Cells Flashcards
(27 cards)
Describe how you could use cell fractionation to isolate chloroplasts from leaf tissue.
- ultracentrifugation to release the organelles and filter
* Make sure solution is cold/isotonic/buffered
What are the 3 parts of a chloroplast.
Stroma, granum (which contains thylakoids with chlorophyll
Pigment) and chloroplast envelope
What two structures in a eukaryotic cell that can’t be identified with a optical microscope?
Ribosomes and mitochondria
Describe how you can make a temporary mount of a piece of plant tissue to observe the position of starch grains in the cells when using an optical (light) microscope.
- thin sample
- add a drop of iodine solution to create a pigment
- place a cover slip over the sample
What’s the difference between TEM and SEM?
- specimens don’t have to be as thin
- SEM directs a beam of electrons onto the surface rather than penetrating it from below
- 3D image can be created easily by the SEM, for the TEM it’s a long and complicated process
- SEM has a lower resolving power but still better than a light microscope
How do you calculate magnification?
- measure the scale (mm to μm)
- convert mm to μm
- Put the converted number over the scale given
What’s the organelle found in plant cells that contains inner membranes arranged in stacks?
Chloroplasts
What’s the function of chloroplasts?
Site of photosynthesis therefore produce sugars and ATP
What organelle is found in both prokaryotic and eukaryotic cells?
Ribosome
Why does a solution need to be cold, isotonic and buffered for centrifugation?
Slows enzyme activity, prevents fluctuations in pH and Temp and prevents osmosis so the cell dosen’t shrivel
What’s the 2 parts of a mitochondrion?
Christae and matrix
What does the mitochondria do?
Produces ATP via aerobic respiration and released energy to contract muscles
What’s the role of microvilli?
To provide a large SA for diffusion
Why does an electron microscope show more detail of cell structure than a light microscope?
Greater resolving power therefore smaller objects can’t be distinguished as it has a shorter wavelength.
Describe ultracentrifugation.
6ish points
- tube of filtrate is placed in centrifuge and spun at low speed.
- heaviest organelles (nuclei) are forced to the bottom of the tube, (pellet)
- the fluid at the top of the tube (supernatant) is removed, leaving the sediment of nuclei
- the supernatant is then spun a faster speed
- the next heaviest organelles (mitochondria) are forced to bottom of the tube
- the process is continued this way increasing the speed each time the supernatant is spun.
Limitations of the TEM.
- whole system needs to be in a vacuum
- complex staining process
- not coloured image produced
- Specimen needs to be extremely thin
What’s the role of the RER
- Provide large SA for protein synthesis and synthesis of glycoproteins
- provide pathway for transport of materials (especially proteins) through the cell
What’s the role of the SER?
- synthesise, store and transport lipids
* synthesise, store and transport carbohydrates
What’s the role of Lysosomes
- Hydrolyse material ingested by phagocytise cells (eg white blood cells and bacteria)
- release enzymes to the outside of the cell in order to destroy material around the cell
- digest worn out organelles so the chemicals they are made of can be re-used
- breakdown cells after they died
What’s the role of the vacuole
- support herbaceous plants by making cells turgid
- sugars and amino acids may act as a temporary food store
- pigment for attracting pollinating insects
What organelles does a bacterial cell have?
Flagellum, genetic material, cytoplasm, ribosomes, cell surface membrane, cell wall, capsule and plasmid
Why would the Elisa test be used in a lab?
Test for antigens in blood plasma ✔️
What’s the point of washing the well after an Elisa test?
Wash away any unbound antibodies, if not washed the old antibodies could bind to the enzyme creating a false positive ✔️
Name the features in a eukaryotic cell structure.
- Nuclear envelope
- Nuclear pores
- nucleoplasm
- chromosomes
- nucleolus ✔️
