Test Three Flashcards
Chemical processes must stay isolated through
Membrane-enclosed compartments
How many compartments in prokaryotic cells
One compartment
Eukaryotic cells contain
Many organelles with specialized functions
What is the structure of the nucleus
Double membraned nuclear envelope with nuclear pores
Function of nuclear pores
Allow RNA to leave cell and bring raw materials into the cell
What is the structure of the ER
Flattened sacs
Where is the location of the ER
Extension of nuclear envelope
Rough ER function
Protein production
Smooth ER function
Production of lipids
What organelle is similar to ER
Sarcoplasmic reticulum
Function of sarcoplasmic reticulum
Stores calcium
Function of golgi
Modified proteins and lipids for transport (modify and package)
Structure of golgi
Contains cisternae that stacks of compartments
Function of lysosomes
Breakdown endocytosed molecules such as macromolecules and old, nonfunctioning organelles
Function of peroxisomes
Breakdown toxins to the cell and breakdown lipids and uses oxidative reaction
Function of endosomes
Sort endocytosed material coming into cell
Structure of mitochondria and chloroplasts
Double membrane
Function of chloroplasts
ATP production through photosynthesis
Function of mitochondria
ATP production through oxidative phosphorylation
Function of cytoskeleton
Hold organelles in place, moving vesicles through the cell, provide structure and support
What are the two theories of organelle evolution theories
Invagination and eukaryotic engulfing
When the cell divides what else divides
Organelles such as the nuclear envelope, ER and golgi
What is invagination
Plasma membrane enfolded to surround and protect the DNA
What is engulfing
Organelles such as a mitochondria were engulfed by an ancient eukaryotic cell and once inside split into two different mitochondria organelles
New lipids come from
Smooth ER
During cell division what organs divide as well
Nuclear envelope, ER and golgi
What happens to proteins in the cell
Formed constantly, sorted and delivered
Why are proteins formed constantly
Need for general maintenance
What is a sorting signal
Amino acid sequence that is part of protein telling where to go
Where are some end destinations of proteins
Mitochondria, chloroplasts, peroxisomes
What are the three types of protein transport
Gated, transmembrane and vesicular
Gated transport occurs only through
Nucleus
Where is nucleus does proteins go through for gated transport
Nuclear pores
Describe type of molecules that go through gated transport
Specific for larger molecules, specific sequence in protein, folded proteins only
Transmembrane transport is what for proteins
Protein translocators
What is protein translocators
Locate proteins across the membrane
Where are transmembrane transports found
ER, mitochondria, chloroplasts, and peroxisomes
Transmembrane transport requires
Unfolding of the protein
Vesicular transport contains vesicles that bud from
ER and take part of membrane with them
Where do vesicles in vesicular transport go
Go to golgi, lysosome, or cell membrane and fuse with their membrane
Vesicles in vesicular transport carry what
Deliver lipids and proteins
What are signal sequences
Sorting signals of 15 to 60 amino acids that get the protein where it needs to go
Signal sequences are cleaved by
Signal peptidases
What happens to protein when signal sequence is cleaved
Protein can now fold correctly once at its new location
What are signal patches
Sorting signal is the 3D conformation that is recognized by sorting receptors
What in nucleus regulates what is going in and out
Inner membrane that contains binding sites
The outer nuclear membrane is similar to what organelle
ER
Function of outer nuclear membrane
Structural support
Outer nuclear membrane is continuous with what
ER
Nuclear pore transport goes through
Nucleoporins
What is the movement of nuclear pore transport
Both in and out
What goes in nucleoporins
Proteins
What goes out of nucleoporins
RNA and ribosome subunits
What channels in nucleus allow for small water soluble molecules to pass through
Water channels
Larger molecules need to have what to be directed into the nucleus in nuclear transport
Nuclear localizing signal (NLS)
What is a nuclear transport receptor
Mediate interaction between cytosol located on the nuclear protein and nuclear pore
How do nuclear transport receptors work
Receptors bind signal on the protein and move through the pore of the nucleus
What is needed for nuclear transport receptor to work
GTP hydrolysis
Proteins being transported into the mitochondria have to be
Unfolded
