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a) What is the use of microscopes and what are the 3 different types of microscopes used?
Magnify small cells and organisms for observation
Light
Scanning electron
Transmission
a) What type of observations are made with the 3 types of microscopes?
Light:
whole cells and tissues
Transmission:
organelles within the cell
Scanning:
objects at certain depth within cell
a) What is the differences between the three microscopes?
Light:
View live specimen
Magnification: x1500
Resolution: 200nm
2D
Transmission:
View dead specimen
Magnification: x100,000
Resolution: 0.2 nm
2D
In black and white
Scanning;
View dead specimen
Magnification: x500,000
Resolution: 3-10nm
What is the name of another microscope and its features?
Laser confocal microscope:
View live specimen
Coloured
3D
b) How do you prepare microscope slides?
Use a sharp blade
Cut thin slices of tissue, then pick the thinnest slice
Place on the microscope slide
Stain before placing cover slip over the specimen about to view
What piece of equipment do you use when measuring a cell under a microscope?
Eyepiece graticule:
Calibrate graticule to the stage micrometre
Work out the number of division per graticule
Measure the diameter of cell 3 times and create an average
Use the calibrated units to calculate diameter
What are the four types of mounts/ preparations?
Wet mount:
Specimen suspended in liquid like water and cover slip placed at angle
Dry Mount:
Cover slip placed directly
Used for plant cells
Squash Slide:
Specimen squashed between two slides
Used for root hair cells
Smear mount:
Using a drop of sterilised water or saline water
Used for blood cells or cheek
How do you use different objective lens to focus specimen?
By switching it from thee lowest lens to the highest
using the fine focus for a clearer image
Why is it crucial to place coverslip at an angle?
To avoid air bubbles
c) What is the use of staining ?
To increase contrast
Organelles can be views easily and better
Name some stains and what organelles you can view?
Sudan III - Lipids
Acetic Erisin - Chromosomes
Iodine - Starch
Mythlene Blue - Cytoplasm
e) What is the magnification formula and how can you change it?
Magnification= Image size / Actual object
Image size = magnification * actual object
Actual objects = Image size / Magnification
f)What is the definition of magnification and resolution?
Magnification: is how many times larger the image size is compared to the actual size
Resolution: ability to distinguish two different points
g) What are the features of the eukaryotic cells and function?
Both cells (Animal and Plant):
Nucleolus:
Contains genetic material
Nuclear envelope:
Contain nuclear pores - help large molecules pass through
Double membrane
RER:
Contains ribosomes
Specifically the membrane holds ribosomes and allows mRNA to fuse with ribosomes
Ribosomes:
Site of protein synthesis
No membrane
SER:
Site of where lipids are formed
Golgi Apparatus:
Stores, modifies and packages complex molecules which leave and enter in vesicles
Vesicles move using microtubles
Lysosomes:
Contain digestive enzymes to breakdown waste products
Mitochondria:
Site of aerobic respiration - produces ATP
Cytoplasm = matrix
Inner layer of membrane = cristae
Plasma Membrane:
Controls what enters and leaves cell
Plants:
Chloroplasts:
Photosynthesis occurs in thylakoids specifically where energy and enzymes are kept
Stacks of thylakoid = grana
Cell Membrane:
Made of cellouse
Permanent Vacuole:
Contains tonoplast which is a membrane filled with cell sap
Cell Wall:
Pores = plasmodesmata
Connects two cells together
Amylose:
Contains starch grains
What are the main differences between Prokaryotic and Eukaryotic?
Unicellular
No membrane bound organelles
Contains DNA plasmid rings instead of nucleus or DNA enclosed in nucleus
Contains flagella
i) What is the interactions between cells to create protein?
mRNA copies instructions from the gene within the nucleus - Transciption
Leaves the nucleus through the pores within the nuclear envelope - Transalation
Travels to the RER and attaches to the ribosome, ribosomes reads instructions - makes proteins
Protein released in a vesicle sent to golgi where it is modified, packaged and stored ready to be released
Pinched off and sent to cell surface membrane
Vesicle fuses with CSM and opens up to release to the body
j) What is the importance of the cytoskeleton
Provides mechanical stability
Allows cell movement
Holds organelles in place