Chapter 10: The Structure and Function of DNA

What is the structure of DNA?

3D double helix. DNA has a sugar-phosphate backbone. Nucleotides are joined together by hydrogen bonds. The backbone forms the rungs of the ladder like structure of DNA by combining Nucleotides into pairs and connecting strands together (A→T, C→G).

Who deciphered the physical structure of DNA?

James Watson and Francis Crick are more commonly accredited from 1953. They won a Nobel prize for their discoveries.

Who is Rosalind Franklin?

She reportedly discovered key aspects of the DNA structure in 1951 in her unpublished research at King’s College in London.

Genes

Code for genetic traits and are located on chromosomes

DNA

The genetic material that makes up genes

DNA is…

a nucleic acid composed of two strands of nucleotides twisted to form a double helix. 4 different nucleotides make up polynucleotides and can be found in the DNA of all cells

RNA

A single stranded nucleic acid similar to DNA.

What does RNA do?

Deliver the genetic information, or instructions from DNA to the ribosomes where proteins are made.

Nucleic Acids

Polymers (long chains) of nucleotides (single unit monomer)

What four nucleotides make up DNA?

Adenine, Thymine, Guanine, and Cytosine

What four nucleotides make up RNA?

Adenine, Uracil, Guanine, and Cytosine

What is the structure of RNA?

A single-stranded nucleic acid composed of a chain of nucleotides.

Base Pair Rules

Two nitrogenous bases. The base on one strand of DNA pairs exclusively with a corresponding base on the other strand resulting in two complementary strands of DNA. DNA: Adenine→Thymine, Guanine→Cytosine. RNA: Adenine→Uracil, Guanine→Cytosine

What three components do each of the four nucleotides consist of?

a nitrogen base, a sugar molecule, and a phosphate molecule

What does DNA stand for?

Deoxyribonucleic Acid

DNA replication

Involves unwinding a DNA double helix and using each strand as a template for a new complementary strand.

When a cell reproduces,

it must duplicate its DNA, providing one copy to the new offspring while keeping one for itself.

DNA polymerase

The enzymes that make the covalent bonds between the nucleotides of a new DNA strand.

What can polymerase help do?

repair DNA that is damaged by toxic chemicals or high-energy radiation.

Origins of Replication

The specific sites where DNA replication begins on a double helix

Replication bubbles

Created when DNA begins to unzip the two complimentary strands at the origins and proceeds in both directions