Lecture 8 - Microbial Genetics Flashcards
What is the Central Dogma?
DNA makes RNA makes Proteins
transcription
transcribing DNA into RNA
translation
translating RNA into protein
What is the difference between transcription and translation?
transcription converts DNA into RNA which are BOTH nucleic acids
#samelanguage
Translation converts RNA into proteins.
RNA is made of nucleic acids wheras proteins are made of amino acids.
#differentlanguages
Describe Pseudomonas aeruginosa?
blue/green colored
hemolytic
flagellated
gram-negative
contains lots of Mg in cell membrane
Genome
describes ALL the genetic information in a cell
Where is the genome found in eukaryotic cells?
Chromosomes
Mitochondrial DNA
Chloroplast DNA
Where is the genome found in prokaryotic cells?
Chromosome
Plasmids
Chloroplast DNA
gene
a segment of a DNA molecule coding for a functional product (i.e. protein)
What are the monomers of DNA and RNA?
nucleotides
4 Nitrogenous Bases found in DNA
(ATCG)
Adenine
Thymine
Cytosine
Guanine
4 Nitrogenous Bases found in RNA
(AUCG)
Adenine
Uracil
Cytosine
Guanine
How are the two strands of a DNA double helix held together?
Hydrogen Bonds between complementary nitrogenous bases on opposing strands of DNA
What are the 3 parts of a Nucleotide?
Nitrogenous Base(ATCGU) attached to a Sugar and Phosphate Backbone
Adenine binds to
Thymine (in DNA)
Uracil (in RNA)
Guanine binds to
Cytosine
Cytosine binds to
Guanine
Uracil binds to
Adenine
Thymine binds to
Adenine
Thymine is only found in
DNA
Uracil is only found in
RNA
genotype
the unique sequence of nucleotides in a gene
(i.e. AGCAACTAGCCT)
phenotype
the observable characteristic of a organism resulting from it expressed genotype
(i.e. green eyes, purple flowers, the presence of a flagella)
Are genes in eukaryotic DNA continuous or not continuous?
not-continuous
(there are exons and introns)
Are genes in prokaryotic DNA continuous or not continuous?
cotinuous
Exon
sections of eukaryotic DNA coding for a functional product
Introns
interrupting sequences of nucleotides within a eukaryotic gene that do not code for a functional product
Which is ultimately expressed? DNA found in introns or DNA found in Exons?
DNA found in Exons
DNA Replication
DNA is replicated in order for cells to divide and reproduce and for both daughter cells to have complete copies of the original DNA
Binary Fission
bacterial cell division/replication
Describe How DNA is Replicated
First, enzymes Gyrase and Helicase unwide and separate the two strands of DNA. Then DNA Polymerase adds nucleotides to both of the original strands to form two new complete, double helix strands of DNA.
Semi-Conservative Model of DNA Replication
The replicated DNA include one strand from the original molecule and one strand that is completely new
DNA Helicase
unwinds the two strands of DNA in the double helix so there is room for transcription or translation to occur
DNA Polymerase
uses the original strand of DNA as a template to form a new complementary strand of DNA using base pairng
In which type of cell does DNA replication occur bidirectionally?
Prokaryotic Cells
because their DNA is circular
Origin of Replication
the point on a bacterial chromosome where DNA replication begins
PCR
Polymerase Chain Reaction
Function of PCR
rapidly replicate DNA in vitro
in vitro
in a test tube
How is PCR Accomplished?