What is in the mitochondria to help refold the protein
Chaperones
Lipids bound for organelles are transported how
Vesicular transport
Proteins transported to ER need to be
Unfolded
Proteins leave the ER in what
Transport vesicles
What types of proteins can enter into ER
Water soluble proteins
What proteins are membrane bound with ER transmembrane transport
Potential transmembrane proteins
What directs the protein to the ER
ER signal sequences
Can proteins be partially formed before they cross the ER membrane
Yes
What are the three types of ribosomes in the ER
Membrane bound ribosomes, free ribosomes and polyribosomes
Membrane bound ribosomes go where in the ER
Attached to the cytosolic side of the ER
Where are free ribosomes in the ER
Unattached, they will make proteins from other nuclear DNA that’s out in the cytosol
What are the polyribosomes in the ER
1 long mRNA with the ribosomes bound to it
What are the components required to direct a protein into the ER
Signal recognition particle (SRP) and SRP receptor
What a re signal recognition particle (SRP)
Bind to signal sequence of protein in the cytosol
Where is the SRP receptor located for protein transport into ER
Membrane bound on ER
Binding of SRP to protein results in
Slowing of synthesis
Does synthesis of protein occur after SRP binds to it
Yes
What cleaves an SRP
Signal peptidases
What is transmembrane transport into ER membrane
The protein remains partially in the membrane
What is a single pass protein
Protein that has only one portion spanning the membrane
What occurs during single pass protein transport into ER membrane
Signal sequence assists the protein getting into membrane till it hits the stop transfer sequence (hydrophobic A.A.) and will stop the protein from entering any further
What is a multi pass protein
Protein the spans the membrane multiple times
How does a multi-pass protein transport into the ER membrane
Contains internal signal sequence (start sequence) in the middle of the protein then contains several stop-signal sequences
What is vesicular transport
Protein goes from ER to Golgi apparatus through transport vesicles
In order for protein to leave ER what must happen
It must be protected/ stabilized with chemical modifications such as carbohydrates added or disulfide bonds added
Secretory pathway of vesicular transport AKA
Exocytosis
What is secretory pathway of vesicular transport
Transport proteins to cell surface or lysosomes
What is endocytic pathway of vesicular transport
It’s an internal pathway that uses selective transport, taking something from outside in
Coated vesicles have what type of coat
Protein
Vesicle coat functions
Forms the membrane into a bud and captures selected molecules, helps develop membrane of vesicle, select molecule interested in carrying. NOT USED FOR PROTECTION!
What is the structure of clathrin-coated vesicles
Triskelion
Clathrin coated vesicles move from
Golgi outward or plasma membrane inward
If a clathrin-coated vesicle is being created, what is needed
Dynamin to help form a ring that contracts and helps pinch off the vesicle from membrane
Function of adaptin
Mediate interaction between clathrin, select molecules for transport, secure clathrin to plasma membrane
What are the two types of adaptin types
Bind cargo receptors in plasma membrane to pull things in or bind cargo receptors in Golgi apparatus to pull things out
COP coated vesicles go to
Golgi and ER
In vesicle docking, transport vesicles have what surface marker
Rab
What is Rab
Surface marker of transport vesicles directing vesicle that are recognized by and binds to tether proteins
What are tether proteins
Help dock vesicle by being the receptor for surface markers, grab hold of Rab
What are the two types of SNAREs
V-SNARE( vesicle) and t-SNARE (target)
What is exocytosis
Proteins exit the cell and this specific and has directed routes
How do SNARE’s interact
Remove water from vesicle to allow for merging and draw membranes together through chemically intertwined snares
What are the two protein modifications in the ER
Formation of disulfide bonds and glycosylation
The formation of disulfide bonds on proteins in the ER help what
Stabilize proteins and protect them
Where do disulfide bonds occur in proteins in ER modification
At cysteine residues
What occurs during glycosylation of proteins in ER modifications
Oligosaccharides side chains attach to proteins and become glycoproteins
What is the function of oligosaccharides in ER modifications
Protects from degredation outside of cell, chaperoning for proper folding, directing to correct location, assisting in INTERCELLULAR recognition between cells.
