6034161
Description
Flashcards by Emma Allde, updated more than 1 year ago
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Created by Emma Allde
over 8 years ago
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| Question | Answer |
| Nothing less than _______ can be called living. | A cell |
| An organised assembly of cells and their extracellular products which carry out similar and coordinated activities within the body | Tissue |
| An assembly of tissues coordinated to perform specific functions within the body | Organ |
| An assembly of organs with specific, related activities, sharing regulatory influences | System |
| A diffuse functional network of cells situated in many parts of the body, sharing specific activities | System |
| The three main characteristics of a prokaryote (3) | 1. single-celled 2. circular, free-lying chromosome 3. no membrane-bound organelles |
| Eukaryotic DNA is | linear and serial |
| Main components of a virus | nucleic acid (DNA or RNA) and proteins |
| Viruses subvert _________ machinery to make more viruses | protein synthesis |
| Viruses are not cells or organisms in the strict sense because.... (2) | 1. They lack a plasma membrane 2. Only operate chemically within host cells |
| Extra-chromosomal DNA is found in | plasmids (pro and eu) and mitochondria (eu only) |
| Ribosome of prokaryotes | 70S |
| Ribosome of eukaryotes | 80s (70s in mitochondria) |
| Transmission Electron Microscope (TEM) | to look inside a cell (electrons go through the specimen) |
| Scanning Electron Microscope (SEM) | to see the cell surface(electrons scattered off cell surface by heavy metal coating e.g. Au) |
| Both types of EM involve elaborate preparation and can only evaluate ___ cells | dead |
| Life span of enterocytes | 5-6 days |
| Life span of erythrocytes | 115 days |
| Life span of neurons | lifespan |
| Limits of the maximum size of a cell | diffusion distance |
| Diffusion efficiency at a distance above _____ is reduced | 50μm |
| Surface Area (SA) : | Volume (V) |
| Sphere: SA = | 4Πr^2 |
| Sphere V= | 4/3Πr^3 |
| How to specialised cells overcome this problem of diffusion distance? (3) | Thin processes, "giant" multinucleated cells and gap junctions |
| Thin processes | Direct transport of substances around cell via cytoskeleton e.g. neurones and oligodendrocytes |
| Giant” multinucleate cells | Gene expression can occur in more than one place e.g. skeletal muscle cells |
| Types of protein filament that make up cytoskeleton | actin, IF and MT |
| Cytosol | 1. The aqueous environment within the plasma membrane 2. Together with organelles make up the cytoplasm |
| The only organelle visible by light microscopy | nucleus, as it is the largest organelle in the cell (diam. 3-10μm) |
| Chromatin | complex of DNA/histone and non-histone proteins |
| DNA winds around histones into _______ | nucleosomes |
| Length of naked DNA | 1.8m |
| Length of DNA packaged into nucleosomes | 95 mm |
| DNA length post mitosis | 120μm |
| Non-dividing chromatin is ____ | decondensed |
| Nucleolus (3) | 1. Where rDNA is transcribed and ribosome subunits assembled 2. Contains a nuclear envelope surrounded by two layers of membrane 3. Nuclear pores allows transport in and out |
| Smooth endoplasmic reticulum (SER) (2) | 1. Biosynthesis of lipids, steroids 2. Metabolise carbohydrates/steroids |
| Rough endoplasmic reticulum (RER) (3) | Coated with ribosomes 1. Ribosomes are involved in the translation, proteins for secretion or insertion into cell membrane 2. Proteins are folded 3. Vesicles are budded from RER and transported to the Golgi body for further transport and modification |
| Golgi body composition | 4-8 closely-stacked, membrane-bound channels (many stacks/mammalian cell) |
| Golgi | 1. Modifies proteins delivered from RER e.g. by adding sugar (carbohydrate) or lipid (fat) side-chains 2. Synthesise/package materials to be secreted 3. Direct new proteins to their correct compartments 4. Transport lipids around cell 5. Create lysosomes 6. Vesicles bud off bud off from the Golgi |
| Golgi vesicles | fuse with the inner surface of the plasma membrane and release their contents (exocytosis) e.g. hormones and neurotransmitters |
| SER concentrations are high in the | liver and kidneys as well as endocrine glands that produce hormones |
| RER concentrations are high in | nuclear membrane; many found in pancreatic secretory cells because they require a lot of enzymes |
| Mitochondria composition (3) | 1. Two layers of membrane, 0.5-2μm long 2. Contain mDNA that encode some of their proteins 3. Inner membrane in folds - cristae – increase surface area |
| Mitochondria | 1. Sugars oxidised to generate ATP (Krebs cycle enzymes located in different parts of the membrane) |
| Number of _______ per cell reflects metabolic activity | mitochondria |
| Functional vesicles | lysosomes, peroxisomes |
| Lysosomes composition (2) | 1. Electron-dense spheres with diameter 80-800nm 2. Lysosomal proteins are tagged with mannose -6- phosphate |
| Lysosomes | 1. Involved in protein, RNA and DNA degradation/recycle/excrete 2. Contain powerful enzymes that require low pH |
| Peroxisomes composition | Large (0.5-1.5μm), not very electron-dense |
| Peroxisomes | 1. Involved in detoxification and phospholipid synthesis 2. Enzymes which generate (and degrade) H2O2 |
| Zellweger syndrome | Inherited absence of peroxisomes |
| Myoclonic Epilepsy with Ragged Red Fibers (MERRF syndrome) (2) | 1. Mutation of mitochondrial gene for tRNA-lys 2. Disrupts synthesis of oxidative phosphorylation enzymes |
| Hutchinson-Gilford Progeria (3) | 1. Mutation in lamin A part of the nuclear envelope 2. Distorted shape of nucleus (blebbed) 3. Production of unique progerin protein |
| Tay Sachs Disease | 1. Mutation of the lysosomal hexosaminidase-A enzyme 2. Causes accumulation of ganglioside that is neurotoxic |
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