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92 Cards in this Set
- Front
- Back
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7 functions of cells... |
1. spatial arrangement 2. membrane boundary layer 3. maintain required energy 4. cells reproduce independently 5. genetic material in cell determines its activity 6. multicellular organisms differentiate in to specialized structures |
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Multiplication of cells results in... |
growth of the organism. In higher organisms, cells differentiate to make different tissues |
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Cells can be compartmentalized in two ways... |
Necessity and Compartmentalization |
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Compartmentalization by Necessity |
Organization based on cells exchanging materials with their environment to meet their physiological needs |
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Compartmentalization Method |
Biochemical reactions are established only in places where they can occur. This can cause an uneven distribution of molecules. ex. a high concentration of amino acids in the mitochondria near the ribosome. |
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What is the only thing more complex in prokaryotes than eukaryotes? |
the peptidoglycan cell wall |
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Type of ribosomes in mitochondria and golgi? |
70s |
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Spirillum |
rod twists or spirals |
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spirochete |
long, helically coiled cells |
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vibrio |
half moon rods |
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diplococcus |
one plane, pairs |
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streptococcus |
one plane, chains |
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tetracocci |
one plane, and perpendicular plane |
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staphylococcus |
many planes, grape bunch |
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sarcinae |
cuboidal packets |
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micro |
10^-6 |
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Largest prokaryote |
Thiomargarita namibiensis, a sulfur chemolithotroph. 10^8 EC volumes, 750um |
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Smallest prokaryote |
Mycoplasma pneumoniae, a pathogen. 2.5 X 10^-3 EC volumes |
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The rate at which nutrients and waste products move in to the cell... |
is inversely proportional to cell size |
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Collision Surface Area |
the larger the surface area to volume ratio, the more easily nutrients can move in to the cell. |
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What happens as cell size increases? |
the surface area to volume ratio decreases and transport becomes less effective |
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If an organism is larger it must become... |
multicellular |
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Structure of a virus |
1. Nucleic acid: DNA or RNA 2. A protein coat called a capsid made of capsomeres |
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What is the exception in viruses nucleic acids? |
Mimivirus, contains both DNA and RNA |
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Obligate intracellular Parasites |
outside the host cell they are unable to reproduce and are non living |
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Viroids |
single stranded circular RNA that pairs up via intra strand base pairing (2ndary structure) makes it stable to exist outside host cell. enters through wound in plant cells. |
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Prions |
prions are polypeptides that lack DNA and RNA. small replicating polypeptides. Infectious forms are Mad Cow and CJD. |
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Do viruses, prions, and viroids have a cell membrane? |
NO |
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Neurodegeneration process via prions? |
Prion enters a healthy organism and induces it to convert to the misfolded form (PrPsc) which causes neurodegeneration. The abnormal form aggregates in neural cells that leads to destruction of neural tissues and neurological symptoms. |
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Width of the cytoplasmic membrane? |
6-8 nm |
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Main function of the cytoplasmic membrane? |
highly selective, enabling cell to concentrate metabolites and excrete waste materials |
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Fxn of membrane in bacteria |
the ETC, the proton motive force |
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What does a phospholipid consist of? |
Two fatty acids esterified to a glycerol (a c3 polyhydroxy alcohol) in bacteria and eukarya. They are ether bonds in archaea. |
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Peripheral membrane proteins |
extrinsic proteins not embedded but associated with the membranes surface. |
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Integral membrane proteins |
tightly bound and fully embedded can span bilayer with exposure on both sides amphipathic proteins hydrophobic region contains an a helix |
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Why does the bilayer vary in thickness? |
to accommodate the change in protein concentration |
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Viscosity of membrane? |
similar to that of motor oil |
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Fluidity of the membrane is determined by... |
temperature and lipid composition |
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Three cell membrane functions: |
1. Permeability barrier: gate and prevents leaks 2. Protein anchor 3. Energy conservation: site of ETC protein motive force. since prokaryotes lack a mitochondria the membrane separates protons from hydroxyl ions. |
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What can readily diffuse across the plasma membrane? |
small nonpolar and fat soluble substances like fatty acids, alcohols, and benzene |
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Sterols |
Absent in prokaryotes, present in eukaryotes 5-25% in membranes rigid planar molecules that stabilize and make it less flexible allows fluidity to remain at lower temps Exception: prokaryote mycoplasma contains it |
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Hopanoids |
molecules similar to sterols present in membrane of many bacteria ex. diplotene |
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What makes archaea bonds different from eukarya and bacteria bonds? |
archaea have ether linkages between glycerol and their hydrophobic side chains |
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Isoprene: |
inside archaea that replace the fatty acids. they are repeating units of a five-carbon hydrocarbon. |
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How did Woese discover Archaea as a different domain? |
the 16s rRNA sequence differences |
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Eukarya Examples |
Animals, Fungi, Plant are the crown species Slime Molds Flagellares Giardia |
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ESTER VS ETHER |
REVIEW PPT SLIDE 34 |
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Major Classes of Lipids in Archaea |
Glycerol diethers and diglycerol tetraethers |
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Phytanyl |
C20: 4 linked isoprenes, glycerol diethers |
