Which of the following codons has a dual role in the genetic code?

(1) AUG

(2) GUG

(3) CUG

(4) UUG

 

What is the major difference between the lagging and leading strands during DNA replication ?

1. On the leading strand, DNA synthesis occurs from 5' to 3', while DNA synthesis occurs from 3' to 5' on the lagging strand.

2. DNA polymerase is able to continuously add new nucleotides on the leading strand while it must keep 'starting over' on the lagging strand.

3. The lagging strand requires only a single primer while the leading strand requires many.

4. Helicase opens the leading stran at a faster rate than the lagging strand.

The inducer of lac operon is :

1. Beta galactosidase

2. Galactose

3. Lactose

4. Glucose

regulatory domains of most activators interact with

1. the transcription factor complex

2. RNA polymerase

3. repressors

4. the DNA binding domain

DNA chemically is less reactive and structurally more stable than RNA. Therefore,

1. DNA has evolved from the RNA

2. RNA can directly code for proteins

3. DNA is the better genetic material than RNA

4. The protein synthesizing machinery has evolved around RNA

A transcription unit does not contain:

1. A promoter

2. The structural gene

3. A terminator

4. An operator

Regulation of lac operon by repressor is referred to as:

1. Inducible regulation

2. Repressible regulation

3. Negative regulation

4. Positive regulation

A synthetic mRNA of repeating sequence 5'-CACACACACACACACAC... is used for a cell-free protein synthesizing system like the one used used by Nirenberg. If we assume that protein synthesis can begin without the need for an initiator codon, what product or products would you expect to occur after protein synthesis?

1. one protein, consisting of a single amino acid

2. three proteins, each consisting of a different, single amino acid

3. two proteins, each with an alternating sequence of two different amino acids

4. one protein, with an alternating sequence of two different amino acids

Fredrick Griffith accidentally discovered transformation when attempting to develop a vaccine for pneumonia. He injected mice with samples from S-strain (virulent) and/or R-strain (nonvirulent) pneumococci bacteria (Sterptococcus pneumoniae). Which of the following results is NOT consistent with Griffith's experiments?

1. injected S-strain; mouse dies. 

2. injected R-strain; mouse lives. 

3. injected heat-killed S-strain; mouse lives. 

4. injected mixture of heat-killed S-strain and live R-strain; mouse lives. 

Which scientists first gave experimental evidence that DNA is the genetic material?