(L5) Bacterial Genetics Flashcards
It is the study of how genetic information is transferred,
either from a particular bacterium to its offspring or
between interbreeding lines of bacteria and how that
genetic information is expressed.
BACTERIAL GENETICS
It is the study of the mechanisms of heritable information
in bacteria, their chromosome, plasmids, transposons,
and phages.
BACTERIAL GENETICS
Who studied the Differences of morphology and other properties of bacteria were attributed
Nageli (1877)
Studied the Transformation of bacteria observed
Frederick Griffith (1882)
Examined at the molecular level by ____________
and his colleagues, who used the process to demonstrate
that DNA was the genetic material of bacteria
Oswald Avery (1944)
Bacterial conjugation discovered by ______________________ was noted
Joshua Lederberg and Edward Tatum (1946)
ARRANGE IN ORDER:
- Transformation of bacteria observed by
Frederick Griffith - Bacterial conjugation discovered by Joshua
Lederberg and Edward Tatum was noted - Examined at the molecular level by Oswald Avery and his colleagues, who used the process to demonstrate that DNA was the genetic material of bacteria
- Differences of morphology and other properties of bacteria were attributed by Nageli
- Differences of morphology and other properties of
bacteria were attributed by Nageli - Transformation of bacteria observed by
Frederick Griffith - Examined at the molecular level by Oswald Avery
and his colleagues, who used the process to demonstrate
that DNA was the genetic material of bacteria - Bacterial conjugation discovered by Joshua
Lederberg and Edward Tatum was noted
Small supplemental circular DNA
molecules of a few hundred or
thousand base pairs in
circumference.
PLASMIDS
Naturally occurring plasmids
are viruses of _________
bacteria
Are the small circular, double stranded, DNA molecules
within a cell, physically separated from chromosomal
DNA that can replicate independently. Which are distinct
from chromosomal DNAs
PLASMIDS
Plasmids are the small circular, double stranded, DNA molecules within a cell, physically separated from ___________ that can replicate independently. Which are distinct from chromosomal DNAs
chromosomal DNA
2 FUNCTIONS OF PLASMIDS:
- Help bacteria to survive stress
2. Make themselves indispensable
PLASMIDS HELP BACTERIA TO SURVIVE STRESS:
• Naturally exist in _________, and they also occur in
some eukaryotes.
• Often the genes carried in Plasmids provide bacteria with genetic advantages such as __________
Bacterial cell ; Antibiotic resistance
PLAMIDS MAKE THEMSELVES INDISPENSABLE:
Bacteria can also transfer plasmids to one another
through a process called _________
conjugation
Ways to classify Plasmids from general to specific:
- Conjugative
- Non-Conjugative
- Incompatibility
Bacteria reproduce by sexual conjugation
Conjugative Plasmids
transfer of genetic material from one bacterial cell to another, either through direct contact or a bridge between the two cells.
Conjugative Plasmids
Some plasmids contain genes called _________
that facilitate the beginning of conjugation
transfer genes
Cannot start the conjugation process, and they can only be transferred through sexual conjugation with the help of
__________
Non-conjugative; conjugative plasmids
In a bacterium, different plasmids can only co- occur if they are compatible with each other. An ____________ will be expelled from the bacterial cell.
incompatible plasmid
Plasmids are incompatible if they have the (SAME or NOT SAME) reproduction strategy in the cell. This allows the
plasmids to inhabit a certain territory within it without
other plasmids interfering.
SAME
Contain transfer genes that allow genes to be transferred from one bacteria to another through conjugation. These make up the broad category of conjugative plasmids.
Fertility F-Plasmids
5 MAIN CLASSES OF PLASMIDS
- Fertility F-Plasmids
- Resistance Plasmids
- Virulence Plasmids
- Col Plasmids
- Degradative Plasmids
Contain genes that help a bacterial cell defend against
environmental factors such as poisons or antibiotics.
