2b) Genetic makeup of bacteria and their classification Flashcards
is the subfield of genetics devoted to the study of bacteria.
Bacterial genetics
Bacteria serve as a good model for
animal genetic studies.
fundamental unit of heredity responsible for a given trait and control only one character.
Gene
Each gene codes for (……..) and hence specific function.
certain protein
The total genetic information essential for growth and metabolism of the cell is called the …….
genome
A cells genome is organized into …..
تنظم جينوم الخلايا في …
chromosomes
Most bacteria have a ……
single circular chromosome
length of DNA containing genes ……
Chromosome
the set of genes carried by an organism represented by the cell …
Hereditable characters^
Genotype
(non-hereditable) Biological characters expressed under certain environmental conditions
Phenotype
Genes that confer a survival advantage e.g.
antibiotic resistance genes
antibiotic resistance genes are contained in
plasmids
(small circular DNA that replicates independently).
plasmids
Plasmid genes are not essential for the normal functioning of …..❤️
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bacterial cells
a single copy, circular, double strand, up to 4,639,2214,377 bp.
Chromosome
Extra-chromosomal, small (1000 to over 400000 bp), transmitted between
bacteria.
Plasmids
Same as plasmid but can integrate into chromosomal DNA.
Episomes
Transposable genetic elements that carry one or more genes (genes for enzyme, virulence , resistance)
Transposons (Tn)
Transposable genetic elements that carry no known genes.
Insertion Sequences (IS)
Bacterial genetic elements 5 ?
❤️
ممكن مقالي
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Chromosome
Plasmids
Episomes
Transposons (Tn)
Insertion Sequences (IS)
deoxyribonucleic acid
DNA
the genetic material of the cell
DNA
Structure of DNA = ❤️
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1) double-stranded helix
2) composed of repeating units of nucleotides
3) each strand consists of a (sugar-phosphate backbone) attached with (nitrogenous bases) (A, T, C and G);
4) two strands are joined together with complementary base pairs formed between
A-T
and
C-G.
one parental DNA gives rise to two identical copies of (daughter DNAs )……
DNA replication
is the key enzyme for DNA replication
DNA polymerase
it has a high proof-reading capability, to make sure daughter DNAs are highly accurate copy of parental DNA
DNA polymerase
the synthesis of a complementary strand of RNA from a DNA template.
Transcription
called messenger RNA, or mRNA
RNA
carries the coded information for making a protein
mRNA
is the key enzyme
RNA polymerase
RNA polymerase it uses ………
RNA polymerase recognizes and binds to a specific site of DNA called
( “promoter” )
(a) it uses a portion of DNA as a template
(b) it recognizes and binds to a specific site of DNA called “promoter” to start transcription.
protein synthesis (genetic information being translated into a protein molecule).
Translation
During translation …
a ribosome moves along an mRNA molecule
molecules are the actual translators
tRNA
they read the genetic code in mRNA and move in a specific amino acid molecule.
tRNA
Flow of Genetic Information =
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DNA replication
DNA polymerase
Transcription
RNA polymerase
Translation
tRNA
Phenotypic Variation
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1) non genetic
2) non hereditable
3) not transmitted from one generation
to the other and
4)is controlled by
environmental conditions.
Genotypic Variation
1) genetic
2) transmitted from one generation to another and 3) is not controlled by environmental conditions (permanent).
Types of Microbial Variation and example for each other ?
- Phenotypic Variation
1) Serratia marscenes
2) Salmonella genotype - Genotypic Variation
1) Transfer of DNA
2) Mutation
Serratia marscenes
produce pigment at …
but no pigment at
22 C
37
Salmonella genotype
flagella+ loose its flagella ……
flagella- has
in phenol
no flagella in presence or absence of phenol
Transfer of DNA =
يحصل فيه
A- Transformation
B- Transduction
C- Conjugation
Mutation
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A- Induced
B- Spontaneous
Point (substitution)
Frame (deletion or addition)
How do bacteria exchange genetic materials to achieve genetic
diversity?
احتمال كبير انه مقالي لانه جاء بسؤاله
- Genetic recombination
2. Mutations
What do Genetic recombination?
a. Conjugation
b. Transduction
c. Transformation
What do Mutations ?
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a. Substitution
b. Insertion
c. Deletion
زي وضع حقين الواسطة
exchange of genes between two chromosomes
Genetic recombination
transfer of DNA from one chromosomal location to another, or from one cell (donor cell) to another cell (recipient cell)
Gene transfer
transfer of naked DNA molecule
Transformation
gene transfer through the sex pili
Conjugation
virus or phage-mediated gene transfer
الفيروس او نقل الجينات بواسطة الملتهمة
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Transduction
uptake of free DNA from the environment when another bacterial
cell (donor) dies and undergoes lysis (…….)
Example ………
Transformation
e.g. Haemophilus, Streptococcus and Neisseria
transfer of host genes from one host to another by a virus
Transduction
transfer of genes from one prokaryotic cell to another by mechanism involving cell-to-cell contact and a plasmid.
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Conjugation
-Each triplet base in the mRNA is called …
codon
…Since there are 4 possible bases in the mRNA
there are (……) possible codons
(ACGU)
4^3
Or
64
64-3 = 61
Sixty one of these codons are called
sense- codons (code for specific amino acids).
64-61 =3
Three of the codons are nonsense codons (UAA, UGA, UAG)
يعني i.e.: they have no complementary anticodons.
nonsense codons (UAA, UGA, UAG)
The nonsense codons terminate the protein synthesis acting as ……
Full stop
The specific sequence of codons is called ……
and It is universal in all living beings.
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genetic code
