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60 Cards in this Set
- Front
- Back
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What is a prokaryote? Give examples.
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-A single celled organism -Blue green algae or bacteria |
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What is a eukaryote? Give examples.
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-multicellular organism -animals, plants, fungi |
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Compare the nuclei and DNA of eukaryotic and prokaryotic cells.
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Eukaryotic -linear DNA (chromosomes) in a nucleus -nucleulous Prokaryotic -no nucleus/nucleuolus, just diffuse area of genetic material -free circular DNA in the cytoplasm |
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Compare the organelles of eukaryotic and prokaryotic cells.
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Eukaryotic -membrane bound organelles -chloroplasts in plants -ER and Golgi -80S ribosomes Prokaryotic -no membrane bound organelles, chloroplasts, ER or Golgi -70S ribosomes |
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Compare the pilli, cell walls and capsules of eukaryotic and prokaryotic cells.
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Eukaryotic -no capsule or pilli -cellulose cell wall in plants -chitin cell wall in fungi Prokaryotic -capsule present -pilli sometimes present -murein/peptidoglycan cell wall |
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Compare the sizes of eukaryotic and prokaryotic cells.
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Eukaryotic- 2-200 micrometers Prokaryotic- smaller than 2 micrometers |
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What features do plant cells have that animal cells do not?
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-chloroplasts -large central vacuole -cell wall with plasmodesmata |
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What are plasmodesmata?
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gaps in the cell walls of plants through which the cytoplasm connects the protoplast of one cell with the adjacent cell
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What is a protoplast?
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Part of the cytoplasm inside the cell wall
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Which organelles are found in animal cells but not plant cells?
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centrioles and flagella cilia are rare in plants, only in cycads |
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Discuss the nucleus, including -structure -functions -how DNA is stored in the nucleus |
Structure -largest organelle in the cell -contains a nucleolus -surrounded by a nuclear envelope (double membrane separated by fluid) -nuclear pores for nucleocytoplasmic transport Functions -indirectly control the cell by providing a template for RNA -nucleolus creates ribosomes DNA -nucleoplasm contains either chromatin or tightly coiled chromosomes (for cell division) |
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What are nuclear pores?
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protein complexes with a central channel
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Discuss mitochondria, including: -structure -functions -where they are most likely to be found in higher numbers |
Structure -ellipsoid shape with a double membrane -inner membrane invaginations called cristae increase surface (many chemical reactions occur on inner membrane) -contain 70S ribosomes and DNA Functions -site of aerobic respiration -create ATP (oxidative phosphorylation) Most numerous in active cells, i.e. muscle and nerve cells |
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What is the endomembrane system?
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-system of folding internal membranes -ER and Golgi body |
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What is the ER?
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-endoplasmic reticulum -system of flattened sacs lined by a thin membrane that is continuous with the nuclear envelope |
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What is the transport system of the cell?
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ER
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Discuss the RER.
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-embedded with ribosomes -makes proteins for secretion -transported to Golgi body for further processing -cells that produce lots of proteins (i.e. enzyme and hormone producing cells) have extensive RER |
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Define lumen.
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the inside space of a cell structure as well as the inside space of cylindrical structures such as the gut, arteries, ureters etc.
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Discuss the SER.
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-no ribosomes -continuous with RER-makes lipids (including phospholipids) and steroid hormones -lots of SER in liver cells, where lipids are metabolised -enzymes for detoxifying lipid soluble drugs and harmful products of metabolism |
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Discuss the Golgi body, including: -structure -functions |
Structure -membranous flattened sacs called cisternae -cisternae are not interconnected -cis Golgi is where vesicles join, trans is where they leave -modifies proteins and lipids for secretion and delivers them to the plasma membrane by wrapping them in membranes forming vesicles -vesicles fuse with plasma membrane releasing contents outside -manufactures lysosomes -synthesis of plant cell wall materials |
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Discuss lysosomes, including: -structure -functions |
Structure -membrane bound spherical sacs -contain hydrolytic enzymes -acidic pH Functions -digests cellular material -material can be from outside cell, i.e. bacteria -material can be from within cell, i.e. redundant or damaged organelles |
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Discuss ribosomes, including: -location -where they are made -structure -functions and differences in functions between ribosomes -difference between ribosomes in eukaryotic and prokaryotic |
Location -free in cytosol -embedded in RER -found in large numbers -made in the nucleolus Structure -small and large subunit initially separate but come together to form a complete ribosome by attaching to a mRNA when protein synthesis is about to begin Functions -manufacture proteins -ribosomes free in the cytosol manufacture proteins for the cell -ribosomes in the RER manufacture proteins for secretion -prokaryotic have 70S ribosomes (smaller) and eukaryotic have 80S ribosomes (larger) |
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Discuss chloroplasts, including: -structure -functions |
Structure -enclosed in chloroplast envelope, made up of two phosopholipid membranes -matrix contains stroma containing enzymes for light independent reactions of photosynthesis -thylakoids contain chlorophyll for light dependent reactions of photosynthesis -each thylakoid contains a lumen -a stack of thylakoids forms a granum, lamellae act as the skeleton of the chloroplasts and attach the grana Functions -absorb light energy -photosynthesis |
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Define a microtubule.
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a small tubule structure in the cytoplasm composed of tubulin, a globular protein arranged in spirals
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What is a spindle? What organises it?
