Biochemistry Session 1 - Genes to Proteins

What is "the central dogma?"

Which of the following terms accurately describes all of the proteins translated from functional mRNA transcripts in a given cell?

The human genome is over six feet long and includes 23,000 coding genes. What percentage of intact human DNA actually codes for an expressible protein product?

The exome is the RNA component remaining after processing, editing, and splicing together __________ from the original primary transcript of RNA derived from DNA. The intervening sequences are called __________.

Proteins need to interact with specific DNA sequences for a variety of reasons. ____________ access specific DNA base-pairing sequences through the ___________ groove. General interactions with DNA occur with the general structural motif of DNA through the ___________ groove. Positively charged amino acids in __________ proteins interact with the negatively charged DNA phosphoribosyl backbone.

The DNA double helix consists of two anti-parallel DNA strands. Which of the following properties listed are responsible for the double helix's stable structure? (Select all that apply)

Histones come together to form an octomer that is the core of a complex called the nucleosome. Nucleosomes are essential to binding and stabilizing DNA. DNA wrapped around a nucleosome core forms the fundamental unit of __________.

Transcription factors are effectively competing for specific DNA sequence binding sites, establishing a protein complex on the DNA that is promoting gene expression. This is most likely describing which chromatin modification?

Which of the following is an example of an irreversible reaction that would block the electrostatic interactions between a histone and the phosphoribosyl backbone of DNA, ultimately leading to reduced nucleosome affinity to DNA?

Cell signaling has activated the histone acetyl transferase (HAT) mechanism. What could we expect to observe? (Select all that apply)

Which of the following could lead to silencing gene expression in DNA?

You are observing a cell and notice transcription and translation are occurring at the same time. This could be a(n) __________ cell. (Select all that apply)

The lactose operon codes for one polycistronic mRNA. Which of the following would NOT result in the expression of this operon?

Which of the following is NOT a cis-element?

On this lac operon, what does "o" bind to?

In a eukaryotic cell, signal transduction networks are triggered by environmental influence. Which of the following is true regarding the activation of trans-elements and the induction of gene expression?

Neurotransmitters, hormones, growth factors, and environmental stimuli can all activate various signal transduction networks, thereby controlling different specific sets of genes. The CRE-CREB transcription factor is an example of one of these signal transduction networks. Protein kinase, PKA, can play a major role in the expression of this transcription factor. Which of the following best describes how PKA influences this pathway?

There are various mechanisms by which transcription can be initiated. Which of the following involves denaturing DNA in and around the promoter and open reading frame?

Which of the following is NOT required for the RNA polymerase reaction mechanism?

During elongation of an RNA transcript, RNA and DNA form a complex in the active site. Which of the following most appropriately describes this complex?

Transcriptional termination can be protein dependent. Which of the following are true regarding rho protein dependent termination? (Select all that apply)

The formation of a secondary structure that blocks the exit channel in RNA polymerase, ultimately causing stress and shearing the DNA-RNA heteroduplex in the active site, is indicative of what type of transcription termination?

If you accidentally ingested an amanita phalloides mushroom containing 2 uM alpha-amanitin - what could you expect to happen? (Select all that apply)

Transcription in eukaryotes is a compartmentalized process. Which of the following processes would you expect to see in the nucleus?

The 3'-polyA tail is found in over 80% of all eukaryotic _________.

Which of the following is NOT true regarding the 5'-cap structure added to the mRNA transcript?

RNA splicing is a key editing mechanism that removes introns from the primary transcript. This mechanism is dependent on the formation of a stable complex called a spliceosome. Which of the following is NOT correct regarding the functional units of the spliceosome?

Which of the following sequences contains splicing information that ensures accurately assembled final processed mRNA and is the source of various important regulatory small RNA fragments generated during processing?

If splice site sequences are mutated, exon skipping may occur. What is another reason splicing may not occur accurately?

Tropomyosin has a primary RNA transcript of 11 exons. Which of the following processed transcripts can result from tropomyosin's primary transcript?

UAA, UAG, and UGA are stop codons on mRNA strands that signal the cessation of translation. Why does this mechanism occur?

What molecule is used to charge a specific amino acid to a specific tRNA?

Looking at a newly synthesized polypeptide that has not been edited, what amino acid must appear at the end?

Select all that apply regarding the genetic code.

Which of the following enzymes attaches specific amino acids to the 3' end of cognate tRNA strands?

Which of the following options helps to maintain the genetic code during translation? (Select all that apply)

Which of the following is representative of a typical eukaryotic ribosome?

What is the first step of prokaryotic initiation of translation?

The protein elongation cycle in prokaryotes is defined by three distinct sites located on the ribosome: A, P, and E. What is the main function of the E site?

During prokaryotic protein elongation, numerous ribosomal conformational changes occur. Which process involves GTP hydrolysis inducing a change in Elongation Factor-G, forcing movement of the ribosomal complex by one codon (relative to mRNA)?

In prokaryotic protein elongation, which elongation factor is involved with the binding of specific aa-tRNA to the A site?

Prokaryotic protein termination requires the use of release factors since there are no tRNAs for the termination codons. If a release factor has bound near or at the A site - what can we assume about that RF? (select all that apply)

RRF, the ribosomal release factor, works together with EF-G and IF-1 to ___________ the two ribosomal subunits. This releases both tRNA and mRNA from the complex. IF-3 binds to IF-1 and the 30S subunit, blocking 50S re-association. Ultimately, this will _________ a new initiation complex.

Ribonucleic acid - protein complexes (RNP) form in eukaryotes and are essential for mRNA stability and regulation of translation. Which of the following is NOT an example of a structure bound within the closed loop mRNP complex?

In eurkaryotes, translation is extremely efficient and a single activated mRNP complex can produce lots of protein from a single stabilized mRNA transcript. Essentially, this becomes a protein synthesis _____________.

There is an extremely toxic compound that disrupts ribosome function (elongation and translocation), blocking protein synthesis, leading to cell death. It consists of a B chain, which binds to the cells surface for cellular uptake, and an A chain, which depurinates and disrupts a highly conserved EF2 binding domain. Which of the following is NOT an enterotoxin that functions in a similar way?

A 1-year-old male with chronic anemia is found to have B-thalassemia. Genetic analysis shows that one of his B-globin genes has a mutation that creates a new splice acceptor site 19 nucleotides upstream of the normal splice acceptor site of the first intron. Which of the following best describes the new mRNA molecule that can be produced from this mutant gene?

A 4-year-old child who becomes easily tired and has trouble walking is diagnosed with Duchenne muscular dystrophy, an X-linked recessive disorder. Genetic analysis shows that the patient's gene for the muscle protein dystrophin contains a mutation in its promoter region. Of the choices listed, which would be the most likely effect of this mutation?

A mutation to this sequence in eukaryotic mRNA will affect the process by which the 3'-end poly-A tail is added to the mRNA.

A 20-year-old anemic man is found to have an abnormal form of B-globin that is 172 amino acids long, rather than the 141 found in the normal protein. Which of the following point mutations is consistent with that abnormality?

A pharmaceutical company is studying a new antibiotic that inhibits bacterial protein synthesis. When this antibiotic is added to an in vitro protein synthesis system that is translating the mRNA sequence AUGUUUUUUUAG, the only product formed is the dipeptide fMet-PHe. What step in protein synthesis is most likely inhibited by the antibiotic?

Which of the following is required for both prokaryotic and eukaryotic protein synthesis?

Which of the following is best described as being trans-acting?

The ZYA region of the lac operon will be efficiently transcribed if: