studying cells

Question 1

Describe how you could use cell fractionation to isolate chloroplasts from leaf tissue.

Answer 1

1.How to break open cells and remove debris filtering it;
2.Solution is cold / isotonic / buffered;
3. Second pellet is chloroplast.

Question 2

what is stack of thylakoid?

Answer 2

granum

Question 2

how do you get a squid free cell

Answer 2

remove supernatant

Question 3

what is a toxin made up of

Answer 3

protein

Question 3

Describe the principles and the limitations of using a transmission electron
microscope to investigate cell structure.

Answer 3

Principles:
1. Electrons pass through / enter (thin) specimen;
2. Denser parts absorb more electrons;
3. (So) denser parts appear darker;
4. Electrons have short wavelength so give high resolution;

Limitations:
5. Cannot look at living material / Must be in a vacuum;
6. Specimen must be (very) thin;
7. Artefacts present;
8. Complex staining method / complex / long preparation time;
9. Image not in 3D / only 2D images produced.

Question 4

Describe and explain how cell fractionation and ultracentrifugation can be used to

isolate mitochondria from a suspension of animal cells.

Answer 4

1. Cell homogenisation to break open cells;
2. Filter to remove (large) debris / whole cells;
   3.Use isotonic solution to prevent damage to mitochondria (osmosis) / organelles;
   4.Keep cold to prevent / reduce damage by enzymes
   5.use buffer to
   prevent protein / enzyme denaturation;
   6.Centrifuge to separate nuclei
3. Re-spin (supernatant / after nuclei / pellet removed) at higher speed to
   get mitochondria in pellet / at bottom.

Question 5

what comes first in the sediment of a centrifuge

Answer 5

nucleus

Question 6

what comes second in a centrifuge

Answer 6

mitochondria and chloroplasts

Question 7

what comes 3rd in the centrifuge?

Answer 7

lysosomes

Question 8

what comes 4th in the centrifuge?

Answer 8

endoplasmic reticulum and ribosomes