Resistance Plasmids
Plasmid that turns that bacterium into a pathogen,
Virulence Plasmids
Plasmid that turns that bacterium into a pathogen,
Virulence Plasmids
Contain genesis that make bacteriocins, which are proteins that kill other bacteria and thus defend the host bacterium.
Col Plasmids
Col Plasmids are also known as
Colicins
Help the host bacterium to digest compounds that are not
commonly found in nature. These plasmids contain genes for special enzymes that break down specific compounds.
Degradative Plasmids
The DNA of most bacteria is contained in a single circular
molecule, called the
bacterial chromosome.
The chromosome, along with several proteins and RNA
molecules, forms an irregularly shaped structure called
the _________. This sits in the cytoplasm of a bacterial cell.
nucleoid
Analogy
BACTERIAL CHROMO:
PLASMIDS: It is circular.
BACTERIAL CHROMO: Linear because of Linear DNA
Analogy
BACTERIAL CHROMO: Essential to cell function
being the genetic information carrier have several thousand genes
PLASMIDS:
PLASMIDS: Not essential but provide survival to host bacteria
Analogy
BACTERIAL CHROMO:
PLASMIDS: Smaller in size
BACTERIAL CHROMO: Larger in size
Analogy
BACTERIAL CHROMO: Have a centromere and two
sister chromatids
PLASMIDS:
PLASMIDS: Have no centromere and sister chromatids
Analogy
BACTERIAL CHROMO: Are not used as gene carriers
PLASMIDS:
PLASMIDS: used as gene carriers for alien cell
Analogy
BACTERIAL CHROMOSOME:
PLASMIDS: small number of genes
BACTERIAL CHROMOSOME: larger number of genes
PROKARYOTE OR EUKARYOTE:
Contains membrane bound nucleus
Eukaryote
PROKARYOTE OR EUKARYOTE:
Does not have nucleus
Prokaryote
PROKARYOTE OR EUKARYOTE:
DNA is sequestered inside the nucleus
Eukaryote
PROKARYOTE OR EUKARYOTE:
Does not have other membrane-bound organelles
Prokaryote
PROKARYOTE OR EUKARYOTE:
Present as a DNA-protein complex called nucleoid
Prokaryote
PROKARYOTE OR EUKARYOTE:
Have plasmid DNA
Prokaryote
PROKARYOTE OR EUKARYOTE:
Replication occurs in cytoplasm
Prokaryote
PROKARYOTE OR EUKARYOTE:
Genes (both introns and exons)
Eukaryote
INTRON or EXON:
Non-coding regions of an RNA transcript or the DNA
encoding it are eliminated by splicing before translation.
INTRON
INTRON or EXON:
Can be separated by intervening sections of DNA that do
not code for protein known as introns
EXON
INTRON or EXON:
Coding sections of an RNA transcript or the DNA
encoding it that are translated soon into a protein.
EXON
INTRON or EXON:
It is any nucleotide sequence within a gene that is
removed by RNA splicing during maturation of the final
RNA product.
INTRON
INTRON or EXON:
Found in the intragenic region, thus the name
INTRON
Is all genetic instructions (genes) for development of:
○ Cellular structures
○ Metabolic functions
○ Regulation
Genome
THE BASIC UNIT OF HEREDITY
GENES
GENES: “BASIC UNIT OF HEREDITY” ● It makes up the body’s blueprint ● We have \_\_\_\_\_\_\_\_ genes in our body ● It is made from \_\_\_\_\_\_\_\_\_ ● It is organized in \_\_\_\_\_\_\_\_
35,000; DNA strands; structures
BINARY FISSION STEPS
- Parent cell
- DNA replicates
- Two daughter cells
- Cytoplasm divides
BINARY FISSION:
the cell elongates with a
septum forming at the middle. The two (2)
chromosomes are also separated in this phase.
