2 - Cells

Question 1

Steps of differential centrifugation

Answer 1

1- Cells broken by grinding in cold (prevents enzyme actions/ no digestion of organelles), isotonic (no osmosis prevents organelles from shrinking or bursting), buffer (maintains pH so no enzymes denatured)
2-homogenate is filtered removes whole cells and cells debris
3- homogenate poured into tube and spun at low speed for less time and heaviest organelle (pellet) forms sediment
4 - heaviest to lightest - nucleus, chloroplasts, mitochondria, ER, ribosomes

Question 2

Role of organelles in producing and storing enzymes

Answer 2

-Nucleus genetic code for protein in genes
-mRNA leaves nucleus and binds to ribosome on RER
- protein synthesis
-Golgi body processes and packages enzymes into vesicles
-Vesicles transport protein to cell membrane where it fuses with membrane and is released out of cells

Question 3

Structure of Mitochondria

Answer 3

• Double membrane
  -Inner membrane is folded (cristae)
  -Fluid interior called matrix

Question 4

Function of SER and RER

Answer 4

SER- Produces and transports fats
RER - ribosomes attached which make proteins and transports proteins to golgi body

Question 5

Structure of chloroplast

Answer 5

-Enclosed by double membrane
-Contains thylakoid discs which contain chlorophyll pigment
- Stacks of thylakoids discs named grana
-Fluid interior called stroma
-Contains own DNA and 70s ribosomes

Question 6

What are the cell walls made out of in plants, algae and fungi

Answer 6

Plants- cellulose
Fungi- Chitin
Algae- cellulose or variety of glycoproteins