Genetics Analysis & Principles

A set of flashcards designed to help review key concepts from the lecture on genetic linkage, mapping, and bacterial genetics.

What defines genetic linkage in eukaryotes?

Genetic linkage refers to genes close together on the same chromosome that tend to be transmitted as a unit.

What does the term synteny mean?

Synteny means two or more genes are located on the same chromosome and are physically linked.

How many linkage groups do humans have?

Humans have 22 autosomal linkage groups, plus one X chromosome linkage group and one Y chromosome linkage group.

What is crossing over and when does it occur?

Crossing over occurs during prophase I of meiosis when non-sister chromatids exchange DNA segments.

What is the impact of crossing over on genetic linkage?

Crossing over can separate linked genes, allowing for new combinations of alleles.

What is a two-factor cross?

A two-factor cross studies the linkage between two genes.

What was Thomas Hunt Morgan famous for?

Morgan provided evidence for the linkage of several X-linked genes in Drosophila.

What are recombinant offspring?

Recombinant offspring are produced by the exchange of DNA between homologous chromosomes during meiosis.

Define genetic maps.

Genetic maps allow estimation of the relative distances between linked genes based on crossover frequency.

What is a map unit?

A map unit is synonymous with centiMorgan (cM) and represents a 1% recombination frequency between two genes.

What are the mechanisms of genetic transfer in bacteria?

The mechanisms include conjugation, transduction, and transformation.

In bacterial conjugation, what is required for the transfer of genetic material?

Direct physical contact between a donor and recipient cell is required.

What role does the F factor play in bacterial conjugation?

The F factor is necessary for the formation of a conjugation bridge and DNA transfer in F+ strains.

What indicates that transformation has occurred in bacteria?

Transformation indicates that a bacterium has taken up external DNA and incorporated it into its chromosome.

What is cotransduction?

Cotransduction refers to the simultaneous transfer of two closely linked genes during transduction.

What did Frederick Griffith discover about transformation?

Griffith discovered transformation while working with strains of Streptococcus pneumoniae, demonstrating gene transfer.

How does horizontal gene transfer contribute to antibiotic resistance?

Horizontal gene transfer allows bacteria to acquire resistance genes from other organisms, enhancing their survival against antibiotics.

What happens during artificial transformation in the lab?

Artificial transformation typically involves treating cells with calcium chloride and a heat shock to facilitate DNA uptake.

What is the significance of cotransformation frequency?

Cotransformation frequency is high for genes that are close together and low for genes that are distant, helping to map genes.

What are the two types of transformation?

Natural transformation, which occurs without help, and artificial transformation, which requires techniques.

How does the genetic map of E. coli help in genetic studies?

The map allows researchers to understand gene order and distances, crucial for studying genetic transfer.

What does the term 'competent cells' refer to in transformation?

Competent cells are bacteria that can take up DNA due to specific proteins facilitating the process.

What are plasmids?

Plasmids are circular pieces of DNA in bacteria that can replicate independently from chromosomal DNA.

What is the purpose of F' factors?

F' factors can carry additional genes when excised imprecisely from the bacterial chromosome.

What is the main function of sex pili in conjugation?

Sex pili allow for attachment between donor and recipient bacteria, initiating the conjugation process.

What type of bacteria are often studied for antibiotic resistance?

Staphylococcus aureus strains, particularly methicillin-resistant Staphylococcus aureus (MRSA).