Questions and Answers
What does one codon in a gene specify?
What is the total number of different codons possible with a four-letter alphabet?
Which of the following statements about bacterial colonies is true?
How can mutations be easily produced in bacteria?
Signup and view all the answers
What is the significance of environmental conditions on genetic expression?
Signup and view all the answers
Why is the short generation time of bacteria advantageous for genetic research?
Signup and view all the answers
What role does nutrient availability play in the genetic expression of organisms?
Signup and view all the answers
What is the primary role of the accessory genome in bacteria?
Signup and view all the answers
Which mechanism allows bacteria to acquire genetic material from other strains?
Signup and view all the answers
Which statement about bacteriophage DNA is true?
Signup and view all the answers
What distinguishes DNA replication in bacterial cells from eukaryotic cells?
Signup and view all the answers
Which of the following is NOT considered a virulence factor in bacteria?
Signup and view all the answers
How do plasmids contribute to antibiotic resistance in bacteria?
Signup and view all the answers
What is a characteristic of the bacterial chromosome?
Signup and view all the answers
Which of the following statements about genotype and phenotype is true?
Signup and view all the answers
What feature of bacterial cells typically aids in their rapid adaptation to environmental changes?
Signup and view all the answers
What is the primary role of plasmids in bacteria?
Signup and view all the answers
How do plasmids differ from bacterial chromosomes?
Signup and view all the answers
Which statement about bacteriophages is true?
Signup and view all the answers
What role do plasmids play in antibiotic resistance?
Signup and view all the answers
Which of the following is an example of a virulence factor encoded by plasmids?
Signup and view all the answers
What is the structure of plamids?
Signup and view all the answers
What does the base pairing rule dictate in DNA?
Signup and view all the answers
What characteristic of bacteriophages allows them to transfer genes between bacteria?
Signup and view all the answers
Study Notes
Bacterial Genetics Overview
- Molecular structure of DNA consists of base pairing and has a 5’→3’ orientation.
- Bacterial cell contains DNA organized as the bacterial genome, encompassing chromosomes, plasmids, and bacteriophage DNA.
Bacterial Genome Composition
-
Bacterial Chromosome:
- Small, circular, double-stranded DNA found in the cytoplasm.
- Self-replicating and typically less than 5Mb in size.
- Most bacteria are haploid, possessing one chromosome (exceptions exist like Vibrio cholerae with two).
- The chromosome is supercoiled and packaged in the nucleoid, totaling a length of 1mm.
-
Core vs. Accessory Genome:
- Core genome consists of essential genes on the chromosome necessary for survival.
- Accessory genome includes genes on plasmids/bacteriophages that provide selective advantages (e.g., antibiotic resistance, virulence factors).
Genetic Code
- Codons consist of three nucleotides that encode amino acids (e.g., ATG = methionine).
- There are 64 different codons formed from the nucleotide combination.
- The genetic code specifies how mRNA nucleotides relate to amino acids in polypeptides.
Genotype and Phenotype
- Genotype: Refers to the organism's inherited genetic information and actual DNA sequence.
- Phenotype: Represents observable properties influenced by genotype and environmental conditions (e.g., Bacillus anthracis expresses a capsule in vivo).
Advantages of Bacteria in Genetic Studies
- Bacteria are haploid, simplifying the production of mutant phenotypes.
- Short generation time allows for rapid experimentation.
- Asexual reproduction ensures progeny are genetically identical.
- Can be grown on agar plates, enabling easy colony isolation and selection of rare mutants.
- Dormancy allows prolonged storage.
- DNA exchange capability facilitates horizontal gene transfer.
Bacterial Colonies
- Each colony represents clones of the original bacterium, resulting in millions of genetically identical bacteria.
Plasmids
- Plasmids are extrachromosomal, closed, circular, double-stranded DNA located in the cytoplasm and vary in size (5 to 500 kb).
- They replicate independently of bacterial chromosomes and can transfer between bacterial species.
- Encode non-essential traits impacting pathogenic properties, such as antibiotic resistance and toxin production (e.g., tetanus toxin, anthrax capsule).
Bacteriophages
- Bacteriophages are viruses that infect bacteria and contain extrachromosomal genetic material.
- Phage genome sizes range from 2 to 200 kilobases and may consist of double or single-stranded DNA.
- Some encode exotoxins, such as cholera toxin in Vibrio cholerae.
DNA Structure
- DNA has a double helical structure with grooves between strands.
- Base pairing rules: A pairs with T, and G pairs with C.
- Each base pair (A-T and G-C) is called a complementary base pair.
- 5' end features a phosphate group, while the 3' end lacks a phosphate at its last nucleotide.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
This quiz covers key concepts in bacterial genetics, focusing on the molecular structure of DNA, the DNA replication process, and the connection between genotype and phenotype. Additionally, it explores the various pathways of inter-bacterial gene transfer. Test your understanding of these fundamental topics in microbial genetics.
