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103 Cards in this Set
- Front
- Back
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What is a an autotroph? |
Think Plants, they make their own food/biological molecules |
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What is a heterotroph? |
Animals, fungi. Must eat their food (or get biological molecules from food) |
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Give two examples of autotrophs? |
Photoautotrohs-plants Chemoautotrophs-energy source is chemical energy (archaea). |
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What is the purpose of Chloroplasts? |
Chloroplasts are the organelle where photosynthesis takes place. In bacteria it takes place in the cytoplasm. |
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Important parts of chlorplasts? |
Lumen is reffered to as the stroma. Within stroma there are stacks of membrane bound vesicles called thylakoids. A stack of thylakoids is a granum (grana is plural) Outer and inner membrane (inner not as important as in animal cells). |
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What is a thylakoid? |
Membrane bound vesicle in chloroplasts. Stack is called granum. Light capturing pigments are found in thylakoid |
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Types of Chlorophyl? |
Chlorophyl A-Dark green Chorophyl B-lighter green. Both absorb violet and blue light/ also red. They reflect green. Chlorphyl have a long hydrophobic tail and a head with lots of carbon rings (double bonds). When light hits these rings the double bonds resonate (get more energetic/less stable) |
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What are carotenoids? |
there are two main types. Carotene (orange and red) Absorb blue and green light. Transmit orange and red. Xyanthophylls (yellow). Plants absorb chlorophyl to use next spring, leaving carotene and xyanth. reason for fall colors. Absorb complementary to yellow (blue) |
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How do the pigments produce energy? |
1.Photon hits the pigment. 2.Electrons begin to resonate in the double bond ring heads. 3.When light is removed, the electrons return to low energy and the difference is released. |
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What are the two steps of photosynthesis? |
1. Light reactions 2. Calvin Cycle |
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Brief overview of the light reactions? |
1. Convert light energy to ATP. Source of hydrogen (water) reduces NADP. Reduced NADP becomes NADPH. |
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Brief overview of calvin cycle? |
1. Use ATP and NADPH from light reaction and carbon dioxide from the evironment to make biological molecules. This process of taking inorganic carbon and turning it into organic carbon is called carbon fixation. |
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Why is plant food proof that they are autotrophs? |
Plant food contains nitrogen, iron, potassium. All inorganic materials, proof that they make their own |
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What are the 3 ways that the light energy is used in plants? |
1. Fluorescence or heat emission- when electron drops back to low energy the difference is released as heat. 2.Resonance-energy transfer-Energy is transfered to a nearby pigment (ideal). 3.Reduciton or oxidation-Electron is transfered to a new compound. |
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What are Antennae complex? |
They are found in the thylakoid membranes (pigments are also in membrane) These antanne complexes absorb solar energy. (basically think of a "dish" comprised of a bunch of the ring heads of pigment molecules) |
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What is the reaction center (photosynthesis) |
Think back to the antennae complex. The center where all the energy needs to be transfered to. This center is always chlorphyl A. Electrons in reaction center gain energy just like in the rest of the antennae complex but here they are used to reduce a molecule. (they have been captured at high energy). Captured by reducing NADP to NADPH (final electron acceptor in plants). |
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How energy is transferred through antenna complex? |
1.A photon hits a photopigment, energy level is raised by electron resonance (excitation). 2.When the energy level drops, the difference is released is enough to excite nearby molecules. 3.Continues in a chain reaction until it reaches reaction center. 4.Electrons are NOT being transfered, just ENERGY. 5.This process is called inductive resonance. |
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Photosystems in Light reactions? |
1.Inductive resonance 2.Remember you need at least two antenna complexes for photosynthesis to work (photocomplex I and II). 3.Both processes happen at the same time but photosystem II goes "First". I is dependent on II. |
