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WorksheetsReview Session #6
Total questions: 98
Worksheet time: 49mins
What is the correct sequence of processes in the Central Dogma of molecular biology?
RNA → DNA → Proteins
Proteins → RNA → DNA
DNA → RNA → Proteins
Proteins → DNA → RNA
Which process is responsible for the synthesis of RNA from DNA?
Translation
Replication
Reverse transcription
Transcription
What is the process called that converts RNA into proteins?
Transcription
Replication
Reverse transcription
Translation
Which base in RNA replaces thymine found in DNA?
Adenine
Cytosine
Guanine
Uracil
What is the main role of mRNA?
It forms the structure of ribosomes.
It codes for proteins.
It is involved in the regulation of gene expression.
It transports amino acids to the ribosome.
What enzyme is responsible for linking new bases during transcription?
DNA polymerase
Helicase
RNA polymerase II
Primase
During DNA replication, what is required by DNA polymerase to add bases?
A 5' primer
A 3' primer
A 3' OH group
A DNA template
What happens to the RNA strand after transcription?
It remains permanently attached to DNA
It forms a double helix
It is displaced from the DNA template
It is proofread and corrected
Why is it acceptable for RNA polymerase to make more mistakes than DNA polymerase?
Because RNA is not involved in protein synthesis
Because RNA is double-stranded
Because RNA is permanent
Because RNA is temporary
What is the function of the promoter region in transcription for eukaryotes?
It is the region where transcription ends.
It is the region where RNA polymerase II binds to start transcription.
It is the region that codes for multiple proteins.
It is the region that releases the sigma factor in bacterial transcription.
What is coordinated gene expression, and where does it occur?
It is when one mRNA codes for multiple proteins, occurring in eukaryotes.
It is when one mRNA codes for one protein, occurring in prokaryotes.
It is when one mRNA codes for multiple proteins, occurring in prokaryotes.
It is when one mRNA codes for one protein, occurring in eukaryotes.
How many types of RNA polymerases do eukaryotes have, and which one is responsible for all protein coding genes?
1 type, RNA polymerase I
2 types, RNA polymerase II
3 types, RNA polymerase II
3 types, RNA polymerase I
Which of the following is unique to eukaryotic transcription?
Prokaryotic mRNA codes for multiple proteins.
Eukaryotic mRNA codes for only one protein.
Sigma factor binds to RNA polymerase.
Genes are spread over DNA without introns.
What is the role of transcription factors in the process of transcription?
They degrade RNA polymerase II
They bind to the promoter region and allow RNA Polymerase II to bind
They prevent RNA polymerase II from binding to DNA
They replicate DNA
Which transcription factor binds to the TATA box?
TFIIE
TFIIH
TFIID
RNA polymerase II
What is the characteristic of the TATA box that makes it the best area for transcription?
It is G-C rich and has three hydrogen bonds
It is A-T rich and has three hydrogen bonds
It is G-C rich and has two hydrogen bonds
It is A-T rich and has two hydrogen bonds
What is the function of TFIIH?
It acts as a ligase
It acts as a helicase and unzips DNA
It methylates the tail of RNA polymerase II
It synthesizes RNA
What additional role does TFIIH have besides acting as a helicase?
It acetylates histones
It phosphorylates the tail of RNA polymerase II
It degrades RNA
It binds to the TATA box
What complex is formed by the addition of general transcription factors and RNA polymerase II?
DNA Replication Complex
Transcription Termination Complex
Transcription Initiation Complex
RNA Processing Complex
What is required for the release of RNA polymerase II from DNA?
Phosphorylation of the tail
Methylation of the tail
Dephosphorylation of the tail
Acetylation of the tail
RNA polymerase can transcribe a gene how many times simultaneously?
Only once
A limited number of times
Many times
Not at all
What is added to the 3' tail of mRNA?
Poly G Tail
Poly T Tail
Poly C Tail
Poly A Tail
What are introns?
Coding sequences
Noncoding sequences
Untranslated regions
Promoters
What do exons code for?
Proteins
Lipids
Carbohydrates
Nucleic acids
What is characteristic of prokaryotic mRNA?
