Final for 1090 Flashcards
What does it take to make a cell?
- Information (all cells posess DNA, which provides info neccessary for making proteins)
- Chemistry (when and how the building blocks of life appeared in the history of Earth)
- Compartments (usually has a single or double layer membrane) examples include mitochondria, chloroplasts, nucleus, ER
What cells lack a nucleus?
- Red blood cells, do not contain DNA and cannot systhesize RNA
Consequence: cannot divide and have limited repair capabilities
- Reason for tis is to have maximum hemoglobin carrying capacity
What is differentiation?
- During development, most cells in multiculleular organism will become specialized throughout the process, important not only to make a cell, but also to create different specific cell types eg muscle, fat cell, immune cell
What is the Miller-Urey Experiment?
Chemical experiment that simulated the conditions thought to exist on the early Earth to test the chemical origin of life under those conditions, conclusion: amino acids (building blocks of proteins) can be generated in conditions that mimic those of early Earth. Later experiments shown that other chemical reactions can generate sugars, bases in nucleotides, and lipids needed to make membranes
Oparin’s and Haldane’s primordial soup hypothesis?
Putative conditions on primitative Earth favoured chemical reactions that synthesized more complex organic compounds from simpler inorganic precursors
Abiogenesis
Chemical origin of life
What responsibility do compartments have?
- Make physical boundaries that enable cell to carry out metabolic activities
- Generate micro environment to spatially or temporally regulate biological processes
What did Robert Hooke do?
Discover cells with early model of microscope
Who created the cell theory and what did it state?
Schwann and Schleiden; all living things composed of cells, cell is most basic unit of life
Who created the third rule in the cell theory and what did it state?
- All cells arise only from preexisting cells, and Virchow
What are the properties of cells?
- Highly complex and organized
- Controlled by genetic program
- Can reproduce
- Can use and gain energy
- Can carry out chemical reactions (using enzymes)
- Can engage in mechanical activities (eg killing off cancer cells)
- Can respond to stimuli (given a task and respond to it)
- Can self-regulate
- Evolves
Who came first prokaryotes or eukaryotes?
Pro were only form on Earth until more complicated Eukaryotic cells came into being through evolution
What do prokaryotes lack?
Cell nucleus
What makes a prokaryote?
- Small
- No nucleus
- No complex internal compartments
- Reproduce asexually
- Genetic material found in nucleoid
What is included in Eukaryotes?
- Protists, fungi, plants and animals more complex
What makes a eukaryote? and what are included?
- Multicellular
- Big
- Nucleus and organelles
- Ribosomes
- Genetic material found in nuclear compartment and arranged as CHS
- Archea and bacteria
The cell and its parts look at diagram…..
in phone
Slime molds what is something cool about it?
Was originally in Fungi branch, now with Protist
Are virses alive? and are they cells?
No are not cells, are macromolecular packages that can function and reproduce only within living cells, outside of cells viruses can exist as inanimate particle called Virion (made of small amount of DNA or RNA that encodes a few hundred genes), protein capsule called CAPSID
What is the Baltimore classification?
cateorizes viruses based on type of genome (RNA/DNA) and method of replication
What type of virus is HIV
Retrovirus, RNA virus that can insert copy of genime into DNA of host cell, causes AIDS (retro been around for while)
Hepatitis B is what type of virus?
Hepadnavirus, affects liver and causes serious infections
What type is Ebola Virus?
Filovirus, encode genome in single stranded negative-sense RNA
What are adenovirus?
Group of viruses that cause respiratory illnesses (eg bronchitis or pmeumonia), or conjunctivitis
Bacteriophage?
Virus that infects and replicates within bacteria and archea
What is the largest virus?
Mimivirus
What fights bacteriophages?
CRISPR-Cas
What is a narrow host range?
Like human cold and influenza that infect epithelial cells of human respiratoryW
What is wide host range?
Like rabies can infect cells in dogs, foxes, bats, raccoons and humans
What are the two types of viral infection?
Lytic: production of virus particles ruptures (and kills) cell (eg influenza, rabies) like lysis in osmosis
Non-lytic: (also known as integrative or lysogenic): viral DNA is inserted into host genome=provirus infected cell can survive, often with impaired function (eg HIV, chicken pox)
Rabies has what type of genome?
A single stranded RNA genome
What does Zika virus do or cause? and how is it transmitted?
microcephaly, directly positive-sense RNA genome into viral protein, asymptomatic
- Causes the head circumference to be smaller then normal
- Mosquitoes, also sexual contact, blood transfusion, mother to fetus through placenta by targeting trophoblasts and macrophages, if infection ocurs during neurogenesis, surivival of neural progenitor cells can be affected
How do RNA vaccines work?
Tricks cells into producing fragment of virus, antigen from RNA template, one strategy to make them more effective at lower doses, or single dose, to incorporate instructions for assembling replicase, which can make lots of copies of RNA template for producing antigens
What is the basic structure of viruses?
