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Flashcards by jithran.pohl, updated more than 1 year ago
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Created by jithran.pohl
over 8 years ago
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| Question | Answer |
| 3 Domains of Life | 1: Bacteria 2: Archaea 3: Eukarya |
| Light Microscopy | Visible light passed through specimen and then through glass lenses |
| Scanning Electron Microscope | For topography of cell. Surface of cell coated with gold, electron beam excites electrons on surface and these secondary electrons are detected |
| Transmission Electron Microscopy | To study internal structure of cells. Electron beam fired through thin section of cell, electromagnets bend electron paths to form image. |
| 3 Important Microscopy Parameters | Magnification - ratio of an object's image size to its real size Resolution - measure of clarity of image Contrast - difference in brightness between light and dark areas |
| Cell Size | Plant & animals cells - 10-100um Bacteria - 1-5um Larger cells have reduced surface to volume ratio |
| Endosymbiont Theory | Early ancestor of eukaryotic cells engulfed prokaryotic cell, stable relationship formed and the engulfed prokaryotes evolved into mitochondria |
| Difference Between Eukaryotic Cell and Prokaryotic Cell | Prokaryotic - has no nucleus, only nucleoid (DNA in region that is non membrane-enclosed) Eukaryotic - DNA found in membrane-bound nucleus |
| Composition of Typical Cell | Building blocks (amino acids, nucleobases, simple carbohydrates, lipids) \/ Macromolecules (proteins, DNA, RNA, complex carbohydrates, lipids) \/ Supramolecular assemblies (membranes, ribosomes, chromatin) |
| Levels of Carbohydrates | 1: Monosaccharides 2: Dissaccharides 3: Oligosaccharides 4: Polysaccharides |
| Monosaccharides | Hexose monosaccharides - building blocks of complex carbohydrates - glucose, fructose, galactose Pentose monosaccharides - usually part of larger molecules - deoxyribose, ribose |
| Dissaccharides | Two monosaccharides joined by a glycosidic linkage (covalent bond formed by a dehydration reaction) - glucose + fructose = sucrose - galactose + glucose = lactose - glucose + glucose = maltose |
| Oligosaccharides | 3 to 10 linked monosaccharides |
| Polysaccharides | Macromolecules. >10 linked monosaccharides. Some are storage material, hydrolysed as needed to provide sugar for cells |
| Functions of Carbohydrates | 1: Cell recognition 2: Energy - only starch and glycogen as alpha 1-4 bonds can be broken by enzyme 3: Structure - cellulose keeps plant cell walls rigid |
| Alpha Glucose | OH group on right hand side is DOWN |
| Beta Glucose | OH group on right is UP |
| Alpha Glucose Monomer Linkage | Form alpha 1-4 glycosidic bonds. All right hand OH groups are down |
| Beta Glucose Monomer Linkage | For beta 1-4 glycosidic bonds. OH groups alternate between up and down |
| Lipids | 1: Not polymers 2: Heterogenous 3: Hydrophobic |
| Functions of Lipids | 1: Structural - e.g. cholestrol and phospholipids in cell membrane 2: Regulatory - cholestrol -> testoterone -> estradiol (oestrogen) 3: Energy - more carbons in fat, thus more carbons oxidised -> more energy |
| 3 Major Forms of Bacteria | 1: Spherical 2: Rod-shaped 3: Spiral |
| Fimbriae | Hairlike appendages for attaching to surfaces (shorter and more numerous than pili, generally) |
| Nucleoid | Region containing DNA in prokaryote |
| Flagella | Protein (flagellin) for movement. Anticlockwise rotation - run Clockwise rotation - random movement (tumble) |
| Capsule (bacteria) | Usually a carbohydrate (if well organised - sticky. If not as well organised - slippery layer) Prevents dessication Increases resistance to phagocytosis Increases adhesion to solid surfaces |
| Gram-positive Bacteria | Has a thick peptidoglycan layer which forms cell wall, membrane is underneath Peptidoglycan traps crystal violet, which masks safranin dye |
| Gram-negative Bacteria | Cell wall made up of an outer membrane, followed by a thin peptidoglycan later. Inner membrane underneath. Crystal violet is easily rinsed away, revealing the red safranin dye |
| Endospore (prokaryotes) | 'Seed' like condensed nuclear material Surrounded by two coats of protein Produced in adverse conditions Allows DNA to resist damage by: -heat -chemicals -dessication |
| Viruses | Obligate parasites Infectious particle consisting of littler more than genes packaged in a protein coat DNA or RNA |