It has a poly A tail
It has a 5' cap
It has one promoter and one long continuous coding region
It has multiple promoters and fragmented coding regions
What is the core of the spliceosome made of?
snurps
lariat structure
exons
What structure do snRNPs pull together during the splicing mechanism?
Exons
snurps
introns to make a lariat
Proteins
What does alternative splicing allow for?
Decreased protein diversity
Increased protein diversity
Reduced coding potential of the genome
The creation of snRNPs
Where is mRNA made in eukaryotes?
Cytoplasm
Nucleus
Ribosome
Mitochondria
After transcription, where is the mRNA moved to in eukaryotes?
Nucleus
Mitochondria
Cytoplasm
Endoplasmic reticulum
Why is mRNA transcribed and translated directly in the cytoplasm in prokaryotes?
Because prokaryotes have a well-defined nucleus
Because prokaryotes have multiple compartments
Because prokaryotes do not have nuclei
Because prokaryotes use DNA instead of RNA
What is the process of using mRNA to make proteins called?
Replication
Transcription
Translation
Mitosis
Where does the process of translation occur?
In the nucleus
At the ribosome
In the mitochondria
On the cell membrane
Are ribosomes large enough to be seen under a microscope?
Yes
No
What is a codon?
A. A type of protein
B. A sequence of three nucleotides that forms part of a stop codon
C. A sequence of three consecutive nucleotides that specifies a specific amino acid
D. A molecule that helps in the replication of DNA
What does the start codon AUG code for?
A. Serine
B. Arginine
C. Methionine
D. It is a stop codon and does not code for any amino acid
What can happen if RNA is not translated correctly?
A. It can lead to a mutation
B. It will code for the intended protein
C. It will enhance the protein function
D. It will have no effect on the protein
What are the two main structural components of a ribosomal subunit?
DNA and ribosomal proteins
mRNA and ribosomal proteins
rRNA and ribosomal proteins
tRNA and ribosomal proteins
How many sites are there on the ribosomal unit?
1
2
3
4
What does the 'E' site on the ribosomal unit stand for?
Entry site
Energy site
Exit site
Enzyme site
What is the function of the 'P' site on the ribosomal unit?
It holds the tRNA carrying the growing polypeptide chain.
It is responsible for the exit of tRNA after delivering amino acids.
It is the site where mRNA is decoded.
It is the site where ribosomal proteins are synthesized.
What does each ribosome bind to during protein synthesis?
1 mRNA and 1 tRNA
1 mRNA and 2 tRNAs
1 mRNA and 3 tRNAs
2 mRNAs and 3 tRNAs
What is the function of tRNA in protein synthesis?
It synthesizes new DNA strands.
It brings the needed amino acids to the ribosome.
It helps in the replication of the cell.
It modifies the mRNA after transcription.
What is the role of the anticodon in tRNA?
It starts the replication process.
It adds nucleotides during transcription.
It recognizes the amino acid sequence on the mRNA.
It prevents the mRNA from degradation.
Where on the tRNA molecule is the amino acid attached?
5' end
Ribosome binding site
3' end
Anticodon loop
Which enzyme is responsible for adding an amino acid to tRNA?
RNA polymerase
Helicase
Aminoacyl-tRNA synthetases
Ligase
What is the energy source used by aminoacyl-tRNA synthetases to attach an amino acid to tRNA?
Glucose
GTP
ATP
NADH
How is the energy from the high energy linkage on tRNAs (+ their amino acid) used during translation?
To replicate the DNA
To transcribe mRNA
To covalently bond amino acid to polypeptide chain
To break down the mRNA
What happens after a stop codon is met during translation?
The ribosomal unit starts the process over again
A release factor binds to it and the ribosomal unit dissociates
A peptide is formed
The mRNA is degraded
What is added by the release factor at the end of the translation process?
An amino acid
A peptide
A carboxy
A tRNA
What are poly-ribosomes?
A single ribosome translating multiple mRNAs at once
Many ribosomes translating on one mRNA molecule simultaneously
A group of ribosomes attached to a single amino acid
Ribosomes that only synthesize polysaccharides
What is the main advantage of poly-ribosomes?
