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F211 Module 1 Cells
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- 1When did Robert Hooke develop the compound microscope?The 1660's.
- 2What is a compound microscope?A microscope with several lenses.
- 3What did Hooke use the microscope to examine and what did he see?Slices of cork taken from beneath the bark of a tree, he saw lots of tiny chambers, like cells in a monastry.
- 4Who created The Cell Theory and when was it accepted?Schleiden and Schwann in the 1840's.
- 5Who extended The Cell Theory and what did it state?Virchow (1855) and Weismann (1880), it states that: all living things are made of cells, new cells are only formed by the division of pre-existing cells, cells contain information as instructions for growth which is passed on to new cells.
- 6What is magnification?The degree to which the size of an image is larger than the object itself.
- 7What is resolution?The degree to which it is possible to distinguish between two objects that are very close together.
- 8How do light microscopes work?Number of lenses, light passes from bulb under stage, through condenser lens, through specimen, focused through objective lens, through eyepiece lens, rotational 4 objective lenses.
- 9What is the maximum magnification of a light microscope?x1500
- 10What is the maximum resolution of a light microscope?200nm
- 11Why are samples stained?Chemicals bind to chemicals on or in the sample, allowing the specimen to be seen more clearly and highlight certain features.
- 12Why are samples sectioned?Specimens are embedded in wax, thin section are cut without distorting the structure, useful for soft tissue, e.g. brain.
- 13What is a micrometre used to measure?As a µm is one millionth of a metre, it is the standard unit of measurement for cells.
- 14How big is the average animal cell?20-40 µm
- 15What are nanometres used to measure?As a nm is one thousand millionth of a metre, they are used to measure organelles and molecules.
- 16What is the average width of a cell surface membrane?10nm
- 17What is the average diameter of a ribosome?20nm
- 18How big is the average virus?40-100nm long
- 19What is the resolution of the human eye?100 µm
- 20What is the resolution of an electron microscope?0.2nm
- 21What is a graticule?A transparent cover for the eyepiece of a microscope with a small ruler etched on it for measuring dimensions of a specimen.
- 22How is magnification worked out?Magnification = Image size/Actual size
- 23How do electron microscopes work?Generate beam of electrons, magnets focus beam onto specimen, black and white image projected.
- 24What is a TEM?Transmission electron microscope, beams pass through thin sample, the denser the sample the more difficult creating contrast, 2D image, magnification x500000.
- 25What is an SEM?Scanning electron microscope, electron beams directed at sample, bounced off, 3D view of surface, magnification of x100000.
- 26What are the advantages of electron microscopes?Resolution 0.2nm, detailed images of organelles, SEM produces 3D images to reveal contours and cellular and tissue arrangements.
- 27What are the limitations of electron microscopes?Electron beams are deflected by air so samples have to be in a vacuum, very expensive, requires skill and training to prepare and use.
- 28What are the 7 characteristics of living things?Movement, respiration, sensitivity, nutrition, excretion, reproduction and growth.
- 29What are organelles?The structures inside a cell, e.g. the nucleus, they make up the ultrastructure.
- 30What is the division of labour?When each organelle has a specific role within the cell.
- 31What is the cytoskeleton?A network of protein fibres used to keep the cell's shape stable by providing an internal framework, they also move organelles around inside the cell.
- 32What are microtubules?Cylinders, 25nm in diameter, made of protein called tubulin, they waft microorganisms through liquid or waft liquid past the cell, using ATP.
- 33What are flagella/undulipodia and cilia?Hair-like extensions that stick out from the cell. They are made of a cylinder that contains 9 microtubules in a circle, with 2 microtubules in a central bundle.
- 34Which are longer - undulipodia or cilia?Undulipodia.
- 35What are vesicles?Membrane-bound sacs found in cells used to carry substances around cells.
- 36What are vacuoles for in plant cells?They maintain cell stability, they are filled with water to make the cell turgid, this is especially important in non-woody plants.
- 37What are plant cell walls made of?Cellulose, a carbohydrate polymer made of glucose subunits, it is a sieve-like network that makes the wall strong, the whole cell is held firm by turgor pressure.
- 38What is the structure of the nucleus?Largest organelle, surrounded by a nuclear envelope, two membranes with fluid between, nuclear pores in envelope, nucleolus inside.
- 39What is the function of the nucleus?Houses genetic material, chromatin consists of DNA and protein, instructions for making proteins, makes RNA and ribosomes.
- 40What is the structure of endoplasmic reticulum?Flattened membrane-bound sacs called cisternae, rough ER is studded with ribosomes, smooth ER is not.
- 41What is the function of ER?RER transports proteins made on ribosomes, SER makes lipids.
- 42What is the structure of the golgi apparatus?Stack of membrane-bound flattened sacs.
- 43What is the function of the golgi apparatus?Receives proteins from ER and modifies them, may add sugar molecules, packages into vesicles to be transported.
- 44What is the structure of the mitochondria?Spherical/oval, two membranes separated by fluid-filled space, inner membrane folded to form cristae, central part is the matrix.
- 45What is the function of the mitochondria?Produces ATP during respiration (adenosine triphosphate).
- 46What is the structure of chloroplasts?Only in plant cells and some protoctists, two membranes separated by fluid-filled space, flattened membrane sacs called thylakkoid (granum/grana) chlorophyll molecules.
- 47What is the function of chloroplasts?The site of photosynthesis in plant cells, light energy used to drive reaction, carbohydrate molecules made from carbon dioxide and water.
- 48What is the structure of lysosomes?Spherical sacs surrounded by a single membrane.
- 49What is the function of lysosomes?Contain powerful digestive enzymes, break down materials, e.g. white blood cell/sperm cell.
- 50What is the structure of ribosomes?Tiny organelles, some free in cytoplasm, some bound to ER, consists of two subunits.
- 51What is the function of ribosomes?The site of protein synthesis, coded information (mRNA) from nucleus is used to assemble proteins from amino acids.
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- Descripción
- Living organisms Cell size and magnification Electron microscopes and cell details Cells and living processes Organelles - structure and function Organelles at work Biological membranes The fluid mosaic model Communication and cell signalling Crossing membranes - passive processes Crossing membranes - active processes Water is a special case New cells Two nuclei from one Cell cycles and life cycles Cell specialisation Organising the organism
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