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Steps in Photosystem II |
1. 4 excited electrons from reaction center (From inductive resonance) reduce Pheophytin. 2. Pheophytin now reduces PQ. 3.PQ reduces cytochrome complex. 4.Cytochrome complex reduces PC. 5.PC reduces Reaction center in photosystem I. 6.The electrons are replaced by the oxygen evolving complex. 7. Remember that energy is lost by the electron at every step in the process. This energy is used to pump protons against their gradient (It pumps them into the lumen where there is a high concentration). These protons return through ATP synthase. PQ moves protons (H+ from water) from the stroma to the lumen in the same way it happened in animals (once e- is removed the H+ is no longer attracted put PQ has gone cross membrane). |
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What two molecules help plants prevent free radical damage? |
Caratenoids and flavonoids |
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What is the oxygen evolving complex? |
How electrons are replaced in photosystem II It is a collection of enzymes that takes water and splits it into electrons, H+ protons and O2 gas. Electrons replace ones lost, O2 released as waste. |
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Steps in Photosystem I |
1. Inductive resonance 2.Causes 4e- to be elevated in energy. 3. These electrons reduce an acceptor molecule (ferredoxin) 4.Rerredoxin reduces the final electron acceptor NADP. It becomes NADPH. 5. Two NADPH are produced (4e- make 2 NADPH). 6.Electrons are replaced by electrons from photosystem II. |
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What is carbon fixation? |
Taking carbon dioxide from the environment and converting it to a biological molecule (calvin cycle). |
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Is calvin cycle endergonic or exergonic? |
Endergonic(anabolic). Energy comes from ATP and NADPH. |
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What is the molecule that the calvin cycle makes? |
G3P (glyceraldehyde-3-phosphate) Two are require to make one glucose. 3 turns of calvin cycle to make one G3P. (6 to make one glucose) |
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Steps of the calvin cycle |
1.CO2 from the atmosphere is fixated to RuBP (ribulose bisphosphate [5 carbons]) with rubisco (the enzyme). there are now 6 carbons and this compound is highly unstable so it immediately splits into two molecules of 3PGA (3-phosphoglycerate). 2.Oxidation of NADPH and reduction of 3PGA. This must happen twice so 2 ATP and 2NADPH are required. 3PGA is reduced to G3P. (remember that after 3 turns of the krebs cycle, there are 6 G3P. Plants only keep one, the rest are recycled.) 3. ATP is used to regenerate RuBP from G3P. |
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How many NADPH and ATP required to make one G3P molecule? (3 Turns of calvin cycle) |
9 ATP and 6 NADPH. 3 of the ATP are used in regenerating RuBP |
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What is Rubisco? |
Ribulase bisphosphate carboxylase This is the regulatory enzyme, and the enzyme that fixates carbon to RuBP. It is allosterically activated by NADPH. When levels of NADPH are high (light reactions are functioning) calvin cylcle functions. (why calvin is dependent on light and is not a "dark reaction). Rubiscos substrate is Co2. If O2 levels are high then rubisco will utilize oxygen insead. Instead of 2 molecules of 3PGA you get 1 along with a two carbon molecule (glycolate). |
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What is glycolate? |
The two carbon molecule made by the mistake of rubisco fixating oxygen instead of co2. It is highly toxic. Plants must transport glycolate to a peroxisome to by catabolized into co2 (this is photorespiration). Photorespiration uses a lot of energy. This all happens because plants evolved before oxygen levels were high. Proof photosynthesis came before cell respiration, cell respiration evolved from photorespiration. Not as a way to make ATP but as a way to get rid of oxygen. |
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What is a tissue? |
More than 1 cell type interacting for a common function (they must remain in contact to perform function) ex)muscle tissue, connective tissue, cartilage |
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What is an organ? |
More than one tissue working for a common fucntion ex) heart-contains muscle tissue, nervous tissue and connective tissue. |
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What is pectin? |
Mixed in the cell walls (cellulose microfibrils). It is a carbohydrate ( a collection of monosaccarides). It is sticky (makes jams and jellys sticky) |
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Why is pectin sticky? |
