Protien Molecules

Question 1

What bonds are amino acids linked by

Answer 1

Covalent bonds in linear chain

Question 2

Primary structure of proteins

Answer 2

Linear amino acid sequence

Question 3

Secondary structure of proteins

Answer 3

Polypeptide folding into regular shapes (forms domains)

Question 4

Tertiary protein structure

Answer 4

Arrangement of one or more domains (3D structure)

Question 5

Quaternary protein structure

Answer 5

Arrangement of multiple polypeptide chains in one protein - forms protein complex with subunits

Question 6

What are domains

Answer 6

How elements of secondary structure are packed together

Question 7

What is the alpha carbon in an amino acid

Answer 7

Linked to amino group (-NH2), a carboxyl group (-COOH), a alpha hydrogen atom and an R group (chiral carbon)

Question 8

What form do amino acids exist in neutral pH

Answer 8

Zwitterion form at neutral pH

Question 9

What does the formation of a dipeptide from two amino acids results in

Answer 9

Loss of water - condensation reaction

Question 10

What is a residue

Answer 10

Each amino acid unit of polypeptide chain called a residue

Question 11

What structure do peptide bonds adopt

Answer 11

Rigid planar structure

Question 12

How are disulphide bonds formed

Answer 12

Between side chains of two cysteine residues under oxidising conditions

Question 13

How can disulphide bonds be cleaved

Answer 13

By reducing agents such as B (beta) - mercaptoe thanol

Question 14

What are histones composed of

Answer 14

DNA packaging - many Arg, Lys => very basic proteins

Question 15

What are membrane proteins composed of

Answer 15

Many Leu, Val and ile = > hydrophobic proteins

Question 16

What amino acids compose extracellular proteins

Answer 16

Many Cys to form disulphide bond, stable protein

Question 17

What is a result of cis configuration of side chains

Answer 17

Neighbouring amino acids can result in steric hinderance

Question 18

Types of non covalent bonds

Answer 18

Hydrogen bonds
Salt bridges (electrostatic interaction)
Vẫn đẻr waals interaction

Question 19

What are Hydrogen bonds essential for

Answer 19

Crucial for protein folding and formation of secondary structure

Question 20

Formation of salt bridges and their importance

Answer 20

-Formed by attractive forces between oppositely charged atoms
- important in quaternary structure formation

Question 21

Where do Hydrogen bonds form on secondary structure of protein

Answer 21

Between -Nh and -CO groups on different but adjacent strands

Question 22

What are the two main secondary structures of a protein

Answer 22

Alpha helixes (a-helices)
Beta sheet (B-sheet)

Question 23

What are tertiary structures composed of

Answer 23

‘Bundles’ (aka domains) of secondary structures

Question 24

Characteristics of a domain

Answer 24

-hydrophilic side chains exposed
-hydrophobic side chains buried in hydrophobic core

Question 25

What is a domain

Answer 25

Region of polypeptide chain that folds independently and self stabilising

Question 26

How do polypeptide chains fold

Answer 26

Fold spontaneously in aqueous environment

Question 27

What does the hydrophobic effect drive

Answer 27

Drives formation of hydrophobic core proteins and promotes tertiary structure formation

Question 28

What are the 3 classes of domain structures

Answer 28

-alpha helical domains -beta sheet domains -alpha/beta domains

Question 29

Characteristics of alpha helical domains

Answer 29

packed together in bundles or ‘coiled -coil’

Question 30

What do common domains consist of

Answer 30

-pair of helices -connected by short loop -packed in anti parallel arrangement

Question 31

What is a beta sandwich and it’s characteristics

Answer 31

-two beta sheets packed together -stabilised by ‘fillings’ - hydrophobic side chains

Question 32

What is the B - barrel and its characteristics

Answer 32

-eight b -strands may form closed ‘barrel’ structure (Chinese finger trap looking like) Hydrophobic residues orientated towards centre of barrel

Question 33

What is the Ross man fold

Answer 33

Beta strand and alpha helical repeats

Question 34

In clonal selection what happens to activated B cells

Answer 34

B cell clone will proliferate and differentiate into antibody secreting cells

Question 35

What is innate immunity

Answer 35

Rapid but non-specific

Question 36

What is adaptive immunity

Answer 36

Based on lymphocyte with antigen receptors - immunological memory

Question 37

What is the epitope

Answer 37

The antigenic determinant and site where antibody binds to on the antigen

Question 38

What is neutralisation in immunity

Answer 38

Binding of antibodies to epitope on surface of pathogens prevents entry to host cells

Question 39

What is opsonisation in immunity

Answer 39

The coating of a pathogen with molecules like antibodies and increases efficiency of phagocytosis

Question 40

What agglutination in immunity

Answer 40

The process of the clumping of pathogens driven by interaction of antibody with antigens and prevents spread of pathogens through the system

Question 41

What is the complement cascade in immunity

Answer 41

Antibody-antigen complex stimulates binding of Cl => activation of protease that triggers chains of amplification cascade

Question 42

What is antibody dependant cellular cytotoxicity in immunology

Answer 42

Mechanism where large pathogens are killed by secretion of cytotoxic

Question 43

What is the stimulation of cytokine release in immunology

Answer 43

IgE antibodies bind to receptors on mast cells and basophils => antigen binding to IgE on these cells stridulate the secretion of cytokines and histamine

Question 44

What does histamine do

Answer 44

Causes vasodilation and leafiness in blood vessels - its release causes allergic reactions

Question 45

What are IgE antibodies produced in response to

Answer 45

Response to parasites and environmental allergens e.g pollen, food and drugs

Question 46

What is the structure of immunoglobulin (Ig)/antibody)

Answer 46

-4 polypeptide chains - two heavy (H) chains - two light (L) chains -linked by disulphide bonds