGAUAGCAU-3′

Transcription is similar to DNA replication in that...

Nucleotide plymerization occurs only in the 5' to 3' direction

Which of the following does not occur before a eukaryotic mRNA is exported from the nucleus? (a) The ribosome binds to the mRNA. (b) The mRNA is polyadenylated at its 3′ end. (c) 7-methylguanosine is added in a 5′-to-5′ linkage to the mRNA. (d) RNA polymerase dissociates.

The ribosome binds to the mRNA

The sigma subunit of bacterial RNA polymerase...

recognizes promoter sites in the DNA