Light microscopes are used to observe whole cells and tissues
Resolution is the ability to distinguish between very small separate structures very close together in great detail
TEMs have a resolution of 0.5nm
TEMs are used to look at organelle detail
TEMs produce a 2Dblackandwhite image
Scanning electron microscopes have a magnification of x100000
Scanning electron microscopes are used to see cell surface detail
Scanning electron microscopes produce a 3Dblackandwhite image
Laser scanning confocal microscopes produce a 3Dcoloured image
To prepare a temporary mount of tissue for a light microscope you:
obtain a thin section of tissue; place tissue in a drop of water; stain tissue on a slide to make structures visible; add coverslip using mounted needle at 45 degrees.
TEMs work by passing a high energy beam of electrons through a thin slice of specimen; focus image onto a fluorescent screen; treat with heavymetalsolution; more dense structures appear darker as they absorb more electrons.
An SEM works by focussing a beam of electrons onto a specimens surface using electromagneticlenses; reflected electronsbounce off at different rates and produce a 3D image.
Laser scanning confocal microscopes work by focussing a laserbeam onto a small area on the samplessurface; specimen treated with fluorescent dye; sample emits protons and image is produced pixelbypixel in correct order.
Microscopic drawings are done with a sharp pencil and solid lines
Microscopic drawings include a scalebar and annotations of visible structures and how they appear on the microscope.
Magnification = image size / actual size
Differential staining is used to differenciate between celltypes of differentparts.
To calibrate microscopes place micrometer on stage, line up with the graticule.
count how many divisions are in 100 eyepiece graticules.
If 100 eyepiece divisions = 60 micrometers
Then 1 eyepiece division = 0.6 micrometers
1 mm = 1000 micrometers
1 micrometer = 1000nm
Include a title in microscopic drawings and ensure the proportions are correct
The nucleolus is dense and is made of RNA and proteins. It assembles ribosomes
Nucleus contains DNA coiled around chromatin which makes chromosomes
Nucleus controls cellularprocesses such as gene expression; specialisation; transcription and mitosis
Nuclear envelope separates nucleus from cell
Rough endoplasmic reticulum is a system of membranes containing fluid filled cavities - cisternae - that are continuous with the nuclear membrane
Rough endoplasmic reticulum is studded with ribosomes
Smooth endoplasmic reticulum is a system of membranes containing fluid filled cavities - cisternae
Smooth endoplasmic reticulum contains enzymes that catalyse reactions with lipid metabolism
Golgi apparatus is a stack of membrane bound flattened sacs. Cis face aligns with RER
Proteins are modified in the Golgi apparatus. molecules are added or its folded into a 3d shape
Ribosomes are small spherical organelles. There are 70s ribosomes in prokaryotic and 80s in eukaryotic cells.
Ribosomes, RER and Golgi apparatus are involved production of proteins.
For protein production:
the ribosomes that synthesise proteins are attached to the RER.
the Golgiapparatus aligns with RER
Mitochondria are surrounded by a double membrane. The inner membrane folds to form cristae. They have a fluid filled space - matrix - that contains mitochondrial DNA, enzymes, lipids and proteins. They can be spherical or rod shaped
Mitochondria are the site of aerobicrespiration to produce ATP.
Chloroplasts are the site of photosynthesis to convert solar energy to chemical energy