cell structure & microscopy incorrect Qs

Question 1

What features of animal cells are not found in plant cells?

Answer 1

• Centrioles; glycogen granules

Question 2

Do bacterial flagella form the 9+2 formation of microtubules?

Answer 2

No

Question 3

What organelles do bacteria not have which eukaryotes do?

Answer 3

mitochondria,

Question 4

Which parts of protein secretion require energy?

Answer 4

• Transport of vesicles
• exocytosis

Question 5

What dye is positively charged and therefore binds to negatively charged components in cytoplasm (leading to staining of cell components)?

Answer 5

• Crystal violet
• Methylene blue

Question 6

What is an example of a negative stain technique?

Answer 6

• Congo red; positively charged and thus repelled by negative cytosol. Creates a stained background against which cells stand out.

Question 7

What is differential staining

Answer 7

Can distinguish between two types of organisms that would otherwise be hard to identify. e.g Gram stain

Question 8

How is Gram staining done?

Answer 8

• Crystal violet is applied, then iodine which fixes the dye.
• The slide is then washed with alcohol.
• G+ retain CV; appear blue or purple.
• G- have thinner cell walls thus lose the stain; these are counterstained with safranin dye which leaves them red.

Question 9

Which bacteria types (G+ or G-) are susceptible to penicillin?

Answer 9

• G+; inhibits cell wall formation.
• G- have much thinner walls which are less susceptible.

Question 10

What other differential staining techniques are there?

Answer 10

• Mycobacterium can be differentiated with the acid-fast technique.

Question 11

What are channel proteins?

Answer 11

Channel proteins create holes/pores that penetrate the membrane, enabling target molecules or ions to flow through via diffusion without interfering with one another.

Question 12

What are carrier proteins?

Answer 12

Carrier proteins are proteins that bind to molecules or ions on one side of the membrane and release them on the other. Conformational change

Question 13

What steps can be taken to increase the validity of microscope slides?

Answer 13

• sharp blade (should be selected)
  so slide is thin enough , individual cells are visible / resolution is high

method for slicing pieces of tissue (thinly)
so slide is thin enough , individual cells are visible / resolution is high

select thin(nest) slides
to ensure maximum light can penetrate sample

wet mount
prevents dehydration / distortion of tissue

squash slide
easier to see individual cells / allows light to penetrate tissue more easily