Genetic Variation and Gene Transfer

This set of flashcards covers key concepts related to genetic variation, mutations, gene transfer mechanisms, and bacterial genetics.

Genetic Variation

Differences in DNA sequences among individuals within a population.

Mutation

Stable, heritable changes in the sequence of bases in DNA.

Point Mutations

Changes affecting a single pair of nucleotides in the DNA sequence.

Tautomerization

The process in which nitrogenous bases shift their position, leading to replication errors.

Transitions

Mutations where a purine is replaced by another purine, or a pyrimidine is replaced by another pyrimidine.

Transversions

Mutations where a purine is replaced by a pyrimidine or vice versa.

Spontaneous Mutations

Mutations that occur without any external influence.

Mobile Genetic Elements

Segments of DNA that can move around the genome, including insertion sequences (IS) and transposons.

Mutagen

An agent that causes changes to the DNA sequence.

Chemical Mutagens

Substances that chemically alter DNA bases, resulting in mutations.

Physical Mutagens

Factors such as radiation that can cause DNA damage and mutations.

Methyl-nitrosoguanidine

A chemical mutagen that modifies DNA by methylating guanine.

Pyrimidine Dimers

DNA lesions caused by UV light, leading to mutations.

Substitution Mutation

Mutations where one base is replaced by another base.

Silent Mutation

A change in the DNA sequence that does not alter the amino acid sequence.

Missense Mutation

A change in the DNA sequence resulting in a different amino acid.

Nonsense Mutation

A mutation that introduces a premature stop codon in the protein sequence.

Frameshift Mutation

Mutations caused by insertions or deletions that shift the reading frame of the codons.

Transposable Elements

DNA segments that can move to different sites within the genome.

Transposition

The process by which transposable elements move within the genome.

Insertion Sequences

The simplest form of transposable elements that carry only the genes necessary for transposition.

Composite Transposons

Transposable elements that contain additional genes beyond those necessary for transposition.

Vertical Gene Transfer

The transfer of genetic material between generations of cells during reproduction.

Horizontal Gene Transfer

The transfer of genes between cells of the same generation.

Bacterial Conjugation

The transfer of genetic material between bacteria through direct contact.

Plasmid

Small, autonomously replicating DNA molecules found in bacteria.

F Plasmid

A conjugative plasmid that allows bacteria to engage in conjugation.

Sex Pilus

A structure that connects F+ and F- bacterial cells during conjugation.

Rolling Circle Replication

A process by which DNA is replicated during bacterial conjugation.

HFr Conjugation

Conjugation involving an F factor integrated into the bacterial chromosome.

F’ Conjugation

Conjugation involving an F factor that has excised incorrectly, transferring additional host genes.

Bacterial Transformation

The uptake of naked DNA from the environment by a competent cell.

Com Proteins

Proteins that facilitate the movement of DNA across bacterial cell walls.

Transduction

The transfer of genetic material from one bacterium to another via bacteriophages.

Bacteriophage

Viruses that infect bacteria and can facilitate gene transfer.

Lytic Cycle

The life cycle of a virus that leads to the destruction of the host cell.

Lysogenic Cycle

A viral life cycle where the virus integrates its DNA into the host genome.

Prophage

Viral DNA integrated into the bacterial chromosome during the lysogenic cycle.

Generalized Transduction

A process where random fragments of bacterial DNA are transferred by bacteriophages.

Specialized Transduction

Transfer of specific bacterial genes by temperate phages after lysogeny.

Excision

The process by which prophage DNA is removed from the host chromosome.

Competent Cell

A bacterial cell that is able to take up extracellular DNA.

Recombination

The exchange of genetic material between different DNA molecules.

Transposase

An enzyme that facilitates the movement of transposable elements.

Target DNA

The DNA segment into which a transposable element is inserted.

Inverted Repeats (IR)

Sequences that border the transposable elements and are recognized by transposase.

Direct Repeats

Sequences that result from the insertion of a transposable element.

Complex Transposon

Transposable elements that carry additional genes, such as antibiotic resistance.

Genome

The complete set of genes or genetic material present in a cell or organism.

Bacterial Chromosome

The main DNA molecule containing the essential genes of a bacterium.

F factor

A genetic element in bacteria that enables conjugative transfer.

External Environment

The surroundings in which a bacterium can acquire DNA through transformation.

Gene Exchange

The process by which genetic material is passed between organisms.

Bacterial Strains

Different genetic variants of bacteria that may exhibit distinct traits.

Competence State

A condition that allows bacteria to uptake DNA via transformation.

Selective Pressure

Environmental factors that influence the survival and reproduction of organisms.

Amplification

The increase in copies of a particular DNA segment, often used in biotechnology.

Gene Variation

Differences in genes among individuals which can lead to variations in traits.

DNA Repair Mechanisms

Cellular processes that correct DNA damage and prevent mutations.

Recombination Events

Processes that lead to the rearrangement of genetic material.

Genetic Diversity

The total number of genetic characteristics in the genetic makeup of a species.