Cell structure - Microscopy and organelles Flashcards
What is the formula for magnification?
Magnification = Size of image/ Size of actual object
What are the four types of Microscope?
- Light Microscope
- Laser scanning confocal microscopes
- Transmission electron microscopes
- Scanning electron microscopes
Describe what a light microscope does
Uses light to look at LIVING samples, but at low resolution and magnification
Describe what a laser scanning confocal microscope does
Uses light in lasers to receive a higher resolution that optical microscopy, but cannot achieve the magnification of electron microscopes. LSCMs allow for a depth selection and can construct 3D images on computers.
Describe what a TEM does
Passes electrons through a sample, getting a high resolution and magnification of a cell’s organelles, but can only provide a flat cross sectional image.
Describe what a SEM does
Bounce electrons off the surface for a 3D surface view of the cells, but has a lower resolution then TEMs.
Why can samples not be alive in electron microscopes?
Because it has to be done in a vacuum.
What are the three steps of preparing a sample for microscopy?
- Sectioning - Specimens are embedded in wax and a thin layer is cut
- Staining - Stains are added that bind to specific molecules, organelles or cell types. These could be coloured or florescent chemicals or metal particles.
- Measuring - An eyepiece graticule and a stage micrometer are used to calibrate light microscopes.
What organelles are found in most eukaryotic cells?
Cell surface Membrane (80S) Ribosomes Golgi apparatus Smooth Endoplasmic reticulum Round Endoplasmic reticulum Lysosomes Nucleus Cytoplasm Mitochondria Centrioles (sometimes Cilia and flagella)
What do plant cells have that animal cells do not?
Cell wall
Permanent vacuole
Chloroplasts
What organelles do prokaryotic cells have?
Plasmid - Small circular DNA Circular DNA - Main loop of DNA Capsule -Mucous layer Pilus - Membrane projections 70S Ribosomes Flagella - Locomotion Cell wall Cell membrane
What is the order of the process of protein synthesis?
- Nucleus codes for proteins via mRNA, which leaves the nucleus through pores
- Ribosomes - convert mRNA into proteins.
- Rough ER - Packages proteins and pinches them into vesicles for transport
- Golgi apparatus - Modifies and packages proteins and pinches them into vesicles for transport
- Cell membrane - Fuses with the vesicle, secreting proteins outside of the cell
What are the four main uses of the Cytoskeleton?
- Keeps cell shape stable
- Allows cell movement by extending cytoplasm
- Provides mechanical strength
- Moves organelles within cells
What is the Cell surface membrane and what is it’s function?
Phospholipid bilayer with membrane proteins; control movement of substances in and out of a cell
What is the nucleus and what is it’s function?
Surrounded by a nuclear membrane; contains DNA and a nucleolus where RNA and ribosomes are formed.
What is the function of the Smooth endoplasmic reticulum?
Synthesises, stores and transports lipids and carbohydrates
What is the function of the rough endoplasmic reticulum?
Coated in ribosomes; Provides large area for protein synthesis
What is the function of the cell wall?
Rigid wall of chitin or cellulose; provides structure and support
What is the function of the lysosomes?
Secrete harmful substances out of the cell
What is the function of the golgi apparatus?
Modifies, sorts and packages proteins
What is the function of the chloroplasts?
Contain DNA and chlorophyll to carry out photosynthesis
What is the function of the mitochondria?
Have folded inner cristae and their own DNA; Respire to produce ATP
What is the function of the ribosomes?
Protein and RNA complexes for protein synthesis
What is the function of the permanent vacuole?
Provides a store for cell sap and can provide support and structure depending on how full of water it is.
What is the function of the cytoplasm?
Where most of the chemical reactions in the cell take place.
How do you create a temporary wet mount?
- Place specimen in the middle of a glass microscope slide
- Use a pipette to drop 1-2 drops of water onto the specimen
- Cover with a glass slip cover so that it is as flat as possible.
