Nucleic Acid Structure and Chromosome Structure

What are the four criteria necessary for a genetic material?

Information, replication, transmission, and variation.

Who showed that genes are located on chromosomes?

T. H. Morgan's group in the 1910s.

What was the significance of Frederick Griffith's experiment in 1928?

Demonstrated that DNA can transform bacteria.

What are the two types of bacteria studied by Griffith?

Pathogenic type S and harmless type R.

What did Avery, MacLeod, and McCarty conclude in their 1944 study?

DNA is the transforming principle responsible for genetic information.

What two main components make up DNA and RNA?

Nucleotides and sugar.

What are the building blocks of DNA called?

Nucleotides.

What are Chargaff's rules?

Amount of adenine (A) = amount of thymine (T) and amount of cytosine (C) = amount of guanine (G).

Describe the semiconservative model of DNA replication.

Each new double helix consists of one parental strand and one newly synthesized strand.

What experiment did Meselson and Stahl conduct in 1958?

It demonstrated that DNA replication is semiconservative using nitrogen isotopes.

How do DNA polymerases add nucleotides during DNA replication?

They add nucleotides to the 3′ end of an existing strand.

What are telomeres, and why are they important?

They protect the ends of chromosomes and prevent loss of essential genes during replication.

What role does telomerase play in cellular biology?

It lengthens telomeres using an RNA template, important in stem cells and cancer cells.

What are Okazaki fragments?

Short segments of DNA synthesized on the lagging strand during DNA replication.

What is the direction of DNA synthesis according to the DNA polymerase activity?

DNA is synthesized in the 5′ to 3′ direction.

What are the components that make up a nucleotide?

A phosphate group, a pentose sugar, and a nitrogenous base.

What enzyme is responsible for unwinding DNA during replication?

DNA helicase.

What is the main function of DNA ligase?

It joins Okazaki fragments together by forming covalent bonds.

Which nitrogen bases are purines?

Adenine (A) and Guanine (G).

Which nitrogen bases are pyrimidines?

Cytosine (C), Thymine (T), and Uracil (U).

What does the structure of DNA consist of?

Two antiparallel strands forming a double helix.