- How does a bacterial ribosome initially bind to the mRNA? The small subunit binds to the 5' guanine cap The small subunit binds to the initiator tRNA, which recognizes and binds to the start codon in the mRNA The small subunit binds directly to the start codon The small subunit binds to ribosomal binding sequence The large subunit binds to the initiator tRNA, which recognizes and binds to the start codon in the mRNA
- Intracellular receptors are activated by signaling molecules that __________ the plasma membrane.In extracellular signaling, ligands bind to ______________.Most types of enzyme-linked receptors function as ________________.In mammals, receptors for ________________ are intracellular.
- A 5'-CUA-3' codon in an mRNA could be recognized by which of the following anticodon sequences in a tRNA? 5'-TAG-3' 3'-GAU-5' 3'-GAT-5' 3'-GUA-3' 5'-GAT-3'
- In transcription, the goal is synthesis of _________.In DNA replication, the goal is synthesis of _________.RNA polymerase and primase both add nucleotides to a ________.During __________, both strands of the DNA will function as a template.During ___________, only one strand of the DNA will function as a template.The enzyme that is involved in replication but not transcription is ____________.
- During the process of translation in a eukaryote ribosomes must be imported into the nucleus. amino acids are synthesized by RNA polymerase. messenger RNA is spliced in the nucleus. mRNA interacts with ribosomes in the cytoplasm. transfer RNAs are joined together by a large enzyme complex.
- How does a eukaryotic ribosome initially bind to the mRNA? The small subunit binds directly to the start codon The small subunit binds to the 5' guanine cap The small subunit binds to ribosomal binding sequence The large subunit binds to the initiator tRNA, which recognizes and binds to the start codon in the mRNA The small subunit binds to the initiator tRNA, which recognizes and binds to the start codon in the mRNA
- The pairing of nitrogenous bases in DNA is specific because the pairing of DNA strands is parallel. amino acids in the DNA form very specific three-dimensional shapes. functional groups on each of the bases form hydrogen bonds with functional groups on only one other base. functional groups on each of the bases form covalent bonds with functional groups on only one other base. the pairing of DNA strands is antiparallel.
- Why is the lagging strand synthesized in a discontinuous fashion? The DNA polymerase enzyme that synthesizes the lagging strand can only synthesize short sequences of DNA before it falls off the template. DNA synthesis must occur in a 5' to 3' direction, which imposes spatial constraints on the synthesis of the lagging strand. The lagging strand is complementary to the leading strand. All of these are reasons why the lagging strand is synthesized in a discontinuous fashion. The template of the lagging strand is discontinuous.
- The copying of the information in DNA is efficient because the DNA molecule can be copied without disrupting the hydrogen bonds between bases. each strand of a DNA molecule carries complementary information and can be used as a template during replication. the pairing of two DNA strands is antiparallel, and strands are held together via hydrogen bonds. any purine (A or G) can pair with any pyrimidine (T or C). each strand of a DNA molecule can be used as a template during replication because each nitrogenous base pairs with an identical base via hydrogen bonding, e.g. A to A, G to G.
- A difference between bacterial and eukaryotic transcription RNA is synthesized 5' to 3' in bacteria, but 3' to 5' in eukaryotes. transfer RNAs (tRNAs) are involved in eukaryotic transcription only. in bacteria, the start signal is an AUG, while in eukaryotes it is a promoter. in bacteria, introns have to be removed from the primary RNA transcript. in eukaryotes, there are different RNA polymerases (I, II, and III).
- Which of the following does not occur during translation in eukaryotes? Introns are removed by the ribosome. tRNAs with no amino acid leave the ribosome through the E site. Base pairing occurs between tRNAs and the mRNA. The growing polypeptide chain adds amino acids at its carboxyl end. Charged tRNAs enter the A site of the ribosome.
- The genetic code is degenerate. That means in two individuals of the same species, some codons may be different. a particular amino acid can be specified by more than one codon. the second base in the codon is usually a variable base. it is possible for a single codon to specify more than one amino acid. the code allows for more than one type of stop codon.
- Which type of RNA is involved in protein synthesis? None of these tRNA rRNA All of these mRNA
- Acetylcholine is a neurotransmitter that conducts a signal from a neuron to a muscle cell, causing it to contract. Atropine is a muscle relaxant that competes with acetylcholine, blocking its activity. Formulate a description of the mechanism by which atropine works. Atropine prevents acetylcholine from entering the muscle cell. Atropine prevents acetylcholine from binding to a ligand-gated ion channel on the neuron. Atropine prevents acetylcholine from binding to a ligand-gated ion channel on the muscle cell. Atropine prevents acetylcholine from leaving the neuron.
- Eukaryotic cells store their DNA in the form of linear chromosomes. This creates problems for replication of DNA at the ends of the chromosomes because DNA polymerase cannot access the nucleus, where the DNA is found. by the time DNA polymerase gets to the ends, there are no more free dNTPs for replication. all of the genes are located in the middle of the chromosomes. base pairs at the ends of chromosomes do not consist of A, C, G, or T. DNA polymerase can only synthesize DNA in the 5' to 3' direction.
- RNA processing does NOT involve which of the following? Lariat Polyadenylation Methylated guanine All of these are involved in RNA processing Removal of exons
- When replication starts, an origin of replication forms, consisting of two _________ moving in opposite directions.DNA double helix is separated into single strands by the enzyme_____________.Newly-exposed, unreplicated DNA is protected by ______________.Short segments of RNA are synthesized, called __________.The enzyme that synthesizes the short segments of RNA is called a __________.The short RNA segments provide a free _____ for replication.New DNA is synthesized in the _________ direction.The enzyme that removes tightened coils ahead of the replication fork is ____________.The enzyme that catalyzes new DNA synthesis is ____________.DNA synthesis occurs continuously on the _____________.DNA synthesis occurs in small sections on the _____________.Fragments of discontinuous DNA synthesis are called __________________.Gaps in the sugar-phosphate backbone of DNA are closed by _____________.
- A mutation in a G-protein prevents the alpha-subunit from dissociating from the beta/gamma-subunit. What effect will this have on the pathway in which the G-protein is involved? The pathway will be under-activated. The pathway will be activated even in the absence of a signal. The pathway will be over-activated.
- The advantage of second messengers is best described as Amplification of the signal Replaces the role of protein phosphatases Speeds up ligand-receptor binding Prevention of signal inhibition Enhanced specificity of the ligand
- Epinephrine inhibits salivary gland activity and muscle cell contraction in the airways, yet stimulates glycogen release in muscle cells and heart muscle cell contraction. How could one hormone have opposing effects on different organs? Only responsive tissues are exposed to the epinephrine in the blood stream. Cells in tissues that are not responsive contain enzymes that break down epinephrine when it enters the cell. Cells in responsive tissues have signal transduction pathways. Cells in the different tissues would have epinephrine receptors coupled to different signaling pathways. Cells in the tissues that are suppressed do not express an epinephrine receptor.