Term
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Definition
- unbound (monomeric) amino acid
- Carboxyl end drops an H+ ion & animo end picks it up --> polarized ends
- amino end attracts OH- (hydroxide) ions in a solution
– carboxyl end attracts H+ ions in a solution
- act as natural buffers (prevent pH changes) |
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Term
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Definition
• help to fold other proteins
• keep out cytoplasmic influences while protein folds spontaneously
• ex: form hollow cavity for shelter |
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Term
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Definition
- Complex lipids (aggregates of lipids grouped with proteins/other mcls)
- Transport triglycerides from intenstines to other tissues |
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Term
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Definition
| Complex lipids that carry cholesterol from intestines around body |
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Term
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Definition
- steroid hormone (non-glyceride lipid)
- Core of 4 fused carbon rings
• Found in mammal cell membrane
• Made in liver (in vertebrates)
• Maintains membrane fluidity
• At low temps, carbon rings keep phospholipids in membrane from collapsing in on each other (aided by kinks in unsaturated fatty acids)
• At high temps, add stability between fluid phospholipids
• Precursor from which other steroids are made |
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Term
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Definition
An alpha-liked (kinked) polysaccharied
• Polymer of glucose
• Energy storage in plants
• Stored as granules within plant cell plastids (including chloroplasts)
• Angle of 1-4 carbon linkages make helical structure
• Ex:
• Amylose (simplest, unbranched)
• Amylopectin (branched) |
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Term
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Definition
Polysaccharide
• Stored in vertebrate liver/muscle cells
• Not sustaining reserves: exhausted in ~1day |
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Term
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Definition
• Straight rather than helical (due to beta linkage)
• Most abundant organic compound on earth
• Attached hydroxyl groups bond → microfibrils (units of grouped parallel cellulose mcls
• Not digestible in humans → passes thru tract, stimulating mucous secretion |
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Term
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Definition
• End-product of catalyzed reaction blocks original enzymes
• Binds to active site of enzyme to keep it from working on more reactions
• Ex: ATP blocks enzyme that turns ADP to ATP |
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Term
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Definition
• Certain mcls compete with substrate for enzyme’s active sites
• Slows down reaction rate, but can be overcome by addition of more substrate
• Note that Vmax doesn’t change (enzyme can still facilitate same # of reactions per unit of time if enough substrate is present…)
• Ex: Sulfa drugs
• block bacteria’s synthesis of folic acid (important enzyme cofactor) by sitting on active site of enzyme that catalyzes synthesis.
• Sulfas get incorporated into the folic acid that is made (instead of PABA) → folic acid is nonfunctional
• They can do this because sulfas and PABA have similar structure
• No functional folic acid → no DNA replication → no cell division (humans can get folic acid from diet, but bacteria have to make it.) |
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Term
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Definition
• Bind to active site & render enzyme permanently inactive
• Ex: Sarin (nerve gas) binds to enzyme acetylhcholinesterase (breaks down neurotransmitter acetylcholine in synapse between nerve cells) → continuous stimulation at synapse → muscles rigid → respiratory muscles eventually paralyzed → dead. |
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Term
| Pseudoirreversible inhibitors |
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Definition
• High affinity for enzyme active site → hard to displace once bound
• Ex: methotrexate (cancer drug) occupies enzyme that turns dietary folic acid into folic acid for DNA synthesis → stops rapid cell division |
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Term
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Definition
| • Bind to some other part of enzyme (not active site) to change enzymes 3D shape (active site’s shape altered) |
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Term
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Definition
• Substances bind to particular allosteric sites on enzyme to increase or decrease efficiency
• Ex: when oxygen atoms bind to one of hemoglobin’s 4 subunits, it creates a change in the other 3, making them more effective at oxygen-grabbing too. |
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Term
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Definition
| Get ATP through anaerobic respiration or fermentation; can’t even survive in presence of O2 |
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Term
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Definition
| can make enough ATP to survive using wither fermentation or respiration (ex: yeast, many bacteria) |
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Term
