2. The Organelles Part 2 Flashcards
What is the main purpose of the rough ER?
site of protein synthesis for proteins targeted to enter the secretory pathway
What is the main purpose of the smooth ER?
steroid hormone biosynthesis and the degradation of environmental toxins
What are the two sites for protein synthesis in cells?
- free ribosomes in the cytoplasm
- ribosomes attached to the rough ER
Where do proteins go that are translated on free ribosomes in the cytoplasm?
peroxisomes
mitochondria
nucleus
cytoplasm
Where do proteins go that are translated on the rough ER?
secreted into the extracellular environment
integral plasma membrane proteins
membrane of interior of the ER, golgi apparatus, or lysosomes
What will determine if a protein will be translated on the rough ER?
presence of a signal sequence
What is a signal sequence?
amino acid sequence at the N-terminus
What type of proteins contain transmembrane domains?
integral membrane proteins
What are transmembrane domains?
signal sequences that are found in the interior of integral membrane proteins
What is an additional function of the rough ER?
initial post-translational modification of proteins such as glycosylation and disulfide bond formation
What are the functions of the Golgi apparatus?
- modification of proteins made in the rough ER
- sorting and sending of proteins to their correct destinations
- synthesis of certain macromolecules
What are the three regions of the Golgi apparatus?
cis stack
medial stack
trans stack
What is exocytosis?
process in which a vesicle moves from the trans Golgi toward the cell surface and fuses with the cell membrane where the contents of the vesicle are released to the extracellular environment
What is the constitutive secretory pathway?
when proteins are sent in vesicles from the Golgi immediately to the cell surface
What is the regulated secretory pathway?
when secretory proteins are stored in vesicles and released at specific times in response to a change in the extracellular environment
