First Aid, Chapter 1 Immune mechanisms: Immunogenetics

Question 1

Name the DNA bases (nucleotides). What are the categories. Which pair together.

Answer 1

Adenine (A), guanine (G), thymine (T), and cytosine (C). A and G are purines. T and C are pyrimidines. A forms a base pair with T and G forms a base pair with C.

Question 2

What nucleotides are in RNA?

Answer 2

A, G, Uracil (instead of T), and C.

Question 3

What is the step-wise process of making protein from DNA and RNA. What is each step called?

Answer 3

 mRNA is copied from DNA and travels to ribosome.  tRNA transports amino acids to ribosome.  rRNA and protein combine to make ribosomes.
Transcription is the synthesis of mRNA from DNA. Translation is the synthesis of proteins from mRNA.

Question 4

What types of mutations are passed down to generations? What mutations do not get passed down?

Answer 4

 Germ-line mutations can be passed down via reproductive cells.  Somatic mutations involve cells outside the reproductive system and generally do not get passed to subsequent generations.

Question 5

What do the following mutations mean? frameshift, missesne, nonsense, silent, and neutral?

Answer 5

Frameshift- Insertion or deletion causes a shift in the translational reading frame. More dramatic effect on peptide sequence.

Missense Single-nucleotide substitution causes the translation of a different amino acid.

Nonsense Single-nucleotide substitution causes an early stop (or termination) codon.

Silent Single-nucleotide substitution does not cause a change in amino acid sequence

Neutral Single-nucleotide substitution causes a different but similar amino acid to be translated

Question 6

What is an SNP?

Answer 6

 A single-nucleotide polymorphism (SNP) is a variation in DNA sequence that occurs when a single nucleotide in a gene of an individual is different from that of other individuals.  SNPs are not mutations. SNPs usually occur more frequently in noncoding DNA sequences. Overall, these occur at a higher frequency than mutations

Question 7

Why are SNPs useful for tracking human genetic variations?

Answer 7

SNPs occur in varying frequency between different geographic and ethnic groups. Therefore, they are useful markers of human genetic variations, which sometimes underlie different susceptibilities to diseases

Question 8

What kind of studies are SNPs used in?

Answer 8

genome-wide association studies (GWAS) as highresolution gene-mapping markers related to various diseases

Question 9

What is the protein encoded by the filaggrin gene? What is the function? What is the relevance in atopy?

Answer 9

Protein - Filaggrin
Function - Essential for epidermal barrier
Atopy relevance - Increased risk of eczema and asthma

Question 10

What is the protein encoded by the 17q12-21 gene? What is the function? What is the relevance in atopy?

Answer 10

Protein - ORMDL3
Function - Unknown
Atopy relevance - Increased risk of asthma

Question 11

What is the protein encoded by the 5q22-32 gene? What is the function? What is the relevance in atopy?

Answer 11

Protein - CD14
Function - Lipopolysaccharide (LPS) receptor
Atopy relevance - Both increased as well as reduced risk of asthma and atopy

Question 12

What is the protein encoded by the 3p21-22 gene? What is the function? What is the relevance in atopy?

Answer 12

Protein - CCR5
Function - Chemokine receptor
Atopy relevance - Protection against nonatopic asthma

Question 13

What is the protein encoded by the Xp22 gene? What is the function? What is the relevance in atopy?

Answer 13

Protein - TLR7 and 8
Function - Pattern recognition receptor for viral ssRNA
Atopy relevance -
Increased risk for asthma, rhinitis, atopic dermatitis, and increased specific IgE

Question 14

What is the protein encoded by the 5q31 gene? What is the function? What is the relevance in atopy?

Answer 14

Protein - IL-13
Function - Cytokine that induces IgE secretion, mucus production, and collagen synthesis
Atopy relevance - Increased risk of asthma, bronchial hyper-responsiveness, and skin-test responsiveness. Linked to response to montelukast

Question 15

What is the protein encoded by the ADRB2 gene? What is the function? What is the relevance in atopy?

Answer 15

Protein - B2 -adrenergic receptor
Function - adrenaline and nonadrenaline receptor
Atopy relevance - Arg/Arg phenotype with decreased albuterol response compared with Gly/Gly phenotype at residue 16

Question 16

What is the protein encoded by the ADAM33 gene? What is the function? What is the relevance in atopy?

Answer 16

Protein - Type 1 transmembrane protein
Function - Involved in cell-to-cell interactions
Atopy relevance - Increased risk of asthma and bronchial hyperresponsiveness

Question 17

What is epigenetics?

Answer 17

changes in gene function that occur without a change in the sequence of DNA. These changes occur as a result of the interaction of the environment with the genome.

Question 18

What are 2 genetic mechanisms that cause epigenetic changes?

Answer 18

DNA methylation and histone modification.