87 Questions
Which bond contributes to the stability of the DNA helix?
H-bonds
What is the structural unit for packaging DNA?
Nucleosome
What is the name of the DNA packaging complex composed of DNA and tightly bound proteins?
Chromatin
Which form of chromatin is found when the cell is transcriptionally active?
Euchromatin
How many pairs of chromosomes do most human cells have?
23
What are the maternal and paternal chromosome pair called?
Homologous chromosomes
What is the name for the functional units of heredity?
Genes
What is the name of the non-coding sequence of a gene that is removed during splicing?
Intron
What percentage of the human genome does not encode protein?
98.5%
Which biomolecule is the basis for nucleic acid?
Nucleotide
What are the 3 components of a nucleotide?
Sugar, phosphate, and nitrogenous base
Which of the 4 bases are purines?
Adenine and guanine
Which of the 4 bases are pyrimidines?
Thymine and cytosine
Why does A always pair with T & G always pair with C?
It is determined by hydrogen bonding
Chargaff’s rule states that the number of purines must equal the number of pyrimidines. Why is this necessary to maintain the DNA double helix?
To ensure stability of the DNA molecule
What forces are needed to stabilize the DNA double helix?
Hydrogen bonds between bases
What is the structure of DNA?
Double helix
How many base pairs are there in one complete turn of the DNA double helix?
10
What is the role of RNA in the central dogma of molecular biology?
Act as an intermediate between DNA and protein synthesis
Which of the following is NOT a chemical difference between RNA and DNA?
Double-stranded helix structure
Which type of RNA serves as a template for protein translation?
mRNA
What is the term for the RNA molecule initially transcribed from DNA?
Pre-mRNA
Which type of non-coding RNA is involved in splicing?
snRNA
Which type of RNA is needed for the basic structure of the ribosome complex?
rRNA
What is the general term for RNA that serves as enzymatic, structural, and regulatory components in the cell?
Non-coding RNA
Which type of RNA forms small nuclear ribonucleoproteins (snRNPs) in the spliceosome?
snRNA
Which of the following RNA molecules is involved in catalyzing the peptide bond between amino acids?
rRNA
What is the term for the process of removing introns from pre-mRNA?
Splicing
Which of the following is NOT a structural difference between RNA and DNA?
Adenine, guanine, and cytosine content
Which type of RNA molecule is responsible for carrying the correct amino acid to the growing polypeptide chain during translation?
tRNA
What is the function of the anticodon region in tRNA?
It pairs with the complementary codon in an mRNA molecule
Which hypothesis explains why there are only 20 amino acids despite 64 possible combinations of nucleotides in a 3 nucleotide codon?
Wobble hypothesis
Which region of the tRNA molecule binds the amino acid that corresponds to the anticodon?
Amino acid binding site
Which type of RNA molecule regulates gene expression by blocking translation of specific mRNAs and promoting their degradation?
miRNA
Which type of RNA molecule reduces gene expression by directly degrading specific mRNA molecules?
siRNA
Which type of RNA molecule can increase or decrease transcription and is involved in X-chromosome inactivation?
lncRNA
Which type of RNA molecule is an adaptor between mRNA and amino acids and is involved in splicing of pre-mRNA?
snRNA
Which type of RNA molecule codes for proteins?
mRNA
Which type of RNA molecule is an important constituent of ribosomes and catalyzes protein synthesis?
rRNA
Which enzyme is responsible for transcription?
RNA polymerase
What is the direction in which RNA polymerase moves during transcription?
5' to 3'
Which region of a gene contains the consensus sequence and specifies the start of transcription?
Promoter region
What is the role of transcription initiation factors in the process of transcription?
They help RNA polymerase recognize the template strand
What are the three main stages of transcription?
Initiation, elongation, termination
Which of the following is NOT a processing step during transcription in eukaryotes?
Polymerization of RNA
Which enzyme is responsible for synthesizing an RNA molecule from a DNA template during transcription?
RNA polymerase
What are the steps of transcription in the correct order?
Initiation, elongation, processing, termination
Which type of RNA molecule carries the correct amino acid to the growing polypeptide chain during translation?
tRNA
What are the steps of translation in the correct order?
Initiation, elongation, termination
Which molecule is responsible for catalyzing the peptide bond between amino acids during translation?
rRNA
How are proteins targeted to a cellular location during translation?
