chapter 8: microbial genetics

What is genetics?

The science of heredity that studies what genes are, how they are transmitted, and their molecular products.

What are genes?

Segments of DNA that code for proteins or functional RNA.

What is DNA composed of?

DNA is a nucleic acid made of nucleotide subunits composed of nitrogenous bases, phosphate, and sugar.

What are the nitrogenous bases found in DNA?

Adenine (A), Thymine (T), Cytosine (C), and Guanine (G).

What are chromosomes?

Physical structures that contain DNA.

What does the genome represent?

The complete set of genes in an organism, including plasmids.

Define genomics.

The study of genomes.

What is the difference between genotype and phenotype?

Genotype refers to the genetic makeup of an organism, while phenotype refers to the observable expression of the genotype.

Describe the structure of DNA.

Double-stranded DNA appears like a twisted ladder, with a sugar-phosphate backbone and nitrogenous bases bonded in the middle.

What key discovery was made by Johann Friedrich Miescher?

He recognized the existence of DNA in the nucleus in 1869.

What major contribution to genetics was made by Watson and Crick in the 1950s?

They proposed the double helix model of DNA.

What was the goal of the Human Genome Project?

To sequence the entire human genome, which was completed in 2003.

What are the main enzymes involved in DNA replication?

Topoisomerase, DNA helicase, DNA polymerase, and DNA ligase.

What does semi-conservative replication mean regarding DNA?

Each new DNA molecule has one original strand and one new strand.

Explain transcription in the context of genetics.

The process of copying genetic information from DNA to mRNA.

What is the role of RNA polymerase in transcription?

RNA polymerase synthesizes mRNA using one strand of DNA as a template.

How does translation occur?

Ribosomes use mRNA to synthesize proteins, with tRNA bringing specific amino acids based on codons.

What is an operon model?

A model describing how groups of genes are regulated together in bacteria.

Differentiate between repressible and inducible operons.

Repressible operons are typically on and can be turned off, while inducible operons are typically off and can be turned on.

What is mutation?

A change in the DNA sequence that can affect protein function.

What is base substitution?

A type of mutation where one base is replaced by another.

Define frame shift mutation.

A mutation caused by the addition or deletion of bases that alters the reading frame of the genetic code.

Describe the three forms of horizontal gene transfer in bacteria.

Transformation is the uptake of naked DNA; conjugation is direct contact transfer; transduction is gene transfer via bacteriophages.