- Nucleic acid genome
- Protein capsid that covers genome
What is the main factor that determines what cell type a virus can infect?
- Surface expression of a specific surface protein
What does SR stand for?
Sarcoplasmic reticulum
What makes up a phospohlid bilayer?
Trilaminar (oreo)
What is the lipid bilayer made of?
Phospholipids
Hydrophobic tails go where? Hyrophilic heads go wear?
On inside, outside
what are micelles?
Formed with only one hydorphobic chain
What is an example of amphipathic molecule?
Two sides to them, means have both non-polar and polar, phospholipid bilayer has that
What do phospholipids composed of? (also phosphate)
- two fatty acyl molecules esterified at sterospecific numbering sn-1 and sn-2 positions of glycerol, and contain a head group linked by phosphate residue at sn-3 position
Where do phospholipids making the plasma membrane come from?
Occurs at the interface of cytosol and outer ER, which has all the molecular machinery (enzymes) for synthesis and distribution
- Phospolpid syhnethesis is multistep, needed activity of many effectors
What is the fluid mosaic model?
Fluid: individual lipid molecules move
Mosaic: particle like proteins, carbs, and cholesterol make up the lipid layer
Where do lipids move easily, and harder?
Within leaflet, and across of leaflet
Who proposed the fluid mosaic model?
Seymour Jonathan Singer and Garth Nicolson
Membrane proteins diffuse within the bilayer…
- Movement of proteins is restricted hard
- Movement is limited
What does biochemical modification do?
- Alters protein mobility, important for signal transduction
What is the Frye-Edidin Experiment?
- Experiment that inspired Singer and Nicoloson for their Fluid model
- After fusion of two cells the surface proteins are segregated, but after a short time surface proteins of both cells diffuse around the unified membrane and mingle rather then being locked to their original location
What are some things that membranes have in common?
- Stable
- Flexible
- Capable of self assembly
What are some differences in membranes?
Contain diff types of lipids and proteins, giving them diff functions
What are some examples of biological membrane differences?
Inner membrane of mitochondria has a very high concentration of protein necessary for ETC and ATP synthesis
Opposite, myelin sheaths have very few types of transmembrane protein, simply consist of layers of plasma membrane wrapped around neurons axon, increases speed at which electrical impulses propogate along myelinated fibre
What are the 3 types of membranre proteins?
- Integral (span the lipid bilayer)
- Peripheral (surfaces of bilayer)
- Lipid-anchored (proteins attach to a lipid in bilayer)
What are integral protein jobs?
Different integral proteins have different functions:
1. Transport nutrients and ions
2. Cell-cell communication
3. Attachment
Are membranes symmetrical or asymmetrical?
Assymetrical
What do outer leaflets contain?
Glycolipids and glycoproteins which are proteins and lipids with proteins attached to them
What affects fluidity of membranes?
Temperature
What does warming and cooling do to fluidity?
Warming increases fluidity
Cooling decreases
What do unsaturated lipids do to fluidity?
Increase fluidty
What do saturated fats do to fluidity?
Reduce fluidity
Lipid composition can be changed by?
- Desaturation of lipids
- Exchange of lipid chains
What does a balance between ordered (rigid) structure and disordered structure allow for?
- Mechanical support and flexibility
- Membrane assemply and modification
- Dynamic interactions between membrane components (eg proteins can come together reversibly)
What does cholesterol do to membrane fluidity?
- Acts as a bidirectional regulator of membrane fluidity becuase at high temps, stabilizes membrane and raises its melting point, but at low temps keep them from going together and stiffining
What happens when membrane added to liquid crystal?
Fluidity will decrease
What happens when membrane is added to crystalline gel?
Fluidity will increase
What is a tranmembrane protein domain?
Peptide sequence that is hydrophobic (uncharged) and spans across PM, sequence permanently attaches
What is the most common protein structure that crosses biological membrane?
the alpha helice
Which amino acids are hdrophobic side chains?
Glycine, alanine, valine, leucine, isoleucine, proline, phenylalanine, methionine, tryptophan
What are tetraspanins (TM4SFs)?
Family of membrane proteins found in all multicellular proteins found in multicellular eukaryotes; they have 4 alpha-helices, and two extracellular domains, one short (EC1) and one longer (EC2), some can be glyosylated (attachment of carbohydrate molecule)
What do tetraspanins do?
Play a role in cell adhesion, motility, proliferation (increase)
What can pass through bilayer easily?
- Small, uncharged molecules can cross easily (example O2, CO2, NO)
What cannot pass through bilayer easily?
Large/polar/charged
What are 4 basic mechanisms for moving molecules across membranes?
- Simple diffusion
- Diffusion through channel
- Facilitated diffusion
- Active transport
1-3 are passive
What is passive movement?