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Definition
• pyruvate loses CO2 → acetaldehyde
(in yeast and some bacteria)
• acetaldehyde accepts electrons from NADH to become ethanol
• NAD+ is restored |
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Term
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Definition
(certain fungi/bacteria, human muscle cells)
• Pyruvate accepts electrons frm NADH & is reduced to lactic acid
• In muscles, lactic acid is converted back to pyruvate (by liver cells) & enters cell respiration when oxygen supply is replenished (amt of oxygen required for this is “oxygen debt”) |
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Term
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Definition
• Pyruvate moves frm cytoplasm to mitochon matrix
• Loses CO2 (decarboxylized) & oxidized (NAD+ →NADH) to acetyl CoA |
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Term
| Citric acid / Krebs / tricarboxylic acid cycle |
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Definition
• Acetyl CoA’s 2-carbon acetyl group combines with 4-carbon oxaloacetate → citrate (6 carbons)
• oxaloacetate regenerated somehow…
• 1 ATP produced by sub-lev-phos (2 per glucose)
• NAD+ & FAD → NADH & FADH2 (2 each per glucose) |
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Term
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Definition
electron carrier mcls in ETC resembling hemoglobin in active site structure
• Functional unit has central iron atom that’s reduced/oxidized repeatedly (reversible redox reaction) |
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Term
| FMN (flavin mononucleotide) |
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Definition
- first mcl in ETC
- Oxidizes NADH |
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Term
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Definition
-Last mcl of etc
- Passes electron to O2 which adds it to H+ ions in surrounding medium to form water |
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Term
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Definition
• Cyanide: blocks electron transfer from a3 to O2
• Dinitrophenol: uncouples etc from proton gradient across inner mitochondrial membrane |
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Term
| 3 protein complexes along ETC |
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Definition
• NADH dehydrogenase
• B-c1 complex
• Cytochrome oxidase complex
o Cytochromes have heme prosthetic group with iron atom that accepts/donates electrons |
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Term
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Definition
2. bypasses first complex & gives electrons to a carrier between 1st and 2nd complexes: ubiquinone (carrier Q – only non-protein member of ETC)
o It’s a ubiquitous FAD to skip first period. |
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Term
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Definition
Activation of fatty acid in cytoplasm before it can be converted to Acetyl CoA in mito matrix (& enter citric acid cycle)
(costs 2 ATP) |
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Term
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Definition
• To feed into glycolysis/citric acid cycle, amino acids must undergo deamination (have amino groups removed)
• Nitrogenous waste excreted as ammonia, urea, etc. |
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Term
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Definition
• hydrocarbons
• accessory pigments
• broaden spectrum of colors that can drive photosynth |
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Term
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Definition
- Only to nearby cells
- Signaling mcls are quickly pulled out of extracellular matrix |
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Term
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Definition
- Only in nerve cells
- Over very short distances
- Electric signals reach aon terminals to cause release of neurotransmitters, which bind to nearby nerve cells, causing electrical signal
- Allows long-dist communication w/o diminished effect |
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Term
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Definition
| - Chem. messengers secreted into bloodstream for widespread distribution |
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Term
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Definition
o Cholesterol-based → pass thru lipid cell membrane of target cells
o Act directly on nuclear DNA
o Often binds to receptor proteins so it can cross nuclear membrane or regulate transcription → steroid-receptor complex |
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Term
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Definition
| • protein that binds to specific DNA sequences, thereby controlling the flow (or transcription) of genetic information from DNA to mRNA |
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Term
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Definition
o A small, non-steroid signaling mcl that can pass thru membrane
o Acts on guanylyl cyclase (enzyme) in cytoplasm → produces cyclic-GMP
• Causes smooth muscle cells to relax when stimulated w/ acetylcholine
o “NOs turns bat GUANo to find a biCYCling GiMP that helps the smooth relax and the skeletal contract with acetylcholine” |
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Term
| Nonsteroid hormone examples |