It is very hydrophillic, your skin is hydrophillic as well. There is also galuronic acid in pectin. Since the acid is donating protons away, this means pectin is negatively charged. The negative charges are attracted to positively charged and helps keep them in contact. |
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What is a secondary cell wall? |
It is inbetween the membrane and primary cell wall. It may be composed of different substances in different plants and in different areas (stem, trunks) |
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How are plant cells held together? |
In between two cell walls of two cells that are held together is something called the middle lamella. It is the “glue” that holds the cell tougher. The middle lamella is comprised of pectin. |
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Why do fruits and vegetables get soft and mushy? |
Pectin is a carbohydrate, it is a rich source of energy. Bacteria, fungi and other microorganisms break down pectin first, this causes the cells to lose their “glue” (middle lamella). |
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How are animal cells kept in contact? |
In animal cells, they are anchored in the extracellular matrix. In certain tissues the cells are not necessarily in contact with each other (connective tissue). The cells do not touch each other. The space in between is extracellular matrix (ECM). These cells still need to maintain their position to maintain integrity. |
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What is an animal plasma membrane built over? |
Cytoskeleton |
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What is a cytoskeleton? |
It is the cells skeleton, the most important protein that makes up the skeleton is actin. It looks like a dense mesh of proteins beneth the membrane. This layer of actin is called the cell cortex. Cell cortex is not the only actin proteins but it is important. |
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What is an integrin? |
A transmembrane protein. They attach to the cortex and project out of the cell. Integrin is a general name for multiple types of proteins that do this. |
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What is fibronectin? |
Another protein, it attaches to integrins. |
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Collagen |
an extra cellular protein, connects to fibronectin, integrin and all cells. A molecule of collagen is a triple helix of three polypeptide chains. Collegen binds everything in a tissue togehter. |
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What is gel forming polysaccarides? |
Mixed with collagen in ECM (Knees and other joints especially or maybe only) Very hydrophillic, combo of this and water makes a gel (spinal disks, connective tissue and cusioning for joints). |
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What is scurvy? |
Lack of vitamin C (hexuronic acid/ascorbic acid). Vitamin C is a coenzyme of collagen without it collagen does nto form properly. Cells begin to not hold well. Carnivores make their own. |
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What causes muscular dystrophy? |
Laminin is another type of fibronectin in muscle cells. The actin in myscle cells binds to dystrophan. In MD, there is a problem with dystrophan so cells lose their funcionality. |
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What are tight junctions? |
essentially it is proteins that “stitch” two cells together. There is no extracellular matrix. transmembrane proteins in two cells bind to each other. General name for these proteins is occludins or claudins Can be found in digestive tract (no leakage) Tight junctions are also good if you need a certain protein to stay on one side (remember fluid mosaic model) Another use is digestive lining, you want to take glucose in which requires acitve transport, so glucose goes into blood not back into intestines. |
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What is a desmosome? |
Looks like tight junctions but in this case the proteins adhere to the cytoskeleton and go all the way through the entire cell. This allows cells to move as a unit (skin, muscle) |
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Plasmodesmata |
This is in plants. It joins the cytoplasms of two cells. It is a membrane tube thta joins two cell cyctoplasms. |
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What is a gap junction |
basically the plasmodesmata in animals. It is a protein tube that connects one animal cell to another. Tube is a conexin. This is needed to facilitate signaling. |
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What is a bioflim? |
Microbes can also adhere to eachother. An group of bacteria stuck together is a bioflim (they are stuck together with carbohydrates). Can make bacteria very drug resistant as the durg cant penetrate the carbs. |
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What is a ligand? |
a ligand is any molecule that bonds on to a receptor, for us the ligand is the chemical messenger) |
