Bio 202 Exam 2
RT-PCR (Reverse Transcription PCR) is used to amplify DNA from an RNA template. What enzyme is essential for this initial step?
Reverse transcriptase
The function of topoisomerase during DNA replication is to:
Correct overwinding ahead of replication forks.
Okazaki fragments are produced during the synthesis of which DNA strand?
Lagging strand
The inherent proofreading function of DNA polymerase significantly reduces the error rate during replication by:
Removing mismatched nucleotides.
Which component is not a part of a DNA nucleotide?
Amino acid
Which enzyme forms the final phosphodiester bonds to join Okazaki fragments together?
DNA ligase
Which eukaryotic DNA polymerase is primarily responsible for leading strand synthesis?
Delta/Epsilon
What is the purpose of the denaturation step in Polymerase Chain Reaction (PCR)?
To separate the DNA double helix into single strands.
DNA replication is described as semi-conservative because each new DNA molecule consists of:
One parent strand and one new strand.
The specific region where DNA replication begins is known as the:
Origin of replication
In DNA, adenine always forms base pairs with which nitrogenous base?
Thymine
In prokaryotes, which DNA polymerase is considered the major replication enzyme?
DNA polymerase III
The leading strand during DNA replication is synthesized:
Continuously towards the replication fork.
Approximately how many times is the target DNA sequence amplified after 25 cycles in a typical PCR reaction?
10^6-fold
Which statement accurately describes the two strands of a DNA double helix?
They are antiparallel in orientation.
During the annealing step of PCR, what binds to the single-stranded DNA templates?
Oligonucleotide primers
After Okazaki fragments are synthesized, which enzyme removes the RNA primers and replaces them with DNA nucleotides?
DNA polymerase I
What is the correct order of information flow in the Central Dogma of molecular biology?
DNA -> RNA -> Protein
Before DNA polymerase can add nucleotides, an initial segment of RNA called a primer is synthesized by which enzyme?
Primase
In mismatch repair, how does the system distinguish between the parental strand and the newly synthesized daughter strand to correctly identify the error?
By methylation patterns on the parental strand.
Which enzyme is responsible for unwinding the DNA double helix at the replication forks?
Helicase
Which type of bond is responsible for holding complementary nitrogenous bases together in a DNA double helix?
Hydrogen bonds
Which protein in the mismatch repair system is responsible for recognizing the mismatched pair?
MutS
Which proteins stabilize the unwound parental DNA strands during replication?
Single-strand binding proteins
In eukaryotes, DNA is wrapped around proteins to form a structure called chromatin. What are these proteins called?
Histones
The enzyme responsible for synthesizing RNA from a DNA template is called:
RNA polymerase
Noncoding sequences that are removed from pre-mRNA during splicing are called:
introns
Protein-coding RNA molecules are classified as which type of RNA?
messenger RNA
Which RNA type is primarily responsible for forming part of the spliceosome in eukaryotic cells?
snRNA
The addition of a string of adenine nucleotides to the 3' end of a pre-mRNA molecule is called a:
poly-A tail
What is the primary function of splicing in eukaryotic gene expression?
joining exons together
The specific DNA sequence where RNA polymerase binds to initiate transcription is called a:
promoter
A complex formed by RNA polymerase and transcription factors at the promoter region is known as the:
transcription initiation complex
A segment of nucleic acid that encodes a transcript.
gene
The type of RNA that functions as the interface between mRNA and amino acids during protein synthesis.
transfer RNA
The process by which an RNA molecule is synthesized using a DNA template is known as:
transcription
In transcription, the newly synthesized RNA is complementary to which DNA strand?
template strand
During transcriptional elongation, what happens to the DNA double helix after the RNA polymerase passes?
it rewinds behind the enzyme
In eukaryotic cells, which RNA polymerase synthesizes all protein-coding genes and miRNA genes?
RNA polymerase II
The nitrogenous base unique to RNA, not found in DNA, is:
uracil
In eukaryotic promoters, which sequence is a common recognition site for transcription factors?
TATA box
The macromolecular complex responsible for removing introns from pre-mRNA is known as the:
spliceosome
What is a key function of RNA polymerase during transcription?
unwinding DNA
Which technique is used to detect the presence, size, and quantity of specific RNA molecules by transferring them to a membrane?
Northern Blot
Which of the following is a difference between DNA replication and RNA transcription regarding the product?
DNA replication produces a double helix, transcription produces a single strand
Which sugar component is found in RNA nucleotides?
ribose
Ribosomal RNA (rRNA) is primarily involved in which cellular process?
protein synthesis
Bacterial genes differ from eukaryotic genes in that bacterial genes typically have:
continuous coding sequences
RNA molecules can form complex three-dimensional structures due to which characteristic?
secondary and tertiary structure
Which of the following RNA processing steps occurs exclusively in eukaryotes?
5' cap addition
What is a codon in the context of gene expression?
