Exam 4: Molecular Biology

DNA replication is started with a(n)________,which,in most cases,in vivo is a short stretch of ________.

The formation of new DNA does NOT require energy.

DNA-binding proteins interact predominantly within which portion of a double-stranded DNA helix?

You are trying to design a protein that will be expressed in Escherichia coli and secreted outside of the cell for purification and use as a pharmaceutical.E.coli is a gram-negative cell and the protein folds after it has exited the cell.Which secretion system would work best for this project? Support your answer with evidence based on the properties of E.coli,the protein,and the secretion system.

Some essential genes and DNA sequences in cells DO NOT encode for proteins but are still essential for cellular growth and replication.Give two examples of a gene or sequence of which this is true and explain why it is essential for growth or replication.

The Tat system is involved in

DNA replication always proceeds in only one direction because the ________ of the incoming nucleotide is attached to the free ________ of the growing DNA strand.

The two strands of the DNA double helix are held together by

In the process of transcription,promoters are specific sequences of ________ that are recognized by ________.

DNA replication involves the synthesis of an RNA primer on one strand of the DNA.

In all cells,genes are composed of

You are studying a protein in Salmonella typhimurium that you believe is a toxin.Whenever you attempt to purify the protein from lysed cell cultures,you get two forms of the protein.One form is smaller than the other and is missing 15 amino acids from the N-terminus compared to the larger form.This leads you to hypothesize that

In complementary base pairing of DNA,adenine pairs with ________ (or ________ in RNA)and cytosine always pairs with ________.

The codon on the ________ matches with the anticodon on the ________ to direct the addition of the correct amino acid to the growing polypeptide chain.

In DNA replication there are leading and lagging strands,because

Discuss how the initiation of DNA synthesis occurs in bacteria using the terms origin of replication,replication fork,and theta structures.

Stop codons are also called ________ codons.

The flow of biological information begins with

Explain why GC-rich DNA requires a higher temperature to denture or melt than AT-rich DNA and hypothesize as to why the GC content of chromosomes in microorganisms from different environments varies widely.

Inverted repeats are common features of transcription termination sequences in all three domains of life.