They prevent protein synthesis
They enable the synthesis of more protein molecules at once, increasing efficiency
They block bacterial protein synthesis
They allow ribosomes to translate without mRNA
What does differentiation refer to in the context of cell biology?
The division of a cell into two identical daughter cells
The process in which a non-specialized cell becomes specialized
The replication of DNA within a cell
The movement of a cell from one part of the body to another
Which example is given to illustrate how gene expression determines cell differentiation?
Mitosis
Cloning
Meiosis
Mutation
What was the outcome when a random cell type with its nucleus removed was implanted into an egg that had its nucleus removed?
The cell could not develop further
The cell turned into a different type of specialized cell
The cell was able to grow into an embryo/baby
The cell died immediately
What are housekeeping proteins?
Proteins that are only expressed in certain cell types
Proteins that are found in all cell types and are constantly expressed
Proteins that are expressed in response to external stimuli
Proteins that are never expressed in cells
What does "constitutive" gene expression mean?
Gene expression that occurs only during cell division
Gene expression that is regulated by external signals
Gene expression that is constant and does not require external signals
Gene expression that is temporary and changes frequently
Why is differential gene expression important?
It prevents the expression of any genes within a cell
It ensures that all cells express the same genes
It allows for variation in cell size, shape, and function
It is not important for cellular function
What is the SLOW version of changing gene expression referred to in the text?
A change in the cell membrane
A change in the making of a protein
A change in DNA replication speed
A change in the organism's behavior
Which of the following is NOT one of the three major types of gene regulation mentioned in the text?
When/How often a gene is being transcribed
The selective degradation of mRNA molecules
The selective activation/deactivation of proteins
The rate of glucose intake by the cell
What does "post-translational" refer to in the context of gene regulation?
Before the gene is transcribed
During the transcription of the gene
After the translation of proteins
During the replication of DNA
What is the function of histone acetylases in chromatin structure?
They remove acetyl groups which closes DNA
They add acetyl groups which opens DNA
They bind to the promoter region near TATA
They add methly which opens the DNA
Where do general transcription factors and RNA polymerase II bind for transcription?
On regulatory sequences
On histone deacetylases
On the promoter region (near TATA)
Far away from genes
What are regulatory sequences?
Sites that remove ATP from DNA
The promoter regions
Sites that are far away from genes and regulate whether/how much a gene is expressed
Sites where RNA polymerase II binds
What is the difference between transcription factors and general transcription factors?
Transcription factors remove acetyl groups, while general transcription factors add them
Transcription factors are the same as general transcription factors
Transcription factors bind to the promoter region, while general transcription factors bind to regulatory sequences
Transcription factors are what actually affect gene expression, different from general transcription factors
What do transcription factors bind to in the DNA? (not general transcription factors)
Promoter regions only
Regulatory sequences specifically and tightly
Any DNA sequence randomly
Only the sequences near the actual gene
What is the primary function of activators as transcription factors?
Decrease gene expression
Bind to enhancers only
Increase gene expression
Cut the DNA strand
Repressors are transcription factors that:
Increase gene expression
Have no effect on gene expression
Decrease gene expression
Only bind to promoters
How can activators and repressors be regulated?
By temperature changes only
By constitutive action or phosphorylation
Only during cell division
By binding to each other
Can transcription factors work on regulatory sequences that are far from the actual gene?
No, they can only work on sequences close to the gene
Yes, but only during replication
Yes, they can work on regulatory sequences very far from the actual gene
No, they do not work on regulatory sequences
Where must activators, also known as transcription factors, bind to regulate gene expression?
To the promoter sequence only
To the enhancer sequence only
To regulatory sequences that can be down/upstream of the gene
Directly to the RNA polymerase
What happens to the DNA structure during gene activation?
DNA remains linear
DNA replicates
DNA bends and a mediator protein mediates b/t promoter and regulatory sequence
DNA breaks apart
What is required to express a protein in terms of transcription factors?
Only one specific activator
A combination of different transcription factors
Repressors only
No transcription factors are needed
What is combinatorial control in eukaryotes?
