Block 1 Heywood 1-4 – Flashcards
Unlock all answers in this set
Unlock answersquestion
| (4) LM methods |
answer
| bright-field, phase-contrast, Nomarski differential-interference contrast, dark-field microscopy |
question
| (5) TEM specimens must be stained using... |
answer
| heavy metal atoms, such as osmium, lead, uranium, tungsten and gold |
question
| osmium tetroxide |
answer
| binds to double bonds between carbon atoms in lipids |
question
| uranyl acetate |
answer
| binds to nucleic acids, so stains nucleoli, ribosomes, and chromatin |
question
| %protein vs. lipid in... myelin? |
answer
| 80% lipid, 20% protein by weight |
question
| %protein vs. lipid in... inner mitochondrial membrane? |
answer
| 75% protein, 25% lipid by weight |
question
| (2) Peripheral proteins normally regulate... |
answer
| ion channels and cell signaling |
question
| (3) Integral proteins normally function as... |
answer
| membrane receptors and transport proteins, and to attach cells to each other/extracellular matrix |
question
| Rhodopsin |
answer
| a protein with several transmembrane proteins arranged to form a pore across the cell membrane |
question
| (2) oligosaccharides are important in... |
answer
| cell-cell recognition, e.g. immunology and embryonic development |
question
| Epidermolysis bullosa simplex |
answer
| mutation in keratin genes, resulting in epidermal cells easily fracturing and causing blistering. (damages desmosomes) |
question
| Focal adhesions and hemidesmosomes link to the extracellular matrix via... |
answer
| integrins |
question
| Focal adhesions / hemidesmosomes anchor to... |
answer
| actin / intermediate filaments |
question
| (2) What closes / opens connexons? |
answer
| Closes - high pH or low Ca2+, opens - low pH or high Ca2+ |
question
| (3) SER is plentiful in... |
answer
| 1) cells producing cholesterol -> steroid hormones, 2) cells that detoxify drugs, and 3) in muscle cells, where calcium is sequestered in the sarcoplasmic reticulum causing relaxation of myofibrils and vice versa |
question
| (3) Free polyribosomes translate proteins of the... |
answer
| cytosol, nuclei, and mitochondria |
question
| (5) RER ribosomes translate proteins of... |
answer
| plasma membrane, Golgi, lysosomes, ER, cell exterior |
question
| What can be made by both RER and free ribosomes? |
answer
| peroxisomes |
question
| (3) Posttranslational entry |
answer
| entry of proteins translated on cytosolic ribosomes into mitochondria, perosixomes and nuclei |
question
| ER cisterna |
answer
| protein folding site; oligosaccharides added |
question
| Stop-transfer signal |
answer
| alpha helix which ensures that transmembrane segments of translated proteins in ER are correctly positioned within the ER membrane |
question
| COP-II coated vesicles |
answer
| hold proteins and lipids; exit the ER and enter the cis-Golgi |
question
| COP-I coated vesicles |
answer
| transport material from cis to trans |
question
| SNARE proteins |
answer
| catalyze the fusion of vesicles to the appropriate membranes |
question
| t-SNARES |
answer
| attached to target membrane |
question
| v-SNAREs |
answer
| attached to vesicles |
question
| Rab proteins |
answer
| GTPases that aid SNAREs |
question
| ER resident proteins |
answer
| function in the ER cisterna, but often are packaged in vesicles because they are soluble. A rentention signal allows them to attach to receptors in the Golgi cisterna to be returned via retrograde COP-I vesicles, which also return membrane to the ER. |
question
| What directs proteins to their appropriate vesicles? |
answer
| Sorting signals |
question
| (3) exocytosis pathways |
answer
| signal-mediated diversion to secretory vesicles, signal-mediated diversion to lysosomes, secretion via the constitutive secretory pathway |
question
| Regulated secretory pathway |
answer
| Golgi products (such as insulin in the beta cells of the pancreas) are stored in secretory vesicles which are released rapidly in response to hormonal or neural stimuli |
question
| constitutive secretory pathway |
answer
| Golgi products are immediately discharged at the cell surface for production of the extra cellular matrix |
question
| extracellular matrix |
answer
| a gel of glycosaminoglycans and proteoglycans in which fibrous proteins are embedded |
question
| (4) embedded fibrous proteins in the ECM |
answer
| fibronectin, laminin, collagen, elastin |