Substances relies on molecular concentrations
- Does not require energy
- Down a concentration gradient- flow is downhill
- Only works for very small and uncharged molecules like O2 and CO2
- Water is also considered uncharged because the bonds between H and O are covalent, in covalent are equally shared between atoms, therefore no net charge appears and remains neural
What is diffusion through channel
- Effective for small charged molecules (ions) like Na+, K+, Ca^2+, Cl-, ions move down concentration gradients-flow is downhill
- Channels are selective, allowing only particular types of ions to pass
- Ion channels are formed by integral membrane proteins- typically multiple subunits-that line an aqueous pore
Can channels be gated? T or F?
T, important because provides channel the ability to respond to diff stimuli (eg neurotransmitters)
- Can turn off/on to diff signals
What are different types of gated ion channels?
- Voltage-gated: eg Na+ and K+ channels, ex neuron and action potentials , under non-depolarized neurons have little amount of Na+ inside
- Ligand-gated channels: eg. acetylcholine receptor, channel responds to binding of specific molecule on its surface a ligand; binding of a ligand produce conformational change in structure of the receptor/channel something binds and changes conformation allow for things to pass through
What does tetrodoxin do?
- Neurotoxin
- Is a Na+ blocker, inhibits the firing of action potentials in neurons by binding the voltage-gated sodium channels in nerve cell membranes and blocking passage of Na+ ion into neuron which prevents the rise of action potential
- Voltage
What does curare do?
- Competitive antagonist of the nictinic acetylcholine receptor, goes on same spot of receptor essentially blocking it to go through
What is facilitated diffusion?
- Compound binds to integral protein
- Needs facilitation to move switch
- Change in transporter conformation allows compoind to be released on other side
- Compound moves down concentration gradient
Where does animal use faciliated diffusion?
- Import glucose from blood into cells down a concentration gradient via this mechanism
What is the process of facilitated diffusion?
- Transporter ready to accept glucose molecule
- Glucose is accepted by transporter
- Intracellulcar side of trasnporter opens
- Glucsoe is released and cycle repeats
What is another type of carrier/facilitated diffusion?
Symporter! Two molecules in the same direction
- Cells may need to move from lower to higher
- Na+-Glucose symporter
What is yet another type of carrier/facilitated diffusion?
Antiporter- two in opposite one goes in, one goes out
- Sodium-proton exhcanger in nephron of kidney, maintains pH and sodium levels in cells
What is active transport?
- Move against concentration gradient
- Requires ATP
What is an example of active?
- Na+/K+ ATPase maintains cellular concnetrations using ATP
- 3 go in, 1 go out
- Cells spend energy ATP to achieve and sustain the chemcial gradient
Hypotonic rbc with a high solute concentration will cause?
Lysis explode
What is an important role in membrane proteins?
Signal transduction by converting extracellular signal into intracellular signals, signals allows cells to rapidly respond to events happening in their environment: grow, divide, surive or not, move, differentiate (time to change)
What is a ligand?
small molecules that binds to receptor (latches l on)
What does ligand binding do?
It changes the conformation of the receptor protein, ligand does not enter the cell; also causes other proteins in the cytosol or membrane bound to become activated (allows for receptors to be present)
What side is affected by the ligand receptor?
The cytosolic side inner not extracellular, is affected
What are the 3 stages to singal transduction?
- Binding of a ligand to receptor
- Signal tranduction via second messengers like cAMP, calcium or G-protein
- Cellular response: cellular growth, cell division, store glucose molecules as glycogen
What are some conditions that happwn with a defect in signal transduction
Cancer, diabetes, different brain disorders
What is an example of signal transduction?
- Glycogenolysis
- How epinephrine (also known as adrenaline) activates conversion of glycogen stored in liver to glucose is a good example
- Ephinephrine binds to receptor on liver cell
Process of transduction w epinephrine
- Epinephrine binds to receptor on liver cell (adrenergic receptor) like adrenal adrenergic
- G protein on using GTP
- Turns on enzyme called adenyl cyclase (green) will accumulate cAMP inside cells
- At end, phosphorylase-P enzyme will release glucose units
What role does anchor membranes do?
- Play an important role by interacting with components of the extracellular matrix (ECM)
- ECM is an organized network of material produced and secreted by cells
What are the functions of the ECM?
- Cell adherence
- Communication between cells
- Cell shape, mechanical support, structural integrity
- Serves as barrier, filters out some particles
What is an example of ECM?
Skin; ECM is abundant in connective tissues of animals (eg tendons, ligaments, dermis)
How are wrinkles formed?
- Facial wrinkles is kind of fibrosis (thickening and scarring) of connective tissues of skin, misrepair-accumulation theory suggests that wrinkles develop from incorrect repairs of injured elastin and collagen fibers, replaced by ones less elastic
What are the major components of the ECM?
- Proteins like collagen and glyocproteins such as laminin, fibronectin
What are proteoglycans?
proteins with chains of polysaccharides
What cells have walls?
Fungi, plants and bacteria
What are plants walls considered as?
ECM
What are cell walls composed of?
- Cellulose, hemicellulose, pectin and proteins, provide structural support to cell and whole organism
- Protect cell from mechanical damage and pathogen attack
What is meant by membranes transition temp?
Temp required to induce a change in lipid physical state from gel to dissolved into liquid crystal
How will the transition temp of membrane be affected if the amount of unsaturated lipids is increased?
Fluidity will increase, temp decreases
What property of transmembrane domains allows them to remain embedded in lipid bilayer?
Have hydrophobic surface, lipids dont like water
Thinking about Na+/K+ pump, how many ATP molecules are required to transport 10 K+ ions in cell
Chat says 5
What is the endosymbiotic theory?
Origin of eukaryotic cells from prokaryotes, organelles distinguishing eukaryote cells evolved through symbiosis (living together close and long term biological interaction)
What is the supporting evidence?
- Binary fission of mitchondria and plastids
- Circular DNA inside similar to bacteria
What is aerobic respiration? And what is equation?
- Converts in presence of oxygen stored in food molecules CH2O+O2 into CO2 and H20+ATP
What is photosynthesis?
- Building carbs using energy and sunlight
CO2+H2O into CH2O and O2
What does the outer mitochondrial membrane do?
- Contains many enzmes with many metabolic functions
- Example is monoamine oxidases breaks down monamines ingested from food, as well as monoamine neurotransmitters (dopamine and serotonin)
- The outer has porins, with large channels permeable (passive diffusion) to many molecules when opened (eg ATP and sucrose)
What is the function of Inner Mitochondrial Membrane?
- Has a high protein: lipd ratio 3:1
- Double layered folds are called cristae- increased membrane surface area and contain machinery for aerobic respiration and ATP formation
- Rich in phospohlipid called CARDIOLIPIN which is a characterisitc of bacterial membranes for optimal function of many enzymes (optimal function cardio)
What are the mitochondria’s two aqueous compartments?
- Intermembrane space
- Matrix: high protein content, gel-like, containing mitochondrial ribosomes and DNA
- In mammals, mitochondrial DNA, total of 37 genes
What does cellular respiration need?
Chemcial energy stored in molcueles such as carbohydrates (glucose) and lipids to produce ATP
What does cellular respiration need?
Catabolic reactions (breakdown of complex)
What is substrate level phosphorylation?
Hydrolysis reactions releases energy to drive phosporylation of ADP to ATP (eg glycolysis where 1 gluose molecule is broken down into 2 pyruvate molecules) - water breaks down bonds (substrate water breaks down)
Oxidative phosporylation
Energy or organic molecules is trasnferred first to electron carriers to create electrochemical gradient that powers ATP synthesis (oxygen energy, gives oxygen to create gradient)
What produces the most ATP?
Oxidative since brings into ETC
Conenzymes acting as electron carriers can exist either as…
Oxidized: accept electrons
Reduced: dontate electrons
Oxidized has less H, reduced has more H
Needs to reduce H, when have NADH go to NAD+ want to get to oxidative
What are the steps on oxidiative phosphorylation?
Step 1: generate electrochemical gradient (electron transport through complexes I-IV and proton (H+)
- High-energy electrons pass from coeznmes (NADH and FADH2) in the matrix to electron carriers in inner mitochrondrial membrane
- Series of intermediate e carriers (respiratory enzyme complexes I, II, III, IV)= etc
- Energy transfer at each complex used to pump H+ into matrix into intermemembrane space
- Low energy electrons are transferred to terminal electrons accetpr O2 that results in productoin of O2 THATS WHY NEED OXYGEN WITH MUSCLES FOR ENERGY
Step 2: Proton movement down electrochemical gradient from matrix to inner to power ATP synthesis
What is the difference between light-dependent and light-independent reactions?
Light-Dependent:
- Occurs in thylakoid membrane
- Chlorophyll in light harvesting complex
sun+H20= O2+e+H+
- e enters ETC
- H+ pumped into thylakoid lumen
- Needs high concnetration of proton in thylakoid lumen for chloroplast and needs high for intermembrane space for mitochondria
Light-independent:
- Dark reactions/calvin cycle
- Occurs in stroma (fluid) of chloroplasts
- ATP and NAPDH made in light reaction used to make CH2O (carb reserve energy)
What is apoptosis?
Programmed cell death normal process death of cells in coordinated sequence of events, part or organimsls growth or development
What is an example of apoptosis?
Interdigital cell death may lead to regression of soft tissue between embryomic digits in many veterbraes
What are bone morpohgenetic protein…
is a secreted protein that binds to Bmp receptors, expression of non-active BmpRs in chicken embryonic hind limbs greatly reduced interdigital apoptosis and resulted in webbed feet
How does apopotsis play a role in plants?
They have mature leaves with holes, use programmed cell death to generate holes
What is apoptosis characterized by?
- Shrinkage of cell
- Blebbing (bulge or protrusion) of plasma membrane
- Fragmentation of DNA and nucleus
- Loss of attachement to other cells
- Engulfment by phagocytosis
What is the intrinsic pathway of apoptosis?
- Intitated by intercellular stimuli like genetic damage, hypoxia, virus
- “Killer” proteins like Bax (attaches on outside of mitochondria) causes changes in mitochondia membrane potential and to leak of Cytochrome C
- Release of apoptotic mitchondrial proteins commits the cell to apoptosis
- Cytochrome C assembles apoptosome in cytoplasm
- Activates executioner CASPASES
- It disrupts cell adhesion, breaks it down, destroys lamins (the filaments), and activates DNase (genome breakdown)
What diseases are causes by too little apoptosis?
Cancer where too little, occurs resulting in malignant cells not dying
If its too much what can happen?
Alzheimers and Parkinsons
What do endosomes do?
Sorting, recycling
What happens in the cytosol?
Protein synthesis and many metabolic pathways
what is an example of a secretory cell?
- Secreted protein (eg mucin, a glycoprotein component of mucus
- Synthsized in rough er
- processed
- further processed in Golgi
- concentrated in vesicles
- delivered to plasms membrane for secretion
How can you use GFP to track cell components?
- Green fluorescent proteins fromy jellyfish can be fused with other cellular proteins, and fusion protein can then be expressed, provides indo about the endogenous protein (where it is located in the cell or organism)
Where does transport go between vesiculars?
Organelle to plasma membrane
Organelle to organelle
- Utilizes transport vesicles
What do vesicles look like?
- Small, spherical, membrane-enclosed organlles that bud off donor compartmnet and fuse with acceptor or recipient compartment
Targeted movement:
- Uses cytoskeleton and motor proteins
- Sorting signals recognized by receptors
What are the key elements of vesicle trafficking to a compartment?
Movement of vesicle- uses cytoskeleton and motor proteins, can be anterograde or retrograde
Tethering vesicle to target compartment-via proteins from the Rab family of protein and other more specialized
Docking of vesicle to target compartment- uses proteins called SNAREs, SNARE assembly provides energy for fusion
Fusion of vesicle and target membrane
What is an example of exocytosis?
organelle to the plasma membrane eg secretion of neurotransmitter
Example of endo?
Plasma membrane to organelle eg.activity-dependent internalization of AMPA receptors
How are chemiosmotic mechanisms used in mitochondria and chloroplasts?
In mito ETC pump H+ ion conncetration, creates gradient drives phosphorylation
In chloroplasts have light dependent and independent
light dependet in thlyakoid, etc creating gradient sythesize ATP
How can GFP be used to track the movement of membrane proteins?
Fuse the 2 see where it goes, use FPAP fluroescence recovery after photpbleacing, bleach area see if it goes back
What are the morphological differences in RER and SER? What are major differences in functions?
Presence of absence of ribosomes
and rough er make proteins, glycosylation of proteins (addition of carbs to proteins), protein folding, protein sythesis, modification and transport and smooth produces lipids, produces steroid hormones like glucocorticoids, androgens and estrogens- endocrine cells, detoxification (liver cells contain enzymes that modify foreign compounds, sequestration (storage) of Ca2+ Ca2+ cannot bring to water, which causes precipitate of phospahtes and makes proteins insoluble, calcium in cytosol is bound by proteins forced out through pumps and trasnporter, or sequestered into specific organelles
How are proteins selectively moved from one compartment to another?
Vesicles (endo and exo)
Transition of a plasma membrane from a liquid crystal state to a crystalline gel
state:
a) Occurs more readily at higher temperatures
b) Requires cholesterol
c) Is aided by phospholipid bilayers embedded with glycoprotein
d) Is favoured when there are more saturated lipids
e) Does not occur in inner mitochondria membranes (IMM)
Is favioured when more saturated
A toxin from toadstools called garafraxin, when added to nerve cells, prevents Na+
ion movement from higher to lower concentrations. A possible explanation for this
might be:
a) The toxin enters and blocks Na+ channels
b) Garafraxin binds acetylcholine and changes membrane potential
c) Garafraxin antagonizes the ligand that activates Na+ channels
d) The toxin deactivates the Na+/K + ATPase pump
e) Both ‘a’ and ‘c’ could be correct
a and c
What is the first step in transducing signals?
Ligand-receptor is from outside or inside
What helps to provide structure?
ECM and cell wall
What are proteins that are involved in dismantling the cell?
Caspases and proteases (pro capper)
Overview of protein synthesis…
- Cytoplasm, ribosomes syhtesize polpypeptides from mRNA (searches for start codon)
2.Beginning of elongation (EPA l to right) but goes APE - Elongation (e is ejected)
- Termination
Where does all protein translation begin?
On free ribosomes (not assocaited with ER)
Translation is completed in one of 2 ways?
Free or ER bound ribosomes
- For on free:
- Cytosolic proteins
- Peripheral membrane proteins
- Proteins targeted to nucleus, mitocondria, peroxisomes, chloroplasts
- For ER
- Secreted proteins
- Integral proteins
- Soluble proteins associated with inside (lumen) of endomembrane system (ie proteins that function within ER, Golgi, lysosomes)
How is the site of translation determined?
