Organelles Flashcards
What are the organelles?
Nucleus
ER
Golgi
Lysosome
Peroxisome
Mitochondria
What are the non-membrane bound organelles?
Ribosome
Proteosome
What structures are found in the nucleus?
Chromatin
Nucleolus
Nucleoplasm
Nuclear lamina
Envelope
Pores
Where are ribosomes initially assembled?
Nucleolus
What is the nuclear envelope?
Two membranes with pores
Outer continuous with rER
Inner membrane supported by lamina
What is the function of nuclear pores?
Mediate translocation
What does the nucleoplasm contain?
Matrix - organizational scaffold
Nuclear particles
What is a polysome?
When many ribosome are bound to the same mRNA strand
Where does translation start?
mRNA first binds to ribosomes in cytosol
When will a ribosome bind to rER?
When there is a secretory signal sequence on mRNA
What is the rER and its functions?
Interconnected sacs studded with ribosomes
Some co- and posttranslational modifications - glycosylation, cleavage
Protein folding by chaperones
What happens when a protein is misfolded?
Bound by chaperones to be correctly folded
Polyubiquitinated to be degraded by proteasome in cytoplasm
What are the functions of sER?
Synthesis of lipids
Drug detoxification
Muscle contraction and relaxation
Sequesters Ca from cytosol
Glycogen metabolism
What is the structure and function of golgi apparatus?
Stacked, flattened cisternae attached by microtubules
Post-translational modification
Protein sorting and packaging
What is the process of a protein through golgi?
Cis-golgi receives from rER in vesicles - anterograde transport
Synthesizes polysaccharides and glycosylation
Adds M6P for proteins for lysosomes
Vesicles bud from trans-golgi for secretion, membrane, or lysosome
Why is O-linked glycosylation important?
Maintain stability
Recognition
Mucins and proteoglycan function
What is the function of the lysosome?
Enzymatic degradation - acidification of luminal space
What signal sequence is required for entry into nucleus?
NLS - uses carrier protein
What are the functions of peroxisomes and where are they most prominent?
Oxidation reactions
Detoxifies H2O2
Most prominent in liver
Different enzymes in different cell types
What is mitochondria?
2 membranes with inter-membrane space
Inner membrane responsible for electron transport chain
Outer membrane regulates transport
