Smooth ER

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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


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