BSC2010 Chapter 14 DNA

Flashcards covering the key concepts and terms related to DNA as outlined in Chapter 14 of the lecture notes.

Frederick Griffith

Transformed living R bacteria into deadly S bacteria by an unknown, heritable substance.

Oswald Avery

Discovered that the transforming agent was DNA.

Hershey and Chase

Demonstrated that DNA entered infected bacteria, confirming DNA as the genetic material.

Edwin Chargaff

Showed that DNA composition varies between species.

Rosalind Franklin

Provided measurements on the chemistry of DNA.

Watson and Crick

Discovered the double helix structure of DNA by modeling based on Franklin’s X-ray data and Chargaff’s rules.

Meselson and Stahl

Demonstrated that DNA replication follows a semiconservative model.

Chargaff's Rules

%A = %T and %G = %C in DNA.

Backbone of DNA

Composed of sugar and phosphate.

Rungs of DNA

Formed by nitrogenous bases.

Purine bases

Adenine (A) and Guanine (G).

Pyrimidine bases

Thymine (T) and Cytosine (C).

Base pairing of adenine

Pairs with Thymine.

Base pairing of cytosine

Pairs with Guanine.

Hydrogen bonds in DNA

Hold base pairs of the two strands together.

Antiparallel structure of DNA

One strand runs 5’ to 3’, the other runs 3’ to 5’.

Semiconservative model of replication

Each strand of DNA serves as a template for the new strand.

Helicase

Enzyme that unwinds DNA at origins of replication.

Primase

Places down RNA primer to initiate replication.

DNA Polymerase III

Adds complementary bases to leading strand in the 5’ to 3’ direction.

Lagging strand

Synthesized in 3’ to 5’ direction using Okazaki fragments.

Leading strand

Synthesized continuously in the 5'-3' direction toward the replication fork.

DNA Polymerase I

Replaces RNA primers with DNA.

Ligase

Seals fragments of DNA together.

Topoisomerase

Relieves overwinding strain ahead of replication forks.

Replication fork

Y-shaped region where DNA is being unwound.

Replication bubble

Forms during DNA replication with two replication forks.

Okazaki fragments

Short segments of DNA added to the lagging strand.

Nucleotide Excision Repair

Repair mechanism where nucleases cut damaged DNA and DNA polymerase with ligase fill in the gaps.

Telomeres

Repeated units of short nucleotide sequences (TTAGGG) at the ends of DNA.

Telomerase

Enzyme that adds nucleotide sequences to telomeres.

Complementary base pairing

Mechanism by which adenine pairs with thymine and cytosine pairs with guanine.

Genetic material

Substance, confirmed as DNA, that carries genetic instructions.

Double helix model

The structural layout of DNA proposed by Watson and Crick.

X-ray diffraction data

Experimental technique used by Franklin to understand DNA structure.

Biological significance of telomeres

Protect chromosomes from degradation and prevent genome instability.

Role of ligase in DNA replication

Connects Okazaki fragments during the replication of the lagging strand.