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Immunology Final > Quiz 3 Part 1 > Flashcards

Quiz 3 Part 1 Flashcards

1
Q

Do B cells circulate or are they stationary?

A

both
They circulate through the blood and plasma but are stationary in secondary lymphoid tissue (ex: lymph node)

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2
Q

Antibodies are members of ____ superfamily and are produced and secreted by _____

A

Antibodies are members of IMMUNOGLOBULIN superfamily and are produced and secreted by PLASMA CELLS (effector B cells)

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3
Q

What is the function of B cells and antibodies?

A

to clear extracellular (bacterial) pathogens and toxins in the ADAPTIVE immune response

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4
Q

What are the 2 ways in which B cells/antibodies act to clear extracellular pathogens in the adaptive immune response? Explain both of them

A

neutralization and opsonization

neutralization – antibody binds to pathogen which prevents it from growing and reproducing

opsonization – coats the pathogen with antibody if the membrane of the pathogen has a recognizable structure (ex mannose) all over its membrane

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5
Q

What can you say about the capabilities of antibodies and B cells to recognize pathogen?

A

they have VAST capabilities for recognition

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6
Q

What are the 2 most common antigens?

A

proteins and carbohydrates

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7
Q

Each B cell manufactures a single form of ____ that recognizes a specific antigen

A

immunoglobulin (another word for antibody)

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8
Q

What happens to B cells that are not stimulated?

A

they continue recirculating and die.
This happens most of the time because it is very rare that the adaptive response is initiated — the innate system is usually able to handle it

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9
Q

What can you say about the receptors on B cells?

A

A B cell has MANY of the SAME receptors on its surface that look exactly like the antibody it can produce

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10
Q

Explain how antibodies are produced

A

a resting B cell (has antibody-looking receptors on its surface) encounters an antigen and binds to it. This stimulates the B cell to give rise to plasma cells that secrete soluble antibodies specific to the pathogen

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11
Q

Describe an antibody from a STRUCTURAL POV

A

From a structural point of view, an antibody has 2 “light chains” on the outside of both forks of the “Y”

and 2 “heavy chains” that stretch from the inside of both forks of the Y and down to the base

THERE ARE ALSO CARBOHYDRATES ATTACHED TO THE BASE OF THE Y AND DISULFIDE BONDS HOLDING THE ANTIBODY TOGETHER

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12
Q

What is N termini and C termini?

A

N termini refers to the ends of the “forks” of the Y and C termini refers to the end of the base of the Y

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13
Q

How many heavy chains are there and how many light chains are there?

A

2 heavy chains and 2 light chains

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14
Q

Describe an antibody from a functional point of view

A

an antibody has a variable region and a constant region

the variable region is the top portion of the forks of the Y.

the constant region is the bottom portion of the forks down to the base of the Y

There is also a hinge region

The antigen binding sites are located at the very top of the Y in the variable region

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15
Q

Which region of an antibody has extensive diversity

A

the variable region (antigen binding site)

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16
Q

What is the function of the constant region?

A

to bind immune components and determine classification and effector function

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17
Q

What are the 5 isotypes of heavy chain

A

gamma
mu (micro symbol)
delta
alpha
epsilon

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18
Q

What are the 2 isotypes of light chain

A

kappa
lambda

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19
Q

What is the most abundant heavy chain and what is the name of the class of antibody proteins with this heavy chain?

A

most abundant = gamma heavy chain

makes IgG antibody proteins

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20
Q

What is the second most abundant heavy chain and what is the name of the class of antibody proteins that it makes up

A

second most abundant = mu

IgM

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21
Q

Which antibodies have 3 modules in the bottom portion of their constant chain as opposed to the normal 2?

A

IgM and IgE

22
Q

Which 2 antibodies have a very short hinge region?

A

IgM and IgE

23
Q

How many total carbohydrates are on IgG?

A

2 (one on each side of the base of the Y)

24
Q

Why is the hinge region of an antibody significant?

A

the hinge region allows for flexibility in binding site arrangement

25
Q

What is the downside of the hinge region?

A

the hinge region makes the antibody susceptible to proteases. The longer the hinge region the less stable the antibody is

26
Q

Explain what happens when an antibody gets clipped by a protease

A

when an antibody is cleaved by a protease at the hinge region, 2 “fab” fragments are produced (previously the stalks of the Y) and a Fc region is produced (used to be the base of theY)

27
Q

Can the Fab fragments still recognize pathogens?

A

yes, but they cant do anything about it. inactivated

28
Q

Name the 3 different ways of describing antibody structure

A
  1. light chain and heavy chain (structural)
  2. Variable and constant region (functional)
  3. Fab and Fc cleavage products (due to proteolytic activity)
29
Q

An antibody molecule has how many globular regions?

A

3 regions with 4 domains (modules) each

30
Q

immunoglobulin domains are made up of around _____ base pair sequence motifs

A

around 100 base pairs

31
Q

Is an antibody composed of alpha helices or beta sheets?

A

bundles of beta sheets

32
Q

Each immunoglobulin domain is composed of _______ and ______

A

each immunoglobulin domain is composed of TWO beta sheets and connecting loop regions

33
Q

The most sequence diversity exists in……

A

(HV) hypervariable regions —- loops

34
Q

The most conserved sequence exists in….

A

(FR) framework regions — beta sheets

35
Q

What exactly forms the antigen binding site on an antibody?

A

hypervariable regions (loops) from both heavy and light chains form the antigen binding site

36
Q

hypervariable regions can also be called….

A

complementary-determining regions

37
Q

If a pathogen has a negatively charged surface and so does the antibody, but their shapes fit perfectly, will stable binding occur?

A

NO

38
Q

If pathogen is hydrophobic and antibody is either postitive OR negative, will stable binding occur? explain

A

NO — hydrophobic will only bind to things with no charge

39
Q

Will hydrophobic pathogen and hydrophobic antibody form a stable bond?

A

yes

39
Q

A stable bond between a pathogen and an antibody is dependent upon which 2 things?

A

structure and chage

40
Q

A lot of antibodies end up recognizing….

A

structures ON THE CELL MEMBRANE of the pathogen (ie: glycoprotein, polysaccharides, peptidoglycans)

41
Q

What is the NAME of the antibody binding site?

A

epitope

42
Q

What does the term multivalent antigen mean

A

antigens can have several different epitopes for antibody binding, OR have repeats of the same epitope (ie: gram negative bacteria has THOUSANDS of LPS on its surface)

43
Q

scenario:

a multivalent antigen has 4 DIFFERENT epitopes. explain what will happen

A

this antigen will bind 4 UNIQUE antibodies to form a complex.
This is a process called neutralization. The antibodies are binding to the toxin

44
Q

scenario:

a multivalent antigen has a REPEATED epitope along its plasma membrane. explain what will happen

A

the SAME antibody will bind all over the pathogen. this is known as opsonization. (this could happen with gram negative bacteria bc LPS is all over it)

45
Q

Is antibody binding covalent?

A

NO it is noncovalent.
it happens due to electrostatic and hydrophobic interactions

46
Q

Where does binding of the antigen occur on an antibody?

A

at HV regions (6 sites that vary in length, sequence, and chemical properties)

47
Q

Give an example of when the HV region of an antibody would bind very strongly to the antigen

A

when the HV regions and the epitope are HIGHLY complementary (ie: lot of positive, lot of negative, or highly hydrophobic and highly hydrophobic)

48
Q

Why is high affinity bonding good?

A

high affinity bonding gives rise to more effective and more selective antibodies

49
Q
A

Immunology Final (12 decks)

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