Ribosomes are targetted to ER by signal sequence
Where is signal sequence located, what does it contain and what does it direct?
- Located in amino-terminus (N-terminus)
- Containes several hydrophobic amino acids
- Directs synthesis to ER
Proteins move through channel into ER for cotranslational import (helps with translation)
What is the process of cotranslational protein import?
- After translation signal sequence, Signal Recogition Particle (SRP) binds to singal sequence and STOPS translation process
- SRP binds to SRP receptro to target whole translational complex to ER
- SRP is released and ribosome binds to translocon, once this is done protein synthesis resumes
- Polypeptide enters ER as it traslates, in the end signal peptide is cleaved off and chaperone folds protein
What happens to free ribosomes that are targeted to mitochondria
TOM complex is equilvalent of SRP complex and translocon
Protein targeted to ER lumen has what of 2 options?
1: retained in ER lumen, if that is where it functions
2: transported to ER to Golgi for further modification and delivered to distal parts of biosyntethic/secretory pathway
Where in chloroplast and mitocondria are highest concentrations of proton found?
Plant is thylakoid mitocondria intermembrane space
Where is cytochome C protein normally found and what does it mean when it is present in cytoplasm?
Found in mitochondria, can indiciate apoptosis
The N-terminus of integral protein is in RER lumen. If GFP is fused to N-terminus of protein, which side of plasma would glow green?
Extracellular side, because of protein synthesis
Where does all protein sythesis initiate?
Ribosomes
Which of the following statements regarding the intrinsic pathway of apoptosis
are not correct?
a) It can be triggered by hypoxia
b) Bax protein binds to the mitochondria inner membrane
c) Cytochrome c leaks out into the cytosol
d) Executioner caspases are activated
e) Nuclear lamins break down
B
Peroxisome? What is syndrome with lack of it?
Is organelle of micro body; found in eukaryotes and are involed in enzymeatic reactions, Zellweger syndrome, has a crystalloid core
How is Zellweger syndrome is inherited…
Autosomal recessive, causes severe brain development defects, hypomylentation, apnea, abnormal retinal function, patients doesnt survivie beyond one year
How is cystic fibrosis caused?
Mutation in the gene cystic fibrosis transmembrane conductance regulator (CFTR); most common mutation, is a deletion of 3 nucleotides, resulting in loss of amino acid phenlalanine, fails to reach other sites
Type 1 single pass transmembrane
Same process N in and other side out
What are different compartments or membranes?
Mitochondria membrane: OMM, IMM; Chloroplast: OCM, ICM, Thylakoid membrane
Mitochondria compartment: intermembrane space, matrix
Chloroplast compartment: stroma, thylakoid lumen
Which way do material move from ER to Golgi then to other?
Proximal to Distal (whats close in proximity)
- Goes from cis-golgi to medial to trans
What is the strcuture of the Golgi Complex?
- Smooth, flat disk like cisterna
- Range from a few to several 1000 stacks per cell
- Curved
- SHOWS POLARITY cis-medial-trans cisternae
- Are biochemcially unique
- Membrane are supported by protein skeleton (actin, spectrin)
- Scaffold linked to motor proteins that direct movement of vesicles in and out of Golgi
What is the difference between cis and trans Golgi nextwork (CGN and TGN)?
CGN: sorting station which should continue or go back
TGN: sorts proteins into diff types of vesicles to go to plasma membrane (since closest) or other intracellular (eg lysosomes)
T or F, Different cisternae of Golgi contain diff enzymes that modify proteins
T
Is Golgi processesing plant?
T
What else does the Golgi do besides processing?
Make polysacchardies and modification of proteins and lipids
What do coat proteins do?
- helps form vesicle
- helps select cargo (material inside or outside)
What do COPI and COPII do?
- Protein complexes that assembles on surface of donor compartments membranes at sites where budding takes place
COPI: retrograde (since day 1)
COPII: anterograde
What are key features of Lysosomes?
- Digestive
- Internal pH of 4.6 (proton pump of H+-ATPase)
- Contains hydrolytic enzymes: acid hydrolyses
- Lysosomal membrane composed of gylcosylated proteins acts as a protective lining next to acidic lumen
A mutation in the gene encoding the BiP chaperone protein might:
a) Cause the Golgi complex to form incorrectly
b) Produce Transport Vesicles with no ribosomes
c) Cause ER lumen proteins to exit to the cytosol
d) Redirect COP II coated vesicles to the ER
e) Result in misfolded proteins in the ER lumen
e
Which of the following properties are different between prokaryotic and
eukaryotic cells?
