F211 Module 1 Cells

Questão	Responda
When did Robert Hooke develop the compound microscope?	The 1660's.
What is a compound microscope?	A microscope with several lenses.
What 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.
Who created The Cell Theory and when was it accepted?	Schleiden and Schwann in the 1840's.
Who 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.
What is magnification?	The degree to which the size of an image is larger than the object itself.
What is resolution?	The degree to which it is possible to distinguish between two objects that are very close together.
How 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.
What is the maximum magnification of a light microscope?	x1500
What is the maximum resolution of a light microscope?	200nm
Why are samples stained?	Chemicals bind to chemicals on or in the sample, allowing the specimen to be seen more clearly and highlight certain features.
Why are samples sectioned?	Specimens are embedded in wax, thin section are cut without distorting the structure, useful for soft tissue, e.g. brain.
What is a micrometre used to measure?	As a µm is one millionth of a metre, it is the standard unit of measurement for cells.
How big is the average animal cell?	20-40 µm
What are nanometres used to measure?	As a nm is one thousand millionth of a metre, they are used to measure organelles and molecules.
What is the average width of a cell surface membrane?	10nm
What is the average diameter of a ribosome?	20nm
How big is the average virus?	40-100nm long
What is the resolution of the human eye?	100 µm
What is the resolution of an electron microscope?	0.2nm
What 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.
How is magnification worked out?	Magnification = Image size/Actual size
How do electron microscopes work?	Generate beam of electrons, magnets focus beam onto specimen, black and white image projected.
What is a TEM?	Transmission electron microscope, beams pass through thin sample, the denser the sample the more difficult creating contrast, 2D image, magnification x500000.
What is an SEM?	Scanning electron microscope, electron beams directed at sample, bounced off, 3D view of surface, magnification of x100000.
What 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.
What 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.
What are the 7 characteristics of living things?	Movement, respiration, sensitivity, nutrition, excretion, reproduction and growth.
What are organelles?	The structures inside a cell, e.g. the nucleus, they make up the ultrastructure.
What is the division of labour?	When each organelle has a specific role within the cell.
What 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.
What are microtubules?	Cylinders, 25nm in diameter, made of protein called tubulin, they waft microorganisms through liquid or waft liquid past the cell, using ATP.
What 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.
Which are longer - undulipodia or cilia?	Undulipodia.
What are vesicles?	Membrane-bound sacs found in cells used to carry substances around cells.
What 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.
What 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.
What is the structure of the nucleus?	Largest organelle, surrounded by a nuclear envelope, two membranes with fluid between, nuclear pores in envelope, nucleolus inside.
What is the function of the nucleus?	Houses genetic material, chromatin consists of DNA and protein, instructions for making proteins, makes RNA and ribosomes.
What is the structure of endoplasmic reticulum?	Flattened membrane-bound sacs called cisternae, rough ER is studded with ribosomes, smooth ER is not.
What is the function of ER?	RER transports proteins made on ribosomes, SER makes lipids.
What is the structure of the golgi apparatus?	Stack of membrane-bound flattened sacs.
What is the function of the golgi apparatus?	Receives proteins from ER and modifies them, may add sugar molecules, packages into vesicles to be transported.
What 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.
What is the function of the mitochondria?	Produces ATP during respiration (adenosine triphosphate).
What 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.
What 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.
What is the structure of lysosomes?	Spherical sacs surrounded by a single membrane.
What is the function of lysosomes?	Contain powerful digestive enzymes, break down materials, e.g. white blood cell/sperm cell.
What is the structure of ribosomes?	Tiny organelles, some free in cytoplasm, some bound to ER, consists of two subunits.
What is the function of ribosomes?	The site of protein synthesis, coded information (mRNA) from nucleus is used to assemble proteins from amino acids.

Próximo

Descrição

Resumo de Recurso

Semelhante

	Criado por lottieweaver quase 11 anos atrás