Cytoplasm Divides
BINARY FISSION:
bacteria uncoils and replicates its chromosome, essentially doubling its content
Parent cell
BINARY FISSION:
a new cell wall is formed at
this phase and the cell splits at the center, dividing
the parent cell into two (2) new daughter cells.
Two daughter Cells
BINARY FISSION:
bacterium starts to grow larger in preparation for binary fission.
DNA Replicates
VARIATIONS OF BACTERIA
- Spontaneous mutation
- Transformation
- Transduction (Plasmids and DNA fragments)
- Conjugation
- Transposons
Bacteria have circular chromosomes that lacks
histone protein on the DNA
Circular Chromosome
Bacteria have different kinds of gene transfer
systems.
Bacterial Gene Transfer Systems
● Stray pieces of DNA from their environment and make it part of their genome.
● Basically, transformation is where a bacterium takes a piece of DNA floating in its environment and then they make it apart of their own genome
Transformation
● Bacterial genes can accidentally get included in
bacteriophage viral DNA
● This is where DNA is accidentally moved from 1
Bacterium to another by a virus.
Transduction
● Strains exchange genes through a cytoplasmic bridge
called _____
●_______ is where DNA is transferred between
bacteria through a tube between cells
Conjugation; pillus
MAIN PURPOSE OF TRANSFORMATION:
Repair DNA damage
WHY IS KNOWING TRANSFORMATION IMPORTANT?
Imagine a harmless bacterium takes up DNA from a toxin
gene, from a pathogenic or diseased causing species of
bacterium. If the receiving cell incorporates the new DNA in its own chromosome, which can happen by a process called __________, then it too may become pathogenic or disease-causing spreading the bacteria in a human’s body.
homologous recombination
Is the process by which foreign DNA is introduced into a
cell by a virus or viral vector
Transduction
TRANSDUCTION STEPS:
- Bacteriophage injects DNA
- Phage enzyme breaks down host DNA
3 & 4. Cell creates phage and host DNA
5 & 6. Transducing phage injects donor DNA to recipient cell - Transduced bacterium contains donor DNA due to recombination
there is the transfer of portion of DNA from one bacterium to another by bacteriophages
Transduction
Again, viruses that infect bacteria in transduction, move
short pieces of chromosomal DNA from one bacterium to
another by _______
accident
These viruses that infect bacteria are called ________.
__________ are the pirates of the biological world, they commandeer a cell’s resources and use them to make more bacteriophages.
Bacteriophages
It is commonly used as vectors in recombinant DNA
technology.
Bacteriophage
STEPS OF BACTERIOPHAGE ATTACHMENT:
- Landing
- Pinning
- Tail Contraction and Penetration
- DNA injection
______ take over the machinery of the cell to make
phage components. They then destroy, or lyse, the cell,
releasing new phage particles.
Lytic phages (virulent)
________ incorporate their nucleic acid into the
chromosome of the host cell and replicate with it as a unit
without destroying the cell. Under certain conditions
lysogenic phages can be induced to follow a lytic cycle.
Lysogenic phages
In chronic infection new phage particles are
produced continuously over long periods of time
but without apparent cell killing.
Lysogenic phage (temperate)
2 TYPES OF TRANSDUCTION
Specialized Transduction and Generalized Transduction
Is it mediated by lytic phages (or virulent phage, a phage which causes lysis of host cell death), where the DNA segment can be transferred by the virus and do not incorporate the segment to the bacterial chromosome.
GENERALIZED TRANSDUCTION
Is mediated by lysogenic phages (temperate phage, your temperate phage allows phage conversion.; wherein specific viral DNA fragments are integrated into the host bacterial chromosome.
