Unit 5 Quiz 1

AP Bio

Objectives-Molecular Genetics Unit 5

1. What is the connection between genes and proteins?

Genes are specific sequences of dna that provide instructions for the formation of proteins 

2. Explain the basic difference between transcription and translation

Transcription is the process by which DNA is transcribed or “copied” to mRNA or pre-mRNA. Translation is the process of building polypeptides using the mRNA’s instructions. 

Transcription occurs inside the nuclear membrane while translation occurs in the cytoplasm

3. What is the relationship between the genetic code, DNA, and mRNA? 

If DNA is made up of genes, the nucleotide bases within each gene can be formed into groups of three for mRNA; these are called codons and they code for specific amino acids. 

4. What does it mean that the genetic code “wobbles”? How is this a defense mechanism for organisms?

The genetic code wobbles, meaning that different codons, groups of three bases, will code for different amino acids, however numerous codons can code for the same amino acid. Out of the three bases, the last base differs between different codons. However the other two bases will maintain the same in order to properly code regardless if the last gene gets mutated, therefore acting as a defense mechanism.

5. Describe the stages involved in mRNA synthesis (transcription)

The rna polymerase will bind to the promoter and continue in the 5-3 direction. It will continuously build the corresponding mRNA nucleotide bases on the strand complementary to the template strand. The stand will rewind as the complementary strand was built. The RNA polymerase will eventually meet a stop codon which is known as the terminator site. When this happens the RNA polymerase will leave the area and mRNA strand will be removed from the DNA strand and the double helix will finish winding up. 

6. Compare and contrast transcription in prokaryotes and eukaryotes. Hint: most of the differences will occur during the initiation stage.

In eukaryotes transcription occurs in the nucleus while in prokaryotes it occurs in the cytoplasm.

7. Describe the processing/editing of mRNA in eukaryotes. 

The RNA processing in Eukaryotic cells consists of the addition of multiple adenosine bases, known as polyadenylation at the 3’ end, a modified guanine nucleotide added to the 5’ end. In addition, to the splicing process that removes introns, which are non-coding sequences, and the joining of exons, coding sequences.