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)