a) The presence of a membrane-bound nucleus
b) The presence of membranes consisting of lipid bilayers
c) The presence of ribosomes to produce proteins
d) The presence of DNA
e) Susceptibility to viruses
a
COP I and COP II proteins:
a) Are synthesized in the ER lumen
b) Direct vesicle traffic in opposite directions
c) Move cargo vesicles uniquely between the ER and the plasma membrane
d) Are excreted from the cell
e) Integrate into the Extracellular Matrix (ECM)
b
The synthesis of a plasma membrane receptor protein begins:
a) In the ER lumen
b) Between the mitochondrial IMM and OMM
c) In the cytoplasm
d) Inside the ER translocon
e) In a transport vesicle
c
Alanine (A), valine (V) and proline (P) are hydrophobic amino acids whereas
arginine (R) and lysine (K) are charged amino acids (M = methionine). Which of
the following is most likely a signal sequence?
a) M-K-K-V-R-K-R-M
b) K-V-A-R-A-V-P-K
c) M-V-P-P-A-R-A-K
d) K-K-R-K-M-M-K-K
c
What happens to the signal sequence after a protein is completely
synthesized in the ER lumen?
Released from the pore and degraded in the ER
What is the energy source for tethering and docking?
Using Rab proteins, docking SNAREs (to grip)`
What are AP?
Cathrin Adaptor Proteins, are coated vesicles move from trans-Golgi netwrork to other vesicles (eg lysosomes, endosomes, plant vacuoles)
- Also help to form endocytic vesicles to move them from plasma membrane to endosomes or lysosomes
What is autophagy? Process
- Normal disassembly of unecessary or dsyfunctional cellular components (phages eat)
- Autophagosome formation (engulf organelles) then lysosomes recruit, then autolysosomes form (fuses with ER-dervied vesicle lysosomes fuse) then digestion and release (exocytosis bye bye)
Degredation?
- Recylcing of plasma membrane components like receptors and extracellular material
- Destroy pathogens like bacteria and viruses
What does a phagotyic cell do?
pathogen is internalzied, degraded by lysosomes, hydrolytic enzymes inside lyosomes degrade and kill pathogen, debris is released outside cell
What are plants vacuoles?
- take up 90% of cells volume
- fluid filled membrane bound
What do vacuoles do?
- Involved in the regulation of pH, cutting off toxic ions, regulation of cell tutor, storage of amino aicds, sugars and CO2 in form of malate
- Intercellular digestion comparable to lysosomes (slightly low pH 5.0, acid hydrolases)
- Mechanical support turgor pressire (gives rigidity, stretches wall during growth)
- Storage (solutes and macromolecules, chemical storage)
What is tonoplast?
Vaculour membrane that contains active transport systems that allows ion and molecules transport (tone is active)
What is a cytoskeleton?
Network of filaments and tubes that extend through cytosol
What are the function of the cytoskeleton?
- Support
- Spatial organization
- Intercellular tranpsort
- Contractiltiy and motility
What are microtubules?
- Largest element
- Polymer of 2 diff proteins alpha and beta dublin
What are Axonemal MT and Cytoplasmic MT?
Axo: highly organized, stable
- Part of structures (axoneme) involved in cell movement eg cilia, flagella
Cytoplasmic MT
- Loosely organized, dynamic
- Located in cytosol
How many profilaments make microtuble?
13
What do heterdimers have to do with microtubles?
Aligned in same direction (head to tail) creating structural polarity, fast growing plus end and slow growing minus
Are MT’s stable?
Rapid turnover of most mTs in vivo, half life within mins, shrinkage occurs quickly at plus end- termed catastrophe
- Formation of MTs is regulated/controlled
What are the central site of MT assembly?
Microtuble-organizing centre
What are the two classes of microtuble-associated proteins?
1 Non-motor:
- Control MT orginzation in cytosol, defective Tau protein which can lead to neurofibrillary tangles and Alzheimers
- Many other MAPs that contribute to growth and dissassembly
- Motor
- Two main types- kinesin and dynein
- Use ATP to generate force
- Can moce material along MT track
- Can generate sliding foce between Mts
What do endocytosis do?
Bring contents in cell (vesicles endoscopes) to lysosomes
Which is the plus end called and minus end called?
Kinesin: plus end
Dynesin: minus end
Motor proteins and movement…
- ATP binding to leading head induces conformational change thst swings to trailing head (one on left) 180 degrees towards the positive end of microtubule, FORCE GENTERATING STEP
- New new leading head binds to tubulin subunit and releases its ADP, moving the kinesins cargo forward
- In trailing head, ATP is hydrolyzed to ADP, which leads to detachment from the microtuble
- ATP binds to leading head to repeat reaction cycle
In the dark, melanin granules are dispersed outward by…
Kinesin causing it to be darkly coloured (spread out)
In the light, melanin granules are aggregated toward the centre by…
Dyein, causing lightly
Microtuble-Organizing Centre is central site of MT assembly in what organisms?
ONLY EUKARYOTIC
2 most important:
- Basal bodies with cilia and flagella
- Centrosomes associated with spindle formation
Why is it important to form sliding forces?
Important during mitosis and CHS seperation
What are intermediate filaments?
