Smooth ER
What will cells that secrete a lot of protein will have?
A lot of rough ER
What will cells that make a lot of cholesterol or lipid will have?
A lot of smooth ER
During the synthesis of the phospholipid what happens?
All phospholipids are initially inserted into the leaflet of the bilayer of the smooth ER
In the end, how are phospholipids distributed the two leaflets of the plasma membrane?
Asymmetrically
Why do liver cells have a lot of smooth ER?
Because they contain a lot of cytochrome p450s
What important function does the Rough and Smooth ER sequester?
Ca++
In the end, how are phospholipids distributed within the two leaflets of the plasma membrane?
Evenly
Does the smooth ER membrane faces the cytosol or away?
Faces the cytosol
True or False: Every cell won't have some type of ER
False
True or False: When cells need more of one type of organelle it won't make more of that type
False
What gives the asymmetric plasma membrane arrangement of the Golgi and Plasma membrane?
Flippases and Floppases
What are the two types of cytoplasmic inclusions?
Glycogen rosettes, and Fat droplets
Describe HMG CoA Reductase
Integral membrane protein in smooth ER membrane, biosynthesis tightly regulated, and Enzyme targeted by STATIN drugs that reduce blood cholesterol
What is the Endoplasmic reticulum (ER)?
Labyrinthine membrane-enclosed compartment in the cytoplasm of eukaryotic cells where lipids and proteins are made
What are the 4 possible mechanisms for lipid movement within, across, and between membrane lipid bilayers?
Laterally diffuse, translocate between two leaflets of the bilayer, lipid transfer protein, carried by vesicular transport
What are some Smooth Er Functions?
Lipid Biosynthesis, Cholesterol biosynthesis, calcium storage and release by ER, and detoxification and breakdown of macromolecues
What keeps the smooth ER, rough ER, Nuclear envelope, and nucleus?
Lipids that have "practically" crystalized
Leaflet bilayer of SER membrane faces what of the SER?
Lumen
What types of macromolecules can cross through one end of the connected membrane to another?
Membrane proteins and lipid
What organelle also sequesters Ca++?
Mitochondria
Define Scrambalse
Moves phospholipids from one leaflet of the bilayer to the other in both direction (does not require ATP)
Define Floppase
Only moves specific phospholipids from the cytoplasmic leaflet to the extracellular leaflet (needs ATP)
Define Flippase
Only moves specific phospholipids from the extracellular leaflet of the bilayer to the cytoplasmic leaflet (needs ATP)
How many parts is the Endoplasmic reticulum divided into?
Rough ER and Smooth ER
What is inside a leydig cell?
Smooth ER and Lipid droplets
Describe smooth ER
Smooth because it doesn't have bound ribosomes, and synthesizes lipids and other functions
Smooth ER is abundant in cells involved in
Steroid synthesis, because steroid hormones are synthesized from cholesterol
Describe Cytochrome p450
Superfamily of heme containing enzymes can be induced and inhibited occur in most tissues works on unusual chemicals (drugs, carcinogens, poisons) and converts them to oxygen so they can be more readily flushed
What do the enzymes of the smooth ER function in?
Synthesis of phospholipids, cholesterol, steroids, sex hormones (from cholesterol), regulation cytoplasmic Ca++ level, and detoxify drugs and poisons
What happens when large amounts of a certain compound like Phenobarbital enter system?
The smooth ER in liver hepatocytes doubles in surface area cell recognizes it needs more cytochrome p450 and needs more membrane to put them in
Where are most drugs ingested and broken in?
The smooth Er
How do phospholipids then reach the other leaflet to even out the bilayer?
Through scramblases, equally into both leaflets
True or False: The ER is one interconnected branching tubule
True
True or False: When cells need less of an organelle, it will degrade that type by autography
True
True or False: Smooth ER synthesizes almost all of the major classes of cellular lipids
True all major classes phospholipids all cholesterol
What are fat droplets?
accumulations of lipid molecules that are prominent in adipocytes, adrenal cortex cells, liver and other cells including steroid-secreting. Not surrounded by a membrane
Describe Rough ER
includes nuclear envelope, contains bound ribosome, synthesizes protein, and is the beginning of the secretory pathway
In the muscle what does Smooth ER form?
sarcoplasmic reticulum that plays a major role in muscle contraction
What will happen after the stoppage of Phenobarbital (drug) in the system?
the hepatocytes will degrade the excess sea within couple of days by autophagy
