به انگلیسی

Address tags for new proteins

Science · Organisms & Life Processes · ages 18-20

Name ______________________ Date ____________

Chains all start in the cytosol but jobs live elsewhere, so no sorting is needed. True or false?
Circle one: True False
What is a signal sequence?
- A short address tag on a new chain
- A sugar tag added later in the Golgi
- The ribosome that builds the chain
Deleting the signal from a secreted protein strands it in the cytosol. True or false?
Circle one: True False
A protein targeting sequence is swapped for another type. What happens?
- Nothing changes wherever the new tag points
- The protein follows the new tag
- Translation stops at once
What does the rough ER build?
- Lipids only and no proteins at all
- Cytosolic enzymes for the home market
- Proteins for export or membranes
How does translation of a secreted protein differ from a cytosolic one?
- It runs straight through without any pause at all
- It stops and starts over from scratch
- It pauses at the signal, then ends on the ER
Proteins without ER signals are secreted outside. True or false?
Circle one: True False
A cytosolic enzyme that gains an ER signal stays cytosolic. True or false?
Circle one: True False

Answer key

For grown-ups. Fold this page away before handing over the rest.

False · One birthplace with many workplaces demands sorting.
A short address tag on a new chain · The short stretch flags the protein for the ER and its station.
True · With no tag, no docking happens and the chain finishes at home.
The protein follows the new tag · Presence and type of tag predict destination.
Proteins for export or membranes · Docked ribosomes feed export and membrane cargo into the ER.
It pauses at the signal, then ends on the ER · Targeting interrupts translation mid stream to dock the ribosome.
False · Without docking they stay in the home market.
False · The new tag docks its ribosome on the ER.