AS LEVEL- Biology- Basic components of living systems (Microscopes 1)
- Created by: Ammarah123
- Created on: 01-11-18 12:42
View mindmap
- Basic components of living systems (Microscopes 1)
- Magnifiication- The number of times larger an image is compared to the actual size of the image
- Magnification = Image size/Actual size
- Resolution- How well a microscope distinguishes between two points that are close together
- Light microscope
- Has a lower resolution than electron microscopes so they are used to look at whole cells or tissues
- Colour of specimen = Depends on stain
- Magnification = Up to x2000
- Size = Small
- Sample preparation = Simple
- Cost = Cheap
- Dead or Alive? Alive
- Resolution = 200nm
- Vacuum? No
- Eyepiece Graticule- *Has a scale on it *Used to estimate the size of a specimen when viewed with a microscope.
- Stage micrometer- *Glass slide with a scale on it *Used to calibrate the eyepiece graticule of a microscope
- Microscopes are used to observe and investigate different types of cells + cell structrure in a range of eukaryotic organisms
- Staining
- *Increases contrast *Helps to differentiatebetween the different organelles
- Iodine- *Used on plant cells *Interacts with starch
- Negative Staining- *Repelled by the negatively charged cell components in the cytoplasm *Doesn't enter the cell leaving the cell unstained *Useful to see the number of cells *Won't be able to see organelles
- Methylene Blue- *Used on animal cells *Positively charged stain so it's attracted to the negatively charged cell components in nucleus + cytoplasm
- Differential staining- When multiple stains are used
- *Makes different things show up *Different organelles/ cells/ organisms absorb different quanities of stain so they appear different
- Gram Stain Technique- *Used to identigy whether bacteria are gram positive (thick cell wall) or gram nagative (thin cell wall) *Thick = purple *Thin = pink
- Acid-Fast Technique- *Used to differentiatespecies of Mycobacterium from other bacteria *2 stains- carbol fuchsin + mythylene blue *Cells are washed with an acid- alcohol solution *Other bacteria are affected so they turn colourless
- Magnifiication- The number of times larger an image is compared to the actual size of the image
Similar Biology resources:
Teacher recommended
Comments
No comments have yet been made