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Name some examples of ligands |
Hormones-insulin, test, est |
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Principals of all signaling pathways |
ligand-receptor Interaction is reversible There must be chemical attraction (polar, ionic, hydro) No covalent bonds, wouldnt be reversible receptors are specific (like enzymes) Signal can do different things in different cells. For example estrogen causes some action but what the action is depends on what cell is involved. |
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what is Signal transduction? |
Basically that once a ligand binds to its receptor a chain of events will happen. This chain of events will cause the cell to change its behavior. |
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Basic steps of signal transduction |
1. Signal reception ( always step 1) a ligand binds its receptor 2. Receptor changes in some way (always step 2) 3. Signal amplification- Active receptor initiates signal transduction cascade. In a cascade, the signal is amplified. (like an avalanche) the number of steps in this cascade are varied. 4. Signal response- target is altered (something is changed, a gene makes its protein, something gets turned on/off) 5. Cells behavior is changed |
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What is the relationship between Kd and ligand-receptor affinity? |
They are inversely proportional |
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What is a Kd value? |
Dissociation constant. The amount of ligand needed to bind 50% of available receptors. If Kd value is high then you need a lot of ligand to get effects, (low affinity). |
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What is Desensitization? |
The pheonomeon of cells responding less strongly to a specific ligand concentration (a mechanism of addiction and drug tolerance). This is something good, you dont want a continuous strong responce (adrenaline) |
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How does desensitization work? |
Via receptor down regulation |
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3 ways receptor down regulation occurs? |
1. Endocytosis. The destruction of the receptor and or ligand. (receptors catabolized) 2. Ligand is pumped out of the receptor. The ligand binds, transduction happens and then the ligand is physically removed or pulled away from the receptor. 3. Some receptors are altered when they bind with ligand. The receptor is altered such that Kd goes up (affinity lowers). |
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Difference between actions of hydrophobic vs hydrophillic receptors/ligands |
If a receptor or ligand is hydrophillic is never enters into the cell (will be transmembrane). If a ligand is hydrophobic they may diffuse through the plasma membrane (receptors will be intracellular). |
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What are the three types of cell signaling systems? |
1. Receptor inside cytoplasm (intracellular receptors). 2.Surface receptors 3.Surface receptors like 2 (both transmembrane) but in this case they are specifically tyrosine kinase receptors. |
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How the intracellular receptor system works? |
Ligands are always hydrophobic (they can diffuse through the membrane. 1. Ligand Enters through the cell membrane and binds its receptor. 2. The receptor and ligand act as a Transcription factor. 3. This TF binds a promoter and then encodes RNA from DNA. 4. The end result is a cell is making a protein that it wasn't before. 5.Example is estrogen. Protein that is made varies (in egg, it makes albumin, in breast tissue, breast tissue expands). Remember most breast cancer is caused by too many receptors. In the liver, choloesterol is produced. (estrogen encourages production of HDL, good cholesterol). Also causes metabolism of fat. |
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Basics of surface receptor (type A, G protein linked receptors) |
Hydrophillic ligands This is most common signal pathway Receptor protein is transmembrane. It is the g protein linked receptor. On the intracellular side of the membrane there is the g protein. which is composed of 3 sub units (alpha, beta and gamma) Attached to the alpha subunit is a molecule of GDP (same as ADP but guanine istead of adenine). 4. |
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What is RNA Polymerase? |
The enzyme that moves along the DNA and synthesizes corresponding RNA. This enzyme has to be able to recognize where the start of a gene is. A promoter does this. |
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What is a promoter? |
It signals to RNA polymerase the start of a gene. The enzyme can only recognize the promoter when it is bound with a transcription factor. Receptor plus ligand in intracellualr receptors act as a transcription factor (estrogen). |
