quiz 3 Flashcards
- BP Size of the E. coli Nucleoid and Number of Proteins Produced
E. coli Nucleoid Size: The entire chromosome of E. coli has 5 x 10^6 base pairs (bp).
Proteins Produced: E. coli has approximately 5000 genes, and over 4000 different proteins have been experimentally identified
Number of BP in Human vs. E. coli
Human: 3 billion bp
Bacteria: 4.6 million bp
Operon in Bacteria
Inducible Operon: turned on by substrate (lac)
Repressible Operon: turned off by the product synthesized (arg)
Lac Operon
Normally off: repressor binds operator locus blocking transcript –> lactose binds repressor, changing its shape and causing it to fall off, allowing transcription
Absence of lactose: the repressor binds to the operator site preventing binding of RNA polymerase and transcription
Presence of lactose: lactose acts as the inducer –. lactose induces enzyme ebression by binding to the Lacl repressor preventing its binding to the operator site.
Arg Operon
Normally on: excess arg binds repressor, changing its shape and allowing it to bind operator, blocking transcription.
absence of arg: arg operon is transcribed and enzymes for the synthesis of arg are produced (on operon)
presence of arg: arg acts as a corepressor and represses its own synthesis. (off operon)
Types of mutation
Point mutation: addition, deletion or substitution of a few bases
Missesne Mutation: causes change in a single amino acid
Nonsense mutation: changes a normal codon into a stop codon
Silent mutation: alters a base but does not change the amino acid
Back mutation: mutated gene revers to its original base composition
Frameshift mutation: The reading frame of mRNA is altered by addition or deletion of nucleotides.
Mutation Repair
DNA polymerase: proofreads nucleotide during replication
mismatch repair: locates and repairs mismatched nitrogen bases not repaired by DNA polymerase
Light Repair: for UV light damage
Excision Repair: Removes and corrects damaged DNA segments.
Ames Test
Purpose: to determine the mutagenic potential of chemical compounds. tries to figure out if a substance can cause genetic mutation that can lead to cancer
Methods of Gene transfer
Transformation: uptake of naked DNA from environment by a bacterial cell
mechnaism: competent bacteria take up exogenous DNA fragments, which can recombine with the bacterial genome
Conjugation: Direct transfer of DNA from one bacterial cell to another through physical connection
mechanism: a donor cell transfers gentic material to a recipietn through a pilus
Transduction: transfer of DNA from one bacterium to another by a bateriophage.
mechanism: during the lytic cycle, bacteriophages accidentally package bacterial DNA and transfer it ot a new host cell.
Transposons:
Class 1: copy and paste
Class 2: cut and paste
respiratory vs cutaneous diphtheria
respiratory: nose, throat tonsils
spread by respiratory droplets
symptoms: cough, sore throat with low grade fever
Cutaneous: skin infection
spread by skin contact
more commonly seen in people with poor hygiene who live in crowded conditions (common in tropical countries)
What bacteria causes diphtheria
Cronebacterium diptheria
- Gram +, irrgular rod shape
- Produces Diptheria toxin
- Prevents polypeptide synthesis and causes cell death
- Entry into the bloodstream results in damage to heart, nerves, and kidneys
Is there a vaccine to prevent diphtheria
DPT, childhood vaccine as an effective preentative measure: Diphtheria-Pertussis-Tentanus
Treatment includes: antitoxin and antibiotics
Cause of the walking pneumonia
1 lower respiratory
2. starts as a cold a bronchitis, apneumnoia
cuases by mycoplasma pneumonia
What common human physiological system is impacted by K. pneumonia
Pathogen : Kelbisilla pneumonia, Capsule
symptoms: Lower respiratory , Pneumonia symptomps with thick bloody sputum
Treatment: antimicrobials
prevention: good aspetic technique by healthcare workers