How does oligosaccharide processing occur in ER modification
Add 14 sugars at a time using oligosaccharide transferase and dolichol to anchor the sugar
What occurs when protein is leaving the ER
Transport vesicle begins to bud, proteins have to be folded correctly and if not chaperones will keep protein in ER.
What occurs with cystic fibrosis mutation and protein exiting the ER
Chaperones wont let the protein out due to a problem with the chloride transport protein
What is the unfolded protein response in the ER
When the ER and chaperones become overwhelmed it triggers a response causing the ER to grow and more chaperones grow but the chaperones can not keep up and causes apoptosis
What is an example of unfolded protein response in the ER
Diabetes
Vesicles from the ER enter where in the golgi
Cis side
What happens if proteins from the ER have ER retention signal
Receptors on the Cis of golgi will see signal and send the protein back to the ER
What occurs when the protein is in the golgi
Oligosaccharide removal and/or addition
What are the two exocytosis pathways
Constitutive and regulated
What is constitutive exocytosis pathway
Default pathway that has no direction specificity
What is regulated exocytosis pathway
Secretion that is specific loading of molecules and specific transport
Where are the destinations for the proteins in exocytosis
Adhesion to cell surface, incorporation into extracellular matrix, diffusion into extracellular fluid
What is not needed for constitutive pathway
No signal sequence necessary
What are the secretory products in regulated exocytosis pathway
Hormones, mucus, digestive enzymes, neurotransmitters
Describe secretory vesicles of regulated exocytosis pathway
Packaged with only one type of molecule
Where are the vesicles located in regulated exocytosis pathway
Near the plasma membrane but will wait for signal to unload
How does the vesicle prepare itself
Gets concentration of aggregated proteins for export and vesicle pinches off
The fusion of membranes is a
Temporary membrane combination
What are the two types of endocytosis
Pinocytosis and phagocytosis
What is pinocytosis
Cellular drinking, taking in fluids but also small molecules
What is phagocytosis
Cellular eating, taking in cellular debris, microorganisms
What endocytosis do all cells use
Pinocytosis
What are phagocytic cells
Macrophages and neutrophils
What is the target material of phagocytes
Dead RBC’s
Function of phagocytes
Digest phagocytosed materials and destroying it with lysosomes
What is the phagocytic process
Materials bind to phagocytic cell through specific surface receptors then the pseudopods extend from plasma membrane and pull pathogen into cell then the phagosome and lysosome fuse and digestion occurs
What are the two surface receptors of phagocytes
Antibody based receptors (specific) and receptors specific for common proteins (general)
What pathogen escapes phagocytic process
Tuberculosis bc want to be eaten by macrophage and prevent phagosome and lysosome from fusing
What materials are engulfed in pinocytosis
Lipids and fluids
What occurs to the plasma membrane components when engulfed through pinocytosis
Returned to cell
Pinocytosis macrophages ingest how much fluid volume in one hour
25%
What is located in smaller vesicle of pinocytosis cell vesicle goes to
Endosomes
Function of endosomes
Where sorting takes place, determine where things are going to
What makes pinocytosis specific
When clathrin coated pits are added
Example of pinocytosis
Cholesterol is taken up specifically by bringing cholesterol into cell then digested by lysosome. If LDL receptor is missing, then there is a build up then you have cholesterol building up in vessels and cant be digested
What are examples of misuse of endocytic pathways
HIV and influenza
What is the structure of endosomes
Contain ends that are called early and late which contains a network of tubes and vesicles
What happens to the receptors on the endosome
Recycled or degraded
How do endosomes sort
Transcytosis
What is transcytosis
Moving the loaded receptor with molecule to another side of the membrane
Structure of lysosome
Stacks of very strong digestive enzymes
What enzyme is used in lysosomal digestion
Acid hydrolases
What is the lysosomal environment and how maintained
Acidic for better function of enzymes and is maintained by H+ pump
What occurs after lysosomal digestion
Membrane proteins allow particles to be exported
What is the inner surface of lysosomal membrane like
Highly glycosylated
What occurs to vesicles that are heading to lysosome
