DNA Structure and Replication

DNA function

Serves as the hereditary instruction manual for building an individual and is common to all living organisms.

Eukaryotic DNA location

Found in the nucleus of eukaryotic cells, organized into chromosomes.

Human chromosomes

Humans have 23 pairs of chromosomes, with one chromosome in each pair inherited from the mother and one from the father.

Autosomes vs. Sex Chromosomes

Autosomes are chromosomes 1-22 (non-sex chromosomes), while sex chromosomes (XX for female, XY for male) determine sex.

DNA nucleotide components

Consists of a 5-carbon sugar (pentose), a phosphate, and a nitrogenous base.

DNA structure backbone

Formed by alternating sugars and phosphates on the outside of the double helix.

Chargaff's Rules (Base Pairing)

A always pairs with T, and C always pairs with G, held together by hydrogen bonds.

Antiparallel nature of DNA

The two strands of the DNA double helix run in opposite directions.

Helicase function

An enzyme that breaks hydrogen bonds to unwind and unzip the DNA helix during replication.

DNA Polymerase function

Reads the DNA template strand and adds complementary nucleotides to synthesize the new strand.

Semi-conservative replication

Each newly made DNA molecule contains one original parental strand and one newly synthesized strand.

Polymerase Chain Reaction (PCR)

A laboratory technique used to rapidly replicate and amplify a specific DNA segment.

Three steps of PCR

1. Denaturation (heating), 2. Annealing (primers bind), 3. Extension (DNA polymerase adds nucleotides).

Gel Electrophoresis

A laboratory technique that separates DNA fragments by size, where smaller fragments travel farther than larger ones.

Short Tandem Repeats (STRs)

Noncoding sections of a chromosome with repeating DNA sequences whose exact length varies from person to person.