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microbio exam [pt.2]
lecture 6: bacterial genetics
| Question | Answer |
|---|---|
| Define genetics | scientific study of heredity. study of genes through their variation. |
| Define genome | the total of all genetic material in a cell |
| Define gene | fundamental physical and functional unti of heredity. segment of DNA located in a specific site on a chromosome. |
| Bacterial chromosomes vs. Bacterial plasmid DNA | [BC] Circular, double stranded molecule of DNA. Self-replicator. Localized in nucleoid and attached to plasma membrane. [BP] Extrachromosomal genetic elements. Replicate independently. Encode traits not essential for normal cellular reproduction. |
| Types of plasmids | Fertility factors (F), Resistance factors (R), Col plasmids, Virulence plasmids, and Metabolic plasmids |
| What is Fertility factors (F)? | F+ cells carry genes responsible for cell attachment (sex pilus) and plasmid transfer between specific bacterial strains during conjugation. F+ cell directs the formation of sex pili and attaches it to a F- cell and transfers duplicate information. |
| What is Resistance factors (R)? | Confer antibiotic resistance. Have genes that code for enzymes capable of destroying or modifying antibiotics or heavy metals. |
| What is Col plasmids? | Kill bacteria cells of the same or similar species that lack the factor. Contains bacteriocins, bacterial proteins that destroy other bacteria. |
| What is Virulence plasmids? | Carry instructions for structures, enzymes, or toxins that enable the bacterium to become pathogenic. Bacteria are better able to resist host defense. |
| What is Metabolic plasmids? | Carry genes for enzymes that degrade substances such as aromatic compounds, pesticides, and sugars. |
| What is Transposable element? | DNA segments that carry genes required for transposition. Moves from one location in a DNA chromosome to another location. Contains antibiotic resistance genese which can transport to other plasmid or bacterial chromosomes. |
| What is genetic recombination? | occurs when an organism acquires and expresses genes that originated in another organism. Transfers DNA from one cell to another, resulting in recombinant DNA molecule. |
| 3 types of bacterial genetic recombination | Transformation, Conjugation & Transduction |
| What is Transformation? | DNA fragment released from dead donor bacteria floats in extracellular space where a living recipient bacteria consumes it and the donor DNA recombines with the bacterial chromomes of the recipient. Only capable if recipient bacteria is Competence. |
| What is Conjugation? | Transfer of DNA from a living donor bacterium to a recipient bacterium. Mediated by a conjugation pili (sex pili). |
| F+ vs. F- cell | F+ cell has the F plasmid which functions as a donor and F- cell lacks the F plasmid so it functions as recipient. F+ binds to F- with a sex pilus and tranfers a copy of F+ plasmid to recipient. Both bacteria are now F+. |
| What is Hfr (high frequency recombinant) conjugation? | When F factor becomes integrated into the chromosome of F+ cell, it makes Hfr cell. Hfr cell passes a fragment of its chromosome into F- recipient, resulting recombinant F- cell. |
| What is Transduction? | Transfer of fragments of DNA from one bacterium to another bacterium by bacteriophage. Phages work like a syringe and injects its DNA into a bacterial cell & withdraws it, sometimes taking bacterial DNA and injects it into a new host, infecting it. |
Created by:
jnguyen
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