Tagged with sugar called M6P
Purpose of M6P tag on vesicles
Keep them from binding to everyone else
What are autophagosomes
Engulf non-functional organelles and form a vesicle from own membrane and deliver to lysosomes
What is a signal transduction
Sending information into cells in language they understand
What are signaling molecules
Neurotransmitters, one receptor and another coming together
An intracellular response causes
Cell signaling
What are the five types of signaling
Endocrine, paracrine, neuronal, contact and autocrine
Endocrine signaling goes where
Whole body signaling
What are the signaling molecules in endocrine signaling
Hormones secreted in bloodstream
What are the signaling cells in the endocrine signaling
Endocrine cells
Example of endocrine signaling
Pancreas secreting insulin
Paracrine signaling location
Local diffusion in extracellular matrix
What are the signaling molecules in paracrine signaling
Local mediators, cytokines
What are the signaling cells in paracrine signaling
Immune cells or injured cells
Example of paracrine signaling
Inflammation and wound healing
Location of neuronal signaling
CNS
Signaling molecules of neuronal signaling
Neurotransmitters
Signaling cells of neuronal signaling
Neurons
Example of neuronal signaling
Crossing synapses to target tissues
Location of contact dependent signaling
Between cells, intimate, short range
Signaling molecules of contact dependent signaling
Receptor binding to ligand
Signaling cells of contact dependent signaling
Any cell because all have receptors
Example of contact dependent signaling
Embryonic development
What is autocrine signaling
Cell will signal to itself
Cell signaling is a selective response and how
Choosing the signals that apply since they are hit from all sides by different signals
What limit what signals the cell receives
Cellular receptors
Cellular receptors have what type of response and due to what
Complex response and due to result of receptor binding
What is an example of a complex response with cellular receptors
Acetylcholine binding to pacemaker to slow down rate or salivary gland causing secretion
What are simultaneous receptor stimulation
Collection of receptors, intracellular signaling yields larger cellular response
How does it take for multiple receptors simultaneously
Longer response due to cell dividing, differentiating or programmed cell death
Single receptor can include what in the signal
Change in cell shape, movement, metabolism or gene expression. This is fast
Large molecules rely on what type of receptor
Extracellular receptor
Small molecules (hydrophobic) can pass directly through membrane and affect what
Enzymes by turning them on or off
Small molecules that pass directly through the membrane bind to what receptor
Intracellular
Example of small hydrophobic molecule that passes through membrane
Hormones
Hormones target what receptors
Intracellular receptors
Examples of hormones
Cortisol, estradiol, testosterone, and thyroxine
When hormones bind to intracellular receptors what happens to them
Conformational change occurs which changes in gene expression
Is nitric oxide a hormone
No
What is the half life of NO
5 to 10 seconds before converted to nitrate
How does NO work
Enters cell directly to activate intracellular enzymes
Example of NO
Endothelial cells NO to relax blood vessels when they are constricted
What enzyme does NO activate
Guanylyl Cyclase to form GMP
What is in a signaling cascade
Primary transduction step, intracellular signal and signaling cascade
What is the primary transduction step
First binding of ligand to receptor
Bind of a ligand to receptor in signaling cascade causes
Intracellular signal leading to multiple intracellular signals (cascade)
What are the steps in functions of signaling cascades
Transforming external signal into intracellular molecule for signaling, relaying signal to cellular response, amplify signal, distributing signal, integration of signal (lead to other pathways)
What are the two types of receptors for molecular switch
G protein coupled receptors and enzyme receptors
How do molecular switches work
Molecular switches are activated when signaled and then turn on other protein and then turn off in response to another signal
molecular switches are
Chemical transducers or signaling messengers
What are the two types a of molecular switches
Phosphorylation activated and GTP binding activated
What is phosphorylation activated and inactivated switches
Kinase adds phosphate to turn on and removes to turn off
