Cells and other smaller lectures Flashcards
Are all cells enclosed by a membrane ?
YES
What three systems do most eukaroyotic organelles belong to ?
Protein Uptake
Secretion Pathway
Uptake and degradation
What are the main differences between euchromatin and heterochromatin ?
Euchromatin is less intensely stained and contains most active genes.
Where does protein synthesis occur ?
In ribosomes present in the cytosol (the ribosome then either stay in the cytosol or bind to ER)
Where are ribosomes assembled ?
In nucleolus at amplified ribosomes genes.
What is the difference between constitutive and secretory vesicles ?
Constitutive bud from Golgi with membrane
Secretory bud from Golgi with packaged secretion
What are the models of Golgi transport ?
Cargo moves forward from sac to next through vesicles (stable Golgi sacs)
Factories move with cargo and recycle in vesicles (maturing Golgi sacs)
What is one reason for Golgi being close to the microtubule tracks ?
Upon secretion from Golgi, vesicles are transported along polarised microtubules track emanating from centrosomes (=MOC)
What is the relation between centrosomes and centrioles ?
In animal cells, 2 centrioles per centrosome
What is the process of uptake and degradation in cells ?
Following endocytosis of material and delivery to endosomes, it is passed on to lysosomes for degradation using low pH and hydrolytic enzymes.
What is autophagy ?
Cytoplasmic components digested in lysosomes.
What is pinocytosis ?
Fluid intake
What is receptor-mediated endocytosis ?
Absorption of protein/virus by inward budding of membrane vesicle containing proteins with receptor for the protein/virus
Where are the functional components of endosomes and lysosomes made ?
RER
How does protein degradation by proteasome work ?
Junk protein tagged with ubiquitin (in cytoplasm, not lysosome).
Proteasome detects it and degrade protein through proteolysis
What are the two great steps in eukaryotic cell evolution ?
Compartmentation
Mitochondria
What is clathrin ?
Scaffold coat aiding vesicle budding
What are the differences between microtubules, intermediate filaments and microfilaments?
Microtubules: thickest. Vesicle track made of tubulin
Microfilaments: thinnest. Generates contractile forces enabling movement and contraction. Made of actin
Intermediate filaments: middle thickness. Helps with strength and support (some in cytoplasm, others support nuclear envelope. Laminin, keratin)
What is the role of the SER ?
Lipid, steroid production and detoxification
What is the role of peroxisomes ?
Breaks down FAs, synthesise specialised lipids and so oxidative reactions using molecular oxygen.
What is the aim of cell replication ?
Condensing chromosomes.
What is the name of the OG cell ?
Totipotent stem cell
What are the stages following totipotent stem cell ?
Totipotent stem cell –> Blastocyst with pluripotent SCs –> Isolated pluripotent SCs + Lematopoietic SCs (lead to blood cells) + neural SCs + mesenchymal SCs (lead to CT)
What is hypercholesteroleamia due to ?
Defective uptake of lipoprotein. May be due to:
1) LDL not properly transported from RER to Golgi for expression on cell surface
2) LDL receptor bound to LDL does NOT cluster in endocytic vesicles on plasma membrane
3) LDL not recycled back to cell surface