Question 4 1 pts

Howard is explaining the process by which DNA determines the structure of proteins. His explanation includes this statement.
“The base pair sequence of a gene determines the sequence of amino acids in a protein.”
Howard’s teacher evaluates this statement, and her critique is that the statement is not accurate in all circumstances. Which feature of gene expression provides the strongest evidence for the teacher’s critique?
During translation, molecules of tRNA bind to specific codons and amino acids.
RNA transcriptase binds to a promoter region before transcription occurs.
Introns are removed from pre-mRNA, and then the exons are joined together.
Gene expression may be controlled by epigenetic mechanisms.

Question 5 1 pts

As a result of a point mutation, the base cytosine (C) was replaced by adenine (A) in a sequence of mRNA. Under which circumstance does this mutation cause the protein to be significantly shorter?
The mutation changed the genetic code used during translation.
The mutation introduced a start codon in the middle of the mRNA molecule.
The mutation introduced a stop codon into the middle of the mRNA molecule.
The mutation occurred in a region of mRNA that is not translated.

Question 6 1 pts

A scientist develops a computer model of gene expression. However, the model does not include introns and exons. Which is the most likely result of a simulation that is based on this model?
Genes are not transcribed into mRNA.
Transcription occurs normally, but some errors occur during translation.
Transcription occurs normally, but mRNA is not translated into proteins.
Pre-mRNA is not edited, and is used as mRNA.

Question 7 1 pts

Professor Marcus has identified a new species of beetle in the Amazon Rainforest. The professor then investigates the process of gene expression in the cells of the beetle. Which is an expected result of the investigation?
The process of translation in the beetle is similar to other organisms, but involves a unique genetic code.
The process of transcription in the beetle is similar to other organisms, but involves a unique set of nucleic acids in mRNA.
The processes of transcription and translation, including the genetic code, are the same in the beetle as in nearly all other organisms.
The processes of transcription and translation are unique in the beetle.

Question 8 1 pts
Daphne identifies the entire sequence of nucleotides in a gene. Based on this information and the genetic code, she predicts the sequence of amino acids in the protein that the gene codes for. What is the MOST LIKELY reason that Daphne’s prediction would be incorrect?
The cell removes introns from DNA.
The gene codes for a carbohydrate, and not a protein.
The removes introns from pre-mRNA.
A mutation changes the genetic code that the cell uses.

Question 9 1 pts

Proteins are assembled at ribosomes using mRNA as a template. Which property of tRNA allows it to assist in this process?
Each of many tRNA molecules contains an anticodon, and it binds to a specific amino acid.
Each of many tRNA molecules contains an anticodon, and it may bind to any amino acid.
One tRNA molecule contains all of the anticodons and binds to all of the amino acids that are specific for the protein.
One tRNA molecule contains all of the codons and binds to all of the nucleotides that are specific for the protein.

Question 10 1 pts

Several differences between DNA and RNA allow the cell to differentiate between the two molecules, ensuring that transcription and translation occur appropriately. Which is one of the properties of RNA that differentiates it from DNA?
RNA contains cytosine (C) instead of guanine (G).
RNA is double stranded instead of single stranded.
RNA contains uracil (U) instead of thymine (T).
RNA includes phosphate groups instead of nitrogenous groups.

The base pair sequence of a gene is not solely responsible for the sequence of amino acids. A gene may have several allele/variants whose expression is controlled by multiple factors. Epigenetic processes such as DNA methylation, do not involve changes in the DNA sequence. Instead they influence the protein amino acid sequence by changes in the process of transcription or even translation.

2. The mutation introduced a stop codon into the middle of the mRNA molecule.

The protein will be shorter if the point mutation causes the creation of a stop codon in the interior of the mRNA strand. Thus, the remaining sequence after the mutation will no longer be used to create the rest of the protein.

3. Pre-mRNA is not edited, and is used as mRNA.

Because no introns and exons are included in the model, the pre-mRNA is not edited. During this step, the introns are removed from the DNA strand. However, due to the fact that the model does not define them and thus differentiate between them and the exons, the pre-mRNA will be used as mRNA.

4. The process of translation in the beetle is similar to other organisms, but involves a unique genetic code.

The processes of translation and transcription are identical in all organisms. The only difference is the DNA sequence itself, which is species or organism specific. Thus, as it is a new beetle species, its genetic code will be unique. However, it will be translated and transcripted in the same manner as that in all other species.Their mRNA will also have and use the same nucleic acids.

5. The removes introns from pre-mRNA.

The pre-mRNA includes both introns and exons. However, only exons are used in the protein synthesis, whereas the introns are removed during the pre-mRNA stage.

6. Each of many tRNA molecules contains an anticodon, and it binds to a specific amino acid.

The anticodon of a tRNA molecule is amino acid specific. Thus, it can bind to one or a few specific mRNA codons.

7. RNA contains uracil (U) instead of thymine (T).

Both DNA and RNA have phosphate groups bound to a nitrogenous base. However, the single stranded RNA has uracil instead of the thymine found in the double stranded DNA. Also, both RNA and DNA have cytosine and guanine.