- Intermediate size
- Exclusive multicellular and animal cells
- provide structural support and mechanical strength
- stable
- NOT POLAR, not used for transport
- Keratins are stained red
- Lamins are blue
Where are intermediate filaments found?
Mostly in axons of neurons
What are microfilaments?
- Thinnest
- Maintain cell shape
- Cell movement
- Vesicle transport
- Muscle contration
- Cytokinesis
What is the main part of MF?
Actin, exists in cells either as monomer (G-actin or globular) or as polymer (F-actin or fibrous)
- Actin is an enzyme that binds and slowly hydrolyzes ATP
- A microfilament is doulbe helix of actin monomers
How is G-actin split?
- 4 subdomains, and is divided by central cleft creating two equal sized lobes
- Actin filament (F-actin) appears as two strands
F-actin filaments are polar T or F?
Polar and have a plus or minus end, plus end assembles/disssembles quickly, while minus assembles/dissambles slowly
The early nucleation steps of G-actin polymerization are…
Slow
What are the steps of G-actin?
G-actin to dimers to trimers to short filaments
Is the process reversible?
Is reversible; ATP hydrolysis stimulates the destabilization of polymer
Orginzation of these structures is regulated by…
Actin-binding proteins
What does actin staining do?
Phalloidin belongs to toxin called phallotoxins; functions by binding and stabilizing filamentous actin (F-actin) and effectively prevents depolymerization of actin fibers
What role does polyermization and branching play a role in?
Directed cell motility
What does actin-binding proteins control?
Microfilament formation in a lamellopodium to allow directed cell movement
What is profilin?
Actin-binding protein that enhances growth of filaments
What is cofilin?
Actin-binding that dissembles actin filamentd
Capping protein?
Blocks exchange of subunit at positive end
F-actin filaments are associated with…
Motor proteins
What are myosins?
superfamily of motor proteins with microfilaments both with m… most move towards positive end
What groups are myosins?
- Conventional myosins: type II, primary motors for muscle contraction
- Unconventional myosins: type I and types III-XVII
What do unconvential myosins do?
generate force and contribute to motility
What does actin based protusion do?
On leading edge; acts on anger pushes
What does myosin-based contraction does what?
Pulls trailing edge, my pull
What can microtuble and microfilament do what?
Intracellular transport
What does the nucelus do?
- Storage, replication, and repair of genetic material
- Expression of genetic material
- Ribosome biosynthesis
Does RNA splice before nuclear import?
YES
What is the nuclear envelope?
- Nuclear membrane
- Nucleus pores
- Nuclear lamina
What is the nuclear concent?
- Chromatin
- Nucleoplasm
- Nucelolus
What makes up the nuclear envelope?
2 parallel phospholipid bilayers seperated 10-50 nm space
- Ribosomes bind on outside of nuclear membrane
Inner nuclear membrane: has integral connects to nuclear lamina
Importance of Nuclear Envelope?
- Seperates nuclear content from cytoplasm
- Seperates transcription and translation processes
- Selective barrier that allows limited movement of molecules between nuclues and cytoplasm
What is the nuclear lamina?
- Supports nuclear envelop
- Lamins (intermediate filaments) found IN ANIMAL CELLS ONLY
- Plants have nuclear lamina, but not made of lamin protein
- Bound to inner membrane
- Provices meshwork
- Lamins in nucleus are BLUE
What are nuclear pores?
- Gateway between cyotplasms and nucleus
- Pores are found where inner and outer membranes fuse
What is the nuclear pore complex?
- Composed of nucleoproins (NUPs) large family of diff proteins
- Octaonal symmetry
- BIG
- Passive diffusion of molecules that are 40 kDA or less
- Rapid
Regulated movement of larger molceules:
- Slow
What is nuclear imports?
Regulated movement of proteins into the nucleus requires a Nuclear Localization SIgnal (NLS)
- Positive charged amino acids within sequence
Steps in how the NLS targets proteins to nucleus?
- Protein with NLS interacts with Importin protein in cytoplasms
- Cargo/imporin complex interacts with FH-NUpa at NPC and enter nucleoplasms
- Ran-GTP interacts with Importin; cargo dissiates and stay in nucleoplasms
- Ran-GTP/Importin complex exists nucleus through NPC
- GTP hydorlysed to GDP, importin released in cytoplasm to find new cargo
Why are nuclear import and export critical for cellular function?
- Nucleotides for transcription
- Structural proteins (eg lamins)
- DNA packaging proteins (histones)
- Proteins for DNA replication, repiar and transcriptiopn
- Proteins for RNA processing
- Proteins for ribosomes synthesis and export
What is the nucelolus??
LARGEST structure inside nucleus, primary function is biosynthesis of ribosomes
Ribosomes consist of what two major components?
- Small ribosomal subunit which read RNA
- Large which join amino acids to form polypeptide chain
what are 40s and 60s?
Are exported to cytoplasm where they are assembled an 80s ribosomes