| Capsid (virus) | Protein shell. Subunits - capsomeres |
| Viral Envelope | Derived from membranes of the host cell |
| Bacteriophages | Viruses that infect bacteria |
| Lytic Cycle of Phage Infection | Replicative process that results in death of host cell. Virulant phages are phages that replicate only with lytic cycle 1: Attachment 2: Entry of phage DNA and degradation of host DNA 3: Synthesis of viral genomes and proteins 4: Self-assembly 5: Release |
| Lysogenic Cycle of Infection | Replication of phage genome without killing host cell. Phages capable of both cycles are temperate phages. Phage DNA mixes with host DNA, then phage DNA called prophage |
| Viroids | Chunks of single strand RNA |
| Prions | Altered form of protein Transmissable Spreads self in cell where mutation occurred Undegradable Attaches to protein and changes it to prion |
| Cell Functions | 1: Manufacture cellular materials 2: Obtain raw materials 3: Remove waste 4: Generate required energy 5: Control all of the above |
| Organelle Functions | 1: Provide special conditions for specific processes 2: Keep incompatible processes apart 3: Allow high concentrations of substances 4: Form concentration gradients 5: Package materials for transport or export |
| Membrane | Provide semi-permeable barrier Can be fluid or viscous If tails are unsaturated packing is prevented and the membrane is fluid If tails are saturated then tails pack together and membrane is viscous Cholestrol in tails - reduces fluidity at moderate temps, but increases fluidity at low temps |
| Functions of Proteins in Membrane | 1: Transport 2: Enzymatic activity 3: Signal transduction 4: Cell-cell recognition (some glycoproteins) 5: Intercellular joining 6: Attachment to cytoskeleton and ECM |
| Diffusion | Movement from high conc. to low conc. So it is passive transport. |
| Facilitated Diffusion | Movement of substances down their conc. gradients. Involves channel or carrier proteins Passive Channels may be regulated (gated) Voltage-gated channels allow ion fluxes Ligand-gated channels open in response to an extracellular signal |
| Active Transport | Movement of specific substances against their conc. gradients Involves pumps Requires energy input (from ATP) |
| Endomembrane System | Endoplasmic reticulum (ER), nuclear envelope, Golgi apparatus, lysosomes, vesicles and plasma membrane |
| Function of Endomembrane System | Synthesis of proteins, transport of proteins into membranes and organelles or out of cell, metabolism and movement of lipids. |
| Smooth ER | 1: Metabolism of carbohydrates 2: Lipid synthesis for membranes 3: Detoxification of drugs and poisons 4: Storage of calcium ions 5: Amount of sER can be increased or decreased to meet demand |
| Rough ER | 1: Rough appearance due to ribosomes 2: Involved in protein synthesis 3: Secreted and membrane-bound proteins enter the lumen (interior) of rER 4: Processed via the endomembrane systems Note: synthesis of cytoplasmic proteins occurs on free ribosomes |
| Vesicles | Sacs made of membrane |
| Golgi Complex | Series of associated sacs Associated vesicles Has polarity: cis face (vesicles from ER arrive here) and trans face (processed vesicles leave here) |
| Golgi Functions | 1: Glycosylation of proteins (sugars added to proteins) - important for surface proteins 2: Sorting proteins (adds molecular markers to direct proteins to correct vesicles) 3: Directing vesicle traffic (adds molecular tags (often short proteins) to direct vesicles to correct compartment) |
| Exocytosis | Transport of molecules out of cell or to cell surface Regulated exocytosis: releases hormones and neurotransmitters |
| Endocytosis | Bringing material into cell Receptor mediated endocytosis: collects and concentrates specific molecules |
| Phagocytosis | Uptake of "food" particles |
| Pinocytosis | Non-selective uptake of solutes |
| Lysosomes | Digest cellular materials Contain hydrolytic enzymes Degrade proteins, lipids, carbohydrates and nucleic acids Digest endocytosed material and unwanted intracellular structures Whole cell destruction: autophagy |
| Cytoskeleton | 3 major components: 1: Microtubules 2: Microfilaments 3: Intermediate filaments |
| Functions of cytoskeleton | Maintain cell shape and holds position of organelles |
| Microtubules | Composed of tubulin (protein) subunits May radiate out from an organising centre (centrosome) Resists compression Provides cell motility for whole cell and organelles |
