MMG 409 Exam 1 Flashcards
(52 cards)
Explain what a eukaryotic cell is and how eukaryotic cells likely evolved.
Eukaryotic cells have membrane-bound nuclei. Likely evolved from archaea that captured a bacterium, symbiosis.
Know which cellular features are specific to eukaryotes and universal to life on Earth
Eukaryotes: membrane-bound nucleus; membrane-bound organelles, lots of genes and non-coding regions.
All life has ribosomes, require an input of free energy, surrounded by a plasma membrane.
Distinguish between cell types based on their features and properties
Archaea: Extremophiles, no nucleus, single-celled, different cell wall from bacteria.
Bacteria: No nucleus, not usually extremophiles, different cell wall from archaea.
Eukaryotes: Membrane-bound nucleus, multicellular.
Define organelle is and the difference between cytosol and cytoplasm
Organelle: membrane bound, preform specific functions and provide the necessary environment for said function.
Cytosol: fluid in cytoplasm surrounding organelles.
Cytoplasm: Everything between nucleus and membrane.
Describe how protein structure and function are controlled by its environment and intermolecular interactions
Proteins must be folded to be functional. Controlled by environment and intermolecular interactions inducing conformational changes to the protein, directly effecting function.
Explain how enzymes function and how their activity is regulated in cells
Enzymes work by lowering the activation energy needed to preform a reaction. They bind to substrates at active sites and induce conformational changes.
Explain what a model organism is and be able to select appropriate models for specific research problems
Model organisms are eukaryotes best suited for studies. They are accessible in lab, reproduce rapidly, easy to visualize, amenable to genetic manipulation. Examples include Free living eukaryotes: yeast (s. cerevisiae), protist (C. spa.); plants (A. thaliana); Invertebrate animals (Nematode, C. elegans and Fruit fly, D. melanogaster); Vertebrate animals (Frog, x. laevis, and zebrafish, D. melanogaster); and vertebrate mammals (Mouse, m. musculus, and humans)
Explain the difference between cultured primary cells and cell lines and decide which would be most appropriate for a given research problem.
Cultured Primary Cells: Cells isolated from intact tissues, differentiated cells, stem cells, physiologically relevant but hard to access large numbers, limited lifespan.
Cell Lines: Cells replicate indeffidently, Immortalized, sometimes cancer cells. Easy to obtain and easier to manipulate, less physiologically relevant.
Explain the utilities and limitations of antibodies and genetic fusions in cell biological research
Immunoglobulins can bind with high affinity to specific molecules. Antibodies bind with high specificity. Useful in western blotting, fluorescence. Allow researchers to ID the protein/organelle they’re looking at. Limitations are that antibodies recognize epitopes, which can change/they only recognize one.
Compare and contrast the use of cell extracts and microscopy to study protein structure and function
In Vivo: Cells are left in tact. Identifies protein interactions, hard to determine if those interactions are direct/indirect and not always physiologically relevant.
In Vitro: Uses cell extracts from lysing population cells to study structure/function. Components separated by mass/density via centrifugations, molecules isolated by chromatography. Determines relative abundance and localization, ID proteins with post-translational modifications.
Know the difference and utility of light, fluorescence, and electron microscopy.
Light microscopy: Outlines cells, detects nucleus, shows live vs. dead cells
Fluorescence: Spatial org. of cell, organelles, and macromolecules. Need biomarkers and tags and probes. Shows specific molecules. Image live and dead cells.
Electron Microscopy: Spatial org. of cell, organelles, membranes. No biomarkers needed, gold particles show electron dense spots. Expensive, time consuming, only fixed/dead cellsz
Explain how antibodies are used to visualize biomarkers by microscopy
Primary antibodies bind molecules of interest, secondary antibodies bind the constant region of primary antibodies, polyclonal antibodies recognize multiple epitopes on an antigen. Anitgens can be made to emit a fluorescent signal when excited.
Explain how proteins are targeted to cellular compartments by signal sequences.
Sorting signals and receptors direct proteins.
Explain the role of mitochondrial physiology in ATP generation by oxidative phosphorylation.
Oxidative phosphorylation is driven by the ETC, which creates a proton gradient across the IMM, powering ATP synthase.
Differentiate between ATP generation by aerobic respiration and fermentation
Aerobic: Uses oxidative phosphorylation and the ETC to generate ATP, generates more ATP than fermentation which occurs when there is no oxygen (Anaerobic).
Explain how the proton motive force is generated and used to synthesize ATP.
As molecules in the OXPHOS system move through the ETC, carrier molecules are oxidized and release protons, generating the proton motive force. As protons try to cross the membrane (diffuse to an area of low concentration) they power ATP synthase, a trans member protein.
Explain why electron transport and oxidative phosphorylation occur in mitochondrial cristae.
Cristae enhance OXPHOS efficiency to max. ATP synthesis, where proton concentration is highest.
Explain the function and spatial organization of electron transport chain complexes and ATP synthase
Electron Transport Chain Complexes:
Complex 1: NADH hydrogenase, moves electrons from NADH to ubiquinone, largest complex, 1/2 of proton motive force.
Complex 3: Cytochrome C Reductase, accepts protons from Complex 1 and releases them to complex 4.
Complex 4: Cytochrome C Oxidase, pumps protons and reduces oxygen to make h2O.
Complex 2: Succinate dehydrogenase, oxidizes succinate and donates electrons.
ATP Synthase: Mechanical energy caused by concentration gradient causes rotations, which change active sites which synthesizes and releases ATP molecules.
Explain the role of mitochondrial lipids in aerobic respiration and cellular homeostasis.
Mitochondrial lipids help to stabilize the super complex composed of the respiratory chain complexes in the crista membrane.
Distinguish between mitochondrial and nuclear DNA and explain maternal inheritance of mtDNA
Mitochondrial DNA is stored within the mitochondria, inherited maternally, 16 kb, circular, little non-coding DNA. Maternally inherited because there is more cytoplasm in female gamete (egg) that (with lysosomes) degrades male mtDNA.
Explain where mitochondrial matrix, IMM, and OMM proteins originate, and which transporters are required for their localization to the mitochondria.
Most mitochondrial proteins are synthesized in the cytoplasm and encoded for in the nucleus. The mitochondria encodes for components of the ETC, and proteins localized in the IMM.
The transporters needed for nuclear proteins localization are: TOM Complex—OMM, translator, inserts proteins into OMM; SAM Complex—Sorting and assembly in OMM; OXA—cytochrome oxidase activity, hydrophobic, inserts nuclear encoded proteins into IMM; TIM—translator into matrix.
List the products of fermentation and explain why it occurs under anaerobic conditions
Occurs when little to no oxygen available to provide energy to the cell. Produces NAD+, lactate or lactic acid (obligate aerobes) or ethanol ( facilitative aerobes
Describe b-oxidation of fatty acids and metabolic coupling of mitochondria and peroxisomes.
Oxidation of fatty acids into acetyl-coA when sugars are limiting. Exclusive to peroxisomes and mitochondria in humans. Uses 1 ATP to generate 1 NADH, 1 FADH2, and 1 acetyl-coA.
Compare ATP generation by sugar metabolism and fatty acid metabolism.
Sugar metabolism: More ATP produced.
Fatty acid metabolism: Less ATP produces.