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How does g protein linked receptor pathway work? |
1.Ligand binds receptor. 2.Receptor is changed allosterically (changes shape). 3.This change in shape causes the g-protein to change shape. 4.G proteins new confirmation changes its affinity. Affinity for GDP goes down but GTP goes up. 5.GDP comes off of alpha sub unit and is replaced by GTP. 6.once GTP is bound, G protein splits apart (alpha sub unit breaks away) 7.Alpha subunit is now activated. 8.Activated subunit no performs some function (an enzyme is allosterically activated almost always). 9. GTP only binds for a split second, then GDP returns and g protein reforms. Two key enzymes in this process, adenylate cyclase and PKA. |
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What is Adenylyl cyclase? |
This enzyme is Off until g-alpha activates it. Adenylyl cyclase turns ATP into cyclic AMP or cAMP. cAMP is a second messenger, it carries the signal onto the next destination. (ligand was the first messenger). |
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What is PKA? |
Protein kinase A. This protein is inactive because it is bound to an inhibitor molecule. cAMP removes the inhibitor and activates PKA. PKA is activated by cAMP. It is a kinase so it phosphorylates the target (dependent on type of cell) |
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Example of something that uses g-protien linked receptor pathway |
adrenaline. proteins that get phosphorylated by PKA are in muscle cells and liver cells. The protein is glycogen phosphorylase. This protein breaks down glycogen into glucose for an energy boost. In heart muscle the proteins that get phophorylated are responsible for speed and strength of beat. |
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What is cholera? |
Disease found in seawater and seafood. Symptoms are diarrhea, muscle cramps and dizziness. In your intestine the bacteria reproduce (use of antacid allows them to bypass stomach acid). Bateria secrete a protein called cholera toxin. Remember that there are ion channels in the intestine to allow flow of liquids, this is turned off and on by adrenaline (g-protein) Cholera toxin binds to GTP molecule when it is attached to alpha sub unit, this prevents deactivation of the response and makes ion channels stay open leading to diharrea and dehydration. |
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Besides adenylylate cyclase, what is another enzyme that is activated by G-alpha protein |
Phospholipase C In this pathway the GTP that is attached to alpha subunit binds to phospholipase C. This enzyme takes a lipd called diaceylglycerol and turns it into inositoltriphosphate. Remember smooth endoplasmic reticulum. One of its functions is to store calcium. There are channels in the membrane that allow the movement of calcium. When inositoltriphosphate is present the channels open and calcium is allowed out calcium binds and activates an enzyme called PKC (c for calcium). In this case calcium is the second messenger PKCs function depends on the specific cell. It phosphorylates a target. When an egg is fertilized, the signal to start dividing is started by this pathway. Once the signal is delivered, the calcium is pumped back. |
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Second transmembrane receptor signal pathway (tyrosine kinase receptors |
Transmembrane receptors Receptor is composed of multiple component proteins, they free float in membrane. Once ligand shows up, receptor components come together due to mutual attraction to ligand. step 2 is the receptor changes in some way, in this case the cahnge is clustering of protein components. The part of the protein group that is extracellular is a receptor, the intracellular type is a kinase. The intracellular parts phosphorylate each other, this is known as cross phosphorylation. In the cytoplasm of the cell are STAT proteins (signal transducer and activator proteins). phosphates added to the proteins in cross phos. now attract STAT proteins which are then phorprylated themselves. STATS are changed so they lose affinity for the tyrosine kinase receptor, they unbind there and then bind with eachother (dimerize) This stat dimer is a TF. Example of this pathway is epidermal growth factor. Also production of antibodies. |
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What is cell division used for in multi vs uni cellular |
Multi-growth or repair of damage. Uni-reproduction |
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what are chromosomes |
Composed of DNA and proteins. Structural protein of chromosome is Histones. |
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How many chromosomes do humans have? |
46. 25,000 roughly genes, each chromosome caries various amounts of genes (they are not all equal) Generally all plants animals etc carry even numbers of chromosomes. Therefore humans have 23 sets (23 pairs). Two chromosomes in a set are same size and carry the same genes. |
