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BIO-CHEM EXAM 3 ACTUAL EXAM WITH QUESTIONS AND
100% CORRECT VERIFIED ANSWERS/ Biochem 301-Exam 3
LATEST 2025-2026 (BRAND NEW!!)
DNA
functions as the primary storage molecule of genetic information RNA functions as the primary information transfer molecule, which includes protein synthesis Three principal types of RNA mRNA, tRNA, rRNA Life depends on the production of ___ and then protein from a ___ template in a highly regulated manner RNA; DNA gene defined as the genetic information that encodes a protein DNA template to _____________ mRNA to ____________ forms protein transcription; translation
Nucleic acids information rich polymers joined together by covalent phosphodiester bond _________ group on RNA makes it sensitive to breakdown hydroxyl Chemical components of a nucleotide Purine or pyridine base, Pentose, Phosphate Phosphate diester nucleoside Nucleoside analogue Acyclovir
P53 is a highly specific transcription activator P53 function requires DNA binding P53 binds to the ___________ of pro-death genes and turns on their expression to kill tumor cells promotor What is DNA replication? The process by which DNA replicates and yields two DNA molecules identical to the original one. What is the purpose of DNA replication? To ensure transmission of genetic information to daughter cells. What is transcription? The process of recording the sequence of bases in DNA as a sequence of complementary bases in mRNA. What type of molecule is produced during transcription?
A single-stranded mRNA molecule. What are three-base codons on mRNA responsible for? Directing the sequence of building a protein. What do tRNAs carry? Appropriate amino acids. What is the role of ribosomes in protein synthesis? They are the machinery for protein synthesis. How is DNA stored: in animal cell chromosome How is DNA stored: in bacterium bacterial chromosome How is DNA stored: in a virus genome
What type of nucleotide is added during DNA synthesis? A nucleotide with a 5'-triphosphate on its sugar. What enzyme catalyzes DNA synthesis? DNA polymerase. How does the rate of DNA synthesis in bacteria compare to other organisms? It occurs much faster in bacteria. What is the function of DNA primase? Synthesizes a short RNA primer. What does the RNA primer provide for DNA synthesis? A 3'-OH group for the attachment of DNA nucleotides. Proofreading Removing incorrect nucleotides during RNA replication
Repair removing incorrect nucleotides from DNA and replacing them with correct ones semiconservative replication daughter helices are the same: both helices have one strand daughter and one strand parent What is the origin of DNA replication? The site at which DNA synthesis begins. What happens at the origin of replication in a circular DNA molecule? A single origin gives rise to two replication forks going in opposite directions. DNA replication is _______________ on the ______________ strand and ______________ on the lagging strand continuous; leading; discontinuous leading strand one daughter strand is synthesized in the same direction that the replication fork moves lagging strand
The predominant mechanism for regulation of gene expression occurs at the level of transcriptional initiation RNA can form stem loops which are complementary RNA sequences anneal to form regions of double stranded RNA that are antiparallel Stem loops have functional significance because they protect RNA from attack by nuclease, and they are recognized by RNA binding proteins. internal ribosome entry site (IRES) highly folded RNA structure IRES is used to direct ribosomes to start protein synthesis at the proper location (polio) RNA synthesis uses ___ dependent ___ polymerase DNA; RNA What group does the last nucleotide added to a growing chain have? 3'-hydroxyl group on the sugar.
What role does the 3'-hydroxyl group play during transcription? Acts as a nucleophile by attacking phosphorus adjacent to the sugar in the incoming nucleotide. What type of group is present on the incoming nucleotide during transcription? 5'-triphosphate on its sugar. What is the rate of transcription? 50 base pairs per second. RNA polymerase 1 ribosomal RNA RNA polymerase 2 messenger RNA RNA polymerase 3 transfer RNA
To initiate transcription, the ____ binding protein find and binds to the ____ box which is located 30 bases upstream of the +1 RNA start site TATA; TATA What is the process of Transcription Elongation? RNA polymerase transverses down the gene. What does RNA polymerase synthesize during Transcription Elongation? One long primary transcript (RNA). What is the relationship between the primary transcript and the DNA template during Transcription Elongation? The primary transcript (RNA) is complementary to the DNA template. What is RNA splicing? The process of removing introns and joining exons in mRNA. What is added to the 5' end of mRNA in animal cells? A nucleotide cap.
What is added to the 3' end of mRNA in animal cells? A polynucleotide tail. What is added to the 5' end of eukaryotic mRNA? 7 - methyl guanosine cap What is the function of the 7-methyl guanosine cap on mRNA? It helps form the translation initiation complex and protects the 5' end from degradation. 3' ends of mRNA are cleaved and polyadenylated What family does HIV belong to? Retroviridae What genus does HIV belong to? Lentivirus What type of virus is HIV?
hiv grows in T lymphocytes Tat: transactivator of transcription tat increases the production of the full-length HIV genome RNA by several hundred fold Codon three consecutive bases represent 1 amino acid redundant except for methionine and tryptophan, each amino acid is encoded by more than one codon. silent mutations change in mRNA sequence to a synonymous codon and therefore usually has no effect on the resulting polypeptide missense mutations change in the mRNA sequence from a codon for one amino acid to a codon for a different amino acid, changing the polypeptide sequence.
nonsense mutation change in the mRNA sequence from a codon for an amino acid to a stop codon, terminating translation and resulting in a truncated polypeptide A site holds an aminoacyl tRNA P site holds the tRNA with growing polypeptide attached E site hold a tRNA that will exit The _' end of the tRNA anticodon can me more flexible in its base pairing (it wobbles) 5' Amino acids are linked ot specific tRNAs by aminoacyl-tRNA synthetase
Polysomes multiple ribosomes of translation on a single mRNA In prokaryotes transcription and translation occur in the same compartment in eukaryotes transcription and translation occur in the nucleus and cytoplasm _terminus to _terminus N; C In bacteria, _________ are used to regulate expression of multiple genes form a single promoter under control of regulatory sequences. operons the lac operon is also under ___________ ____________________ control positive transcriptional _________ and other _________ _________ are bound by ____________ __________
Enhancers; control elements; transcription factors ________________ _____________ that stabilize RNA pol at the promoter are called ______________ transcription factors; activators ___________________ ____________ that destabilize RNA pol on the promoter are called
Transcription factors; repressors principal means of regulation occurs at the level of transcriptional initiation To initiate transcription, the ____ binding protein finds and binds to the _____ box, which is located 30 bases upstream of the +1 RNA start site TATA; TATAA Transcription-Elongation RNA pol transverses down the gene and synthesizes one long primary transcript (RNA) which is complementary to DNA template myc gene