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-a system of microtubules that separate the chromosomes during cell division -organised by the centrosome |
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What are centrioles, including: -structure -which cells they are found in -function |
-microtubules arranged in nine triplets forming a cylinder -occur in pairs near the nucleus -animal cells only -help separate the chromosomes during cell division by helping create the spindle |
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Discuss the cilia, including: -structure and where found -functions |
Structure -microscopic, hair like structures that extend from the plasma membrane -ring of nine pairs of microtubules surrounding two central microtubules -present in large numbers in prokaryotic and eukaryotic cells Functions -move liquids across the surface of the cell -propel cells |
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Discuss the cell wall (in plants), including: -structure -functions -protoplasts |
Structure -long cellulose molecules called microfibrils, twisted into rope like macrofibrils -sometimes lignin or suberin present Functions -prevent cell bursting and provide support -apoplast system to transport water Protoplasts -plasmodesmata connect protoplasts for transport |
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Discuss flagella, including: -structure -functions |
Structure -tail like structures composed of microtubules -usually found on their own but can occur in pairs -same structure as cilia but longer Functions -propel cells -allow single celled organisms to move around |
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Give the stages of the production and secretion of proteins in a cell.
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1. the nucleolus manufactures ribosomes for protein synthesis in RER 2. nucleus manufactures mRNA which is needed by ribosomes to make proteins 3. ribosomes in RER make proteins 4. RER processes the proteins which are sent in vesicles to the Golgi body 5. Golgi body further processes proteins and sends them in vesicles to plasma membrane 6. vesicles fuse with plasma membrane to secrete finished protein product |
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Define secretion.
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the production and release of a substance from a gland or cell
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What is the cytoskeleton made up of?
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Microtubules and microfilaments (both of which are made from proteins)
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What are microfilaments made up of?
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actin
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What are microtubules made up of?
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tubulin
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What are the three functions of the cytoskeleton? Give examples where possible.
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-cellular movement, e.g. cilia and flagella move the cell -intracellular movement, forms a 'track' which organelles can move along in the cell, i.e. movement of vesicles and chromosomes during cell division -strengthening and support, helps keep the cell in shape |
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What is cell fractionation? Why is it used?
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Breaking the plasma membrane so that its contents spill out into a mix called a homogenate to analyse organelles |
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What are the conditions needed for cell fractionation? Why are they so important?
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-pH buffer to keep pH constant -isotonic to prevent osmosis and organelle bursting -cold temperature to stop enzymes, i.e. hydrolytic enzymes will be released from lysosomes -to ensure organelles stay normal for accurate analysis |
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How are the organelles isolated in cell fractionation?
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-centrifuge is spun at different speeds to allow heaviest parts to form a pellet at the bottom
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How do light/optical microscopes work? What are they used for?
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-light passes through the sample -view larger cellular structures |
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How do transmission electron microscopes work? What are they used for?
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-electrons pass through sample -can see internal structure of organelles -study intracellular structure |
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How do scanning electron microscopes work? What are they used for?
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-electrons bounce off of the surface of the sample -study external features |
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How do laser scanning confocal microscopes work? What are they used for?
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-a laser bounces light off of the surface of a sample -uses fluorescent dyes -locating specific parts of cells |
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Give two advantages of laser scanning confocal microscopes.
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-laser can be focussed to specific depths, eliminating blur and producing clearer image -can take images at successive depths to construct a 3D image |
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Define resolution.
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the ability of a microscope to distinguish two adjacent points as being separate
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Define magnification.
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the ability of a microscope to enlarge an image
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Give the formula for magnification.
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Magnification = size of image / actual size of object
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Why do electron microscopes have better resolution than light microscopes?
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Light has a longer wavelength than electrons
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What is the difference between the stage and eyepiece graticule?
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The stage graticule gives the true length and its scale does not change with magnification. The eyepiece graticule stays constant and therefore changes with magnification, and has to be recalibrated.
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A cell measures 5 micrometers in diameter, which is equivalent to 10 divisions of the stage graticule. The magnification is changed. 3 divisions of the stage graticule is equal to 1 division of the eyepiece graticule. How much is one division of the eyepiece graticule. |
1.5 micrometers
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What is the cytoplasm?
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The space between the plasma membrane and nucleus.
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What is the cytosol?
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The fluid surrounding organelles.
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Discuss pili, including: -structure -which cells they are found in -functions -significance in evolution |
Structure -thin fibre proteins that protrude from the surface of a cell -only found in prokaryotic cells Functions -attach bacteria to specific surfaces or other cells Significance -can connect bacteria and pass genetic material (conjugation) helping genetic variability |
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What are capsules made out of? Which cells are they found in? What is their function? |
-polysaccharides -prokaryotic -protection from being engulfed by predator cells, mediate adherence to other surfaces |
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Discuss the different ways of preparing slides to view under a microscope.
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-cut a fresh specimen with a sharp blade -prepare a fixed sample -freeze a sample in liquid nitrogen or carbon dioxide and cut into small sections using a cryostat |
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What is the method for preparing a fixed sample in microscopy?
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-fix specimen using preservative such as formaldehyde -dehydrate in ethanol solutions -impregnate with paraffin wax or another resin -slice thinly using a microtome -remove paraffin wax -stain and mount using a resin and cover slip |
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Why is staining needed in microscopy? How is it effective?
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Most living tissue cells are transparent Some structures absorb some dyes, making them visible |
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Define differential staining.
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staining a sample with multiple dyes to show up tissues with it
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True or false Most colours in a light micrograph are true colours |
False However some are, for example chloroplasts are green |
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Discuss staining in electron microscopes.
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-electrons have no colour, so stains are black or shades of grey -heavy metal compounds used, i.e. phosphotungstic acid -colours on electron micrographs added after using imaging software |
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Name as many parts of a microscope as you can! (Aim for 10!)
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-arm -base -stage -objective lens -eyepiece -diaphragm -mirror or light -coarse adjustment knob -fine adjustment knob -stage clips |
