2.1.1- Cell Structure + Microscopy Flashcards
what are the 3 main microscopes used in biology?
- light microscope
- transmission electron microscope
- scanning electron microscope
what is a light microscope?
a microscope that uses light to produce an image.
what is a transmission electron microscope?
a microscope where a beam of electrons are transmitted through a specimen, producing a 2D image of the surface of the specimen.
what is a scanning electron microscope?
a microscope where a beam of electrons are sent across the surface of a specimen, producing a 3D image.
what is a laser scanning confocal microscope?
when a stained (with fluorescent dye) specimen is hit with a laser that filters through, producing an image.
compare the light microscope + T + S electron microscope?
- wavelength= L= 400nm, E=0.4nm
- resolution= L= 200nm, T=0.2nm, S= 3-10nm
- magnifaction= L=1500x T= 500,000x, S=100,000x
- image= L=natural colour, E=black+white (enhanced)
- specimen= L=living/non-living, E=non,living, stain/vacuum kill it
- easy? L= yes easy E=no, difficult due to preparation
what staining is used for light microscopes?
coloured chemicals/fluorescent dyes
what staining is used for electron microscope?
salts of heavy metal ions/particles
why is staining used? 2 reasons?
- enhance visualisation
- to differentiate structures + living/dead cells
what is magnification?
the number of times larger an image is compared to the object itself.
what is resolution?
the ability to distinguish between objects very close together.
what is the equation of magnification?
image size / actual size
what is a eukaryotic cell?
a cell that contains a membrane and a membrane-bound nucleus.
what is a cytoskeleton?
a network of protein fibres in cell cytoplasm
what is the function of the cytoskeleton?
- to give structure + shape
- to move organelles around inside
- to enable movement
what is the function and key notes on the NUCLEUS?
function= controls activities of cell, stores + protects DNA notes= double membrane/nuclear envelope, with pores
what is the function and key notes of the NUCLEOLUS?
function= site of ribosome assembly
key notes= composed of RNA + protein, is the inner region of the nucleus
what is the function and key notes of the SMOOTH ENDOPLASMIC RETICULUM?
function= lipid + carbohydrate synthesis/storage
key notes= made up of a network of membranes that are bare
what is the function and key notes of the ROUGH ENDOPLASMIC RETICULUM?
function= synthesis/transport of proteins between organelles
key notes= a membrane network, studded with ribosomes
what is the function and key notes of the GOLGI APPARATUS?
function= involved in sorting, storing, modification + export of secretory products
key notes= assembly of vesicles, folded membranes near cell membranes
what is the function and key notes of the RIBOSOMES?
function= makes proteins for amino acids
key notes= no membrane, made of RNA/protein, found on RER or free
what is the function and key notes of the MITOCHONDRION?
function= aerobic respiration
key notes= double membrane, inner membrane, folded into internal cristae
what is the function and key notes of the LYSOSOMES/VESICLES?
function= break down waste material
key notes= membrane sacs filled with hydrolytic enzymes, important role in immune system+cell death
what is the function and key notes of the CHLOROPLASTS?
function= photosynthesis
key notes= found in green part of plant, double membrane, internal stacks of membranous discs.
what is the function and key notes of the CELL MEMBRANE+WALL
function of CW= provides strength/protection against mechanical stress function of CM= keep toxic substances out, only allow specific molecules in, protect/organise cell
what is the function and key notes of the CENTRIOLE?
function= involved in cell division + positioning of structures
key notes= hollow cylinders containing ring of microtubules
what is the function and key notes of the FLAGELLA?
function= moves cells
key notes= hairlike cylinders, on surface of cells
what is the function and key notes of the CILIA?
function= moves liquids across surface
key notes= hairlike cylinders, cells contain a large number
what is the function and key notes of the PLANT VACUOLE?
function= store water/solutes, supports plants
key notes= large sac, bound in single membrane, cell can become turgid
what is protein secretion?
the method used by organisms to actively move protein molecules manufactured within a cell to the space outside of the cell.
what is an example of protein secretion?
cell in pancreas making insulin
what is the first step of secretion?
1- NUCLEUS
- mRNA copy of instructions for protein hormone is made
- mRNA leaves through the nuclear pore
what is the second step of secretion?
2- RER/RIBOSOME
- mRNA attaches to ribosome, reads instructions to assemble
- protein molecules ‘pinched off’ in vesicle towards gologi
what is the third step in secretion?
3-GOLGI
- vesicle fuses to golgi, where protein is processed/packaged for release
- packaged protein in vesicle transported to cell membrane
what is the fourth step in secretion?
4-CELL SURFACE MEMBRANE
-vesicle fuses, opens to release protein outside of cell
what are the 3 similarities between eukaryotic cells + prokaryotic cells?
- both contain ribosomes
- have a cell wall (plant)
- living cells
what are the 3 differences between eukaryotic cells + prokaryotic cells?
E=nucleus, P=no true nucleus, DNA carried in single chromosome
E=membrane bound, P=no membrane
size, E is larger than P
what are two examples of staining?
- acid-fast technique
- gram stain technique.
what are the steps involved with the gram stain technique?
- apply crystal violet
- apply iodine to fix dye
- gram positive bacteria= blue/purple
- gram negative bacteria= don’t take up violet, so safrarin must be added.