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Definition
• Atrial natriuretic peptide: Released by heart; influences kidneys’ water absorbtion
• Calcitonin: calcium regulation
• Glucagon: blood sugar regulation |
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Term
| types of cell surface receptors |
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Definition
• Ion-Channel-linked (ligand-gated)
• G-Protein linked
• Enzyme-linked |
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Term
| Ion-channel linked (ligand gated) receptors |
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Definition
o Neurotransmitters, peptide hormones
o Span membrane
o When ligand binds, conformational change creates tunnel through membrane
o Often allows ions (Na+ or K+) to pass, changing charge across membrane
o Ligand soon dissociates from receptor, closing tunnel |
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Term
| G-Protein linked receptors |
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Definition
o G-proteins dissociate from receptor on cytoplasm side & bind to nearby enzymes inside cell
o “second messengers”: small mcls in cell that activate key enzymes/transcription factors
• ex: cyclic AMP (cAMP), calcium phosphates
o many-step conversions |
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Term
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Definition
o Act directly as enzymes or activate enzymes in the cell
o Most turn on kinases (enzymes that regulate activity of proteins by phosphorylation (adding phosphate groups to them) ) |
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Term
| Phospholipid types (different R groups on phosphate) |
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Definition
o Phosophotidylcholine
o Sphingomyelin
o Phosphotidylethanolamine
o Phosphotidylserine (Serine R group)
• Negatively charged (all other neutral) |
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Term
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Definition
| signaling lipid in cell memebrane that converts nonsteriod hormone messages into “second messages” |
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Term
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Definition
o Lipids with carbohydrates attached (by Golgi apparatus)
o Supposed purposes
• transmission of electric impulses
• cell-to-cell recognition
o Ganglioside (most common)
• Galactose sugar attached to glycerol (w/ fatty acid tails) |
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Term
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Definition
(Most common glycolipid)
Galactose sugar attached to glycerol (w/ fatty acid tails) |
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Term
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Definition
| protein/carb-rich coating on cell surface |
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Term
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Definition
(active transport)
Membrane proteins that use ATP to change shape so mcls can be brought in/out against concentration gradients
- Present in every cell membrane
- Maintain unequal concentrations of ions
- Important in nerve signal conduction… |
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Term
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Definition
o Antiport: transport of two mcls in opposite directions (vs. symport)
o Pulls 2 K+ ions into cell
o Kick 3 Na+ ions out
o Keeps cytoplasm negatively charged
o Helps control solute concentration in cell (prevents shrinking or swelling) |
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Term
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Definition
o Uniport pump (only 1 ion moves thru)
o Embedded in membrane of ER
o Transports calcium from cytoplasm into ER lumen → high concentration of Ca++ stored in ER
o ER of muscle cells (sarcoplasmic reticulum) depolarized by action potential from nerve cell → releases store of calcium ions → cytoplasm flooded with C++ → allows myosin/actin filaments to slide past each other → rapid muscle contraction
• To increase reactivity of skeletal muscle to acetylecholine, you’d have to increase # of calcium ions stored in sarcoplasmic retic |
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Term
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Definition
- Occluding (tight)
- Anchoring
- Communicating (gap) |
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Term
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Definition
• Proteins wind tightly bw adjacent plasma membranes
• Total barrier to transport and diffusion
• Intestines:
• Special cells absorb nutrients from one side, transport them thru cell and out the other side (into bloodstream)
• Tight junctions keep glucose in bloodstream from diffusing back into intestinal tract |
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Term
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Definition
• connect one cytoplasm to another w/ anchoring proteins
• protein connect to actin filaments in cytoplasm and linker proteins across intercelluslar space
• found b/w cell under stress from shearing/contacting forces
• not a linking of cytoplasm but physical joining so cell don’t shear away
• when fibers holding junctions together contract, cells themselves contract into large tubelike tissues
• Ex: desmosomes
• In heart cells & bw epithelial cells in skin
• Attach 2 cells with intermediate filaments (not actin filaments) |
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Term
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Definition
