Cells Flashcards
What microscope has a higher resolution and magnification?
Electron microscopes
What microscope gives a colour image?
Light microscope
What microscope is lighter and cheaper?
Light
What microscope is more expensive?
Electron microscope
What resolving power and magnification do TEM and SEM have and what one has the highest resolving power?
Both have high resolution and magnification TEM has higher resolving power
What condition must the cell be in to use a TEM or SEM? What process is complex?
Must be vacuum can’t be living and must be extremely thin and complex staining process
What one out of TEM and SEM produce colour images?
SEM
What may the images contain when using a TEM or SEM?
May contain artefacts
What one out if SEM and TEM produce a 3D image?
SEM
What is the formula of magnification?
Magnification = size of image\ size of object
What is the definition of resolution?
The minimum distance apart that two objects can be in order for them to appear as separate items?
What is cell fractionation?
The process where cells are broken up and the different they contain are separated out
What are the 3 conditions the tissue must be place in by cell fractionation?
Cold, buffered and same water potential
Why must the cell be placed in a cold solution?
To reduce enzyme activity that may break down the organelles
Why must the cells be placed in buffered solution?
So ph doesn’t change which could alter the structure of the organelles or affect the function of the organelles
Why must the cells be place in a solution which is the same water potential/ isotonic?
To stop osmosis to prevent organelles bursting or shrinking due to osmotic gain or loss of water
What are the two stages of cell fractionation?
Homogenisation and ultracentrifugation
What is homogenisation?
Cells are broken up by a homogeniser which breaks down the cell wall and membrane releasing the organelles from the cell to produce a fluid called homogenate which is filtered to remove cells and large pieces of debris
What is ultracentrifugation?
Process where the fragments in the filtered homogenate are separated in a machine by a centrifuge it spins the tubes of homogenate at a high speed to create a centrifugal force
What are the 3 steps of ultracentrifugation?
- Spun at slow speeds to remove heaviest organelles
- Fluid at top called supernatant removed and transferred to another tube and spun again at a faster speed
- Next heaviest organelle taken out then spun until all the organelles are separated
What is calibration of a microscope?
Where you line up the stage micrometer and eye piece graticule so you can find the difference in magnification by seeing how many eye piece graticule fit inside the stage micrometer to work out the magnification
What is the nucleus function?
Contains hereditary material and controls cells activities
What is the nuclear membrane?
Double membrane which is continuous with the ER and it controls the entry and exit if materials ad contains the reactions in the nucleus
What do nuclear pores do?
Allow passage of large molecules
What is the nucleoplasm?
Granular jelly like material that makes up most of the nucleus
What are chromosomes ?
Consist of linear hound dna by proteins
What is the nucleolus?
Small spherical region in nucleoplasm produces RNA and assembles ribosomes
What are the 3 functions of the nucleus?
- Control centre of cell produces RNA and tRNA and protein synthesis
- Retains genetic material in the form of DNA and chromosomes
- Manufacture ribosomal RNA and ribosomes
What shape and size are mitochondria?
Rod shaped 1-10 micrometers
What is the function of the double membrane around the mitochondria?
Controls entry and exit of materials
What is the cristae in a mitochondria?
Inner of two membranes is folded to form extensions providing a larger sa for attachment of enzymes and proteins for respiration
What is the matrix in the mitochondria?
Make sup most of it contains proteins, lipids, ribosomes and DNA allows them to control production of their own proteins
What is the function of mitochondria?
Sites of aerobic respiration production of ATP required for active transport
What is the general shape of chloroplast?
Disc shaped 2-10 micrometres long 1 micrometer diameter