4. Gene mutations to mucoviscidosis

Question 1

Cystic Fibrosis Transmembrane Conductance Regulator

Answer 1

Impaired Cl- secretion

Enhanced Na+ absorption

Hyperabsorption of fluid and electrolytes

Decreased Airway Surface Liquid (ASL)

Bicarbonate secretion impaired

Mucoviscidosis

Question 2

Class I defect

Answer 2

No protein synthesis

Question 3

Class II defect

Answer 3

No processing / trafficking

Question 4

Class III defect

Answer 4

No regulation

Question 5

Class IV defect

Answer 5

Altered conductance

Question 6

Class V defect

Answer 6

Partial synthesis or processing

Question 7

DNA double helix

Answer 7

Executes a turn every 10 base pairs

Comprises a major and minor groove

Right handed helix major form

Question 8

Nucleosome

Answer 8

ds DNA + histones H2a, H2b, H3 and H4

146 bp of DNA form each nucleosome

Question 9

30 nm chromatin fibre

Answer 9

Nucleosomes + histone H1

Question 10

Giemsa staining

Answer 10

Heterochromatin = dark bands

Euchromatin = light bands

Question 11

CFTR gene

Answer 11

Chromosome 7
q = long arm
region = 31.2

Question 12

ΔF508 deletion

Answer 12

deletion on phenylalanine

CTT → ATT

Question 13

Centromere

Answer 13

specialized DNA sequence

α-satellite DNA binding site

Question 14

Telomeres

Answer 14

repeated nucleotide sequences

enable efficient replication

Question 15

DNA replication

Answer 15

Helix unwinds and the two complimentary strands separate

Each strand acts as a template for the formation of a new DNA molecule

New strand complimentary to template strand

2 new DNA helices are formed

each is identical to the parent

Enzyme – DNA polymerase

Question 16

RNA processing

Answer 16

Remove the introns and splice the exons of the message together

Add a cap structure to the 5’ end

Add a polyA+ tail to the 3’ end

Question 17

Transcription

Answer 17

RNA polymerases catalyze formation of phosphodiester bonds

moves along the unwinding DNA helix

5’-to-3’ direction

mRNA passes through the pores of the nuclear membrane into the cytoplasm

one end becomes attached to a ribosome

Question 18

What term is used to describe the nuclear material where transcription of genes is taking place?

Answer 18

Euchromatin

Question 19

The ΔF508 mutation of CFTR results in what class of error in protein production?

Answer 19

Class II - no trafficking

Question 20

What is the first amino acid that appears in the primary structure of all human proteins?

Answer 20

Methionine

Question 21

Ribosome

Answer 21

When not actively synthesizing proteins the two subunits of the ribosome are separate

Join together on an mRNA molecule
near its 5’ end

mRNA is pulled through the ribosome

as its codons encounter the ribosome’s active site the mRNA nucleotide sequence is translated into an amino acid sequence using the tRNAs as adaptors

stop codon

ribosome releases the finished protein

two subunits separate again

Question 22

Protein degradation

Answer 22

Proteases degrade proteins into short peptides

ubiquitin marks proteins to be destroyed by proteasomes

ΔF508 mutation 99% protein degraded

Question 23

Osmolarity

Answer 23

the number of moles (osmols) of particles per litre of
solution

(Osmol/L or Osmol . L-1)

Question 24

Osmolality

Answer 24

the number of osmols of particles per kg of solvent

Osmol/kg or Osmol . kg-1

Question 25

P-type ATPases

Answer 25

Active transport

Involved in H+, Na+, K+, and Ca2+ movement

The protein becomes phosphorylated by ATP during the transport process

Question 26

ABC Transporters

Answer 26

Contains two highly conserved ATP-binding cassettes

Use ATP binding and hydrolysis

Question 27

Passive Carrier-Mediated Transporters

Answer 27

1) Uniporter
2) Symporter
3) Antiporter

Question 28

Symporter

Answer 28

both molecules moving in same direction

Na+/ Glucose

Question 29

Antiporter

Answer 29

molecules moving in opposite directions

Cl- / HCO3-