DNA structure and replication

Bacteriophage

A virus that infects and kills bacteria cells.

X-ray crystallography

A technique used to study the structure of DNA by taking pictures of it.

Semi-conservative replication

The type of DNA replication where half of the old strand is in each of the new strands.

Nucleotide

The monomer (subunit) of DNA made up of a phosphate, sugar (deoxyribose), and a nitrogenous base.

DNA Polymerase

An enzyme that synthesizes new strands of DNA by attaching free floating nucleotides to a template.

Adenine (A)

A nitrogenous base that pairs with Thymine (T) in DNA.

Thymine (T)

A nitrogenous base that pairs with Adenine (A) in DNA.

Cytosine (C)

A nitrogenous base that pairs with Guanine (G) in DNA.

Guanine (G)

A nitrogenous base that pairs with Cytosine (C) in DNA.

Pyrimidines

Nitrogenous bases with a single carbon ring structure; includes Thymine and Cytosine.

Purines

Nitrogenous bases with a double carbon ring structure; includes Adenine and Guanine.

Chargaff's Rule

The observation that A nucleotides always pair with T nucleotides, and C nucleotides always pair with G nucleotides.

DNA Ligase

An enzyme that bonds Okazaki fragments together by filling in the phosphate-sugar backbone.

Hydrogen bonds

Weak bonds that hold the nitrogenous bases together in the middle of the DNA molecule.

Antiparallel

Referring to the opposite direction of the sugar-phosphate backbones in a DNA molecule.

Helicase

An enzyme that unwinds and separates the DNA strands during replication.

Okazaki fragments

Short sequences of DNA synthesized discontinuously on the lagging strand during DNA replication.

Watson and Crick

Scientists credited with discovering the double helix structure of DNA.

DNA structure

Described as a double helix, resembling a twisted ladder composed of a sugar-phosphate backbone and nitrogenous base pairs.

RNA primers

Short RNA sequences that serve as starting points for DNA synthesis.

Frederick Griffith

Frederick Griffith was a scientist known for his experiment in 1928 with Streptococcus pneumoniae that demonstrated the process of transformation, showing that non-virulent bacteria could acquire virulence when exposed to heat-killed virulent bacteria.

Francis Crick and James Watson

Scientists credited with uncovering the double helix structure of DNA.

Maurice Wilkins

A scientist known for his work on the structure of DNA using X-ray crystallography.

Hershey and Chase Experiment

An experiment conducted in 1952 that demonstrated that DNA is the genetic material by using radioactive labeling of bacteriophages.

Steps of DNA Replication

1. Unwinding of the DNA helix by helicase. 2. Binding of RNA primers. 3. Addition of nucleotides by DNA polymerase. 4. Joining of Okazaki fragments by DNA ligase. 5. Rewinding of the DNA helix.

DNA Structure

Described as a double helix, resembling a twisted ladder composed of a sugar-phosphate backbone and pairs of nitrogenous bases.

Frederick Griffith

A scientist known for his 1928 experiment with Streptococcus pneumoniae that demonstrated the process of transformation.

Hydrogen Bonds in DNA

Adenine (A) pairs with Thymine (T) using 2 hydrogen bonds, and Cytosine (C) pairs with Guanine (G) using 3 hydrogen bonds.

Avery, McLeod, and McCarty Experiment

An experiment in 1944 that provided definitive evidence that DNA is the genetic material by demonstrating that DNA extracted from pathogenic bacteria could transform non-pathogenic bacteria into pathogenic forms.

Avery, McLeod, and McCarty (1944)

Researchers who conducted the experiment that concluded DNA is the substance that causes bacterial transformation.