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Does the number of chromosomes ever change? |
NO. Before cell division the number of DNA doubles, but chromosome number stays the same. (goes from a single line to a bow tie joined by centromere) |
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How many of a specific gene in non replicated DNA? in Replicated? |
2 in non replicated (2 chromosome pairs). 4 in replicated |
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what are the 4 steps in the cell cycle? |
G1-Cell functions normally S-DNA synthesis G2-cell prepares to divide First three refered to a s interphase Mitosis-actual division |
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When is DNA easy to see? |
DNA is packed in preparation to divide, and is then unpacked after division has taken place (so it can be used) |
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What is a chromatin? |
When a chromosome is spread out "unpacked" |
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Stages of mitosis |
Interphase (not really a stage)-most important part is DNA replication (single chromosome to bow tie chromosome) 1.Prophase-Chromosomes condense "pack". Spindle apparatus forms and chromosomes attach to it at kinetochore (proteins attached to centromere). Nuclear membrane breaks up. 2.Metaphase-Chromosomes are pulled to an equatorial position. 3.Anaphase-Half of chromosomes are pulled to one side, other half is pulled to the other. When chromosmes are pulled apart they are called chromatids. This is accomlished via the spindle apparatus. 4.Telophase-Nuclear envelope reforms around the two groups of chromatids, chromosomes begin to condense back (chromatin). 5.Cytokeneisis-cell divides. Actin-myosin ring causes plasma membrane to pinch in. |
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How spindle fiber apparatus works? |
Microtubules are attached to kinetochore, which are proteins that are attached to centromere. microtubules are made up of sub units caled tubulin (circle of straws attached end on end) Microtubules grow out of centrioles. Tubulin subunits can be added or subtracted from microtubule to shorten or lengthen. Tubulin grows from minus end (the centriole) to the plus end (centromere) A protease cuts the proteins that hold the chromatids together In order to separate the chromatids, the tubulin bingins to come off the plus end of the microtubule, shortening its length and separating the chromosome. |
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What protein links the kinetochore to the mcirotubule? |
Dynein protein. Dynein has a strong affinity for the microtubule, as the tubule shortens, the dynein keeps pulling the chromatid towards it due to its high affinity |
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What phase in the cell cycle do we see the most variation in cell lifespan? |
G1 phase. |
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What is cell cycle arrest? |
When a cell stays in G1. also called G0 |
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What is an example of cells that stay in G0? |
Nerve cells in your brain. After adulthood, you dont make any more nerve cells in brain |
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What is an example of a cell that can go from G0 back to G1? |
Liver cells. Stay in G0 unless there is damage, in which case they reenter cell cycle. |
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Where are the checkpoints in the cell cycle? |
One in G1 (cycle arrest), one in G2, two in mitosis. |
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What were the two experiments that discovered how checkpoints were regulated? |
1. A chemical treatment was used to fuse cells into one larger cell (heterokaryons). These heterokaryons were formed between two cells in different phases. The cells were found to jump to the stage of the other cell (if a G1 was fused to a mitosis phase, it would immediately jump to mitosis even though it didnt have replicated DNA). This gave rise to the idea that a chemical signal is what told cells when to move past the checkpoints. 2. This experiment used oocytes, pre egg cells. OOcytes are stoped at G2 phase until it is time to become egg cells. They took mature frog eggs and removed the cytoplasm. They added this cytoplasm to the oocytes and they instantly started to divide. Maturation promotion factor (MPF) is what the reulatory chemical was called until the 80's. In the 80's it was determined to be cyclin-dependant kinase 2 (CDK-2). |
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What is CDK-2? |
Cyclin-dependant-kinase-2. It phosphorylates. It is called cyclin2 because it regulates G2 checkpoint. It is cyclin dependant Concentration of CDK -2 was found to never change throughout all cell stages. When activity was measured, it was found to only be active in G2, and then in mitosis it would go back down to 0 throughout the rest of the stages. |
