Organelles And Microscopes Flashcards
What is the smallest thing that can be seen with a:
Light microscope
Electron microscope
1) mitochondria
2) lipids and other small molecules
Formula for magnification
Image/real
How many nanometers in a micrometer
1000
Light microscope: Resolution Magnification Ocular lens Image produced
200nm
X1500
X10
2D
Advantages and disadvantages of light microscope
✅ Portable Little space Specimens are easy to prepare Can see nucleus in cells ❌ Low resolution and magnification as wavelength of light is too long Cannot see ultrastructure
TEM: Resolution Magnification Image produced What is it?
0.2nm
X500,000
2D
Beam of electrons is transmitted through s specimen and focused to produce an image
Pros and cons of TEM
✅ Used to observe fine detail High magnification ❌ Not portable 2D image Expensive equipment
SEM: Resolution Magnification Image produced What is it?
0.2nm
X100,000
3D
A beam of electrons is sent across a surface of specimen and reflected electrons are collected
Pros and cons of SEM
✅
3D image
❌
Not portable
Name and explain the four types of slide preparation
Dry mount= solid specimen with a cover slip on top
Wet mount= specimens suspended in water or oil cover slip on top
Squash slides= wet mount but using a lens tissue apply pressure to cover slip to squash the specimen
Smear slides= edge of slide is used to smear the specimen then cover slip is added
What are the three advantages of staining
- With coloured chemicals that bind to cell organelles and make them visible
- provides a contrast
- allows us to identify different types of cells and organelles
Explain the purpose of gram stain technique
Used to see gram positive bacteria with thick peptidoglycan cell walls and gram negative bacteria with thin peptidoglycan cell walls.
Describe the process of gram stain technique
The bacteria are taken and crystal violet is added, they are then decolorized using alcohol and counter stained with safranin, the difference in colour allows us to identify which a gram positive and negative bacteria
Which bacteria can be killed by penicillin
Gram positive ( it breaks down the cell walls)
What is the purpose of acid fast technique
Used to identify mycobacterium (tb) from other bacteria
Describe the process of acid fast technique
Carbol fuchsin dye (red) is carried into cells using a lipid solvent, acid/alcohol wash will remove stain from any bacteria but not mycobacterium
What is fixing
When chemicals are used to preserve specimens in as near natural state as possible
What is sectioning
Specimens are dehydrated and placed in a wax mould to form a hard block- then is thinly sliced with a knife
What is staining
When a substance is treated with different coloured chemicals to show the ultra structure
What is mounting
The specimens are then secured to a microscope slide with a cover slip
Where does most of the reactions take place inside the cell- what separates it
The cytoplasm
Cell surface membrane
Describe the structure of the nucleus
Contains genetic information
DNA contained within double membrane called nuclear envelope
Contains pores
Nucleolus- inside nucleus responsible for producing ribosomes
What does chromatin do
Creates chromosomes
The chromatic coils and condenses to form the structure
What is the job of the nucleolus
What’s it made from
Produces ribosomes
Proteins and RNA
Describe the structure of mitochondria
Has double membrane
The inner folding is called cristae
Space inside where DNA is is called matrix
Describe vesicles
Membraneous sacs was hat have storage and transport roles in the cell
What type of enzymes do lysosomes have
Hydrolytic enzymes
Explain microfilaments
Contractile fibres made from the protein actin
Responsible for cell movement and contraction during cytokinesis
What is cytokinesis
When cytoplasm of a single cell is divided into two daughter cells
What are microtubules
Tubulidentata proteins that polymerise to form tubes that form a scaffold like structure - can also create spindle fibres
What are intermediate fibres
Fibres that give mechanicsl strength to cells and help maintain their integrity
What is treadmilling
When certain subunits are added at one end and removed at the other
Describe the arrangement if cilium
9+2 arrangement
What is endosymbiosis
When an organism lives within the cell
Eg mitochondria chloroplast
Acquire double membrane
How is dna packaged in a eukaryotes
DNA-wrapped around Histone protein- supercoiled to form chromatin- condenses into chromosome
When using a eyepiece graticule: what equals 1EPU
1000 micrometers
What happens when using a laser scanning confocal microscope
A high intensity laser is moved across the specimen
This causes fluorescence from the components in the specimen which have been labelled with a dye
Omitted light from the specimen is filtered through a pinhole aperture
Only light from the focused plane is detected
Advantages of laser scanning confocal microscopy
No Blur
Very high resolution
Can visualise specific proteins and structures within a cell and watch them move
3D image
