Chapter 1 Flashcards
Why do we preserve specimens?
To enable them to be cut into sections to observe under microscope.
To enable them to be treated with a variety of different stains to distinguish between different types of cells.
Function of the eyepiece on a microscope?
Magnifies specimen
Function of the barrel on a microscope?
Passes light from objective lens to eyepiece
Function of turret on microscope?
Holdd objective lenses
Rotates to enable selection of objective lens
Function of objective lens on microscope?
Magnifies and resolves specimen.
Function of stage on microscope?
Supports slide in correct position at 90 degrees to illumination source.
Enables light to pass through specimen
Function of iris diaphragm on microscope?
Controls amount of light reaching specimen
Best definition achieved with lower light intensity.
Function of substage illumination?
Source of illumination
Blue light bulb can be used to use light of shorter wavelength to improve resolution.
Advantages of the method of preparing a temporary slide?
Rapid and simple procedure - No complex apparatus or skill required.
Can mount specimen in glycerine to prolong examination period.
What does fixation do for a permanent slide?
Preserves specimen in lifelike condition.
Minimises distortion.
What does dehydration do for a permanent slide?
Removes traces of water from fixed material.
Achieved by placing specimen in increasing conc of alcohol.
What does clearing do for a permanent slide?
Addition on xylol removes dehydrating alcohol.
Ensures material is made transparent.
What does embedding do for a permanent slide?
Supports material so itβs firm enough for sectioning.
Can be resin, plastic or wax.
What does sectioning do for a permanent slide?
Use a microtome to cut fine slices so light can pass through specimen.
What does differential staining do for a permanent slide?
Improves contrast between different tissues and/or structures.
What does mounting do for a permanent slide?
Embeds and protects material.
Ensures material can be observed over a long period of time.
Advantages of using differential stains?
Most biological specimens are colourless so staining makes it easier to observe tissues and distinguish between different types of cells,eg.
Advantages of using a light microscope?
Low skill set needed by user.
Can be transported to use in field work
Can observe living microorganisms
Relatively inexpensive so available for schools and colleges.
Disadvantages of using a light microscope?
Low resolution
Limited magnification
Many internal cellular structures canβt be seen, eg, ribosomes, cristae.
How does a CLSM work?
NOT FINISHED!!!!!
Advantages of EM?
Greater resolution
Higher magnification can be used
Finer detail can be seen
Disadvantages of EM?
Specimen has to be placed in vacuum so must be dead.
Highly expensive
High skill set required - training before use.
More prone to artefacts due to complex preparation procedure.
Advantages of using a CLSM?
Ability to reduce background information away from focal plane to reduce image degradation.
Ability to obtain high resolution images
Ability to obtain 3D reconstructions.
Area of a transverse section?
π r squared.
Area of olique section?
π a b
Area of longitudinal section?
hw.
What is flow cytometry used for?
Analysing the activity of molecules found in the cell surface membrane and within the cell.
Assessing purity of samples
Analysing cell size and volume.
Procedure of flow cytometry?
Making a single-cell suspension from a cell culture or from tissue samples.
Cells are incubated in tubes with either unlabelled or fluorochrome-labelled antibodies.
Cells are analysed in flow cytometer
NOT FINISHED!!!!
What is the function of the nucleus?
Contains genetic, hereditary material in form of DNA.
Carries instructions for production of polypeptide chains.
Role of nucleolus?
Found within the nucleoplasm
Produces rRNA
Assembles ribosomes
Function of nuclear envelope?
Surrounds nucleus.
Outer membrane of NE is continuous with RER
Function of nuclear pore?
Enables cell to control what enters and exits nucleoplasm from cytosol.
Function of mitochondria?
Site of aerobic respiration.
Function of smooth endoplasmic reticulum?
Series of flattened membrane sacks (cisternae) that form sheets in they cytosol.
Site of lipid, carbohydrate and steroid hormone synthesis, storage and transport.
Function of rough endoplasmic reticulum?
Series of flattened membrane sacks (cisternae) that form sheets in the cytosol
Has ribosomes attached to outer surface of cisternae.
Site of protein and glycoprotein synthesis.
Sire of folding of ppc into 2, 3 structure.
Function of ribosomes?
NOT membrane bound.
Cytoplasmic granules made from rRNA and protein.
Site of translation of mRNA to produce polypeptide chains - which late fold to form active proteins.
Function of Golgi apparatus?
Assemble polypeptides into proteins.
Package proteins and lipids made by RER and SER.
Function of golgi vesicles?
Used in phagocytosis and endocytosis?
Function of lysosomes?
Contain different types of hydrolytic enzymes.
Function of centrioles?
Organise spindle fibres in nuclear division
Function of chloroplasts?
Site of photosynthesis
Function of large permanent vacuole?
Contribute to cell turgidity and act as a reservoir for water.
Function of cell wall?
Gives cell shape and provides strength and support to cell.
Function of plasmodesmata?
Cell to cell connections between adjacent plant cells that enable materials and chemicals to be transferred between cells.
Function of circular DNA?
Contains genetic information for replication and protein synthesis
Function of plasmids?
Very small circular pieces of DNA.
Function of mesosome?
Formed by invaginations of cell surface membrane.
Function of pili?
Hair-like extensions that extend through cell wall.
Enable bacteria to adhere to each other or other surfaces.
Function of flagellum?
Specialist extension of csm and cytosol.
Enables motility and movement of bacteria.
