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| Question | Answer |
|---|---|
| What does it mean when we say the genetic code is degenerate or redundant? | More than one codon can specify the addition of the same amino acid. |
| Intervening sequences that are transcribed, but not translated into protein are called | introns. |
| A particular triplet of bases in the template strand of DNA is 5’ AGT 3’. The corresponding codon for the mRNA transcribed is _____. | 3’ UCA 5’ |
| How does termination of translation take place? | A stop codon is reached. |
| Which is not a component of the translation machinery? | Protein polymerase |
| In eukaryotes, mRNA processing involves all of the following events except | elongation of the transcript |
| Fewer different tRNA molecules exist than might have been expected for the complexity of its function. This is possible because | the third position of the codon does not have to pair conventionally |
| uring translation elongation, the existing polypeptide chain is transferred to | the tRNA occupying the A site |
| prokaryo initiation & elongation(1) initiator tRNA binds start codon on mRNA (2) small ribosomal subunit binds to mRNA (3) large ribosomal subunit binds (4) tRNA entry and peptidyl transfer reaction (5) translocation of ribosome and release of tRNA | 2, 1, 3, 4, 5 |
| A sequence of three RNA bases can function as a | codon |
| If the DNA triplet code were ATG CGT, the corresponding tRNA anticodons would be | AUG CGU. |
| Which of the following terms does not directly pertain to translation? | DNA |
| What is the function of the 5´ cap and the 3´ poly-A-tail? | Protects mRNA from degradation |
| Eukaryotic mRNA molecules are modified | in the nucleus. |
| Translation directly requires _____. | mRNA, tRNA, and rRNA |
| During elongation, which site in the ribosome represents the location where a codon is being read? | A site |
| Post-translational modifications of proteins may include the _____. | addition of carbohydrates to form a glycoprotein |
| In eukaryotes, translation takes place | on ribosomes. |
| In eukaryotes, the 3' poly-A tail is attached to | mRNA. |
| A single base substitution mutation is least likely to be deleterious when the base change results in _____. | a codon that specifies the same amino acid as the original codon |
| Which of the following occurs in prokaryotes but not in eukaryotes? | concurrent transcription and translation |
| In humans, the two-nucleotide deletion causes a pre-mature stop codon to be translated later. This is an example of a: | Nonsense mutation |
| There are ~ 4.6 million base pairs in an E. coli chromosome. If its DNA polymerase makes 1 mistake every 109 bases, about how many new mutations will there be in a colony containing 109 bacteria if it doubles in size? | ~5,000,000 |
| The first repair of mistakes during DNA replication is made by | DNA polymerase |
| MAPK and MEK are intracellular signaling proteins that mediate cell division induced by growth factors. When mutations in the normal MAPK & MEK genes result in an abnormally high level of MAPK & MEK activity and an increased rate of cell division, called | oncogene |
| If the copy number of a proto-oncogene is increased by gene duplication then the proto-oncogene has undergone | gene amplification |
| Codons are part of the molecular structure of | mRNA |
| In a healthy cell, the rate of DNA repair is equal to the rate of DNA mutation. When the rate of repair lags behind the rate of mutation, what is a possible fate of the cell? | The cell can be transformed to a cancerous cell. |
| A nonsense mutation in a gene _____. | introduces a premature stop codon into the mRNA |
| Which of the following types of mutation, resulting in an error in the mRNA just after the AUG start of translation, is likely to have the most serious effect on the polypeptide product? | a deletion of two nucleotides |
| A species with four sets of homologous chromosomes can have __ different combinations of chromosomes in its gametes? | 16 |
| The different components of the protein synthesizing machinery used directly in translation include all of the following except | RNA polymerase. |
| Which of the following must happen for transcription to be initiated? | RNA polymerase must have access to the DNA double helix and also must be capable of binding to the gene's promoter. |
| A bacterial gene regulatory system is likely to have all the following except | one or more introns. |
| When E. coli cells produce the amino acid tryptophan, a cluster of five genes is transcribed together. This cluster of genes is referred to as the | trp operon. |
| Why is the lac operon said to be an inducible operon? | When activated, the lac operon transcribes genes for lactose-metabolizing enzymes. |
| What is the difference between positive and negative gene regulation? | |
| What is the difference between repression and induction? | |
| When the concentration of glucose in the medium falls, the concentration of _______ rises | cAMP |
| The lactose analog isopropyl-b-D-thio-galactoside (IPTG) is often used to regulate gene expression systems in bacteria. IPTG does not act as a substrate for b-galactosidase, but can bind to, and inactivate, the repressor. In this case, IPTG serves as a(n) | inducer. |
| How are inducible and repressible systems similar? | In both systems the regulatory molecules function by binding to the operator |
| If the gene encoding the lac repressor is mutated so that the repressor can no longer bind the operator, will transcription of that operon occur? | Yes, because RNA polymerase will be able to bind the promoter and transcribe the operon |
| If the gene encoding the trp repressor is mutated such that it can no longer bind tryptophan, will transcription of the trp operon occur? | Yes, because the trp repressor can only bind the trp operon and block transcription when it is bound to tryptophan |