| Cilia | For whole cell motility. Rowing-like motion -> motion perpendicular to direction |
| Organelle Motility | ATP-powered motor proteins can "walk" organelles along microtubules |
| Microfilaments | Double chain of actin subunits (two intertwined strands, like string) Resists tension Cortical network under plasma membrane helps maintain cell shape |
| Intermediate Filaments | One of several different proteins (e.g. keratins, vimentins, and lamins) Resists compression and tension Super coiled into cables Less dynamic than MT and MF Maintain cell shape Anchor organelles to stop them from moving Form nuclear lamina - holds nucleus in place |
| Cell Junctions | Three major types: 1: Tight junctions 2: Desmosomes 3: Gap junctions |
| Tight Junctions | Neighbouring cells tightly pressed together May form continous seal Prevent movement of fluid across cell layers |
| Desmosomes | Anchoring junction Attachments between sheets of cells e.g. muscle Act like rivets (a "torn" muscle is a torn desmosome) |
| Gap Junctions | A point of cytoplasmic contact between cells Ions and molecules may pass from cell to cell Allow rapid intercellular communication |
| Extracellular Matrix | Composed of: Material secreted by cells (fibroblasts) Mainly glycoproteins Most abundant glycoprotein is collagen |
| Collagen Fibers | Great tensile strength Approx. 50% of total body protein Embedded in proteoglycan matrix |
| Proteoglycan Matrix | Resists compression and retains shape Proteins with extensive sugar additions Traps water in ECM |
| Fibronectins | (Glycoprotein) Attaches cells to ECM |
| Integrins | (Membrane proteins) link ECM to cytoskeleton |
| Why Cells Need Energy | 1: To do work 2: Movement 3: Pumping substances across membranes 4: To maintain order |
| Cytosol (Energy Generation) | Glycolysis (breaking down sugar) 1: reduces glucose into smaller units 2: releases some energy (2 ATP/glucose) 3: transfers electrons to the electron carrier NAD |
| Mitochondrial Matrix (Energy Generation) | Citric acid cycle (Kreb's cycle) 1: Processes pyruvate 2: Releases energy (2 ATP/glucose) 3: Transfers electrons to NAD and FAD |
| Intermembrane Space (Energy Generation) | Oxidative phosphorylation 1: Electron transport and chemiosmosis 2: Releases energy (26-28 ATP/glucose) |
| Mitochondria Structure | Enclosed by two lipid bilayers Membranes contain special proteins Inner membrane is highly folded - cristae |
| Exergonic Processes | Release energy |
| Endergonic Processes | Driven by exergonic processes Absorb energy |
| ATP Hydrolysis | An exergonic reaction One phosphate group is broken off Product = ADP + energy Couples to endergonic reactions |
| Coupling Example | Phosphate from hydrolysed ATP couples to glutamic acid to form a phosphorylated intermediate (more reactive, so it allows reaction to proceed). Phosphorylated intermediate can bind with NH3 and phosphate group breaks off. Therefore products are glutamine, ADP and P |
| Fermentation | Catabolism without oxygen |
| Aerobic Respiration | Catabolism with oxygen |
| Cellular Respiration Steps | 1: Electrons stripped from glucose are transferred to NAD (an electron carrier) 2: A dehydrogenase enzyme removes 2 hydrogen atoms from glucose 3: Transfers 2 electrons and 1 H+ to NAD+ 4: Above forms NADH - used to power electron transport chain |
| ATP Synthase | Made from combining ADP and Phosphate An ion pump in reverse Uses H+ gradient to power ATP formation H+ ions flow into half channel H+ ions bind to rotor and change its shape Rotor spins After 1 turn of rotor, H+ ions exit to the mitochondrial matrix Rotor turns the rod which activates catalytic sites to produce ATP |
| Nucleus | 5-10um diameter Contains most of cells genes Function: serves as repository of genetic info. |
| Nuclear Envelope | Surrounds nucleus - composed of two membranes (both phospholipid bilayers) Inner surface lined by the nuclear lamina |
| Nuclear Lamina | Composed of intermediate filaments Helps maintain shape of nucleus Organises packing of DNA |
| Pores in Nuclear Envelope | Allow mRNA, rRNA, tRNA to leave nucleus Control signal movement into nucleus Energy and materials into nucleus |
| DNA | A nucleotide polymer Double helix combined with histone proteins to form chromatin fibres |
| Chromatin | Stores DNA |
| Formation of Chromatin | Helix interacts with histone to form a 10nm diameter fibre \/ Further interaction forms 30nm fibre \/ 30nm loops to form 300nm fibre |
| Euchromatin | Less dense chromatin Often genetically active |
