Microscopy and cell strucutures Flashcards
What is magnification? The equation for it? What is resolution?
Magnification is the ratio of image size to object size (size of image/size of object). Resolution is the ability to distinguish between two objects that are close together — the ability to provide detail in the image.
What is the magnification range of a light microscope? resolution range? Use? Advantages? Disadvantages?
Magnification: 1000-2000x, Resolution: 50-200 nm. Used for viewing cells and tissues. Advantages: Cheap, easy to use, allows viewing of living things. Disadvantages: Limited resolution.
What is the magnification range, resolution range, and use of a scanning electron microscope? What is the magnification, resolution, and use of a transmission electron microscope? A strength that electron microscopes have over light microscopes? Strengths scanning electron microscopes have over transmission electron microscopes? Weaknesses of electron microscopes? How can the last weakness be amended? The name for this?
Scanning Electron Microscope: Magnification 50,000-500,000x, Resolution 0.4-20 nm, used for viewing cell surfaces and providing depth in 3D images. Transmission Electron Microscope: Magnification 300,000-1,000,000x, Resolution 0.05-1.0 nm, used for detailing organelle ultrastructure. Strength of electron microscopes: Better resolution than light microscopes. Strengths of SEM over TEM: Gives 3D images, good for viewing surfaces. Weaknesses: Large and expensive, require trained operatives, sample must be dried (dead), images in black and white (false color added later).
What is staining? Why do we do it? Five examples of stains, what colour they are, and what specific component they are used to stain? What are the stains like in an electron microscope? Why?
Staining makes objects visible in light microscopes, increases contrast, and is often specific to certain tissues or organelles. Examples: Acetic orcein (chromosomes, dark red), Eosin (cytoplasm), Sudan Red (lipids), Iodine in potassium iodide (cellulose - yellow, starch - blue/black). In electron microscopes, stains are heavy metals that reflect or absorb electrons.
What are cells? What do all eukaryotic cells have? What do each of these do? How do you prepare cells/tissues for viewing under a microscope? What is important when viewing cells?
Cells are the basic unit of life. Eukaryotic cells have membrane-bound organelles, each with a function. Preparing cells involves creating a smear or thin section, staining, and covering with a cover slip. Important skills: Interpreting and drawing what is seen.
What is the ultrastructure of a cell? What does the cellulose cell wall do? Microtubules? Chloroplasts? Cilia? Smooth endoplasmic reticulum?
Ultrastructure refers to fine cell details seen with an electron microscope. Cellulose cell wall supports plant cells. Centrioles organize microtubules and spindle fibers. Chloroplasts perform photosynthesis. Cilia move fluids or the organism. Smooth ER synthesizes, stores, and transports lipids/carbohydrates.
What is the cytoskeleton? What does it do? What are flagella? What do they do?
The cytoskeleton is a network of microtubules and microfilaments providing cell structure and movement. Flagella are large cell extensions that move fluids or enable locomotion.
What does the golgi apparatus do? Lysosomes? Mitochondria? The nucleus? What does the nucleus contain? When doesn’t it?
Golgi apparatus modifies and repackages proteins. Lysosomes contain hydrolytic enzymes. Mitochondria are the site of aerobic respiration. The nucleus contains genetic material (chromatin/chromosomes) and controls cell activities.
What is the nuclear envelope? What does it do? What does the nucleolus do? The ribosomes? The Rough Endoplasmic Reticulum?
Nuclear envelope separates genetic material from cytoplasm and has nuclear pores for mRNA passage. Nucleolus assembles ribosomes. Ribosomes synthesize proteins. Rough ER has ribosomes and a large surface area for protein synthesis.
Why do organelles work together? What are the 7 steps of protein synthesis?
Organelles coordinate functions, particularly protein production. 1. mRNA leaves nucleus. 2. Ribosomes synthesize proteins. 3. Vesicles transport proteins to Golgi. 4. Cytoskeleton moves vesicles. 5. Golgi modifies and repackages proteins. 6. Vesicles move proteins to membrane. 7. Vesicles fuse with membrane for secretion.
What are the two types of cell? How are they the same? How do they differ?
Prokaryotic and eukaryotic cells. Both may have flagella and ribosomes. Differences: Eukaryotes are larger, have a nucleus, membrane-bound organelles, larger ribosomes, DNA with histones, and different flagella structure.
