Chapter 15

unfolded protein response (UPR)

- Activation of the UPR results in the production of more ER membrane. - Activation of the UPR results in the production of more chaperone proteins. - Activation of the UPR results in the cytoplasmic activation of gene regulatory proteins.

vesicle budding from the Golgi

- Adaptins interact with clathrin. - Once vesicle budding occurs, clathrin molecules are released from the vesicle. - Clathrin molecules act at the cytosolic surface of the Golgi membrane.

Facts about the ER

- The ER is the major site for new membrane synthesis in the cell. - steroid hormones are synthesized on the smooth ER. - The ER membrane is contiguous with the outer nuclear membrane.

After isolating the rough endoplasmic reticulum from the rest of the cytoplasm, you purify the RNAs attached to it. Which of the following proteins do you expect the RNA from the rough endoplasmic reticulum to encode?

- soluble secreted proteins - ER membrane proteins - plasma membrane proteins v

appropriate order through which a protein destined for the plasma membrane travels?

ER -> golgi -> plasma membrane

membrane-enclosed organelles

In a typical cell, the area of the endoplasmic reticulum membrane far exceeds the area of plasma membrane.

What is the role of the nuclear localization sequence in a nuclear protein?

It is bound by cytoplasmic proteins that direct the nuclear protein to the nuclear pore.

Your friend works in a biotechnology company and has discovered a drug that blocks the ability of Ran to exchange GDP for GTP. What is the most likely effect of this drug on nuclear transport?

Nuclear transport receptors would be unable to release their cargo in the nucleus.

You are interested in Fuzzy, a soluble protein that functions within the ER lumen. Given that information, which of the following statement must be true?

Once the signal sequence from Fuzzy has been cleaved, the signal peptide will be ejected into the ER membrane and degraded.

protein families involved in directing transport vesicles to the target membrane?

SNAREs Rabs tethering proteins

secretion

The membrane of a secretory vesicle will fuse with the plasma membrane when it discharges its contents to the cell's exterior.

Most proteins destined to enter the endoplasmic reticulum

begin to cross the membrane while still being synthesized.

Photosynthesis occurs

chloroplasts

In which cellular location would you expect to find ribosomes translating mRNAs that encode ribosomal proteins?

cytosol

Where are proteins in the chloroplast synthesized?

cytosol and chloroplasts

Your friend has just joined a lab that studies vesicle budding from the Golgi and has been given a cell line that does not form mature vesicles. He wants to start designing some experiments but wasn't listening carefully when he was told about the molecular defect of this cell line. He's too embarrassed to ask and comes to you for help. He does recall that this cell line forms coated pits but vesicle budding and the removal of coat proteins don't happen. What proteins might be lacking in this cell line?

dynamin

new membrane synthesis

er

modification of secreted proteins

golgi

Degradation of worn out organelles

lysosomes

oxidative phosphorylation

mitochondria

transcription occurs

nucleus

organelles part of the endomembrane system?

nucleus, golgi, lysosomes

breakdown of lipids and toxic molecules

peroxisomes

steroid hormone synthesis

smooth ER

N-linked oligosaccharides on secreted glycoproteins are attached to

the asparagine in the sequence Asn-X-Ser/Thr.

An individual transport vesicle

will fuse with only one type of membrane.