Cell structure and microscopy Exam Qs Flashcards
Why can you not determine structures inside a cell with an optical microscope
Resolution is too low
Because wavelengths are too long
Describe role of one named organelle in digesting foreign material
Lysosomes
Fuse with vesicle/ phagosome
Release hydrolytic enzymes/ lysozymes
Structures found in all Eukaryotic cells and prokaryotic cells
Cell surface membrane
Ribosomes
DNA
Cytoplasm
Suggest why plasmid replication is higher in high concentration of amino acids
amino acids used in protein synthesis
So more DNA polymerase
Describe how a sample of chloroplasts can be separated from leaves
Break open calls and filter
In cold, isotonic and ph buffered solution
Centrifuge/ spin until nuclei collects at bottom of test tube
Remove nuclei and spin at higher speed until chloroplasts settle
Give one feature of a chloroplasts that allows it to synthesise its own protein
How is it different to similar features in other organelles
Chloroplasts DNA
Is not associated with histone proteins where nuclear DNA is
Is circular where DNA is linear
Is shorted than nuclear DNA
Describe role of organelles in production, transports and release of proteins from eukaryotic cells
DNA in nucleus codes for protein
RER produces proteins
Mitochondria produces ATP for protein synthesis
Golgi body packages and modifies protein by adding carbs to form glycoproteins
Vesicles transport protein to CSM where it fuses with CSM and is released from cell
give one advantage of viewing a biological sample using a transmission electron microscope compared to a scanning electron microscope
higher resolution
so can view internal structures
why could organelles not be seen in detail using an optical microscope
light has longer wavelength
so lower/ poorer/ weaker resolution
name an organelle found in both chloroplast and prokaryotic cell
ribosome
a biologist separated cell components to investigate organelle activity. She prepared a suspension of organelles in a solution preventing damage to the organelles
describe 3 properties of this solution
cold - to prevent enzyme activity
isotonic - to prevent lysis/ bursting of organelle
pH buffered - prevents denaturing of enzyme protein
name the process by which prokaryotes divide
binary fission
name main biological molecule in prokaryotic:
- cell surface membrane
- cell wall
CSM- phospholipid
cell wall- murein or glycoprotein
contrast an optical microscope and a transition electron microscope
- how they work
- limitations of each
- TEM use electrons, optical uses light
- TEM allows greater resolution, so smaller organelles can be observed in greater detail
- TEM only used for dead and dehydrated specimen, optical can view live specimen
- TEM can’t show colour, optical can
-TEM requires thinner specimens - TEM more complex/ time consuming preparation
name two structures present in plant cells that aren’t present in animal cells
- chloroplasts
- cell wall
- vacuole
- starch grains
why do you need to blend and filter in ultracentrifugation
break open cells/ homogenise
remove unbroken cells and larger debris
