8 Ass 4prac stuff Microscopy and cells pt 2

Question 1

What is Plasmodium?

Answer 1

A group of large parasitic eukaryotes that cause malaria

Question 2

Name 3 structures that Plasmodium would have 3

Answer 2

Golgi body, ribosomes, mitochondria

Question 3

How big are viruses?

Answer 3

20nm - 500nm

Question 4

How many um in 1 mm?

Answer 4

1000

Question 5

How many nm in 1 mm?

Answer 5

1000 000

Question 6

What are the key features of viruses? 7

Answer 6

Only replicate inside living cells

non-living

parasitic

genetic material takes over host cells protein synthesising system

Contain either DNA or RNA but never both

Capsid (protective protein coat)

some have phospholipid envelope

Question 7

Can a light microscope see a virus that’s 30nm in diameter?

Answer 7

No, because the virus is 30nm and a light microscope’s resolution is too low, and can only distinguish points 200nm or more apart

Question 8

How does a virus enter the cell? 3

Answer 8

It attaches to the receptors on the cell surface membrane

and enters the cell by endocytosis,

forming a vesicle inside the cell

Question 9

Define endocytosis 4

Answer 9

A type of active transport

moves particles like large molecules ,cells and cell parts into a cell

plasma membrane of cell engulfs target cell target particle

forms vesicles on other side of membrane

Question 10

What is the formula for calculating magnification?

Answer 10

I
AM

Question 11

How do you calculate magnification using a scale bar? 3

Answer 11

1. measure length of scale bar in mm
2. convert length in mm to um by multiplying by 1000
3. use I AM to find magnification

Question 12

How do you calculate magnification by measuring the size of a known cell? 3

Answer 12

1. measure diameter of cell in mm
2. Convert diameter to um by x by 1000
3. use magnification equation, using your known size as your actual size

Question 13

How do you calculate size when magnification is provided? 3

Answer 13

1. Measure the diameter of the cell in mm
2. convert to um by multiplying by 1000
3. use rearranged magnification equation to find actual size in um

Question 14

What is cytosol?

Answer 14

fluid contained in cell cytoplasm

Question 15

One function of lipid droplets is to store triglycerides. Triglycerides in droplet are surrounded by a monolayer of phospholipids. Why are phospholipids used for outermonolayer? 2

Answer 15

Phospholipids have both a hydrophobic and hydrophilic portion, whereas triglycerides are only hydrophobic

Phospholipid heads interact with the cytosol

Question 16

define hydrolytic

Answer 16

involving hydrolysis, a chemical reaction with water

Question 17

Why do lysosomes need acid hydrolases (hydrolytic enzymes that function in acid pH) to perform their function?

Answer 17

They are active in a lysosomes acidic pH and help to digest toxins and old cell organelles

Question 18

q22 d i) complete the diagram of trehalose

Answer 18

See marked paper

Question 19

How would one test for non-reducing sugars? 5

Answer 19

1. add 5cm^3 of food fresh food sample to test tube
2. boil food sample with hydrochloric acid
3. Neutralise test solution by adding sodium hydroxide
4. add 5cm^3 of Benedict’s reagent
5. heat test tube in thermostatic water bath set to 80 degrees C for 3 min

Question 20

What would the results of a test for non- reducing sugars be?

Answer 20

Colour change to brick red = non- reducing sugars

If darker solid forms, it has both reducing & non-reducing

if no colour change, then no sugar

Question 21

What is meant by a higher Km value? 3

Answer 21

The enzyme has a lower affinity,

so enzyme substrate complexes form and lead to products less readily

so it needs a higher higher substrate concentration to reach Vmax

Question 22

What does enzyme affinity mean? 2

Answer 22

A measure of how readily enzyme-substrate complexes form & lead to products

low affinity= substrate can leave active site without any reaction taking place

Question 23

What is meant by Km? 4

Answer 23

Michaelis-Menten Constant

can predict theoretical affinity of enzyme

value is substrate concentration at which enzyme works at 1/2 Vmax

lower Km=higher affinity bc Vmax reached at higher substrate concentrations & vice versa

Question 24

What is trehalase? 3

Answer 24

enzyme found in small intestine

catalyses conversion of trehalose to glucose

Optimal in low (acidic) pH

Question 25

Regulatory trehalase is only found in cytosol, and non-regulatory trehalase is in external surface of cell surface membrane & inside cell.

Where inside the cell can non-regulatory trehalase be found? 2

Answer 25

In the lysosome
because it’s acidic & trehalose is optimal in low pH

Question 26

Define intracellular

Answer 26

Found inside the cell

Question 27

Can both regulatory and non-regulatory trehalose be described as intracellular?

Answer 27

Yea, bc they’re both inside the cell

Question 28

22 f) read context and look at fig 4.3, also see 22 E context

with reference to fig 4.3, and to the 2 types of trehalase enzyme produced by S. cerevisiae, state & explain what can be deduced about the type of trehalase present in S. boulardii

Answer 28

Likely to be regulatory trehalose

because its optimum pH is 6.6,

which is nearer to the optimum at regulatory trehalose which is pH 7.0

There is very little activity at pH 4.5

Question 29

q 23a) read context & calculate magnification (scale bar is 37 mm)

Answer 29

Formula: M= Image size/actual size

image length= 37x 1000= 37000um

Actual length= 150 um

M= 37000/150

M=X247

Question 30

23 b) Read context and see fig 6.2 & state name of process which takes bacteria into cell at Z and describe the way it occurs 3

Answer 30

It’s endocytosis

Bacteria are engulfed by the membrane

and form vesicles on other side of membrane

Question 31

Describe the role of lysosomes in intracellular digestion 3

Answer 31

They are used to break down unwanted substances & old cell organelles

The fuse to the phagosome

Contain hydrolytic enzymes like prokaryotes & lipases