Biochemistry LE 5: Gene III: Translation and Genome Defense

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What is the normal theme for gene expression?

Multiple genes lead to 1 protein

1 mRNA leads to 1 protein (correct)

1 gene leads to multiple mRNAs and proteins

Multiple mRNAs lead to 1 protein

What is alternative splicing?

The process of translating one mRNA into one protein

The process of translating one mRNA into multiple proteins

The process of using different reading frames to translate one mRNA

The process of transcribing one gene into multiple mRNAs (correct)

What is a characteristic of prokaryotic mRNA?

It is processed before translation

It is polycistronic (correct)

It has a cap at the 5' end

It is monocistronic

What is the function of the cap at the 5' end of eukaryotic mRNA?

It helps ribosomes recognize the mRNA Signup and view all the answers

What is the first amino acid in prokaryotic proteins?

Formyl-Met Signup and view all the answers

What is the composition of the small subunit of prokaryotic ribosomes?

16S rRNA and 21 proteins Signup and view all the answers

What is the function of elongation factor EF-T in prokaryotes?

It elongates the polypeptide chain Signup and view all the answers

What is the mechanism of shut-off in prokaryotes?

Dimerization of ribosomes Signup and view all the answers

How many subunits does the eukaryotic initiation factor eIF2 have?

3 Signup and view all the answers

What is the function of the cap-binding complex and the 43S-initiation complex?

To bind to mRNA and initiate scanning for the start codon Signup and view all the answers

What is the role of eIF4E and PABP in the initiation of translation?

To bind the 5' and 3' end of mRNA, respectively Signup and view all the answers

What happens to the mRNA during stress or starvation?

The mRNA is not translated into protein Signup and view all the answers

What is the function of 4EBP during stress?

To prevent the assembly of the cap-binding complex Signup and view all the answers

What is the role of mTORC1 during normal conditions?

To phosphorylate p70S6K1 Signup and view all the answers

What happens to the eIF4 complex during stress or starvation?

It does not bind to mRNA and translation is halted Signup and view all the answers

What is the function of the 43S-initiation complex?

To bind to mRNA and initiate scanning for the start codon Signup and view all the answers

During stress or starvation, what happens to the phosphorylation of p70S6K1?

It is prevented Signup and view all the answers

What is the function of the cap-binding complex?

To facilitate the attachment of the 43S-initiation complex Signup and view all the answers

What happens to the eIF2-GDP complex during normal conditions?

The GDP is exchanged with GTP, leading to the production of the eIF2-GTP complex Signup and view all the answers

What is the effect of elevated P38 MAPK during viral infection?

Prevention of the assembly of the cap-binding complex Signup and view all the answers

What happens to the ribosomal apparatus when it reaches the stop codon?

It dissociates, and the components do not reassemble Signup and view all the answers

What is the role of eIF2B during normal conditions?

It exchanges GDP with GTP, leading to the production of the eIF2-GTP complex Signup and view all the answers

What is the effect of phosphorylated eIF2 during stress?

It prevents the removal of GDP, halting protein synthesis Signup and view all the answers

What is the role of the 40S initiation complex?

It scans the ORFs in the 5'-UTR of mRNA Signup and view all the answers

What is the outcome when the ribosomal apparatus reaches the main ORF?

It initiates translation of the main ORF Signup and view all the answers

What is the effect of the MAPK-interacting kinase during viral infection?

It enhances the binding of 4E-BP1 with eIF4E Signup and view all the answers

What is the number of Open Reading Frames (ORFs) in the 5'-UTR of mRNA?

Four Signup and view all the answers

What is epigenetics defined as?

The inheritance of altered characteristics without alterations in the DNA sequence Signup and view all the answers

What is the effect of DNA methylation on gene expression?

It silences gene expression Signup and view all the answers

What is the role of Methyl-Cytosine Binding Protein (MeCP) in DNA methylation?

It enhances DNA methylation Signup and view all the answers

What is the result of histone deacetylase binding to MeCP?

Deacetylation of histones Signup and view all the answers

What is the effect of histone deacetylation on gene expression?

It silences gene expression Signup and view all the answers

What is the outcome of DNA methylation in the ripening of fruit?

It silences genes involved in plant ripening Signup and view all the answers

What is the role of DNA demethylation in gene expression?

It enhances gene expression Signup and view all the answers

What is the result of the aggregation of nucleosomes?

Gene expression is silenced Signup and view all the answers

What is the significance of epigenetic modifications?

They are involved in gene expression and regulation Signup and view all the answers

What is the genetic defect in patients being treated with mipomersen?

Mutation on the Apolipoprotein B gene Signup and view all the answers

What is the mechanism of action of mipomersen?

It blocks the production of Apolipoprotein B mRNA Signup and view all the answers

What is the effect of mipomersen on LDL-C particle synthesis?

It decreases the assembly of LDL-C particles Signup and view all the answers

What is the purpose of modifying the 2' position of ribose in siRNA?

To resist nuclease degradation Signup and view all the answers

What is the purpose of lipid-based delivery systems like SNALPs?

To increase the stability of siRNA in blood Signup and view all the answers

What is the effect of reducing APOB and APOC3 production?

Decreased VLDL, IDL, LDL, and hypertriglyceridemia Signup and view all the answers

What is the level at which siRNA affects gene expression?

Translational level Signup and view all the answers

What is the function of cluster of tandem repeats around the centromere?

To protect against the spread of repeated DNA sequences Signup and view all the answers

Where are the cluster of tandem repeats around the centromere especially active?

In reproductive cells of higher animals Signup and view all the answers