| The mechanism by which the inducer causes the repressor to detach from the operator is an example of | allosteric regulation |
| The three basic parts of an operon are the | promoter, the operator, and the structural gene(s) |
| An inducer | combines with a repressor and prevents it from binding the operator |
| _______ acts as a corepressor to block transcription of the tryptophan operon | Tryptophan |
| What effect does the presence of ample glucose have on the amount of lac operon transcription? | It decreases the rate of transcription. |
| The most commonly occurring mutation in people with cystic fibrosis is a deletion of a single codon. This results in _____. | a polypeptide missing an amino acid |
| Most repressor proteins are allosteric. Which of the following binds with the repressor to alter its conformation? | Inducer |
| A promoter is the region of | DNA that binds RNA polymerase. |
| RNA polymerase by itself cannot bind to the chromosome and initiate transcription. It can bind and act only after regulatory proteins called _______ factors have been assembled | transcription |
| Which molecule is used to mark or label proteins for destruction? | Ubiquitin |
| In positive control of several sugar-metabolism-related operons, the catabolite activator protein (CAP) binds to DNA to stimulate transcription. What causes an increase in CAP activity in stimulating transcription? | A decrease in glucose and an increase in cAMP |
| Compare and contrast the regulation of transcription in prokaryotes and eukaryotes | |
| Transcription factors are | proteins that bind to regulatory DNA sequences |
| In eukaryotic cells, promoters are | neither transcribed nor translated |
| Which of the following is not a feature of TATA boxes in eukaryotes? | They are part of the intron consensus sequence |
| Transcriptional control-proteins called activators increase the rate of transcription by binding to | enhancer sequences within the DNA. |
| Discuss the different aspects of chromatin remodeling, both cause and effect. | |
| In neurons, the globin gene contains many methylated cytosines. The globin gene, therefore, is | not expressed |
| Imagine that the TATA box for gene X becomes highly methylated. How will this affect the expression of gene X? | Gene X will not be transcribed or translated. |
| Expression of some eukaryotic genes can be regulated by translational control. One advantage of translational control is that it | provides a means for rapid change in protein concentrations |
| You are studying the effects of specific transcription factors on the activation of gene expression. You notice that one particular transcription factor binds far away from the promoter of its target gene. What can explain this? | DNA looping brings the transcription factor closer to the promoter and initiates gene transcription |
| During elongation, which site in the ribosome represents the location where a codon is being read to match the anticodon in a charged tRNA? | A site |
| Transcription of structural genes in an inducible operon _____. | starts when the pathway's substrate is present |
| The trp repressor blocks transcription of the trp operon when the repressor _____. | binds to tryptophan |
| Transcription factors are | proteins that bind to the DNA promoter sequence. |
| What would happen initially to cells that lack a functional ubiquitin? | Protein degradation would decrease. |
| ________ is to transcription as ________ are to translation. | RNA polymerase; ribosomes |
| A researcher determined that a strain of E. coli is producing a shortened version of a protein required for glucose metabolism. What type of mutation could be responsible for this shorter than normal protein? | nonsense mutation |
| What proteins influence the ability of RNA polymerase to transcribe genes? | Transcription factors |
| Future kidney cells and heart cells can differentiate into their respective specialized cell types because they | express different genes and utilize different transcription factors during development |
| You thinly slice a carrot root & place the slices on a medium containing nutrients and hormones necessary for plant growth. After a few weeks, you see that there are many little entire carrot plants growing from the root slices. The cells in the root are | totipotent |
| Which of the following is not true of animal development? | Development occurs by loss of unneeded DNA |
| Define & distinguish among: Totipotent, Pluripotent, Multipotent, & Unipotent cells. | |
| A muscle precursor cell would be considered to be | determined. |
| If you isolate a pancreatic beta cell & put it in the proper growth conditions, it will divide by mitosis & produce new beta cells, but it will not produce pancreatic alpha cells or pancreatic cells that release digestive enzymes. The pancreatic beta is | unipotent |
| What characteristic distinguishes stem cells from cancer cells? | Stem cells regulate their growth |
| Which of the following is most likely false about the prior example? | Clones are being created of one or both of the parents |
| Which of the following statements about stem cells is false? | Stem cells are only found in embryos. |
| To begin transcription, RNA polymerase must bind to a segment of DNA called the ____. | promoter |
| Enhancers are the binding sites for the | specific transcription factors. |
| Which of the following is most likely to have a small protein called ubiquitin attached to it? | a cyclin protein, that usually acts in G1, in a cell that is in G2 |
| What do we call a cell that is able to give rise to every cell in the adult body? | Totipotent |
| Post-translational modifications of proteins may include the _____. | addition of carbohydrates to form a glycoprotein |
Created by:
pendleem