B1.1 Flashcards
so goood cells and microscopes
describe how light microscopes and staining can be used to view cells (PAG) :preparing the specimen pt 1
Preparing the specimen
- cut the specimen into a thin slice if it isn’t already to let light through
- take a clean slide and use a pipette to put one drop of water/ mountant to secure specimen
- use tweezers to place specimen on slide
- add a drop of stain if specimen is transparent or colorless to make it easier to see
- place a cover slip at on side of the specimen at at angle with a mounted needle
- carefully lower the cover slip onto the slide pressing gently to remove any air bubbles
- describe how light microscopes and staining can be used to view cells (PAG) : veiwing
- clip the slide contain the speminin onto the stage
- select the LOWEST POWERED objective lense
- use the coarse adjusting knob to move stage just below the objective lense
- then looking down in the eyepiece move the stage downwards until the specimen is just about in focus
- adjust the focus using the fine adjustment knob until you get a clear image of the specimen
- if a greater magnification is needed swap to a higher -power objective lense
name the main subcellular structures of eukaryotic cells(animal cell)
(Nada can make raspberry cake)
- nucleus
- cytoplasm
- mitochondria
- ribosomes
- cell membrane
explain the function of the nucleus
- nucleus - contains DNA in the form of chromosomes
- controls cell activity
explain the function of the cytoplasm
- gel like substance where most of the chemical reactions of the cell occur
- contains dissolved nutrients and salts and structures called organelles
Explain the function of mitochondria
- Contain enzymes needed for cellular respiration
- where most energy is released in respiration
Explain the function of ribosomes
- Tiny structures where protein synthesis occurs.
Explain the function of cell membrane
- holds the cell together
- Controls what goes in and out of the cell
- Has a selective barrier and is semipermeable only lets certain molecules diffuse across
Name the sub cellular structures do plant cells have that animal cells don’t
- Cell wall
- chloroplasts
- vacuole
Explain the function of chloroplasts in plant cells
- contains the green pigment, chlorophyll, which absorbs light energy for photosynthesis.
- Contains the enzymes needed for photosynthesis
Explain the function of the cell wall in plant cells
- Made of cellulose which strengthens the cells and supports the plant
Explain the function of a vacuole in a plant cell
- Filled with cell sap to help keep the cell turgid
- The pressure created by the cell wall stops too much water entering and prevents cell lysis.
Name the sub cellular structures in prokaryotic cells
- Cell membrane
- Cytoplasm
- Cell wall
- A single loop of DNA
- plasmid
- (sometimes) flagellum
explain the function of a plasmid
- Circular pieces of DNA found in bacteria, which can act as a vector to transfer DNA from one organism to another.
Explain the function of flagella in prokaryotic cells
- These can rotate or move in a whip-like motion to move the bacterium
Explain how electron microscopy has increased our understanding of sub cellular structures
- there are many sub-cellular structures in animal and plant cells
- most of these cannot be viewed using a light microscope because the magnification** and **resolution of is too low.
- The transmission electron microscope (TEM) is used to examine thin slices or sections of cells or tissues with a magnification around ×1,000,000 and less than 1nm resolution
- The TEM has revealed structures in cells that are not visible with the light microscope
- In more detail such as mitochondria needed for aerobic respiration and chloroplasts needed for photosynthesis and has helped scientists to figu out how they function in the cell
