Cells and Organelles Flashcards
FOM 1, Exam 1, Lectures 5, 6, 19
What are primary functions of the plasma membrane?
selective permeability
exocytosis/endocytosis
cell-to-cell communication
What are the three types of endocytosis?
phagocytosis
pinocytosis
receptor-mediated endocytosis
What is phagocytosis?
engulf a large amount of material
What is pinocytosis?
engulf a small amount of extracellular fluid/ content to help with cellular processes or rebuilding cell membrane
What is receptor-meditated endocytosis?
requires binding to a receptor
needs coded proteins
What is the function of clathrin?
clathrin is a protein that is under the cell membrane and helps the ligand-bound receptors engulf the ligand from the surface
What is the function of clathrin?
clathrin is a protein that is under the cell membrane and helps the ligand-bound receptors engulf the ligand from the surface
What is the distribution of cholesterol in the cell membrane bilayer?
evenly distributed in both leaflets of bilayer
What is the distribution of phospholipids in the cell membrane bilayer?
asymmetric
What is the distribution of glycolipids in the cell membrane bilayer?
exclusively on outer leaflet of bilayer
What are the two faces on an electron micrograph image of a cell membrane?
E - face
P - face
What is the E-face on an electron micrograph image of a cell membrane?
inner surface of outer leaflet
closer to extracellular space
What is the P-face on an electron micrograph image of a cell membrane?
outer surface of inner leaflet
closer to protoplasm
What is the protoplasm?
all living parts of the cell on the inside (organelles)
What two types of proteins are found in the cell membrane?
integral proteins
peripheral proteins
What are integral proteins?
span across the whole membrane (ex. receptors, ion channels)
What is the glycocalyx?
a coating on the cell membrane that helps cells adhere to and recognize one another
What is the fluid mosaic model?
proteins are clustered in the lipid bilayer but they can move around
What does the membrane asymmetry of the fluid mosaic model refer to?
proteins usually stay on their own sides of the membrane
What does the membrane mobility of the fluid mosaic model refer to?
proteins can either move rapidly around the membrane or be held stable by intracellular structural elements
What are the most common type of membrane receptors?
integral membrane glycoproteins
What are the three domains of glycoproteins?
extracellular, transmembrane, and intracellular
What are the three main functions of membrane receptors?
- control membrane permeability
- bind extracellular matrix molecules to cytoskeleton via integrins
- relay messages to respond to extracellular events
What are venoms?
inactivate acetylcholine receptors of skeletal muscle sarcolemma at neuromuscular junctions
What is the function of channel-linked receptors?
open when a ligand bind to allow molecules/ions to move across membrane
What is the function of enzymatic (catalytic) receptors?
ligand (usually protein kinases) that bind the receptor induces catalytic activity in associated peripheral proteins
What is the function of G-protein coupled receptors?
ion channels/enzyme bound to the cytoplasmic surface of the cell membrane;
bind ligands that change the shape of its G-protein subunit, activating intracellular second messengers
What is the most common G-protein coupled receptor pathway?
cyclic adenosine monophosphate (cAMP), Ca2+, and inositol phospholipid-signaling pathway
What is familial hypercholesterolemia?
inability to take in cholesterol normally ingested by receptor-mediated endocytosis of LDLs
What are venoms?
inactivate acetylcholine receptors of skeletal muscle sarcolemma at neuromuscular junction
What is the cause of autoimmune diseases?
self-antibodies that bind to and activate plasma membrane receptors
What are two diseases that result from a damaged G-protein?
Cholera toxin (diarrhea) Pertussis toxin (whooping cough)
What organelles are at the root of all protein synthesis?
nucleus and ribosomes
What is the process to make vesicle-packaged proteins?
Nucleus → Ribosomes associated with rough ER → Golgi complex → vesicle packaging of proteins
What is the process to make cytoplasmic proteins?
Nucleus → Free ribosomes → Cytoplasmic proteins
What are cristae in the mitochondria?
folds in the inner membrane
What is the mitochondrial intercristae/matrix space enclosed in?
inner membrane
What ion granules are found in the mitochondrial matrix?
calcium
What are the three functions of the mitochondria?
- citric acid and ATP synthesis
- buffering of intracellular calcium (organelle of last resort)
- induce apoptosis
How does hypoxia affect the mitochondria?
- destroy proteins for oxidative phosphorylation
- swells
- ETC will be damaged
What tissues do mitochondrial defects affect the most?
tissues that use large amounts of ATP (ex. muscle cells and neurons)
What is the cause of myoclonic epilepsy with ragged-red fibers?
aggregation of abnormal mitochondria that look like red fibers due to mutation in mitochondrial DNA
What is myoclonus?
muscle spasms
What are the symptoms of myoclonic epilepsy?
muscle weakness
ataxia
seizures
cardiac and respiratory failure
What is ataxia?
impaired coordination
What are the components of ribosomes?
two subunits and rRNA
What is the function of ribosomes?
synthesize proteins
What is the template that ribosomes use to synthesize proteins?
mRNA
What is rough endoplasmic reticulum comprised of?
tubular system of membranes that is continuous with the nuclear membrane
What is the function of endoplasmic reticulum?
synthesize proteins
- secretion
- form other organelles
- package to transport to Golgi
What are the six functions of the smooth endoplasmic reticulum?
- detox
- steroid hormone synthesis
- cholesterol metabolism
- buffering of intracellular calcium (organelle of first resort)
- break down glycogen in liver
- lipid synthesis
What is the Golgi apparatus comprised of?
stacked cisternae with vesicles budding off
What are the three functions of the Golgi apparatus?
- receives proteins and lipids from rough ER
- package proteins and send out
What enzymes do lysosomes contain?
hydrolytic (acid hydrolases)
In what cells are lysosomes abundantly present?
phagocytic cells (ex. macrophages)
What is the difference between primary and secondary lysosomes?
primary - brand-new assembled by Golgi complex
secondary - activated when fused with phagosomes
What are phagosomes?
vesicles containing phagocytic materials
What are residual bodies?
works on breaking down debris that lysosomes have a hard time digesting
What do residual bodies contain?
lipofuscin - a yellowish fat soluble pigment
What do proteasomes break down?
cellular proteins that have been tagged by ubiquitin
What is the function of ubiquitin ligase?
connect proteins with ubiquitin
What are the four functions of peroxisomes (microbodies)?
- production and breakdown of hydrogen peroxide (bactericidal)
- lipid metabolism
- bile salt synthesis
- detox
What oxidative enzymes do peroxisomes contain?
amino acid oxidases
hydroxyacid oxidase
What do peroxisomes use to break down hydrogen peroxide?
catalase
What are secretory granules?
small granules that release things outside of the cell (ex. neurotransmitters, hormones, enzymes, etc.)
What are three types of inclusions in the cell?
- fat droplets
- glycogen granules
- pigment deposits
What are the four different types of pigment deposits?
- melanin
- hemosiderin
- lipofuscin
- bilirubin
What are the three components of the cytoskeleton?
microtubules
actin filaments
intermediate filaments
How are microtubules formed?
alpha and beta subunits that grow off the “leading edge” into a cylinder