question
| fibronectin |
answer
| attaches fibroblasts to the ECM |
question
| laminin |
answer
| to attach epithelium to basal lamina |
question
| Leishmania |
answer
| a parasite which prevents vacuoles from fusing with lysosomes; uses phagocytosis to enter cells. |
question
| (2) what causes the clathrin pit to pinch off as a coated vesicle in receptor-mediated endocytosis? |
answer
| Dynamin and GTP |
question
| End product of receptor-mediated endocytosis |
answer
| endosome |
question
| lysosome |
answer
| contains proteases, lipases, phosphatases with optimal activity at ph=5, maintained by ATP-driven proton pumps |
question
| what protects lysosomal enzymes against autolytic protease digestion? |
answer
| glycosylation |
question
| How do lysosomes digest things? |
answer
| Molecules via receptor-mediated endocytosis, cells and cell fragments via phagocytosis, old cell components from their own cells via autophagy. Lysosomal enzymes break down their substrates into amino acids, sugars and nucleotides which then enter the cytosol via transport proteins in the lysosomal membrane. |
question
| What is a lysosome's defining enzyme? |
answer
| Phosphatase |
question
| What happens to lysosomal enzymes when golgi vesicles containing them fuse with the plasma membrane |
answer
question
| What happens when golgi vesicles containing lysosomal enzymes fuse with the plasma membrane and release their contents? |
answer
| Lysosomal enzymes attach to the M6P receptor and re-enter the cell when it is endocytosed. |
question
| I-cell disease |
answer
| Deficiency of enzyme which phosphorylates mannose = no targeting of enzymes to lysosomes. Substrates (mucolipids and mucopolysaccharides) build up in cytosol causing coarse facial features, mental retardation and skeletal abnormalities. |
question
| Tay-Sachs disease |
answer
| absence of lysosomal enzyme Hexoaminidase A results in build-up of gangliosides in the brain -> mental retardation, blindness, and death by early childhood in the infantile version of the disease |
question
| (4) Peroxisomes |
answer
| Single membrane surrounding a granular matrix. Creates hydrogen peroxide, breaks down hydrogen peroxide, inactivates toxic molecules by oxidizing them using hydrogen peroxide, break down fatty acids. Abundant in liver. |
question
| Zellweger's Syndrome |
answer
| Build-up of toxins in cytosol results from poor coduction of enzymes to peroxisomes. Hepatomegaly and high levels of iron and copper in the blood stream result, often fatal in infancy. |
question
| Neonatal adrenoleukodystrophy |
answer
| Very long chain fatty acids cannot be broken down in peroxisomes, resulting in a build-up in the brain. This destroys myelin sheaths and causes a deficiency of adrenal steroid hormones in the adrenal glands. = Lack of the degradative proteins needed for beta-oxidation to occur. |
question
| catalase |
answer
| enzyme by which peroxisomes break down hydrogen peroxide |
question
| cristae |
answer
| invaginations of the IMM |
question
| IMM contains... |
answer
| ATP synthases which extend into the matrix |
question
| (5) mitochondrial matrix contains... |
answer
| enzymes for Krebs cycle and for oxidation of fatty acids and pyruvate. Also ribosomes, tRNAs and mitochondrial DNA. |
question
| mitochondrial site where protons accumulate |
answer
| intermembrane space |
question
| Glycolysis occurs in the |
answer
| cytosol |
question
| Glycolysis yields |
answer
| glucose -> 2 pyruvate + 2ATP + 2NADH |
question
| 2 pyruvate -> 2 acetyl-CoA occurs where and yields what |
answer
| mitochondrial matrix, 2CO2 and 2 NADH |
question
| cytochrome c oxidase |
answer
| site in electron-transport respiratory chain at which O2 and water are formed |
question
| oxidative phosphorylation |
answer
| phosphorylation of ADP to ATP driven by the flow of protons across the IMM |
question
| TCA cycle yields |
answer
| 4CO2, 2GTP, 6 NADH (and 2FADH2 after 2 turns) |
question
| total mitochondrial yield |
answer
| 30-38 molecules of energy (ATP and GTP) per glucose molecule |
question
| hsp70 chaperone protein |
answer
| prevents mitochondrial proteins (which are coded by nuclear genes and translated on cytosolic polyribosomes) from folding, and is necessary for the import of these proteins into the mitochondria. |
question
| (4) Import of mitochondrial proteins requires |
answer
