Cells & Microscopy - MICROSCOPY Flashcards
Name 3 main types of microscopes
- Light microscope
- Electron microscope
- Confocal laser scanning microscope ( CLSM )
Name 2 types of electron microscope
- Transmission electron microscope ( TEM )
2. Scanning electron microscope ( SEM )
Definition of light microscope
Uses visible light to illuminate a thin section of a specimen
Definition of electron microscope
Uses a beam of electrons to visualise a specimen
Definition of of CLSM ( confocal laser scanning microscope )
Uses lasers to produce an optical section which is used to produce a 3D image
What is the max. magnification of a light microscope
2000x
What is a light microscope used for looking at ( 2 things )
- Cells and tissues
- Some living things eg. a single cell layer
What is the max. magnification of a TEM ( transmission electron)
5 000 000x
What is a TEM used for looking at ( 4 things )
- very thin cross section of an object ( such as a cell )
- internal structure of objects
- objects at very high resolution
- relationships between structures at high resolution
What is the max. magnification of a SEM ( scanning electron )
500 000x
What is a SEM used for looking at ( 2 things )
- surface of objects at high resolution
- objects in 3D
Definition of magnification
Number of times larger an object appears compared to the real specimen
Definition of resolution
Ability to distinguish 2 distinct objects separately and to see detail
What does resolution depend on
Wavelength of radiation used
What is the wavelength of visible light
400-700 nm
What is the max. magnification of a CLSM ( confocal laser scanning )
2000x
What is a CLSM used for looking at ( 4 things )
- thin slices in a sample while keeping sample intact
- specific parts of a cell ( eg. Individual proteins) by labelling them with fluorescence
- living cells
- ( highlighted individual components of a cell )
What does cell theory state ( 3 things )
- All living things consist of 1 or more cells
- cells are the basic structural and physiological units of all living organisms
- cells come from pre-existing cells
Place the following in order of largest to smallest:
Plant cell Chloroplast Animal cell Mitochondria Nucleus DNA RNA Cell surface membrane Ribosome Virus Bactria
- Plant cell
- Animal cell
- Nucleus
- Chloroplast
- Mitochondria / Bacteria
- Virus
- Ribosome
- Cell surface membrane
- DNA
- RNA
Name 3 main types of blood cells
- Erythrocytes ( red blood cell )
- Thrombocytes ( platelets )
- Leukocytes ( white blood cell)
Name 3 main types of Leucocytes ( white blood cells )
- Neutrophil
- Lymphocytes
- Monocyte ( = macrophages once moved into tissues )
Definition of erythrocytes
Red blood cells
Description of erythrocytes ( 4 things )
- biconcave discs = flexibility squeeze through capillaries
- large SA : volume ratio
- no nucleus
- naturally red in colour
Function of erythrocytes ( 2 things )
- carries oxygen TO respiring tissues around the body
- carries carbon dioxide FROM respiring tissues around the body
Definition of thrombocytes
- platelets = cell fragments used in blood clotting
Description of thrombocytes ( 3 things )
- Biconvex discs of cytoplasm fragments from giant cells ( megakaryocytes )
- no nucleus
- takes a pale stain
Function of thrombocytes
Contributes to blood clotting and clot formation
Definition of leukocytes
White blood cells
Definition of neutrophil
Type of granulated phagocytic white blood cell
Description of neutrophil ( 4 things )
- most numerous leukocyte
- lobed nucleus = flexibility
- granular cytoplasm
- nucleus takes a darker stain than the cytoplasm
Function of neutrophil
Engulfs bacteria by process phagocytosis
Definition of monocyte
Large phagocytic white blood cell, which can develop into a macrophage
Description of monocyte ( 4 things )
- largest kind of leukocyte
- large bean shaped nucleus
- clear ( agranular ) cytoplasm
- nucleus takes a dark stain
Function of monocyte
Carry out phagocytosis in bloodstream and eventually move into the tissues ( now called macrophages )
Definition of lymphocyte
Smallest kind of leukocyte
Cells of the immune system= B or T cells
Description of lymphocytes: B & T ( 3 things )
- large
- darkly stained nucleus
- clear cytoplasm
Definition of B lymphocyte
Specialised white blood cell which that is produced and matured in the bone marrow
Function of B lymphocyte
Forms plasma cells which produce antibodies
Definition of T lymphocyte
Specialised white blood cell that is produced in the bone marrow and natures in the thymus gland
Name 2 types of T lymphocytes
- Helper T cells
2. Cytotoxic T cells
Function of helper T cells
Coordinate immune response
Function of cytotoxic T cells
Destroy infected cells
Definition of differential stain
Staining processes that use more than 1 chemical stain to distinguish between different cellular components
Explain differential stains in more detail
Differential stains are chemicals that bind to some parts of the specimen and make different structures different colours in order to make them visible and increase contrast
Name 3 stains that can be added to live cells
- Iodine
- Methylene blue
- Eosin
Name a stain that can only bind to cells that have been fixed in alcohol ( dead cells )
Leishman’s stain
Why is the process of differential staining used ( 2 things )
- most biological specimens have no colour and are almost transparent
- colourless = difficult to differentiate between structures
function of methylene blue stain
Binds to nucleic acids = stains nuclei and ribosomes blue- purple
Function of eosin stain
Binds to cytoplasmic proteins = stains them pink-red
Function of Leishman’s stain
Stains leukocytes = reveal differences in the shape of their nuclei = can be identified in a blood smear
How to prepare a blood smear ( 9 steps )
- Wear latex free gloves ( prevent contamination of blood )
- Place small drop of blood at end of a sterile, clean, dry microscope slide
- Spreader held at 30° angle = pushed along slide to spread the blood by capillary action = form a smear
- Label microscope slide with patient details
- Allow slide to air dry
- Fix using methanol ( alcohol= dead cells )
- Flood with Leishman’s stain & leave for 2 mins
- Dilute with distilled water & leave for 5-7 mins
- Wash slide until it appears pale pink
Formula for calculating magnification
I AM
Magnification = Image size / Actual size
Formula for calculating actual size
I AM
Actual size = Image size / Magnification
I AM triangle what do letters stand for
I = image size
A= actual size
M = magnification
Millimetres to micrometers
x1000
millimetres to nanometres
x ???
micrometer to millimetre
/ 1000
Micrometre to nanometre
x ???
nanometre to micrometre
x ???
nanometre to millimetre
x ???
