B2 Cells

Question 1

Name 3 components of the plasma membrane

Answer 1

Phospholipids
Proteins
Glycoproteins
Glycolipids
Cholesterol

Question 2

What organelle contains genetic information?

Answer 2

nucleus

Question 3

Describe the components of the nucleus

Answer 3

nuclear envelope- double me,brand surrounding nucleus
nuclear pores - gaps in nuclear envelope
nucleoplasm - granular, jelly-like material
chromosomes - make of DNA bound to his tones
nucleolus - inside nucleoplasm

Question 4

what is the role of the nucleolus

Answer 4

manufactures ribosomal RNA

Question 5

whats the job of the nuclear pores

Answer 5

allows mRNA to leave nucleus

Question 6

Whats the approx size of nuclear pores

Answer 6

400 - 100 um

Question 7

What organelle is found in large number of active cells

Answer 7

mitochondria

Question 8

What are the cristae made of and what are they for?

Answer 8

Extensions of the inner membrane Enzymes and proteins are attached to it Large surface area for respiration

Question 9

What is found in the matrix of the mitochondria?

Answer 9

Proteins
Lipids
Ribosomes
DNA

Question 10

Why do mitochondria have their own ribosomes and DNA?

Answer 10

to make their own proteins

Question 11

What organelle is found in plant and algae cells but not animal cells?

Answer 11

Cell wall
Cell vacuole Chloroplasts

Question 12

What are the grana made up of in chloroplasts?

Answer 12

Stacks of thylakoids

Question 13

What can be found inside thylakoids?

Answer 13

chlorophyll

Question 14

Explain how chloroplasts are adapted for their function?

Answer 14

Thylakoid membranes provide a large surface area for electron carriers

involved in the first stage of photosynthesis

The stroma contains the enzymes needed for the second stage of photosynthesis

Chloroplasts contain DNA and ribosomes so they can quickly make their own proteins

Question 15

What does the SER do?

Answer 15

Synthesises lipids

Question 16

9. What does the golgi body do?

Answer 16

Modifies proteins (eg forms glycoproteins)
And forms vesicles to transport modified proteins to cell membrane

Question 17

10. What is the function of a cell wall in plant cells?

Answer 17

Provides mechanical strength and prevents lysis when water enters

Question 18

11. What name do we give to a group of similar types of cells working together?

Answer 18

tissues

Question 19

12. What is an organ?

Answer 19

A group of similar tissue working together to perform a function

Question 20

13. What type of cell are animal and plant cells?

Answer 20

eukaryotic

Question 21

14. What type of organelles do prokaryotic cells not have?

Answer 21

no membrane bound organelles

Question 22

15. Describe the DNA in a prokaryote

Answer 22

Short
Circular not linear
Plasmids
Not associated with histones
No introns

Question 23

16. Name 3 structures that make up a virus

Answer 23

Genetic material
Capsid
Attachment protein

Question 24

17. Contrast the structure of a bacterial cell and the structure of a human cell.

Answer 24

1. Bacterial cell is much smaller than a human cell;
2. Bacterial cell has a cell wall but human cell does not;
3. Bacterial cell lacks a nucleus but human cell has a nucleus;
4. Bacterial cell lacks membrane-bound organelles but human cell has membrane-bound organelles;
5. Bacterial ribosomes smaller than human ribosomes
6. Bacterial DNA is circular but human DNA is linear;
7. Bacterial DNA is ‘naked’ whereas human DNA is bound to histones / proteins

Question 25

18. What cannot be seen in an optical microscope but can be seen in an electron microscope?

Answer 25

ribosomes

Question 26

19. What can be observed using an optical microscope that cannot be observed using an electron microscope?

Answer 26

Living specimens Specimens in colour

Question 27

20. Why does an electron microscope have a better resolution than an optical microscope?

Answer 27

Electrons have a shorter wavelength than light

Question 28

21. Contrast how an optical microscope and a transmission electron microscope work and contrast the limitations of their use when studying cells.

Answer 28

1. TEM use electrons and optical use light; 2. TEM allows a greater resolution; 3. So with TEM smaller organelles can be seen and in greater detail 4. TEM view only dead specimens and optical can view live specimens; 5. TEM does not show colour and optical can; 6. TEM requires thinner specimens; 7. TEM requires a more complex and time consuming preparation; 8. TEM focuses using magnets and optical uses (glass) lenses;

Question 29

22. What laboratory process can be used to separate the organelles?

Answer 29

Cell fractionation (homogenisation and ultracentrifugation)

Question 30

23. Explain two conditions needed for the process above.

Answer 30

Cold – slows/stops enzyme activity to prevent digestion of organells Isotonic (same water potential) – prevents osmosis so no lysis of organelles Buffered – maintains pH so that enzymes/ proteins not denatured

Question 31

24. Describe and explain how cell fractionation and ultracentrifugation can be used to isolate mitochondria from a suspension of animal cells.

Answer 31

1. Cell homogenisation to break open cells; 2. Filter to remove large debris; 3. Use isotonic solution to prevent damage to organelles; 4. Keep cold to reduce damage by enzymes / 5. Use buffer to prevent protein / enzyme denaturation; 6. Centrifuge at lower speed to separate heavy organelles; 7. Re-spin supernatant at higher speed to get organelle at bottom.