What kinases are used in phosphorylation activation switches
Serine threonine kinase and tyrosine kinase
GTP binding activated switch works how
Add entire GTP and is activated, loses phosphate to GDP and becomes inactivate
What are the three classes of receptors
Ion channel coupled, G protein coupled, and enzyme coupled
What are ion channel coupled receptors
Ions bind to channels, open channels and ions enter
What are G protein coupled receptors
Ligand bind to receptor, activates G protein, G protein can then activate enzyme
How do enzyme coupled receptors work
Ligand binds them to enzyme and they become activated or they can bind to ligand that then binds to enzyme and binds to another enzyme to activate it
Ion channel coupled receptors use what type of channel
Transmitter gated ion channel and act between synapses
How do transmitter gated ion channels work
Turn chemical signal into electrical signal and changes membrane potential causing receptor to change conformation
What is the largest family of receptors
G protein coupled receptors
What is the structure of G protein coupled receptor
Weaves through membrane 7 times (transmembrane receptor protein)
Example of G protein coupled receptor
Photo receptor, olfactory receptor, yeast mating receptor
How is a G protein coupled receptor stimulated
Binds to a ligand, G protein becomes activated intracellularly
Structure of G protein
Contains three subunits (alpha, beta and gamma)
Inactivate form of G protein contains
GDP
Active form of G protein contains
GTP
When GTP removed on G protein what else separates
A subunit
How is a G protein stimulated
Activation of receptor, alpha-GTP and gammabeta subunit bind together and interact with intracellular targets to trigger cascade
How to inactivate G protein
Remove phosphate to become GDP
G protein inactivation example
Cholera toxin changes the alpha subunit preventing the conversion of GTP to GDP, G protein always active
What inactive protein causes G protein to always be off
Whooping cough, keep alpha subunit in inactive state
What activates ion channel
Subunits of G proteins activate ion channels or enzymes
Example of activation of ion channel
Acetylcholine binds to G protein receptor causes alpha subunit to activate that then causes gammabeta subunit bind to K+ channel to open it, to close it lose phosphate
How are enzymes activated in G protein coupled receptors
Target adenylyl cyclase which then produces cAMP that then could activate phospholipase C to produce IP3 and DAG
What activates second messengers
Stimulation of G proteins
How is cyclic AMP stimulated
Ligand binds to receptor to activate G protein and the alpha subunit turns of adenylyl cyclase and then activates and increase in cyclic AMP
How to inactivate cyclic AMP
Phosphodiesterase turns cAMP to AMP making it difficult to move through cell
Pathway of cAMP
CAMP binds to cAMP-dependent protein kinase to activate it so that it can phosphorylate intracellular proteins such as PKA
What causes PKA to change conformation
CAMP
What us calmodulin
Calcium binding protein that response to increase Ca2+, it will change conformation and wrap itself around target protein
What are the target proteins of calmodulin
CaM kinases
Where is the domain in the enzyme coupled receptors
Intracellular domain that is the enzyme
Enzyme coupled receptors are involved in changes in the
Cytoskeleton
Structure of RTKs (receptor tyrosine kinases)
Single pass protein with an alpha helix
How to RTKs become activate
Two RTKs come together to form a dimer active at the intracellular tails and the tails phosphorylate each other and act like a kinase
What are the stopping signal of RTKs
Protein tyrosine phosphotases that remove receptor
Where do you see Ras pathway in real life
Cancer which is overreaction of Ras and causes cell division
RTKS activating Ras causes phosphorylation cascade resulting in
Change in gene expression
Activated Ras protein can cause
Activation of MAP kinase cascade
What inhibits Ras
Antibodies in pathway grab Ras, cell cant respond to extracellular signals
What happens with overstimulation of Ras
Continuous cell proliferation, 30% of all cancer has Ras defect
PI 3-kinase promotes
Cell growth and survival
PI 3-Kinase phosphorylate s
Inositol phospholipids
AKT inactivate
Bad to promote cell survival
Akt activates what
Tor to promote cell growth
Cytokines activate
Gene regulatory proteins
Cytokine receptors associate with
JAKs
JAKs phosphorylate what gene regulatory proteins
STATs
Cellular receptors induce
Gene expression and cellular response
