Information flow or central dogma of modern biology is

RNA → Proteins → DNA
DNA → RNA → Proteins
RNA → DNA → Proteins
DNA → RNA → Proteins

Triplet UUU codes for

leucine
methionine
phenylalanine
glycine

Which of the following statements about DNA replication is false?

Okazaki fragments are the initiators of continuous DNA synthesis along the leading strand.
Replication forks represent areas of active DNA synthesis on the chromosomes.
Error rates for DNA replication are often less than one in every billion base pairings.
Ligases and polymerases function in the vicinity of replication forks.

Solution

Okazaki fragments are found only along the lagging strand.

The key finding of the Hershey and Chase experiments on the mechanism of viral replication was that

protein, not DNA, is the hereditary material.
DNA, not protein, is the hereditary material.
protein and DNA play an equal role in determining inheritance.
neither protein nor DNA play a role in determining inheritance.

Solution

Hershey and Chase used radioactive labeling of sulphur and phosphorus to clearly demonstrate that DNA, and not protein, is the material that carries hereditary information.

Which of the following statements about the process of DNA replication is false?

Many different enzymes are needed for the process to function properly.
Mistakes can be corrected at multiple steps in the process.
Uncorrected mistakes introduce mutations into the DNA base sequence.
Mistakes in the copying process are very common occurrences.

Solution

Even though DNA replication typically occurs millions of times during the life of a multi cellular organism, it is remarkably error-free. Those errors that do occur are usually corrected with a high degree of reliability.

Assume that you chemically label both strands within a molecule of DNA. You then allow this DNA to replicate using unlabelled nucleotides. Which of the following statements about the two resulting DNA molecules is false?

Both will have the chemical label.
One will have the chemical label, the other will not.
One strand within each molecule will have the chemical label.
Assuming no replication errors, both molecules will be genetically identical.

Solution

In DNA replication, each strand of the original molecule serves as a template for the formation of anew strand,thus, each new molecule will have half of its nucleotides(and the chemical label) from the original molecule.

In order for the information contained in a gene to be used to produce a functioning protein, the

DNA must be replicated.
information must be transcribed into mRNA and then translated into amino acids.
tRNA must be transcribed into rRNA and then translated into amino acids.
ribosome must be converted from rRNA into mRNA.

Solution

Protein synthesis is a two-step process involving transcription in the cell nucleus followed by translation in the cytoplasm. All the other choices are either factually inaccurate or, if accurate, need not necessarily take place for protein synthesis to occur.

DNA is acidic due to

sugar
purine
phosphoric acid
pyrimidine

Nucleosome is

intron interrupted DNA
double helix DNA
negatively charged DNA wrapped around positively charged histone octomer
satellite DNA

Genes can be inactivated by

inaccurate removal of introns.
transposable genetic elements.
movement of genes to heterochromatic regions of the chromosome.
All of the above

Solution

Inaccurate removal of introns can create mRNAs that are missing coding sequence or that have extra non-coding sequences. Transposable genetic elements can move into the coding regions of genes, inactivating those gene products. Moving a gene to a heterochromatic (transcriptionally inactive) region of a chromosome results in that DNA beings inaccessible to the transcription complex.

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