A three-nucleotide sequence on mRNA
What is the primary function of DNA ligase during DNA replication?
Joining Okazaki fragments
The removal of introns and splicing together of exons is a crucial step in which process?
RNA splicing
What is the primary function of a 5' cap and Poly-A tail in mRNA processing?
Protecting mRNA and aiding translation
The 'start codon' for most proteins is:
AUG
In the process of transcription, what serves as the template for the synthesis of mRNA?
A DNA strand
Where does the synthesis of mRNA primarily occur in a eukaryotic cell?
The nucleus
What is the correct sequence of the three main stages of translation?
Initiation, Elongation, Termination
Keratin, found in hair and horns, is an example of which protein function?
Structural protein
Which site on the ribosome is where the peptidyl-tRNA is typically found during elongation?
The P site
Proteins that function to selectively accelerate chemical reactions, such as digestive enzymes, are categorized as:
Enzymatic proteins
Which of the following amino acids is classified as an electrically charged, basic amino acid?
Lysine
Which of the following serves as a 'stop codon' in translation?
UAG
What happens at the 'A site' of the ribosome during translation elongation?
New aminoacyl-tRNA molecules enter
The process of converting genetic information from mRNA into a sequence of amino acids in a protein is known as:
Translation
The enzymes responsible for attaching the correct amino acid to its corresponding tRNA are called:
Aminoacyl tRNA synthetases
The primary structure of a protein is defined by what?
The sequence of amino acids
Which cellular component is responsible for synthesizing new DNA strands during the replication process?
DNA polymerase III
What is the main role of chaperone proteins in a cell?
Facilitating proper protein folding
Which interactions are primarily responsible for packing nonpolar side chains into the interior of a folded protein?
Hydrophobic interactions
Which enzyme is responsible for synthesizing RNA from a DNA template during transcription?
RNA polymerase
Hemoglobin, which transports oxygen in the blood, is an example of which type of protein function?
Transport protein
Which enzyme is responsible for synthesizing an RNA primer on the DNA template during replication?
DNA primase
Which molecule carries specific amino acids to the ribosome during the translation process?
Transfer RNA
What type of bond is formed between amino acids to create a polypeptide chain?
Peptide bond
Specific splicing factors can either repress or activate the splicing of what?
Specific exons
In the specific example of iron storage protein, what molecule, when present, relieves translational repression?
Iron (Fe)
What region of a miRNA is critical for its target recognition and binding to the mRNA response element (MRE)?
Seed region
mRNAs with short half-lives are often associated with what type of cellular functions?
Regulatory functions
Where does RNA processing control primarily occur in a eukaryotic cell?
Nucleus
In a generalized model of translational repression, what binds to the 5' end of the mRNA to prevent protein synthesis?
A translation repressor protein
Kinases involved in phosphorylation typically target which amino acids?
Serine/Threonine and Tyrosine residues
How many different proteins can potentially be encoded by the single Neurexin3 gene through alternative splicing, according to the notes?
Approximately 1000
Proteins destined for import into the ER often contain a specific ______ at their N-terminus.
Signal sequence peptide
miRNAs can form complex regulatory networks because they can have multiple target mRNAs, and a single mRNA can be regulated by what?
Multiple miRNAs
What happens when a miRNA's seed region perfectly matches its target mRNA?
Deadenylation and degradation of mRNA
In the example of insulin, proteolytic processing removes which section to make the protein functional?
Connecting polypeptide
The spliceosome, a complex macromolecule in eukaryotic cells, is composed of over 300 different proteins and what other key components?
snRNPs (small nuclear ribonucleoproteins)
Cell fate is determined by the combinatorial action of which three types of regulatory molecules?
Transcription factors, splicing factors, and miRNAs
What structural feature of mRNA is often associated with its half-life?
Secondary structure (e.g., in the 5' UTR)
Which laboratory technique is mentioned for detecting alternative splicing by amplifying different isoforms?
RT-PCR (Reverse Transcription Polymerase Chain Reaction)
What is the process that removes introns from a pre-mRNA molecule and joins exons together?
RNA splicing
Which of the following is NOT a mechanism for mRNA localization within a cell?
Direct nuclear export into the peroxisome
List the three main processing events that convert a primary RNA transcript into mature mRNA in eukaryotes.
5' capping, RNA splicing, 3' polyadenylation
The attachment of a phosphate group to a protein is known as what type of covalent modification?
Phosphorylation
Alternative splicing allows a single gene to produce multiple different ______.
protein isoforms
The biogenesis of miRNAs begins with the transcription of a primary transcript (Pri-miRNA) by which enzyme?
RNA polymerase II
Proteins are disassembled in the cell by which multi-protein complex?
Proteasome
What is the observed circulating level of miR-132 in Alzheimer's Disease patients?
Decreased
What is the name of the process that involves modifications to pre-mRNA, such as capping, splicing, and polyadenylation, occurring in the nucleus?
RNA processing control