structure of anchoring junction found in heart cells & bw epithelial cells in skin
Attach 2 cells with intermediate filaments (not actin filaments like many anchoring junctions) |
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Term
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Definition
proteins that build tubes/pores bw 2 cells’ cytoplasms (communicating/gap junction)
many form a unit: connexon |
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Term
| Communicating/gap junctions |
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Definition
• Undisrupted & very fast signal transmission across wide area of tissue
• Ex: gap junctions
• In heart cells: rhythmic contractions of large sections at once
• In esophagus: waves of muscle contraction
• In fish: rapid/complex tail flip
• Ex2: Plasmodesmata (plant equiv of gap junction)
• Allow free flow of nuclei bw cells
• Plant viruses exploit them to move rapidly bw sections of plant |
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Term
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Definition
(plant equiv of gap junction)
• Allow free flow of nuclei bw cells
• Plant viruses exploit them to move rapidly bw sections of plant |
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Term
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Definition
o Dense structure within nucleus
o Not surrounded by membrane
o Site of ribosomal RNA (rRNA) synthesis |
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Term
| Bound ribosomes on rough ER |
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Definition
o make proteins…
• bound for a membrane
• These proteins have hydrophobic transmembrane domains that are threaded through rough ER membrane as they’re synthesized
• Signals in protein sequence/strucutre make it stay put when it reaches destination
• to be secreted from cell
• These proteins have only one hydrophobic signal sequence: the signal peptide
• Inserted into ER lumen when synthesized
• Later released from cell
o Certain ribosomes must bind to ER to complete protein synthesis bc certain proteins (ex: lysosomal hydrolase) are too dangerous to synthesize in cytoplasm. |
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Term
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Definition
stacks closest to ER
o Sacs budding off ER fuse with cis Golgi
o Modified & repackaged for delivery elsewhere
o Ex: Glycosylation- adding sugar groups to proteins (after translation) to form glycoproteins (destined for cell membrane) |
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Term
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Definition
adding sugar groups to proteins (after translation) to form glycoproteins (destined for cell membrane)
Happens in cis golgi |
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Term
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Definition
stacks closest to plasma membrane
o Sorted in to vesicles based on proteins’ signals like…
• Protein primary sequence
• Structure
• Post-translational modifications
o Proteins then move the final destination
• Lysosome
• Plasme membrane
• These maintain their orientation they had when interested into the ER during synthesis as they pass through Golgi to vesicles to plasma membrane
• Exterior of cell
• These where to lumen of ER (“and remain in the lumen of the ER to the Golgi”)…?
• Then secretory vesicles fuse with plasma membrane to release proteins
• Golgi / ER (some are retained here) |
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Term
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Definition
- Digestion:
o break down proteins, carbs, nucleic acids
o help renew cell components by releasing molecular building blocks into cytosol for reuse
o In white blood cells: break down bacteria / damaged cells
o In injured/dying cell: lysosome membrane rupture to release hydrolytic enzymes & digest own contents
o In protists: provide food
- Contain hydrolytic enzymes
- pH 5 (slightly acidic) –
o lysosomal enzymes most active @ this pH
o rest of cell protected from digestion by lysosomal membrane |
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Term
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Definition
- Contain oxidative enzymes → speed reactions that produce/degrade hydrogen peroxide
- Break fats into smaller mcls for food
- In liver: detoxify harmful compounds (ex: alcohol)
- Forms (toxic) H2O2, but has enzymes that convert it to water
- Compartmentalized (bc the peroxides are reactive & could “covalently alter” other cell components)
- Glyoxysomes: specialized peroxizomes in fat-storing tissues of plant seeds
o Have enzymes that break fatty acids to sugar
o Energy/carbon source of (non-photosynth-capable) emerging seedling
- Don’t bud from ER like lysosomes
- Grow by encorporating proteins (from cytosol), lipids (made in ER or in peroxisome) |
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Term
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Definition
specialized peroxizomes in fat-storing tissues of plant seeds
o Have enzymes that break fatty acids to sugar
o Energy/carbon source of (non-photosynth-capable) emerging seedling |
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Term
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Definition
- Globular protein
o Monomer: G-actin
o Filament made of linked monomers: F-actin
o “Double-stranded helical protein filament”
o Note “actin filaments” = “microfilaments”
- Most abundant protein in cytoplasm
- Concentrated just inside plasma membrane