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What is cyclin? |
A protein. It is required to be present in order for CDK-2 to function. Cyclin allosterically activates CDK-2. Cyclin levels mirror CDK activity Mitotic cyclin plus CDK-2 is the mitotic MPF. |
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What is the MPF and what does it do? |
Maturation promotion factor. 1.Cause condensation of DNA into chromosomes (packing). Basically CDK phosphorylates protiens that cause them to pack DNA tightly and condense) 2.The kinase phosphoryates proteins in the nuclear membrane, which causes nuclear membrane fragmentation (prophase). 3.Certain enzymes are phosphorylated which allow formation of spindle fiber aparatus (prophase) 4.CDK-2 activates proteases (the ones that break down proteins that hold replicated chromatids together. Another one of these proteins gets rid of cyclin. Levels fall so CDK-2 activity drops. |
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What causes cyclin levels to rise? |
Transcription factors. (for example growth enzyme in skin cells). Remember signal transduction in skin cell example, cyclin is activated |
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How is G1 checkpoint operated? |
Same way as G2 but with different proteins. CDK-1. CDK-1 activity rises from 0 in G1 phase and peaks in s phase and immediately drops to zero. Cyclin is S-phase-cyclin. Concentration of s phase cyclin begins to rise in g1 phase, but before activity levels, peaks just before activity peak and then immediately drops. Regulation is identical. S phase cyclin plus CDK-2 is the s phase MPF. |
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Steps the s phase MPF takes |
1. Production of enzymes and other proteins needed for DNA replication. (DNA polymerase is one) 2.Activates proteases that degrade s phase cyclin. |
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Mitosis checkpoints |
If not all chromosomes attach properly to the spindle aparatus then the cell is stopped at metaphase. Anaphase is delayed until all kinetochores attach properly. |
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What are the two categories of genes that code for proteins that cause cells to advance or stop? |
Proliferation genes-Code for proteins that cause cells to advance through checkpoints (mitotic cyclin, s phase cyclin, CDK, epidermal growth factor, STAT proteins). Antiproliferation genes-code for proteins that cause cell cycle to stop at checkpoints. |
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What are the two types of mutations that deal with anti/proliferation genes? |
Expression mutations-Amount of proteins being made is off. One way this can occur is if there is a problem with the promoter (which attracts TF). IF mutation affects promoter and its affinity goes down under expression happens. If mutation increases affinity then over expression. If over exprression of a proliferation then cancer. If under expression of anti then cancer. Functional Mutations-proteins that are made are innefective or over effective. |
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What is an example of an antiproliferation gene that is mutated? |
Antiproliferation genes are known as tumor supressor genes. Most important one in animals is called P53. More than 50% of cancer is caused by a mutation of this gene. (underexpression or loss of function). |
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What is P53? |
The guardian of the genome. Steps. 1.P53 is activated in response to DNA damage. P53 begins making its protein when activated. 2.Protein that P53 makes is P53 protein. This protein is a TF for a gene called WAF1. 3.WAF1 makes a protein (WAF1 Protein) that binds and inactivates s phase cyclin 4.Now there is no s phase MPF which means cell cycle is halted at G1 checkpoint 5.Cell temperoriarily goes into arrest. 6. Now one of two things will happen 7. the first thing is that an enzyme will atempt to repair the DNA. If sucessful then P53 levels go back down and cell reenters cycle. 8. If unsuccesful then the cell is destroyed. This happens by an enzyme being activated (caspase). Caspase activates caspace activated DNAse (CAD). This enzyme digests all the DNA in the cell and the cell dies. This is cell suicide AKA apoptosis. |
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What are BRCA genes? |
Breast cancer genes. 10% of breast cancer is caused by these genes (inherited kind) BRCA 1. Estrogen and the estrogen receptor in breast cell tissue is a transcription factor. The gene that is factor is fore is the gene that makes the progesterone receptor. Progesterone binds these receptors and makes more s phase cyclin. BRCA 1 makes BRCA 1 protein which down regulates progesterone receptors. |
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What are protooncogenes |
(pre/early cancer genes). When they mutate they become oncogenes (cancer genes). |