Specialized Transduction
Used to insert new genes into bacteria engineered
plasmid used
Biotechnology
Used to insert new genes into bacteria engineered
plasmid used
Biotechnology
This is an engineered plasmid used in biotech
pUC18
pUC18 has been genetically engineered to include:
- gene for antibiotic resistance to Ampicillin (ampR)
2. gene and its promoter for the enzyme beta-galactosidase (lacZ)
________ is the process by which one bacterium
transfers genetic material to another through direct
contact. During _________, one bacterium serves as
the donor of the genetic material and the other serves
as the recipient. The donor bacterium carries a DNA
sequence called the __________.
conjugation; Fertility F-Factor
Example for Conjugation:
Cytoplasmic bridge allows transfer of DNA
Eschirichia coli and Mycobacterium smegmatis
Donor cells typically act as donors because they have a a chunk of DNA called your ________
Fertility F-Factor
If the F factor is transferred during conjugation, the
receiving cell turns into an _______ that can make its
own pilus and transfer DNA to other cells.
F-plus Donor
- A _________ is an enzyme that catalyzes the hydrolytic cleavage of phosphodiester linkages in the DNA backbone, thus degrading the DNA.
- The ______ are one type of nuclease which is a generic term for an enzyme capable of hydrolyzing phosphodiester bonds that link nucleotides.
Dnase
mediated by the expression of plasmid genes
E. coli conjugation
mediated by genes on the bacterial chromosome
Mycobacterial conjugation
- A piece of DNA that moves from one location in genome to another (as seen in the diagram)
- ________ is a class of genetic elements that can jump to different locations within a genome.
Transposons (Jumping Genes)
The chunks of DNA “jump” from one place to another within a genome, cutting and pasting themselves or inserting copies of themselves in new spots.
Transposable Elements
a bacterium takes up a piece of DNA
floating in its environment.
Transformation
DNA is accidentally moved from one
bacterium to another by a virus
Transduction
DNA Is transferred between bacteria
through a tube between cells.
Conjugation
GENE REGULATION:
Which encode regulatory genes,
are often at the five-prime (5’) end to the start site of
transcription of the gene they regulate
Regulatory Sequence
GENE REGULATION:
Is a sequence of DNA needed to turn a gene
on or off
Promoter
GENE REGULATION:
Are clusters of genes that share the same
promoter and are transcribed as a single large mRNA that contains multiple structural genes or cistrons
Operons
GENE REGULATION:
Substances that act on an operon to inhibit
messenger RNA synthesis
Repressor
GENE REGULATION:
Gene involved in controlling the
expression of one or more other genes.
Regulatory Gene
POSITIVE CONTROL or NEGATIVE CONTROL:
Protein known as an
activator binds to the DNA
in order for transcription to
take place
POSITIVE CONTROL
POSITIVE CONTROL or NEGATIVE CONTROL:
Protein known as a
repressor binds with the
DNA and blocks
transcription
NEGATIVE CONTROL
POSITIVE CONTROL or NEGATIVE CONTROL:
Transcription under
negative control
NEGATIVE CONTROL
POSITIVE CONTROL or NEGATIVE CONTROL:
Transcription is under
positive control
POSITIVE CONTROL
POSITIVE CONTROL or NEGATIVE CONTROL:
Example is Lactose operon which deals with lactose
POSITIVE CONTROL
POSITIVE CONTROL or NEGATIVE CONTROL:
Example is Tryp operon that deals with tryptophan
NEGATIVE CONTROL
● Raw material of evolution
● Deals with changes in base sequences of DNA
● As well as changes in DNA that affect the genetic
information
● No variation, no evolution
● DNA polymerase
Mutation
TYPES OF MUTATION
- Substitution
- Insertion
- Deletion
- Inversion
○ Occurs when specific bases (A, T, C, or G) in a gene
are swapped for different ones
Substitution
is the addition of one or more nucleotide
base pairs into a DNA sequence
Insertion
Involving the loss of genetic materia
Deletion
This where a chromosome rearrangement in which a
segment of a chromosome is reversed end to end (it
is inverted)
Inversion
Example of Inversion
Opitz - Kaveggia syndrome
Example of Substitution
Sickle-Cell anemia
Example of Insertion
One form of beta-thalassemia
Example of Deletion
Cystic Fibrosis
