Test 142  (Genetics)

1. DNA:

a. is found in herpes virus

b. is found in the nucleosomes

c. is found outside the cell nucleus

d. is replicated in the S phase of the cell cycle

e. duplicates simultaneously in all chromosomes
 

Answer
a.T   b.T   c.T   d.T   e.F
Nucleosome beads occur where DNA is wound
around four pairs of histone molecules.
It is found in the mitochondria.
DNA in heterochromatic duplicates late.

2. The following are true about mitochondria:

a. they are the main site of protein synthesis 

b. they have DNA arranged in circles

c. the inner membrane contains the enzymes needed 
    for Kreb's cycle

d. they contain a bilayer membrane

e. they contain DNA which are inherited exclusively 
    from the mother

Answer
a.F   b.T   c.T   d.F  e.T
Protein synthesis occurs in the ribosomes. They contain 
two bilayer membrane: both the inner and outer membrane are bilayer.

3. Heterochromatin:

a. contains a highly repetitive sequence of DNA

b. is the inert segment of the chromosome adjacent 
    to the centromere

c. may be lost without harmful effect in Robertsonian 
    translocation

d. is tightly coiled during the interphase 

e. makes up the p arm of the acrocentric chromosomes

Answera.T  b.T  c.T  d.T  e.T

4. Increase number of chromosomes occur in:

a. Turner's syndrome

b. fragile-X syndrome

c. Down's syndrome

d. Klinefelter's syndrome

e. Retinoblastoma

Answer
a.F   b.F  c.T  d.T  e.F
Turner's syndrome is one chromosome short.
The number is normal for fragile-X syndrome and retinoblastoma.

5. The following are true:

a. mRNA can be detected with Southern blotting

b. DNA can be detected with Northern blotting

c. restriction endonucleases cut the DNA into 
    lengths of about 20 nucleotide base sequences

d. restriction fragment length polymorphism occurs
    mainly in the coding region of the DNA

e. polymerase chain reaction requires the use of 
    DNA polymerase 

 
Answer
a.F   b.F  c.F   d.F  e.T
Southern blotting is used to detect DNA whereas Northern blotting for mRNA. Restriction endonucleases cut the DNA into lengths of 4 to 6 nucleotide base sequences.
Restriction fragment length polymorphism (RFLP) are due to intron polymorphisms. Introns are sections of DNA that will be spliced out after transcription, but before the RNA is used. 

 

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