By signal sequences
What is the function of the Shine-Dalgarno sequence?
Needed in binding initiation of small ribosomal subunit
Which of the following is NOT a role of elongation factors in translation?
Binding to the stop codon
What happens during termination in translation?
All of the above
What is the first amino acid added to any polypeptide?
Methionine
Which of the following describes the correct order of translation initiation in eukaryotes?
Small ribosomal subunit binds to the 5’ cap and scans the mRNA until it reaches AUG, then Met-tRNAi binds to the P site
During transcription, which of the following proteins bind the TATA box within the promoter region?
TFII D
Which of the following are CORRECT regarding RNA processing?
Splicing is catalyzed by snRNA and proteins complexed into snRNPs
What might happen if a nucleotide was accidentally inserted into the middle of a gene?
The gene would produce a completely different protein
Which of the following is TRUE about the mRNA transcript produced in prokaryotes?
It can begin translation right away
What is the role of the 5’ cap in mRNA processing?
It is involved in translation
What is the role of the Poly A tail in mRNA processing?
It protects the 3’ end of the mRNA from degradation
Which of the following is true about protein synthesis in prokaryotes?
The small ribosomal subunit binds to the Shine Dalgarno sequence
Which of the following is true about protein synthesis in eukaryotes?
The small ribosomal subunit binds to the 5' cap and scans the mRNA until it reaches the start codon
What happens after a protein is fully translated?
All of the above
What is the role of polysomes in protein synthesis?
To speed up the rate of protein synthesis
Which of the following is a clinical application of understanding protein synthesis?
All of the above
What is the purpose of the Shine Dalgarno sequence in prokaryotic protein synthesis?
To bind the small ribosomal subunit to the mRNA
Which of the following is NOT a way a cell can regulate the amount of a particular protein available to a cell?
Location of the protein
Which of the following is true about histone acetylation?
It is carried out by histone acetyltransferases (HAT)
What is the function of histone methylation?
It promotes transcriptional activation
Which of the following is NOT a way mRNA stability can be regulated?
Histone modification can stabilize mRNA
What is the relationship between the stability of mRNA and protein synthesis?
The longer an mRNA lasts in the cytosol, the more protein will be made
What is the role of chromatin remodeling complexes in transcription regulation?
They reposition nucleosomes on DNA
What is the role of histone modifications in transcription regulation?
They increase transcription
Which of the following is true about DNA methylation?
It typically results in transcriptional silencing
What is the function of non-coding forms of RNA, such as miRNA or siRNA?
They promote mRNA destruction
Which of the following is true about histones?
They are highly dynamic structures regulated by nuclear proteins
Which of the following is false about targeting proteins to the rough ER for translation?
Translation of proteins destined for the rough ER occurs in the mitochondria.
What happens when a protein containing a stop transfer sequence comes into contact with the translocator during translation?
Translation is paused and the translocator discharges the polypeptide into the cytosol.
Which of the following is true about the amino acids in the stop transfer sequence?
They are nonpolar.
Which region of the tRNA molecule binds the amino acid that corresponds to the anticodon?
Acceptor stem
What is the function of the signal recognition particle (SRP) in protein targeting to the rough ER?
To direct the ribosome to the rough ER
Which of the following is true about the targeting of proteins to the nucleus, mitochondria, or peroxisomes during translation?
Proteins are translated on free ribosomes in the cytosol.
What is the role of the stop transfer sequence in protein targeting during translation?
To pause translation
Which of the following is true about the targeting of proteins to lysosomes, ER, cell membrane, or secretion during translation?
A signal peptide sequence is translated, which binds a signal recognition particle (SRP).
Match the events of translation to the steps they occurs in:
Initiation = AUG (methionine) marks the start of the codon and the small ribosomal units bind with a 5' end of mRNA Elongation = tRNA binding, Peptide bond formation, Large subunit translocation, Small subunit translocation Termination = Stop codons UAA, UAG, UGA marks the end of a peptide, peptidyl transferase catalyzes the reaction with water releasing the COOH group Translation = The mRNA has been brought out of the nucleus and into the cytosol where protein synthesis can occur
Test your knowledge of the Central Dogma of Molecular Biology with this quiz. Explore the basis of nucleic acids and their role in DNA and RNA.
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