- High temps are used to denature and break apart the DNA double helix
- Taq DNA Polymerase from the hyperthermophile Thermus aquaticus is used repeatedly to create new strands of DNA
- The cycle is repeated to amplify the number of DNA strands
Ingredients for PCR
- Desired DNA to Copy
- Nucleotides
- Primers
- Taq DNA Polymerase
- Buffer
- Thermocycler Device
Describe a PCR Cycle
1 - Denaturing of DNA
2 - Annealing
3 - Extension/Elongation
Often used in criminal investigations to test small amounts of DNA that were collected
PCR
Often used to test for pathogens such as COVID
PCR
RNA polymerase
uses complimentary base pairing to transcribe a strand of RNA from a strand of DNA
mRNA
messenger RNA
tRNA
transfer RNA
rRNA
ribosomal RNA
Type of RNA that Undergoes Translation to Form a Protein
mRNA
Type of RNA Used to Deliver Amino Acids to the Ribosome for Proteins to be Assembled
tRNA
Type of RNA that Helps Make the Ribosome which is the Unit where Translation Occurs
rRNA
pre-mRNA
RNA that still includes the introns
How is pre-mRNA converted into mRNA?
introns are excised and the exons are spliced together to form mRNA
How is mRNA translated?
The mRNA attaches to a ribosome. Next, tRNA will base pair with each codon (set of 3 consecutive nucleotides on the mRNA). Each tRNA carries a corresponding amino acid. As each codon is “read” the amino acids attached to the tRNA are bonded together to form a growing protein.
How many amino acids are there?
20
In Eukaryotes, where does DNA replication occur?
Nucleus
In Eukaryotes, where does RNA transcription occur?
Nucleus
In Eukaryotes, where is pre-mRNA converted to mRNA?
Nucleus
In Eukaryotes, where is mRNA translated?
Cytoplam
In Prokaryotes, where is mRNA translated?
Cytoplam
codon
set of 3 consecutive nucleotides on the mRNA whcih codes for a specific amino acid
AUG codes for
methoinine
Start Codon
AUG
mutation
permanent change in the genotype which will be passed to offspring
mutagens
cause mutations
carcinogens
cause mutations that can cause cancer
Point Mutation
substitution of one nucleotide for another
Silent Mutation
the mutation in the DNA sequence does not change the amino acid coded for and therefore does not change the protein made
Missense Mutation
the mutation in the DNA sequence changes the amino acid coded for. It may or may not significantly affect the function of the resulting protein.
Nonsense Mutation
the mutation in the DNA sequence does not code for an amino acid and consequently the protein is not fully formed and functions improperly or not at all
Frameshift Mutation
a nucleotide in the DNA sequence is deleted or an extra one is inserted which changes the reading frame of codons and consequently the sequence of amino acids
3 Types of Horizontal Gene Transfer
- Genetic Transformation
- Conjugation
- Transduction
Horizontal Gene Transfer
the process in which an organism transfers genetic material to another organism that is NOT its offspring
Transformation
a type of horizontal gene transfer where naked DNA in a solution is taken up by a bacteria and recombined into its chromosome
Discovered Transformation of DNA
Frederick Griffith
Conjugation
a type of horizontal gene transfer where a sex pillus is formed and connects two bacteria allowing the transfer of plasmids and genetic material from one bacteria to the other
R factors
genes for antibiotic resistance
Transduction
a type of horizontal gene transfer in which genes are transferred from a donor cell to a bacteria by a bacteriophage virus
Method of Generalized Transduction
A bacteriophage injects its genetic material into a bacteria and causes the bacterial DNA to lyse. As new bacteriophages are formed inside the infected bacteria, some bacteriophages may include the lysed bacterial DNA. If that bacteriophage injects the bacterial DNA into another bacterial cell, that DNA can be incorporated into its chromosome.
(Note: This process is very random.)
Specialized Transdction
Only certain bacterial genes are tranfered.
A phage injects its DNA into a bacteria. The phage DNA incorporates into the bacterial DNA forming a prophage. The prophage is incorrectly excised and and some bacterial DNA is stuck to it. The phage replicates and then the phages infect new host cells and in the process add the DNA from the original bacterial cell into the new bacterial cells.
Transposons
DNA sequenes that move from one location in a genome to another. This results in mutations or an increase/decrease in the amount of genomic DNA.
Discovered Transposons
Barbara McClintock
