Cell Biology Exams Multiple Choice Questions And Verified Guaranteed Answers 100% Correct Answers.

Dna and Rna use the same 4 letter Alphabet (T or F) - correct answer false eukaryotic cells can contain mitochondria and chloroplasts not both (T or F) - correct answer false Higher concentration of enzymes gives rise to a higher turnover number (T or F) - correct answer false Enzyme acts on a tyrosine residues on a target protein to create a binding site for the SH2 domain, the enzyme is most specifically which of the following - correct answer kinases Condensation and hydrolysis are very important metabolic reactions in the cell, which of the following molecules plays a very crucial role in the two reactions? - correct answer water the observation that proteins often renatures into their biological conformation after they have been unfolded by a denaturing solvents implies by which of the following statements? - correct answer Info needed to specify the 3d shape of a protein is encoded and its amino acid sequence) what happens when a protein does not have a leading sequence - correct answer it stays in the cytoplasm what is this called? (picture) Does not have a phosphomoity? attached to five prime: Nuceloside - correct answer nucleoside Which of the following describes the defining features of a protein domain? - correct answer discrete and functionally unit within a protein Three dimentional relationship of polypeptide chains in a multi subunit protein or complex - correct answer quarternary structure which of the bonds in involved in polymerization? - correct answer phosphodiester bond Which of the following building blocks is polymerized to make a lipid membrane - correct answer fatty acid which of the following enzyme breaks down the nucleic acids by hydrolyzing bonds between the nucleotides - correct answer nuclease which of the following describes a pathway in the cytosol in which sugars are partially metabolized to produced ATP? - correct answer glycolysis which of the following is more likely to be used by lithotrophs as a source of electrons for reducing CO2 to form useful organic molecules and as a energy source for generating ATP? - correct answer H2S Which of the following is not a covalent modification - correct answer hydrophobic interaction which of the following mechanisms involves the breakdown of organic molecules and release of energy - correct answer catabolism Which of the following non covalent bonds explains the force exerted by the hydrogen bonded network of water molecules that bring two non-polar surfaces together by excluding water between them - correct answer hydrophobic bond Polysacharide used to store energy in plant cell - correct answer starch (glycogen in animals) which of the following represents an activated carrier molecule - correct answer NADH Which of the following does not describe a mechanism that cells used to regulate enzyme activities - correct answer allosteric co-operativity (correct answers: compartmentalization, gene regulation to check enzyme activities, covalent modification) which of the following term defines a process by which the sequence of nucleotides and mRNA molecules directs the incorporation of amino acids into protein? - correct answer translation which of the following term defines the loss of electrons from an atom? - correct answer oxidation which of the following term defines the affinity of a substrate for the enzyme in an enzyme kinetic reaction - correct answer Km which of the following term defines a total genetic information for a cell that and its complete DNA sequence? - correct answer genome which of the following term defines the major category of living cells with an absence of nucleus - correct answer prokaryotes a protein that catalyses a specific chemical reaction - correct answer enzyme region of DNA that controls a discrete heredatory characteristic of organisms, usually corresponding to a single protein or a structural, catalytic, or regulatory RNA? - correct answer gene small molecules tightly associated with protein catalyst and participates in a chemical reaction by forming a covalent bond to a substrate - correct answer co enzyme picture of negative feedback recognition - correct answer number 5 which amino acid can be phosphorylated - correct answer serine why do secondary messengers like cAMP or cGMP do not get incorporated into the nucleotide synthesis - correct answer they like 3' hydroxyl groups what would you add to a protein mixture with several disulfide bonds, if you wanted to get rid of them? - correct answer DTT, reducing agent which of the following is not true regarding the members of protein pathway in general? - correct answer They can functionally replace each other. (correct: they have syn conformations, share same ancestory/are homologs, gene sequences are less preserved, they have expanded through gene duplication events over time) enzymes can catalyze cellular reaction through various mechanisms, which of the following statements is not true regarding them? - correct answer they can accelerate the reaction by destabilizing the transition state! (correct: they can provide the chemical group necessary for the simultaneous acid and base catalysis, higher affinity for a transition state than for a stable form, they can form covalent bonds with the substrate during catalysis, they can strain a substrate to force it to a specific transition state) as a general rule, eukaryotic mRNAs have a shorter half life compared to bacterial mRNAS (T/F) - correct answer false as an mRNA molecules is processed in the nucleus, it loses some proteins and binds to new ones, some of which are used in mRNA surveillance pathways. The presence of which of the following molecules on an mRNA is a signal that the mRNA is still not ready for nuclear transport? - correct answer snRNPs used in splicing coactivators are - correct answer factors that bind to other proteins, not to DNA directly DNA and RNA polymerase differ in all of the following except: - correct answer the type of chemical reaction they catalyze DNA glycosylases constitute an enzyme family found in all three domains of life. They can, - correct answer remove a purine or pyrimidine base from DNA during DNA replication in the cell, DNA primase makes short primers that are extended by the replicative DNA polymerases. These primers.. - correct answer generally have a higher number of mutations compared to their neighboring... during DNA replication, the single stranded DNA binding protein (SSB) - correct answer prevent the folding of a single stranded DNA Each nucleosome contains - correct answer a histone octamer composed of two copies of" H2A, H2B, H3 and H4 each replication fork requires both leading and lagging strand synthesis because - correct answer the DNA templates are antiparallel and yet DNA polymerase can only work in one direction 5-3' eukaryotic pre-RNAs undergo a number of modifications such as capping the 5' end. A 5' cap... - correct answer is identical for all mRNA that are transcribed by RNA polymerase II how do eukaryotic transcription factors exert their effects on transcription when their binding sites can be thousands of base pairs away from the promoter? - correct answer the DNA between the bound site and the polymerase-promoter complex loop out, increasing proxomity in different regions of the chromosome, the ratio of histone H1 to histone H2A may vary, but the ratio of H2A to histone H2B is generally the same. If the amount of H1 increases in a region of chromatin, what will be its effect on compaction of the DNA and transcription in that region? - correct answer transcription in that region will decrease several mechanisms contribute to the diversity of the mRNAa and proteins encoded by a single gene in our genome. Which is normally not one of them? - correct answer alternative choice of the reading frames some viruses encode a protease that cleaves the translation initiation factor eIF4G. rendering it unable to bind to eIF4E. What is the consequence of this cleavage? - correct answer it shuts down most host cell protein synthesis and diverts the translation machinery to IRES-dependent initiation thus favoring viral protein synthesis the activator for the lac operon is - correct answer CRP binding of tryptophan to the Trp repressor protein results in - correct answer conformational change in repressor that allows the repressor to bind to operator enzyme that catalyzes the initial processing of miRNA in the nucleus - correct answer drosha the function of the rev protein encoded by the HIV genome is to - corre