Ch. 17 Quiz Flashcards Preview

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Flashcards in Ch. 17 Quiz Deck (17)
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1
Q

Why might a defective gene not have an effect on an organisms phenotype?

A

Because the organism is diploid and the other copy compensated for the defective copy

2
Q

Which of the following is the first molecular disease to be identified?

A

Sickle cell anemia

3
Q

What causes Down syndrome?

A

An extra copy of chromosome 21

4
Q

What are dominant negative mutations?

A

A mutant protein that loses its own function and also interferes with the function of another, non-mutated, protein

5
Q

What are dynamic mutations?

A

Tandem repeats of bases within the coding regions of DNA that increase in number each generation

6
Q

When does imprinting occur?

A

Methylation patterns in gametes survive and affect gene expression in the new organism

7
Q

Why are mitochondrial defects surprisingly prevalent?

A

All of the above

  • damage to DNA due to reactive oxygen species is much higher
  • mitochondrial DNA is not protected by histones
  • mitochondria contain few repair systems
  • mitochondrial DNA has much higher mutation rate than nuclear DNA
8
Q

How are mitochondrial disorders inherited?

A

Maternally

9
Q

In what way can the presence of a genetic defect on a segment of DNA be screened after positional cloning?

A

All of the above

  • sequencing of the DNA
  • hybridization of mRNA extracted from the tissues most affected by the disease to suspect DNA
  • by the presence of open reading frames
  • identification of CpG islands
10
Q

Which ion channel is defective in people with cystic fibrosis?

A

Chloride transporter

11
Q

What advantage does a delta(F508) heterozygote have over a patient with cystic fibrosis (i.e. homozygous for delta(F508))?

A

They are more resistant to the effects of enteric diseases, such as typhoid and cholera

12
Q

Which statement about CRISPR is false?

A

CRISPR is exactly the same as RNAi.

13
Q

Of the following nucleases, which is currently in clinical trials for gene editing?

A

Zinc-finger

14
Q

Which of the following has been approved for age-related macular degeneration?

A

Aptamers

15
Q

Why is mating between close relatives not a good idea, genetically?

A

Recessive genes within the family have a chance to come together and cause disease

16
Q

What is a specific case in which genetic screening has saved and improved the quality of life for an individual through diet modification?

A

Phenylketonuria

17
Q

True about CRISPR

A
  • CRISPR is a bacterial system that combats foreign DNA
  • CRISPR uses guide RNAs derived from foreign genetic material
  • Cas nuclease destroys foreign genetic material
  • short sequences of foreign DNA are stored within the hosts own genome