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19 Cards in this Set
- Front
- Back
Define magnification |
Degree to which the size of the image is larger than the size of the object |
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Define resolution |
Ability to distinguish between two objects that are very close together |
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Microscope: resolutions & magnification |
Light: 200nm x1500 TEM: 0.1NM x500,000 SEM: 0.1nm x1,000,000 |
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Claculation magnification |
magnification = image / actual |
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Staining with light microscopes-why |
Coloured dye is taken up more by different parts of the object to show contrast |
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Staining with electron microscopes-why |
Sipped in heavy metal solution so metal ions scatter the electrons in the beam, showing contrast between different areas |
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Nucleus |
-surrounded by nuclear envelope with nuclear pores that allow exchange between nucleus and cytoplasm (i.e. mRNA) -contain chromatin, made up of proteins and DNA (controls cell activity) -nucleolus makes ribosomes |
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Chloroplasts |
-small, flattened structure in plant cells -double membrane -thylakoid membranes stack up to form grana where photosynthesis takes place -photosynthesis also takes place in stroma (thick fluid in chlorophylls) |
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Endoplasmic reticulum |
-system of membranes forming flat sacs called cisternae -RER has ribosomes attached where protein synthesis takes place -SER for lipid and protein (i.e. hormone) synthesis |
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Golgi apparatus |
-stack of fluid sacs called cisternae collects and processes molecules ready for transport -formed at one end from vesicles arriving from RER -broken down at other end to form golgi vesicles -these golgi vesicles either become lysosomes or exocytosis out of the cell |
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Mitochondria |
-two membranes -carry out later stages of aerobic respiration to make ATP |
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Lysosomes |
-spherical sac with single membrane -contain digestive enzymes for breakdown of unwanted structure within the cell (i.e. worn-out organelles or bacteria) |
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Centrioles |
-small hollow cylinders made of microtubules -used to grow the spindle fibres for nuclear division |
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Flagella |
-stick out from cell but still surrounded by plasma membrane -made of microtubules that contract to make the flagella move -act as outwards motors to propel the cell forward (i.e. sperm cells 'swimming') |
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Cilia |
-small, hair-like structureson the plasma membrane -made up of microtubules (in 9+2 arrangement) which allow cilia to move -used to move substances along the cell's surface |
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Cell wall |
-made of the carbohydrate cellulose -rigid structure that supports plant cell |
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Organelles that only appear in plant cells VS organelles that only appear in animal cells |
-animal only=centrioles -plant only=cell wall, chloroplasts and vacuole |
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Role of cytoskeleton |
-moves organelles within the cell -strengthen the cell/maintain its shape -transport materials within cells -can cause cells to move as a whole |
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Production and secretion of proteins process |
-instructions to make protein are in the DNA in the nucleus -nucleus copies DNA code on mRNA -mRNA leaves through nuclear pore and attaches to ribosome on RER -ribosome uses code on mRNA to assemble protein -pinched off in a vesicle, taken to golgi -golgi packages the content of the vesicle -exocytosis (vesicle fuses with membrane and releases its contents outside the cell) |