Bacterial-genetics-and-Gene-transfer.pdf

autonomic as well as somatic sites.
❖ Choline is actively taken up by the
axonal membrane and acetylated with
the help of ATP and coenzyme-A by
the enzyme choline acetylase << this
results in acetylcholine.
❖ ACh is hydrolyzed by the enzyme
cholinesterase (AChE), and choline is
recycled immediately after release.
Cholinoceptors
❖ Two classes of cholinoceptors are
muscarinic and nicotinic:
1) Muscarinic receptors:
These receptors are selectively stimulated by
muscarine and selectively blocked by atropine.
They are located in the heart, blood vessels, eye
and glands of the gastrointestinal, respiratory, and
urinary tracts, sweat glands, and in the CNS.
The muscarinic receptors have been divided into 5
subtypes M1, M2, M3, M4, and M5 (we will not
discuss 4&5).
❖ The first 3 have been functionally characterized:
M1: has a major role in mediating gastric secretion and relaxation of the lower
esophageal sphincter caused by vagal stimulation.
M2: Cardiac muscarinic receptors are predominantly M2 and mediate vagal bradycardia.
M3:Visceral smooth muscle contraction and glandular secretions are elicited through M3
receptors.
Vagal = related to vagus nerve which is the 10th cranial nerve. It mediates many
parasympathetic actions.
Abdulrahman Jabr 0780518028 Basic Pharmacology Karamology Academy
❖ Muscarinic actions
Blood vessels: only a few (skin of face, neck) receive cholinergic innervation.
Smooth muscle contraction in most organs.
Secretion from all parasympathetically innervated glands is increased (sweating,
salivation, lacrimation, and gastric secretion)
Bronchial muscles constrict (asthmatics are highly sensitive // muscarinic agonists are
contraindicated in asthma)
Contraction of circular (sphincter)
muscle of iris → miosis
Contraction of ciliary muscle →
reduction in intraocular tension
(especially in glaucoma patients)
2) Nicotinic receptors: this is another group of ACh receptors:
Nm: are present in the skeletal muscle, mediate skeletal muscle contraction are
selectively stimulated by phenyl trimethyl ammonium(PTMA) blocked by tubocurarine.
Nn: are present on ganglionic cells of ANS (both sympathetic and parasympathetic
ganglia), adrenal medullary cells, in the spinal cord and certain areas of the brain. They
are selectively stimulated by dimethyl phenyl piperazinium (DMPP) blocked by Nicotinic receptors: this is another group of ACh receptors:
Nm: are present in the skeletal muscle, mediate skeletal muscle contraction are
selectively stimulated by phenyl trimethyl ammonium(PTMA) blocked by tubocurarine.
Nn: are present on ganglionic cells of ANS (both sympathetic and parasympathetic
ganglia), adrenal medullary cells, in the spinal cord and certain areas of the brain. They
are selectively stimulated by dimethyl phenyl piperazinium (DMPP) blocked by
hexamethonium.
Nicotinic actions:
Activation of Nn = activation of both SNS & PSNS.
Activation of Nm = contraction of skeletal muscles (this is related to the somatic NS).

1. BACTERIAL GENETICS AND GENE TRANSFER

11. Genotype / Wild Type :Representsallpotential
genes of bacteria cell.. Its genome.. All Inherited
essential biological features & growth patterns.
Phenotype:The expressed genes. The observed
characteristics of the individual bacteria
species/strain. Expressed by physical & biochemical
properties. Growth patterns, Fermentation products,
Antibiotic resistance, Toxins production. .etc.

20. Jumping genes/copy and paste (Class1) or cut and paste (2)
Between plasmids or between chromosomes and plasmids
•medical importancesince many antibiotic resistance genes
are encoded by transposons in antibiotic resistance plasmids

23. MISSENSE MUTATION: RESULT IN DIFFERENT AMINO
ACIDS BEING INSERTED IN PROTEIN

24. Nonsense mutation: change a codon encoding an amino acid
into stop codon that result in failure of protein synthesis

25. •Frame shift mutation: One or more base are added or deleted, Shift in the
reading frame

26. Silent mutation: the change in the nucleotide sequence doesn't result in
a change in protein sequence

27. THERE ARE THREE TYPES OF HORIZONTAL GENE TRANSFER

33. •Hfr bacteria are still able to initiate conjugation with F-cells, but the
outcome is completely different from conjugation involving F+
bacteria. IT IS called an F’ instead ( F prime )

41. Specialized transduction:
**In specialized transduction, bacteriophage transfer only a few restricted gene
(DNA fragments) from donor bacteria to recipient bacteria. Specialized
transduction is carried only by temperatebacteriophage .
bacteriophage (phage) are viruses of bacteria -can be either lytic
or temperate (Lysogenic)
* lytic -always lyse (kill) host bacterial cell
* temperate-can stably infect and coexist within bacterial cell
(lysogeny) until a lytic phaseis induced
* the phage genome during lysogeny is called the prophage, and
the bacterial cell is called a lysogen