8 Ass 4prac stuff Microscopy and cells pt 2 Flashcards
What is Plasmodium?
A group of large parasitic eukaryotes that cause malaria
Name 3 structures that Plasmodium would have 3
Golgi body, ribosomes, mitochondria
How big are viruses?
20nm - 500nm
How many um in 1 mm?
1000
How many nm in 1 mm?
1000 000
What are the key features of viruses? 7
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
Can a light microscope see a virus that’s 30nm in diameter?
No, because the virus is 30nm and a light microscope’s resolution is too low, and can only distinguish points 200nm or more apart
How does a virus enter the cell? 3
It attaches to the receptors on the cell surface membrane
and enters the cell by endocytosis,
forming a vesicle inside the cell
Define endocytosis 4
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
What is the formula for calculating magnification?
I
AM
How do you calculate magnification using a scale bar? 3
- measure length of scale bar in mm
- convert length in mm to um by multiplying by 1000
- use I AM to find magnification
How do you calculate magnification by measuring the size of a known cell? 3
- measure diameter of cell in mm
- Convert diameter to um by x by 1000
- use magnification equation, using your known size as your actual size
How do you calculate size when magnification is provided? 3
- Measure the diameter of the cell in mm
- convert to um by multiplying by 1000
- use rearranged magnification equation to find actual size in um
What is cytosol?
fluid contained in cell cytoplasm
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
Phospholipids have both a hydrophobic and hydrophilic portion, whereas triglycerides are only hydrophobic
Phospholipid heads interact with the cytosol
define hydrolytic
involving hydrolysis, a chemical reaction with water
Why do lysosomes need acid hydrolases (hydrolytic enzymes that function in acid pH) to perform their function?
They are active in a lysosomes acidic pH and help to digest toxins and old cell organelles
q22 d i) complete the diagram of trehalose
See marked paper
How would one test for non-reducing sugars? 5
- add 5cm^3 of food fresh food sample to test tube
- boil food sample with hydrochloric acid
- Neutralise test solution by adding sodium hydroxide
- add 5cm^3 of Benedict’s reagent
- heat test tube in thermostatic water bath set to 80 degrees C for 3 min
What would the results of a test for non- reducing sugars be?
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
What is meant by a higher Km value? 3
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
What does enzyme affinity mean? 2
A measure of how readily enzyme-substrate complexes form & lead to products
low affinity= substrate can leave active site without any reaction taking place
What is meant by Km? 4
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
What is trehalase? 3
enzyme found in small intestine
catalyses conversion of trehalose to glucose
Optimal in low (acidic) pH
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
In the lysosome
because it’s acidic & trehalose is optimal in low pH
Define intracellular
Found inside the cell
Can both regulatory and non-regulatory trehalose be described as intracellular?
Yea, bc they’re both inside the cell
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
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
q 23a) read context & calculate magnification (scale bar is 37 mm)
Formula: M= Image size/actual size
image length= 37x 1000= 37000um
Actual length= 150 um
M= 37000/150
M=X247
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
It’s endocytosis
Bacteria are engulfed by the membrane
and form vesicles on other side of membrane
Describe the role of lysosomes in intracellular digestion 3
They are used to break down unwanted substances & old cell organelles
The fuse to the phagosome
Contain hydrolytic enzymes like prokaryotes & lipases
