cell structure and microscopy Flashcards
describe the role of one named organelle in digestion of bacteria (3)
- lysosomes
- fuse with vesicle
- release hydrolytic enzymes
explain why its not possible to see small structures using a optical microscope (2)
- resolution is too low
- as wavelength of light is too long
give 3 organelles present in all prokaryotic and eukaryotic cells
- ribosomes
- cytoplasm
- cell membrane
describe how a sample of chloroplasts can be isolated from leaves (4)
- break open cells and filter
- in cold, isotonic, buffered solution
- spin in centrifuge and remove nuclei
- spin at faster speed, chloroplasts settle out
outline the role of organelles in the production, transport and release of proteins from eukaryotic cells (4)
- DNA in nucleus is code for protein
- ribosomes produce proteins
- mitochondria produce ATP for protein synthesis
- Golgi apparatus package proteins
- vesicles transport proteins
give an advantage of viewing specimens using a transmission electron microscope rather than scanning electron microscope (1)
has a higher resolution
can view internal structures
name an organelle found in both a chloroplast and prokaryotic cell (1)
70s ribosome
describe 3 properties of solution used in separating cells (3)
- cold to reduce enzyme activity
- buffered to prevent denaturing of enzyme
- same water potential to prevent bursting of organelle
contrast how an optical and transmission microscope work and contrast their limitations (6)
- TEM use electrons, optical use light
- TEM allows greater resolution
- TEM can see smaller organelles
- TEM only view dead specimens, optical can view live specimens
- TEM does not show colour, optical shows colour
- TEM requires thinner specimens
- TEM focuses using magnets and optical uses glass lenses
why are no organelles visible in red blood cells (1)
cytoplasm is filled by haemoglobin
name 3 structures in a eukaryotic cell that cannot be viewed using an optical microscope
- ribosome
- endoplasmic reticulum
- lysosome
describe how to make a temporary mount of a piece of plant tissue to observe the position of starch grains when using an optical microscope (4)
- add drop of water to glass slide
- obtain thin section of plant tissue and place on slide
- stain with potassium iodide
- lower cover slip using mounted needle
name 2 structures found in ALL bacteria that are not found in plant cells (3)
- murein cell wall
- circular DNA
- 70s ribosomes IN CYTOPLASM
name 2 features of HIV particles that are not found in bacteria
don’t include attachment protein (2)
- capsid
- RNA genome
- reverse transcriptase
- lipid envelope
give 3 structures found in all prokaryotic cells and all eukaryotic cells
- cell membrane
- cytoplasm
- ribosomes
name the biological molecule in the cell membrane of a bacterium cell
phospholipids
name the biological molecule in the murein cell wall of bacteria
peptidoglycan
Describe how HIV is replicated (4)
- attachment proteins on HIV bind to RECEPTOR molecules on the T cell
- virus injects it’s nucleic acid into host cell
- reverse transcriptase converts RNA into DNA
4.host cell makes viral proteins, they are assembled and released, the cell bursts
is RNA present in: bacteria
virus
yes in bacteria and virus
is a cell wall present in:
bacteria
virus
yes in bacteria
no in virus
are enzyme molecules present in:
bacteria
virus
yes in bacteria and virus
is a capsid present in:
bacteria
virus
no in bacteria
yes in virus
describe and explain a difference between images produced by a transmission and scanning electron microscope
SEM produces 3D image whereas TEM produces 2D image
because electrons are deflected with SEM but pass through with TEM
a student determined the size of a cell from a photograph using a ruler and calculator and gave the answer in micrometres,
describe how (2)
- measured length of structure and divided by magnification
- multiplied by 1000 from mm
describe how to use information from calorimeter and calibration curve (2)
- measure light absorption
- draw line to curve
explain how the electron microscope is able to resolve objects better than the optical microscope
EM uses electron beam which has smaller wavelength than light beam
explain why specimens have to be kept in a vacuum to be viewed effectively with an electron microscope
air would absorb the electrons
would prevent electrons reaching the specimen
compare scanning and transmission electron microscopes (6)
- both use electron beam
- both use dead specimens
- both use a vacuum
- both may contain artefacts
transmission
- 2D image
- need thin specimen
- electron beam goes through specimen
- higher resolution
scanning
- 3D image
- don’t need thin specimen
- electrons scattered on surface
- lower resolution
explain the advantages and limitations of using a transmission electron microscope (6)
advantages
- can view internal structures
- uses electron beam
- this has short wavelength
- high resolution
limitations
- cant examine living specimens
- need a vacuum
- lots of preparation needed
- may result in artefacts
