Lecture 7 DNA Flashcards
What is DNA’s full name
Deoxyribonucleic Acid
What are the monomer building block of DNA CALLED
deoxyribonucleotides
What is DNA composed of
– 5-carbon sugar deoxyribose
– a nitrogenous base
– a phosphate group
Name the four nitrogenous bases found in DNA
– Adenine (A)
– Guanine (G)
– Cytosine (C)
– Thymine (T)
Does DNA consist or one or two complementary stands
Two
Are DNA complementary stands single or double stranded
Double stranded
What does Adenine pair with
Thymine
What does Guanine pair with
Cytosine
Name the 4 stages of DNA replication
• Initiation
• Elongation
• Proofreading
• Termination
DNA polymerase can add free nucleotides to only where
the 3’ end of the newly-forming strand.
DNA polymerase can add a nucleotide only to what pre-existing group
3’-OH group
Name the two stages of Gene expression
•Transcription
•Translation
Describe Transcription
• Initiated at the promoter region upstream of the gene
• RNA polymerase copies the DNA and produces an RNA transcript (mRNA)
Describe Translation
• mRNA is decoded by ribosomes and tRNA molecules to specify
• the exact sequence of amino acids in a protein
How many adjacent nucleotides encode a particular amino acid
A set of 3
What is the genetic code called
Codon
What affects RNA polymerase
Rifampicin
What affects ribosome and protein synthesis
Macrolides (erythromycin), Kanamycin,
Tetracycline
Mutations in the antibiotic target can lead to what
Bacterial resistance
What targets DNA Gyrase
Ciprofoxacin
What does the enzyme Gyrase do
unwinds bacterial DNA during replication.
What does Ciprofoxacin prevent
Cell division
What type of antibiotic is Ciprofoxacin
Quinolone antibiotic
Name the 3 plasmid genes
– Antibiotic resistance genes (often multiple)
– Virulence genes (e.g. toxins)
– Metabolic genes
What is the most common source of genetic variation
Mutations
Name the three types of mutations
– Substitution
– Deletion
– Insertion
What is the Asparagine codon called
•AAC
•Faulty protein
•Missense mutation
What is the stop codon called
•UAG
.•Incomplete protein
•Nonsense mutation
What is the Tyrosine codon called
•UAU
•Normal Protein
•Silent mutation
What is the second Tyrosine codon called
•5’UAC
•Normal protein
•Wild type
Example of physical mutagen
Radiation
Example of chemical mutagenesis
– Base analogues
– Intercalating agents
– Metals - ROS
Example of biological mutagen agents
•Viruses
•Transposon
What is genetic exchange
Modes of genetic transfer between bacterial cells
Example of naturally competent bacteria
Streptococcus pneumoniae
What does conjugation describe
Plasmid transfer between bacterial cells
What does conjugation require
•cell-to-cell contact & can occur between different bacterial species
•even between G+ve and G-ve
In conjugation where do plasmids replicate
replicate in the donor cell prior to transfer into the recipient cell
What is Transduction
DNA transfer between bacteria via infection with a bacteriophage
What infect the bacterial cell and replicate in Transduction
Phage
What does Transduction involve the incorporation of
Phage DNA into phage capsids (heads)
What are Transposons
DNA sequences that can ‘jump’ within the bacterial genome and from the genome to plasmids within the same cell
What do Transposons often contain
Antibiotic resistance genes
Example of a mutation
Drug resistance in Tuberculosis
Example of Transformation/Transposition
Penicillin resistant gonorrhea
Example of conjugation
Multi resistance shigella