o Changing filament lengths → regulation of complex movements (phagocytosis, pseudopod extension)
• Growing ends can push/direct parts of cell membrane
• Shrinking ends pull other membrane region towards growing edge
• Pinching off of cell in cytokinesis (filaments degrade/shorten like drawstrings on bag)
• Assembly/dissembly mechanism
• As monomers added to filament, they trap ATP within structure
• Enzymes hydrolyze ATP → monomer falls off |
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Term
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Definition
- Motor protein
- Allow actin/other filaments to pull along one another
- arm-like extension attach to actin & pull “hand over hand”
o remember: ER of muscle cells (sarcoplasmic reticulum) depolarized by action potential from nerve cell → releases store of calcium ions → cytoplasm flooded with C++ → allows myosin/actin filaments to slide past each other → rapid muscle contraction |
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Term
| Microtubule-associated proteins (MAPs) |
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Definition
attach to tubulin & slide along microtubules
o Kinesins: Shuttle things towards outer perim of cell
o Dyenins: Pull things towards centrosome
• Also found in flagella/cilia |
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Term
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Definition
(protein; building block of microtubules)
(protein)
o organized in series of rings
o tubulin dimers fall off ends of microtubules as GTP (the way ATP does in actin) |
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Term
| Intermediate filaments (including examples...) |
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Definition
- Thicker than actin, not as thick as myosin → intermediate
- Thin fibers wound together into long coils
- Found
o Beneath nuclear membrane (form nuclear “lamina”) → give stability
o Throughout cytoplasm
- Examples
o Keratins: in skin, hair, nails
o Laminins: in nuclear lamina
o Vimenten… |
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Term
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Definition
o Microtubule triplets
o Anchor cilia/flagella into cell membrane
o Used by tubulin dimers as foundation for making new microtubules |
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Term
| Phases of cell cycle (during interphase) |
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Definition
o G1 phase: normal routine of getting food, using energy, growing
o Chemical change after G1 commits cell to S phase
• Mammal nerve/muscle cells never cross this threshold after adulhood
o G0 phase (resting state) some remain here forever or resume cycle after indef period
o S phase (Synthesis) cell’s DNA is replicated
o G2 phase: Growth before mitosis
• Some cells double in size here
• Others (ex: rapid proliferating embryonic cells) have short G2 → quickly dividing clump remains same size despite increasing # of cells in clump |
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Term
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Definition
o Cylindrical structures of 9 microtubule triplets
o Single pair copy themselves during S phase & move to opposite poles
o Form poles bw/ which microtubule spindles will form
o Form foundation for centrosomes
o Centrioles not necessary for microtubule formation at centrosomes (Plant cells have centrosomes with centrioles) |
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Term
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Definition
o microtubule organizing centers
o shoot linked tubulin proteins across cell as mitosis starts |
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Term
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Definition
• Chromatin becomes well-defined chromosomes seens as X-shaped sisters connected by centromere (DNA sequence)
• Mitotic spindle forms / elongates from centrosomes |
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Term
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Definition
• Nuclear membrane dissolves
• Spindle microtubules enter nucleus
• Kinetochore microtubules: those that attach to chromosomes (kinetochore = proteins found at chromosomal centromere)
• Non-kinetochore microtubules = “polar” microtubules |
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Term
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Definition
| • Kinetochore microtubules push from poles to align chroms in center along “metaphase plate” |
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Term
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Definition
• Kinetochore microtub.s shorten → Sister chromatids separate
• Polar microtub.s lengthen to push poles further apart |
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Term
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Definition
• Separated sister chromatids groups near centrosome regions
• Nuclear envelopes form around the 2 groups |
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Term
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Definition
• Ring of actin proteins in cell center contracts → cleavage furrow
• Membrane pinches off → two identical cells. |
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Term
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Definition
• Vesicles filled with cell wall materials merge along metaphase plate (guided by polar microtubules left over from mitosis)
• Merged vesicle structure = cell plate |
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Term
| 2 proteins regulating cell cycle |
