Cell 1 Flashcards
(41 cards)
What does the plasma membrane consist of and what %’s?
50% protein
45% lipid
5% carbohydrates
What is a method of membrane cleavage?
What are the 2 sides of the membrane called?
To which side do most membrane particles remain attached to?
Cryofracture (freeze fracture)
Protoplasmic face (P) and Extracellular face (E)
P
What are the 3 functions of peroxisomes?
- Oxidize organic substances by transferring H atoms to molecular oxygen
- The product hydrogen peroxide is toxic and removed by catalase, which is inside the peroxisome
- Beta oxidize long chain and branched fatty acids
Describe the steps of Receptor-Mediated endocytosis
- Binding of ligands to receptors causes receptors to accumlate in coated pits coated by clathrin
- The coated pit invaginates and pinches off forming a coated vescicle containing the receptor & bound ligand
- Coated vescicles lose their clathrin and fuse w/ endosomes. Clathrin detaches and recycles back to PM
How do new mitochondria arise?
By fission of existing mitochondrias
What subunits do eukaryotic ribosomes consist of?
Where is RNA synthesized in eukaryotic cells?
60S and 40S.
in the nucleus
What does the SER do in muscle cells
It participates in contraction. Here it is called the sarcoplasmic reticulum is involved in the sequestration/release of ca2+ during contraction
What is the cytoskeleton composed of?
What is its function?
Microtubules, microfilaments, and intermediate filaments.
It provides shape and allows movement of cells
What is the unit membrane composed of?
An electron lucent layer b/w 2 electron dense layers
How are the proteins of the PM made?
They are SYNTHESIZED in the Rough ER, MODIFIED in the Golgi, and transferred to the cell membrane
What is the thickness of the Plasma Membrane?
7.5-10nm
visible by EM
What do ribosomes bind to in the ER?
A signal recognition particle (SRP)
In what direction in the golgi are vesicles transported?
Convex Cis face (close to RER) TO concave trans face
What happens to the PM vesicles that invaginate due to pinocytosis?
They eventually fuse with lysosomes
What are the 3 types of movement of molecules through the PM?
Simple diffusion,
Carrier protein,
Channel protein
The rough ER does what?
It segregates proteins NOT destined for the cytosol
What is the environmenet inside lysosomes?
Where are lysosomes abundant?
Internally acidic, containing hydrolytic enzymes.
Abundant in phagocytic cells like macrophages
What is actin important for?
Motility, shape, and movement of organelles
What are special about endosomal membranes? What does this cause?
They contain ATP-driven proton pumps which acidify the interior compartment.
This causes the separation of ligand/receptor complexes, allowing receptors to cycle back to PM
How many types of cells are there in humans?
200
Where are lysosomal membranes/proteins packaged?
How are they delivered?
In the TRANS-Golgi network.
They are delivered separately in clathrin-coated vesicles to late endosomes forming endolysosomes which mature to become lysosomes.
What are the 4 types of integral membrane proteins?
- Transport proteins (eg Na, K, and ATPase)
- Ion selective channels
- Receptors
- Anchoring structural proteins
What are zymogen granules?
Membrane bound vesicles containing digestive enzymes
What is the glycocalyx?
What charge is it and why?
A cell surface coat consisting of externally exposed oligosaccharide chains from proteins and lipids.
The glycocalyx has a negative charge due to the presence of carboxyl groups and sulfate ions.