| Heterochromatin | Densely packed Genetically inactive Dynamic relationship between eu/heterochromatin |
| Plasmodesmata | Channels between plant cells walls so molecules can move between cells |
| Vacuole Structure | Surrounded by single membrane (tonoplast) |
| Vacuole Functions | 1: Storage - Primary metabolites (growth associated) - Seconday metabolites (not growth associated) *molecules for defence (eg alkaloids) *molecules for signalling (pigments -> anthocyanins) 2: Degradation - breakdown of organelles and macromolecules (vacuoles contain hydrolytic enzymes) 3: Turgor - rigidity of plant cells - ^ concentrations of solutes in vacuoles have negative osmotic potential, so water uptake -plant cell wall enables water uptake without bursting -plant cells build up pressure - turgor pressure |
| Plastids | Chloroplasts, chromoplasts, leucoplasts, proplastids |
| Chloroplast Structure | Bound by two membranes Contains a third membrane system (thylakoid) Contains nucleic acid Outer membrane highly permeable Inner membrane more selective |
| Chloroplast Function | Capture light energy and convert it to chemical energy |
| Three Compartments in Chloroplasts | Stroma Thylakoid space Inter-membrane space |
| Thylakoid Lumen | Space between thylakoid membranes |
| Chromoplasts | Give colour to flowers and fruit Increased cartenoids (pigments) and decreased thylakoid membranes As fruit ripens chloroplasts are converted into chromoplasts |
| Leucoplasts | Storage of 1: Pigments 2: Proteins 3: Lipids 4: Starch |
| Two Stages of Photosynthesis | 1: Light reactions in chloroplasts 2: Calvin cycle in stroma, powered by light reactions |
| Chlorophyll | Pigments that absorb light Chlorophyll a and b Embedded in membrane of granum (stacks of thylakoid) |
| Photosystem | Molecule located in thylakoid membrane 1: Photon absorbed by chlorophyll 2: Transfer of energy to different chlorophyll molecules 3: Excitation of an electron from special chlorophyll 4: Electron transferred to primary electron acceptor |
| Light Reactions | Electrons move from Photosystem II to cytochrome complex (H+ ions transport into thylakoid space, conc. grad. generated), then to Photosystem I, then to NADP+ reductase to form NADPH. H+ ions from Photosystem II and cytochrome complex go to ATP synthase to form ATP |
| The Calvin Cycle | ATP and NADPH produced in light reactions used to fix CO2 and produce carbohydrate 3 Steps: 1: Carbon fixation: 3x5C + 3CO2 -> 6x3C 2: Reduction: 6ATP -> 6ADP 6NADPH -> 6NADP+ + 6Pi 3: Regeneration of CO2 acceptor: 3ATP -> 3ADP |
| Cell Wall Composition | Cellulose - glucose polymer, highly ordered, long ribbon-like structures Cellulose forms microfibrils |
| Microfibrils | Highly organised structures. Strong. Form major component of primary and secondary cell walls |
| Middle Lamella | Thin layer rich in pectin. Between primary cell walls of adjacent cells |
| Primary Cell Wall | Produced by young cells Relatively thin and flexible Cells are still able to grow 25-30% cellulose 15-25% hemicellulose 35% pectin 5-10% extensin |
| Primary Cell Wall Composition | 2 phases: 1: Crystalline microfibullar phase - cellulose 2: Non-crystalline matrix - pectic polysaccharides - hemicellulosic polysaccharides |
| Pectin | Branched, negatively charged polysaccharides. Bind water and have gel-like properties |
| Hemicellulose | Heterogenous group of polysaccharides |
| Extensins | Associated with cell wall extensibility Can be organised When disorganised (extensin cross-linking of pectin and cellulose) - dehydrates cell wall, reduces extensibility and increases strength |
| Synthesis of Primary Cell Wall | Coordinated synthesis and delivery of: 1: Cellulose microfibrils of plasma membrane 2: Polysaccharides in the Golgi complex and transported to the wall in vesicles 3: Cell wall proteins (extensins) from the rER |
| Primary Cell Wall Function | Structural support and influences cell morphology Protection Prevents excessive water uptake |
| Secondary Cell Wall | Not all plants have sec. wall Produced only after cell growth has stopped Thicker and stronger than primary cell wall Provides more structural support than primary cell wall Made up of multiple layers |
| Chemical Characteristics of Sec. Cell Wall | More cellulose Less pectin 15-35% lignin |
| Lignin | Complex phenolic polymer Provides strength, rigidity and hydrophobicity to sec. cell wall |
| Pit Fields | Areas of multiple plasmodesmata |
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