cell structure Flashcards
what is the resolution and mag of an optical microscope?
res - 200nm
mag - up to 1500x
what is the resolution and mag of a scanning electron microscope?
res - 1 nm
mag - up to 100 000x
what is the res and mag of a transmission electron microscope?
res- 0.2 nm
mag - 2 000 000 x
how does a confocal microscope work?
use intense beams of light to scan the specimen, which is tagged with a flurecent dye. the laser causes the dye to give off light which is focused through a pinhole (blocks any unfocused light) onto a detector which is hooked up to a computer to give an image. can be used to look at different depths in different specimens.
how does a transmission electron microscope work?
It uses electromagnets to focus a beam of electrons through a specimen. Denser parts of the specimen will absorb more electrons which makes them appear darker. used to study a range of organells.
how does a scanning electron microscope work?
it scans a beam of electrons across the specimen, this knocks off electrons form the specimen which are collected by a cathode tube to form a 3D but lower res compared to the TEM
why do we stain our samples?
because in light microscopes light will pass through the specimen, an image will form because some parts will absorb more light. Sometimes the whole specimen will look transparent because the light will just pass straight through which makes studying it really hard. so we stain them.
what is differential staining ?
When some stains will stain different structures of the cell so they can be easily identified.
how does staining work?
stains are coloured chemicals that will bind to molecules in or on the specimen.
what does acetic orcein stain?
binds to DNA and stains chromazones dark red
what does eosin stain?
cytoplasm
what does Sudan red stain ?
lipids
what does iodine stain?
cellulose in plant cell walls yellow
and stains starch blue/black, under a microscope this will look violet
how do you make perminently fixed slides?
dehydrate the specimen- so that no bactiria can survive to decompose it
embedd them in wax- to pervent shape distortion
slice thinly - so that light/ electrons can get through.
how do you prepare a dry mount slide?
Thinly slice the specimen
Use tweezers to pick it up and put in the middle of slide
Put a cover slipe over the top
how to prepare a wet mount?
use a pipette to put a drop of water on slide, then place specimen ontop
to put the cover slip on stand the slip upright next to water drop, tilt slip and lower it onto the specimen
try not to get air bubbles under there
next add a stain, put a drop on one side of the cover slip and put a peice of paper towel on the opposite side to draw the stain from one side to the other under the cover slip.
magnification formula
image size/actual size
what is the structure of the nucleus ?
surrounded by a double membrane called the nuclear envelope which contains pores.
what is the structure of the rough endoplasmic reticulum?
system of membranes, containing fluid-filled cavities(cisternae) it is a part of the nuclear membrane and is coated with ribosomes
what is the structure of the smooth endoplasmic reticulum?
structure
system of membranes, containing fluid filled cavities(cisternae) is an addition of the nuclear membrane, but not coated in ribosmomes
what is the structure of the golgi apparatus?
flattened stacks of membrane
secretory vesscles bring materials to and from the golgi
what is the structue of mitochondria?
they are surrounded by double membrane with a fluid filled space between them. the inner membrane is highly folded into cistae
the inner part is a fluid filled matrix
what is the structrue of chloraplasts?
large organells 4-10 micrometers and surrouned by a double membrane
the inner membrane is continuous with stacks of flattened membrane sacs called thylakoids (look like a pile of plates)which contain chloraphill. each thylakoid is called a granum. the fluid filled matrix is called the stroma.
what is the structure of the vacuole?
surrounded by a membrane called the tonoplast, and contains fluid.
what is the structure of lysosomes?
small bags formed by the golgi and each is surrounded by a single membrane. they contain powerfull hydrolytic enzymes.
what is the structure and function of chromatin?
chromatin is the genentic material, consisting of DNA wound around histone proteins. When the cell is going to divide the chromatin condense and become chromazones
what is the nucleolus ?
where ribosomes are made, it is in the center of the nucleas
what is the structure and function of the nuclear pores?
when the outer and inner nuclear membrane fuse to give the pores, it is to allow bigger substances like mRNA to pass through.
what is the nuclear envelope?
separates DNA from cytoplasm
what type of image does a transmission electron microscope give?
2D, high res, black and white image
what type of image does a confocal microscope give?
3D false colour image
what is the mag and res of a confocal microscope?
mag - up to 17000x
res - 180nm
what type of image does a scanning electron microscope give?
3D black and white but can add colour
what is the function of the nucleus?
nucleus is in control of cell, stores organisms genes, transmits genetic info and provides instructions for protein synthisis
what is function of the SER?
contains enzymes that are involved with lipid metabolism like
synthisis of cholesterol
synthisis of lipids/phospholipids needed by the cell,
synthisis of steriod hormones
involed with absorbtion, synthisis and transportation of lipids from the gut
what is the function of the golgi apparatus?
proteins are modified and packaged here
what is the function of mitochrondria?
site of aerobic respiration in eukaryotic cells
the matrix contains enzymes needed for aerobic respiration, producing atp
they are self replicating so the cell can produce more if more energy is needed
what is the function of chloroplasts ?
site of photosynthisis
the light is trapped by chloraphill and used to make ATP at the grana. water is split to supply hydrogen ions
when hydrogen reduces carbon dioxide using energy from ATP to make carbohydrates in the stroma
what is the function of the vacuole?
it is filled with water and solutes and maintains cell stability because when it is full it pushes on the cell wall and makes the cell turgid.
if all plant cells are turgid then the overall plant stays supported.
what is the function of lysosomes?
can engulf old cell organells and foreign matter and return digested components for reuse.
they are abundant in phagocytes in order to digest invading pathogens.
what’s the definition of magnification ?
The number of times larger the image is compared to the object
what Is the definition of resolution ?
Ability to see two objects that are close together as separate objects
