Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Molecular Physiology And Pathophysiology > Lecture 2 > Flashcards

Lecture 2 Flashcards

1
Q

MUC =

A

Mucins in humans

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Muc =

A

Mucins in mice

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the major mucin in the small intestine?

A

MUC2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What happens to aspirin when it goes into the stomach?

A

When combined with the acid it becomes uncharged and so it can cross the cell membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What happens do ethanol when it is in the stomach?

A

It has its own charge and so it can be absorbed across the stomach

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What type of organ is the stomach?

A

It is a non-absorptive organ

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What types of mucin are absorbed in the stomach?

A

MUC5AC and 6

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the MW of a mucin polymer?

A

2million MW and when it forms complexes the MW is 10 million

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the structure of a mucin polymer?

A

Has a variable tangent repeat, a density glycosylated region, Globular domains and disulphide bridges linking subunits into polymers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are VNTR also called?

A

An STP region as they contain serine, theronine and proline

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What can attach to the STP region?

A

Carbohydrates can attach

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the regions between the VNTR?

A

They are exposed to proteolytic enxymes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How do the mucin polymers polymerise?

A

By disulphide brides - can polymerise at the C and N terminal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What needs to happen in order for mucin to form a gel?

A

Mucin needs to be polymerised

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What can the gaps in between the VNTR be degraded by?

A

Can be degraded by pepsin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What ends up in the colon?

A

A soluble mucin glycoprotein that can’t be further digested by proteinase, so it wont be able to form a gel.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What type of balance is needed in the stomach?

A

A dynamic balance - between secretion and the pepsin that is degrading the mucus from the surface - a dynamic balance is needed to maintain the thickness of the mucus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is pepsin?

A

It is a damaging agent and is found in the stomach in gastric juice

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What pepsin subgroups are found in gastric juice in humans?

A

A and C

20
Q

Can pepsin diffuse through mucus?

A

No because it is too large

21
Q

How does pepsin get to the cell surface?

A

Mucus would need to be digested

22
Q

What pepsin is the most negatively charged?

A

Pepsin 1

23
Q

What type of pepsin is the least negatively charged?

A

Pepsin 6

24
Q

What are two ways to separate pepsins?

A

Gel electrophoresis and HPLC

25
Q

What are the main pepsins in gastric juice?

A

5,3,1- and they are separated by anion exchange

26
Q

What happens to pepsin during reflux?

A

Some of the gastric juice will end up on your larynx, this will be neutralised but the pepsin will be stuck to the larynx. Th next reflux there is a drop in pH, as the pepsin that got stuck is already sitting there

27
Q

When is pepsin activated?

A

When there is a change in pH

28
Q

What covers the active site of pepsin?

A

A lid which is formed by the n terminal

29
Q

What are the two points of cleavage on the pepsin molecule?

A

16 and 17 and 44 and 45

30
Q

Where does pepsin cleave?

A

Between 2 hydrophobic amino acids

31
Q

What is the difference between pepsin and pepsinogen?

A

Pepsin has a bit missing, and end chopped off

32
Q

What happens to the lid at a pH of 5?

A

To is held away from the active site, and it is held up by salt bridges or charge-charge interactions

33
Q

What happens above pH5?

A

Histamine, lysine and arginine and +ve charged and aspartate and glutamate are -ve charged

34
Q

What happens when the pH decreases below pH5?

A

Aspartate and glutamate will get protonated - they wont be charged anymore, they have lost the negative charge

35
Q

What happens when the bridge is lost? Below pH5

A

The lid will drop into the active site, the active site becomes activated and cleaves the end terminal between 1-16 amino acids

36
Q

What can propepsin interact with?

A

Other propepsin molecules or full active pepsin molecules

37
Q

What is the pepsin structure?

A

N terminal is slightly different to the c terminal, a central valley is where the active site is held

38
Q

What is pepsinogen structure?

A

The N and C terminals are almost identical

39
Q

What does the active site in the pepsin structure rely on?

A

Relies on two aspartate residues (32 and 215)

40
Q

What is the active site residue reliant on?

A

Relies on one aspartate being ionised and the other being protonated

41
Q

Can you reform pepsinogen from Pepsin?

A

No - because pepsin has the N terminal chopped off

42
Q

When does pepsin denature?

A

At pH8

43
Q

What is the structure/ stability of pepsin at pH 8?

A

Long and denatured, the molecule has been unfolded

44
Q

What happens if pepsin was to be refolded after it had been denatured?

A

It won’t fold properly because the n terminal is not in the right shape, instead of a valley for the active site there is a an open plane - you can reactivate pepsin once it has been denatured

45
Q

How long is pepsin in humans?

A

47 amino acids long

46
Q

Why is pepsin a good antimicrobial?

A

Because it will digest the bacteria. The bits cleaved off the pepsin will also have good antimicrobial activity

Molecular Physiology And Pathophysiology (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions