8 Ass 4prac stuff Microscopy and cells pt 2 Flashcards

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1
Q

What is Plasmodium?

A

A group of large parasitic eukaryotes that cause malaria

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2
Q

Name 3 structures that Plasmodium would have 3

A

Golgi body, ribosomes, mitochondria

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3
Q

How big are viruses?

A

20nm - 500nm

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4
Q

How many um in 1 mm?

A

1000

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5
Q

How many nm in 1 mm?

A

1000 000

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6
Q

What are the key features of viruses? 7

A

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

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7
Q

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

A

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

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8
Q

How does a virus enter the cell? 3

A

It attaches to the receptors on the cell surface membrane

and enters the cell by endocytosis,

forming a vesicle inside the cell

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9
Q

Define endocytosis 4

A

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

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10
Q

What is the formula for calculating magnification?

A

I
AM

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11
Q

How do you calculate magnification using a scale bar? 3

A
  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
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12
Q

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

A
  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
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13
Q

How do you calculate size when magnification is provided? 3

A
  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
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14
Q

What is cytosol?

A

fluid contained in cell cytoplasm

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15
Q

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

A

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

Phospholipid heads interact with the cytosol

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16
Q

define hydrolytic

A

involving hydrolysis, a chemical reaction with water

17
Q

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

A

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

18
Q

q22 d i) complete the diagram of trehalose

A

See marked paper

19
Q

How would one test for non-reducing sugars? 5

A
  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
20
Q

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

A

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

21
Q

What is meant by a higher Km value? 3

A

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

22
Q

What does enzyme affinity mean? 2

A

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

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

23
Q

What is meant by Km? 4

A

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

24
Q

What is trehalase? 3

A

enzyme found in small intestine

catalyses conversion of trehalose to glucose

Optimal in low (acidic) pH

25
Q

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

A

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

26
Q

Define intracellular

A

Found inside the cell

27
Q

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

A

Yea, bc they’re both inside the cell

28
Q

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

A

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

29
Q

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

A

Formula: M= Image size/actual size

image length= 37x 1000= 37000um

Actual length= 150 um

M= 37000/150

M=X247

30
Q

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

A

It’s endocytosis

Bacteria are engulfed by the membrane

and form vesicles on other side of membrane

31
Q

Describe the role of lysosomes in intracellular digestion 3

A

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

The fuse to the phagosome

Contain hydrolytic enzymes like prokaryotes & lipases