| signal sequence, hsp70 chaperone protein, proton gradient across IMM and ATP. |
question
| Mitochondrial DNA |
answer
| mtDNA, maternal inheritance in humans, lacks histones. circular double helix in humans. |
question
| cycloheximide |
answer
| eukaryotic protein synthesis is sensitive to this, but prokaryotic and mitochondrial is not. |
question
| chloramphenicol |
answer
| eukaryotic protein synthesis is insensitive to this, but mitochondrial and prokaryotic is sensitive. |
question
| mitochondrial ribosomes |
answer
| are smaller than cytosolic ribosomes, affecting antibiotic efficacy. |
question
| Heteroplasmy |
answer
| caused by mutations in mtDNA - some fine, some damaged. cell damage or death results if too many are damaged. |
question
| Leber's Hereditary Optic Neuropathy |
answer
| CGU->CAU = arginine->histidine in NADH dehydrogenase, inactivating the enzyme. ATP formation is blocked in many mitochondria of optic nerve cells, causing them to die -> blindness (maternally inherited) |
question
| microtubules in the cilia are stable or dynamic? |
answer
| stable (long-lived) |
question
| alpha is +/-? beta is +/-? |
answer
| alpha = -, beta = + |
question
| vinblastine and vincristine |
answer
| drugs which depolymerize microtubules |
question
| What is F-actin formed from? |
answer
| G-actin monomers |
question
| ARP complex |
answer
| site of de novo synthesis of F-actin. contains two Actin Related Proteins. Pre-existing F-actin is polymerized during normal movements of cells like fibroblasts. |
question
| Listeria |
answer
| a bacteria which polymerizes actin to get to a host's cytoplasm and cause food poisoning. |
question
| 2 structures with actin inside |
answer
| stereocilia, microvilli |
question
| (3) actin-binding proteins |
answer
| fimbrin (bundles them together), filamin (cross-links them), gelsolin (fragments them) |
question
| myosin moves toward which end of actin microfilaments? |
answer
| + end |
question
| Nuclear lamins |
answer
| intermediate filaments which occur in the nucleus. lamins A, B, and C are phosphorylated in late G2, causing breakdown of the nuclear lamina. |
question
| motor molecules associated with microtubules |
answer
| kinesin, dynein |
question
| another word for centriole |
answer
| basal body |
question
| what kind of enzyme is dynein? |
answer
| ATPase |
question
| what connects subdoublets in cilia? |
answer
| nexin |
question
| bacterial flagella |
answer
| a group of protein filaments the end in a circular motor, the rotor. an intermembrane proton pump fuels the rotor, pushing protons past the filaments to rotate them. |
question
| (3) each chromosome consists of specialized DNA for |
answer
| the centromere, the telomeres, and the replication origins of DNA. |
question
| nuclear lamina |
answer
| fibrous layer (intermediate filaments) inside the inner nuclear membrane. disperses when lamins are phosphorylated in late G2 and early prophase; reappears in telophase |
question
| nuclear pores are made up of proteins called |
answer
| nucleoporins |
question
| nuclear transport protein complex |
answer
| binds to proteins over 40,000 daltons that need to cross into the nucleus and transports them. a similar process drives export of ribosomal subunits, tRNA and mRNA back into the cytoplasm. |
question
| nucleopores have a high/low rate of bidirectional transport |
answer
| high |
question
| nucleolar organizing regions |
answer
| 10 groups of rRNA genes which are are located on both homologs of 5 chromosomes (200 total) |
question
| which rna polymerase makes pre-rRNA subunits? |
answer
| rna polymerase 1 |
question
| ribosomes are formed in the nucleolus or the cytosol? |
answer
| cytosol - the subunits are made in the nucleolus, but they don't come together until the start of translation in the cytosol |
question
| phases of the cell cycle |
answer
| G1, S, G2, M |
question
| G0 |
answer
| lengthy G1-type phase for cells that are not actively dividing |
question
| In late G2, a __________________ causes widespread phosphorylation |
answer
| cyclin-dependent kinase |
question
| phosphorylation of _________ causes chromosome condensation and this does what? |
answer
| histones; stops transcription |
question
| what drives polymerization of MTs to form the mitotic spindle? |
answer
| phosphorylation |
question
| 3 types of spindle MTs |
answer
| aster MTs, overlapping MTs, kinetochore MTs |
question
| when is a chromatid a chromosome? |
