Microbiology Basics

Transformation

• A process in which one strain of bacteria is changed by a gene or genes from another strain of bacteria.

Bacteriophage

• A kind of virus that infects bacteria.
• Infects bacterial cells, sticks to the surface, and injects its genetic information.
• The viral genes make many new bacteriophages, which destroy the bacterium.

DNA

• Stands for Deoxyribonucleic acid.
• Main jobs: store information, copying information, and transforming information.
• Made up of nucleotides, which are the building blocks of nucleic acids.
• Nucleotides are composed of three basic parts: a 5-carbon sugar called deoxyribose, a phosphate group, and a nitrogenous base.

Nucleotides

• There are 4 different types of nucleotides: Adenine, Guanine, Cytosine, and Thymine.
• These nitrogenous bases pair with each other in a specific manner: Adenine (A) pairs with Thymine (T) and Cytosine (C) pairs with Guanine (G).

Chargaff's Rule

• A rule that states the percentages of Adenine and Thymine bases are almost equal in any sample of DNA.
• The same is true for Guanine and Cytosine.
• Observed that A=T and G=C in DNA samples from diverse organisms.

Franklin's X-Rays

• Showed that the X-ray pictures of DNA strands are twisted around each other, forming a helix shape.
• Suggested that the nitrogenous bases are near the center of the DNA molecule.

Double Helix Structure

• Held together by hydrogen bonds, which are fairly weak bonds.
• The two strands of DNA run in opposite directions, forming an antiparallel arrangement.

Replication

• The process of copying DNA prior to cell division.
• Involves the unwinding of the double helix, and the formation of new strands.
• DNA polymerase is the main enzyme involved, joining individual nucleotides to make new strands of DNA.

Enzymes in DNA Replication

• Pull apart a molecule of DNA, breaking the hydrogen bonds between base pairs.
• Unwind the 2 strands.
• DNA polymerase produces the sugar-phosphate bonds that join nucleotides together to form the new strands.