When a gene is controlled by a single transcription factor
When a gene is controlled by a few transcription factors that are all activators
When a gene is controlled by MANY transcription factors/groups and the combination determines the final rate of transcription initiation
When a gene expression is random and not controlled by transcription factors
What can combinatorial control of transcription factors create?
Only one cell type
Different cell types through different combinations of transcription factors
The same protein in all cell types
No change in cell types
What was demonstrated by implanting a transcription factor for an eye on the leg of a fly?
That transcription factors are not specific for what they do
That transcription factors can only function in their original location
That transcription factors can lead to a positive feedback loop to encode for additional transcription factors
That transcription factors have no role in determining where body parts grow
How can chromatin structure be propagated from parent to child cell?
Through DNA replication
Through epigenetic inheritance
Through transcription factors
Through cell division
Can DNA methylation patterns be inherited?
No, they cannot be inherited
Yes, but only through mutations
Yes, they can be inherited
No, they are always acquired anew
What happens once a cell has been differentiated?
It can easily change into another cell type
It loses all its specialized functions
It stays differentiated and cannot change back
It divides into pluripotent cells
What are Induced Pluripotent Cells (iPS)?
Cells that can only differentiate into one cell type
Cells that remain in their differentiated state
Cells that can differentiate into other cell types but cannot be reverted back to iPS
Cells that are given certain transcription factors to revert back to a pluripotent state
What type of chromatin is considered "open" and generally associated with active gene expression?
Heterochromatin
Euchromatin
Maintenance Methyltransferase
Histone tail
What is the role of Maintenance Methyltransferase?
It ensures acetylation is passed off to new DNA during replication.
It ensures methylation is passed off to new DNA during replication.
it maintain methylation on already created DNA
What does acetylation of histone tails result in?
Closing of chromatin and activation of genes.
Opening of chromatin and suppression of genes.
Opening of chromatin and activation of genes.
Methylation of DNA.
Which of the following is a reversible chemical modification on histone tails?
Ubiquitination
Acetylation
Methylation
All of the above
What are post-transcriptional controls?
Controls on a gene before transcription has started
Controls on a gene after transcription has been started
Controls on a gene during DNA replication
Controls on a gene during the translation process
Which of the following is NOT an example of post-transcriptional control?
Alternative splicing
UTR regions affecting binding of activators/repressors
Small regulatory RNAs causing degradation of mRNA
Histone tail modifications
What components are removed by snRNPs during splicing?
Exons
Introns
UTRs
mRNA
What can affect the binding of transcription factors to the 5' UTR region?
Shape of the 5' UTR
Number of exons
Length of the mRNA
Size of the introns
Which of the following can influence whether mRNA can make protein?
Protein binding
A small molecule
Temperature
All of the above
What is the role of noncoding RNAs found on the "junk" part of DNA?
They are involved in DNA replication
They play a role in gene expression
They are not involved in any cellular processes
What is the function of Micro RNA (miRNA)?
It enhances the expression of genes
It base pairs with specific mRNA to control stability and translation to silence genes
It repairs damaged DNA
It assists in the replication of viral RNA
What is RNA Interference (RNAi) primarily involved in?
Enhancing gene expression
Degrading foreign RNA molecules
Facilitating DNA replication
Silencing DNA segments
Which molecule is attracted by RNAi to degrade foreign RNA?
RISC
DICER
snurps
mRNA
What is the purpose of siRNA?
To enhance the replication of viruses
To shut down foreign viruses
To promote gene expression
To assist in protein synthesis
What is proteolysis?
The process where proteins synthesize enzymes
The process where enzymes break proteins down into their amino acids
The process where amino acids are linked together to form proteins
The process where proteins are synthesized from nucleic acids
Which enzymes are responsible for breaking down proteins?
Lipases
Proteases
Amylases
Nucleases
What is the role of ubiquitin in protein degradation?
It synthesizes new proteins
It folds proteins into their correct shape
It marks proteins for degradation/proteolysis
It transports proteins across the cell membrane
What is the consequence of protein degradation on gene expression?
It initiates gene expression
It enhances gene expression
It has no effect on gene expression
It halts gene expression