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Definition
o Cyclin-dependent protein kinases (Cdk)
• Activate other proteins to start next step in cell cycle
o Cyclins (proteins that bind to Cdk’s to activate them)
(certain kinds of cyclin bind to certain Cdk @ diff points in cell cycle) |
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Term
| proto-oncogenes vs. oncogenes |
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Definition
- Proto-oncogenes: normal genes controlling cell growth/division
- Oncogenes: genes w/ mutations that no longer maintain control over certain aspect of growth/division |
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Term
| 4 genes associated with cell division |
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Definition
- growth factors
- growth-factor receptors
- intracellular signal-transducing proteins
- nuclear transcription factors |
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Term
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Definition
• proteins released by cells, circulate through blood/tissue
• act on cell surface receptors to initiate growth/division
• density-dependent inhibition: normal cells suppress growth when near other cells
• different cells release different growth factors
• skin cells: epidermal growth factor (EGF)
• nerve cells: nerve growth factor (NGF)
• cells lining blood vessel walls: platelet-derived growth factor (PDGF)
• things that could go wrong
• mutations in genes that code for g.f. production → overproduction → uncontrolled cell division
• genes make growth factors that bind more strongly to cell receptors → signal propagated for too long
• ^ growth factor production alone isn’t enough to induce cancerous transformation, but it does ^ proliferation, which ^ chances of spontaneous/induced cell mutations |
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Term
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Definition
• membrane-spanning proteins
• one area binds to growth factors
• transmit signal from growth factors to second messengers
• things that could go wrong
• mutation → receptors formwith ^ affinity for g.f.
• mutation → overproduction of g-f receptors
(both lead to persistent activation of second messengers) |
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Term
| intracellular signal-transducing proteins |
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Definition
• second messengers; carry signals (to turn on/off certaingenes) from receptors to nucleus
• to numeros/too active → increase transcription of genes for cell growth/division
• Ras protein: mutations implicated in over 30% of cancers
• Src (protein kinase): ^ phosphorylation rate of intracellular proteins → amplify growth signals from receptors |
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Term
| nuclear transcription factors |
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Definition
• proteins facilitating activation of partic genes
• abnormal activation →
• growth/division genes constantly activated
• ^ mRNA transcription
• ^ cyclin production (& other mitosis-inducing proteins: fos and myc) |
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Term
|
Definition
• “guardian of the genome” / “tumor suppressor gene”
• accumulates in response to DNA damage
• activates p21 → p21 inhibits Cdk → shuts down cell cycle mid-G1 phase
• half of human tumor cells lack functional p53 |
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Term
|
Definition
• named for eye cancer retinoblastoma (2 copies defective pRB present)
• regulator of transcription
• binds to/inhibits transcription factor E2F → cell can’t move into S phase
• mutated pRB → continual, rapid movement into S phase (found in lung/bladder/breast cancer cells) |
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Term
| electron microscope types |
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Definition
• Scanning electron microscope
• Detailed study of surface - topography
• Sample surface coated w/ thin layer of gold
Scanner beam excited electrons on surface → detected& translated into pattern
• Transmission electron microscope
• thin section stained with heavy metal atoms → ^ electron density of certain parts of cell
• Aim electron beam thru
• Electrons scattered more in denser regions → fewer transmitted
• Uses electromagnets instead of glass lens to bend electron path & put image on screen |
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Term
| electorn microscope (method, resolution, disadvantages) |
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Definition
- Focus beam of electrons thru/onto specimen
- Greater resolution bc: Resolution inversely related to wavelength of microscope’s radiation --> Electrons have shorter wavelength than visible light
- Resolution: Theoretically .002nm, practically 2nm
-Disadvantages
• Must kill cells
• Can introduce artifacts |
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Term
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Definition
o Visible light passed through specimen, then through glass lensis that refract light to magnify image
o Magnification: ratio of image size to real size
• Max: ~1000x
o Resolution: min distance two points can be separated and still distinguished
• Limited by shortest wavelengthused to illuminate specimen
• At beset: .2 micrometers (200nm) – size of small bacteria
• Subcellular structures are too small to be seen.
o Contrast
• Accentuates diff parts of sample
• Staining/labeling cell components helps |
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