Lecture 6: Cell Phy 2 Flashcards
Why does the cell need an intact cell membrane?
-To provide structure and keep al of the organelles in the cell
- To create a barrier between the interior of the cell and the external environment
- Cell signaling
- Transport
True/False: Cell membrane has carbohydrates.
True
How are glycoproteins or glycolipids formed?
carbs form glycoproteins or glycolipids
What are proteoglycans?
carbohydrates attached to small protein cores
Where are proteoglycans found?
loosely attached to outer surface of cell membrane
What is the glycocalyx and what does it do?
- negatively charged outer layer that lines the cell membrane (part of the blood-brain barrier)
- prevents exposure of plasma components to the endothelial surface in the brain
- attaches some cells together
What kind of charge does the surface of the cell have?
Negative
What is the function of the negatively charged cell surface?
- helps repel other negatively charged particles or cells
- Prevents unwanted interactions or clumping of cells.
True/False: Many carbs act as receptors to bind hormones (e.g. insulin) to start internal enzyme cascade
True
Explain the insulin signaling pathways.
Food is digested and glucose is released into bloodstream, insulin is then secreted by the pancreas. Insulin then binds to receptors on the cell’s surface, causing GLUT4 (transporter) molecules to come to the cell’s surface and take glucose into the cell
What is the nucleus?
The control center of the cell
What is contained in the nucleus?
- Contains DNA (genes)
- Contain nucleoli
What is the function of DNA in the nucleus?
determine characteristics
of cell’s proteins
What is the cytosol?
clear portion of the cytoplasm that contains dissolved proteins, electrolytes, and glucose
What are the 5 organelles in the cytoplasm?
- Endoplasmic reticulum
- Golgi apparatus
- Mitochondria
- Lysosomes
- Peroxisomes
What is the general function of endoplasmic reticulum?
Produces proteins and
lipids (fats) for cell survival
What is rough ER and what does it do?
Attached to the outer surfaces of many parts of the ER are Ribosomes (made of RNA and protein) that make new protein* molecules
What is smooth ER and what does it do?
- Does not have attached ribosomes
- Makes lipids: Phospholipids and Cholesterol
- creates transport vesicles that transport substances to Golgi apparatus
What is the function of Intracellular vesicles?
replenish internal membranes
What is the function of smooth ER secretions?
- Forms vesicles, breakaway from Golgi apparatus and diffuse through cell
- Primarily forms Secretory vesicles to be secreted through cell membrane surface by exocytosis
Newly synthesized proteins are
extruded into the _____.
ER matrix
Describe the surface of the rough/Granular ER?
Outer membrane surface
covered with ribosomes
What are the types of proteins processed inside the matrix?
- crosslinked
− folded
− glycosylated (N-linked)
− cleaved
What is the function of the golgi apparatus?
- Makes some carbohydrates not able to be made by ER
- E.g. Hyaluronic acid and Chondroitin sulfate
- Receives transport vesicles from smooth ER
- Substances are concentrated, sorted, and packaged for secretion.
What is the function of Hyaluronic acid and Chondroitin sulfate?
- Compose proteoglycans in mucus and other secretions
- Ground substance in interstitium: collagen fibers and cells
- Cartilage and bone
What are the functions of the Golgi apparatus in association with ER?
- ER synthesizes new products
- Packs them in transport vesicles (ER vesicles)
- Pinch off from ER
- Fuse with Golgi apparatus
- Processed to form lysosomes, secretory vesicles
What is the structure of the golgi apparatus?
- Membrane composition similar to that of the smooth ER and plasma membrane
- Composed of four or more stacked layers of flat vesicular structures
What are Substances formed in the ER?
- “processed”
− phosphorylated
− glycosylated
What is exocytosis?
- Secretory vesicles diffuse through the cytosol and fuse to the plasma membrane.
- Lysosomes fuse with internal endocytotic vesicles.
What is in the nucleoli?
accumulation of RNA
and proteins
What is the function of the secretory vesicles?
- contain proteins synthesized in RER bud from the Golgi apparatus
- fuse with plasma membrane to release contents
How does stimulated secretion get activated?
It needs a trigger
How does constitutive secretion happen?
randomly
