Bio Unit 6
Cells that contain only circular chromosomes are most probably which of the following?
Bacterial cells
A particular genetic disorder results from a single change in the amino acid sequence coded for in a gene. Parts of the sequence in normal and mutated genes are shown below. Based on the codon chart above, which of the following amino acid changes is most likely found in the mutated protein?
Glu → Val
Figure 1 represents part of a process that occurs in eukaryotic cells. There are untranslated regions (UTR) in this sequence. Which of the following best explains the process represented by Figure 1?
The enzyme-regulated processing of pre‑mRNA into mature mRNA.
Nondisjunction during meiosis can negatively affect gamete formation. A model showing a possible nondisjunction event and its impact on gamete formation is shown in Figure 1. Which of the following best describes the most likely impact on an individual produced from fertilization between one of the daughter cells shown and a normal gamete?
Because nondisjunction occurred in anaphase I, all gametes will have an abnormal chromosome number and the individual will likely exhibit phenotypic evidence of the nondisjunction event.
Which of the following correctly compares the two processes shown above?
Both processes increase genetic variation.
Figure 1 illustrates processes related to control of transcription and translation in a cell. Which of the following scientific claims is most consistent with the information provided in Figure 1?
Different genes may be regulated by the same transcription factor.
A model of a process involving nucleic acids is shown in Figure 1. Which of the following best explains what process is represented in Figure 1?
New DNA strands are being synthesized in the 5' to 3' direction from their DNA templates.
Which of the following best describes an event during step 2 in the simplified model below?
Noncoding sequences are removed from a newly synthesized RNA molecule.
Phenotype is determined, in part, by which genes are expressed. The diagram below illustrates how the product of gene X regulates the expression of other genes. Which of the following statements best explains how protein X regulates gene expression?
Protein X is responsible for activating transcription of some genes but not others.
Which of the following best illustrates the flow of information required for the synthesis of proteins encoded in the genome of a retrovirus?
RNA DNA RNA Protien
Erwin Chargaff investigated the nucleotide composition of DNA . He analyzed DNA from various organisms and measured the relative amounts of adenine (A), guanine (G), cytosine (C), and thymine (T) present in the DNA of each organism. Table 1 contains a selected data set of his results. Which of the following statements best explains the data set?
Since the %A and the %T are approximately the same in each sample, adenine and thymine molecules must pair up in a double-stranded DNA molecule.
Retroviruses have an RNA genome. HTLV-1 is a lysogenic retrovirus that establishes a latent infection in human cells. By which of the following mechanisms does infection by a retrovirus such as HTLV-1 most likely cause long-lasting genetic changes to host cells?
The RNA viral genome is reverse transcribed into DNA that integrates into the host genome.
Figure 1 represents part of a process essential to gene expression. Which of the following best explains what strand X represents?
The antisense strand, because it is serving as a template.
A scientist adds a chemical to a culture of dividing cells in order to disrupt DNA replication. The replicated DNA produced by the cells is double-stranded, but sections of it lack covalent bonds between adjacent nucleotides (Figure 1). Which of the following claims is best supported by the data?
The chemical inhibits DNA ligase.
Beta thalassemia is a disorder caused by mutations in the HBB gene. Examination of the HBB protein in an individual with beta thalassemia shows that the protein is missing many amino acids at its carboxyl terminus. Which of the following is the most likely explanation for how a mutation in the DNA could result in the loss of the carboxyl terminus of the HBB protein?
The mutation changes a codon in the coding region of the HBB transcript to a stop codon such that translation terminates earlier than it should.
11. Maximal transcription of the lac operon requires
the presence of cyclic AMP and lactose.
