Biochem Exam 3 (old exams)

Which of the following statements about insulin are not true?

Insulin inhibits gluconeogenesis via an allosteric effect on PEP carboxykinase

In addition to the insulin receptor being able to signal to mTOR and up regulate things like lipids biogenesis and translation, another biosensor in the cell can sense energy levels and nutrient biosensor's name is?

Glucagon

When v-snares and t-snares pull together what is the result of the membrane and proteins involved?

There is a tension supplied by t-snares and v-snares that results in membrane fusion and the subsequent deliver of protein to the extracellular space

Which of the following chemicals can be used to block all de novo (new) proteins synthesis in a cell?

Cycloheximide

Which of the following best describes the role of EF-Tu (elongation factor Tu) in elongation of protein synthesis?

It is involved in the correct binding of amino acyl tRNA to the A site of the ribosome

Real-time PCR is used to indirectly analyze the levels of what molecule?

mRNA

A western blot is used to detect levels of which of the following?

Protein

The intracellular portion of the G-coupled protein that exchanges GDP for GTP dissociating from the other two and become active is called?

alpha?

Used DNase enzyme to prove Fred Griffith correct

Oswald, Avery, Colin MacLeod

Found that the ratios of A:T and C:G are 1:1

Erwin Chargaff

Used T2 bacteriophage and radioactive sulfur and phosphorus to confirm that DNA is the genetic material, not protein

Hershey and Chase

Estimated the diameter and pitch of the helix from other X-Ray defractions

Wilkins and Alex Stokes

Had their direct X-ray defraction results used by Watson and Crick and only got recognition by the Nobel Committee after they were deceased

Rosalind Franklin

Had solved the structure of the alpha helix and was trying to apply this to DNA

Linus Pauling

DNA transforms R pneumococci into the S form but had some protein contamination issues and therefore was not conclusive enough

Fred Griffith

Which of the following statements about hormones are correct?

1) hormones can be peptides, steroids, or amino acid derivatives

2) Hormones can stimulate the synthesis of target proteins through the activation of specific genes

3) Hormones can directly activate or inhibit enzymes through the action of signal molecules

4) Hormones can increase the cellular uptake of metabolites

1,2,4 correct

Under which conditions are the lac structural genes expressed least efficiently

No cAMP, no lactose

Posttranslational modifications include all except

disulfide bond formation

glycosylation

N-acylation

Carboxylation

Removal of introns

Removal of introns

The process of translation is extremely accurate (1 mistake in 10,000) due to

Codon/anti-codon interactions & amino-acyl tRNA synthetases

Prokaryotic DNA is packed very differently than eukaryotic DNA. Which of the following statements is true of prokaryotic DNA packaging?

None of the above

Which of the following statements about the ubiquitination of proteins are true?

1) Ubiquitin is a relatively small protein that is widely expressed in eukaryotic cells

2) It is covalently attached to target proteins in an ATP-dependent reaction

3) A carboxyl group of ubiquitin forms amide bonds with free amines found on the target protein

4) Target selection is determined by ubiquitin-protein ligases

1,2,4

A researcher will do which of the following to elucidate how a known steroid receptor protein sends its signal through the cell ultimately changing transcription of a gene.

Clone that affected the genes promoter into a luciferase vector to study the control of the transcription of that gene

Why would siRNA be preferred over a chemical inhibitor that targets the same molecule?

Off targets of chemical inhabitation may occur where siRNA in specific to a desired mRNA

If the length of the resulting real-time PCR products are identical use the melt curve data below. If peak A has consists of DNA with only G-C base pairs and peak E consists of DNA with all T-A base pairs, which of the peaks has the 2nd highest amount of A-T compared to G-C base pairs?

The peak labeled B has the 2nd highest amount A-T compared to G-C base pairs

A protein destine for insertion into the rough endoplasmic reticulum contains a sequence that instructs it to go there. this sequence is called a

signal sequence

cloning a promoter in front of luciferase and transfecting this newly created plasmid into a cell will enable a researcher to do which of the following?

Determine the status of transcription of the gene associated with the promoter is