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Biphytanyl |
C40: 2 linked phytanyls, diglycerol tetraethers |
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What makes up a glycerol diether? |
1 glycerol, 2 phytanyls attached by ether bonds |
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What makes up diglycerol tetraether? |
2 glycerols, 2 biphytanyls attached by ether bonds also can be thought of as 4 phytanyl divided in to two couples where each couple is covalently bonded |
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Crenarchaeol |
5 and 6 C Rings most cultured are hyperhtermophiles four cyclopentyl and one cyclohexyl |
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What forms the lipid bilayer structure? |
glycerol diether |
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What forms the lipid monolayer? |
diglycerol tetraether forms a monolayer because the lipids interact. extremely resistant to heat denaturation. Mostly hyperthermophiles which are prokaryotes that grow above 80C |
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How do you calculate the initial velocity of transport? |
Si/time |
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When do you measure velocity? |
when solute inside is initially zero and solute outside is varied |
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Simple diffusion |
nonsaturable |
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Facilitated diffusion |
saturation at high concentrations of solute: specificity for solute |
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Simple Active |
energy from ion gradients/proton motive force' single membrane spanning protein |
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Group Translocation |
energy from ATP involves a series of proteins transport in or out |
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ABC(ATP-Binding casette) |
chemical modification of solute as it is transported; 3 components periplasmic proteins can bind solute even in extremely low concentrations |
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What is the common factor among membrane spanning proteins? |
All similar due to evolutionary roots. commonly 12 a helices that wind back and forth through the membrane forming a channel through which solute enters/exits the cell. |
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Lac Permease of E. Coli example |
example of simple active transport symporter of lactose and a proton metabolizes lactose |
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ATP Binding Cassette Transport 3 components |
1. periplasmic binding protein: binder 2. membrane integrated transporter: channel 3. ATP hydrolyzing protein (a kinase): energy source |
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ATP binding cassette in gram positive |
Gram positive don't have a true periplasm so they have specific substrate binding proteins |
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Process of group transloctation |
E1 takes PEP to HPr to E2a to E2b to E2C where glucose crosses and takes the phosphate. this series of enzymes is a family of 5 proteins called the phosphotransferase system. unique 2a per each sugar. E2C is the transporter. |
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What is group translocation popular among? |
anaerobic and facultative anaerobic bacteria |
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Secretory System Proteins: |
YEG: transmembrane transporter A: ATP hydrolyzing enzyme B: prevents protein folding DF: involved in translocation 7 proteins total |
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what is the function of the enzyme translocase? |
moves proteins to be secreted or inserted in to the cell membrane in order for them to work. |
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Why is protein export important in bacteria? |
Many proteins are destined to function outside of the cell, called exoenzymes |
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Type lll secretion |
a way for pathogens to use this system to secrete toxins in to a host |
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most important role of the cell wall |
protection from osmotic pressure and prevents cell lysis |
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Peptidoglycan |
rigid layer primarily responsible for strength of the cell wall |
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Gram Positive Layers |
one thick layer of peptidoglycan dehydrated by alcohol |
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Gram Negative Layers |
Two smaller layers: one peptidoglycan and one LPS sometimes called the envelope |
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Components of peptidoglycan layer |
2 sugar derivs: N acetylglucosamine and Nacetylmuramic acid Group of aa: L alanine, D alanine, D glutamic, and either L lysine(+) or DAP (-) |
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Percentage of peptidoglycan in cell walls of bacteria? |
as much as 90% in gram positive as much as 10% of the cell wall in gram negative |
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What is glycan tetrapeptide? |
the sugars and amino acids of peptidoglycan. chains are connected through the cross linking of amino acids. the glycan portion is the same on both gram + and gram - |
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Gram positive bacteria when treated with lysozyme in an isotonic solution? |
produces protoplast |
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gram negative bacteria when treated with lysozyme |
produces a spheroplast (partial cell wall because LPS layer is not weakened by lysozyme) |
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Two types of bacteria with no cell wall: |
Mycoplasma: lives in osmotically protected environments with sterols for added membrane strength Thermoplasma: species of Archaea; tough monolayer with lipoglycans (similar to sterols) |
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What do you call the outer membrane of gram negative bacteria? |
LPS, lipopolysaccharide membrane |
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Pseudomurein |
present in cell walls of archaea. similar to peptidoglycan. contains acetylglucosamine (same g as peptidoglycan) and acetylosaminuronic acud (T). has B 1-3 links instead of B 1-4. resistant to lysozyme. L amino acids instead of D. |
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Major fxn of the LPS |
keep proteins from diffusing away from the cytoplasmic membrane ex. amylase, ABC transporter, chemoreceptors |
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LPS as an endotoxin |
toxic to animals in high conc. associated with the lipid A portion, hence endo can cause fever, low BP, coagulation, inflammation presence of LPS in blood can cause septicemia ex. Shigella, Salmonella, e coli |
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How do external proteins and molecules reach the periplasm? |
Sec Protein Exporting system |
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Permeability of the LPS |
not permeable to large proteins and molecules O layer not permeable to hydrophobic molecules hydrophilic small molecules cant cross lipid A |
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Why are hydrophobic antibiotics not effective in GRAM - bacteria? |
O layer not permeable to hydrophobic molecules |
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How do small hydrophilic molecules get in to the periplasm? |
porins in the outer membrane |
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specific porins |
contain binding site for solutes |
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non specific porins |
water filled channels |