answer
| when the chromatids separate at the metaphase/anaphase transition |
question
| anaphase a |
answer
| kinetochore MTs depolymerize, pulling the chromatids apart |
question
| anaphase b |
answer
| sliding occurs between overlapping MTs, pushing apart the poles. astral MTs contribute at the cell periphery (the minus end) |
question
| during telophase, the nucleolus is formed from |
answer
| 10 small nucleoli at the sites of rRNA genes |
question
| what forms a contractile ring during cytokinesis? |
answer
| actin and myosin II |
question
| necrosis features |
answer
| an inflammatory response |
question
| (2) apoptosis features |
answer
| endonucleases and macrophages |
question
| (4) similarities between prokaryotes and eukaryotes |
answer
| membrane structure, DNA structure, the genetic code and some metabolic pathways |
question
| (5) differences between prokaryotes and eukaryotes |
answer
| p's are smaller and unicellular. they have no organelles or cytoskeletal components. p's have a nucleiod. |
question
| nucleoid |
answer
| region of DNA in prokaryotes that has no nuclear envelope or organization |
question
| (6) how are specimens prepared for TEM and LM? |
answer
| fixed in buffered, isotonic fixative like glutaraldehyde. washed in buffer, dehydrated in ethanol, embedded in plastic |
question
| thymidine stain |
answer
| used for nuclear DNA only |
question
| sodium and glucose symports occur where? |
answer
| only the apical surface of intestinal endothelium. glucose passes by passive transport at the basolateral surfaces. |
question
| catenin |
answer
| links cadherins to actin filaments |
question
| what removes signal sequences? |
answer
| signal peptidases |
question
| glycocalyx |
answer
| oligosaccharides extending from proteins in the cell membrane, creating a sugary coat |
question
| KDEL |
answer
| lysine-aspartate-glutamate-leucine ER retention signal for ER resident proteins at their carboxyl ends |
question
| pinocytosis |
answer
| "little drinking" = non-selective uptake of extracellular material |
question
| transcytosis example |
answer
| mother's stuff going to her baby (early endosomes are sorting stations) |
question
| example of endocytosed stuff staying in the cytosol |
answer
| yolk nutrients (early endosomes are sorting stations) |
question
| mtDNA lacks ___________ and is replicated throughout ___________. the universal code varies how? |
answer
| histones, interphase. UGA -> tryptophan |
question
| TOM and TIM complexes |
answer
| protein Translocator on Outer/Inner Mitochondrial membrane |
question
| intermediate filament structure |
answer
| 2 monomers wrap -> dimer, 2 dimers of opposite polarity w/ noncovalent bonds stagger -> tetramer, 8 tetramers! w/ noncovalent bonds |
question
| cytoplasmic intermediate filaments |
answer
| keratin in epithelium, neurofilaments in nerve cells, vimentin in CT, muscle and neuroglia |
question
| Z lines have which types of cytoskeletal help? |
answer
| intermediate filaments |
question
| progeria |
answer
| premature aging in children due to mutations of proteins of the nuclear lamins |
question
| what energy form is required for microtubule growth? |
answer
| GTP |
question
| Taxol |
answer
| excessive assembly of tubulin = anti-cancer drug |
question
| colchicine |
answer
| excessive disassembly drug with bad side effects, so not used for cancer like vincristine and vinblastine |
question
| myosin-II |
answer
| can slide actin filaments relative to each other, unlike myosin-I. (is important in cytokinesis and muscle contractions. myosin-I is in all cells) |
question
| retinitis pigmentosa |
answer
| kinesin defect in retinal cells |
question
| herpes uses _________ to move along microtubules |
answer
| kinesin |
question
| lidocaine |
answer
| inhibits kinesin movement in axons and therefore anterograde transport of neurotransmitters |
question
| myosin-VI |
answer
| mutations cause deafness in mammals |
question
| primary cilia |
answer
| sense and signal - do not move. defects -> polycystic kidney disease -> overproduction of kidney cells. |
question
| where is the Na-K pump located in gut epithelial cells? |
answer
| basal surface |
question
| immunocytochemistry |
answer
| using fluorescently-labelled antibodies to identify specific molecules |
question
| peripheral heterochromatin |
answer
| darker than euchromatin in rest of interphase nucleus |
