Bacterial Genetics and Biotechnology

Flashcards covering bacterial genetics, mutations, DNA repair, horizontal gene transfer, plasmids, biotechnology tools like restriction enzymes and PCR, and genetic engineering applications.

What is Mutation through vertical gene transfer?

Change in nucleotide sequence passes to the offspring.

What is Horizontal gene transfer?

DNA transfer by a process other than reproduction.

What are Spontaneous Mutations?

Random genetic changes that result from normal cell processes and are passed on to the cell’s progeny. Occur in absence of mutagens.

Name three examples of spontaneous mutations.

Base substitutions, Frameshift mutations and Transposons.

What are Base Substitutions?

Most common type of mutation. Occurs during DNA synthesis (errors)

What is a Point mutation?

When only one base is changed.

What is Silent (synonymous) mutation?

Incorrect nucleotide leading to a codon that encodes the same amino acid.

What is Missense mutation?

Incorrect nucleotide leading to a codon for a different amino acid.

What is Nonsense mutation?

Incorrect nucleotide leading to a stop codon (shorter protein).

What is Frameshift Mutation?

Addition or deletion of nucleotides.

What are Transposons?

Move from one location to another in the cell’s genome (transposition).

What is Insertional inactivation?

Gene into which transposon jumps is inactivated; the function of the gene is disrupted.

What is a Mutagen?

Agent that induces a change in the DNA.

What are Base modifiers?

Change a base.

What are Base analogs?

Look like a DNA base leading to the wrong nucleotide potentially being incorporated opposite the base analog.

What are Intercalating agents?

Increase frequency of frameshift mutations. Flat molecules intercalate between adjacent bases of DNA, pushing the nucleotides apart.

What does UV light (non-ionizing) do?

Causes thymine dimers.

What do X-rays (ionizing) do?

Causes single and double-stranded breaks in the DNA. Double-stranded breaks can be lethal to the cell.

What is Proofreading?

DNA polymerase can back up, remove incorrect nucleotide and fix inserting the correct one.

What is Mismatch repair?

Methylation of DNA indicates the new strand.

What is Base excision repair?

Modified nucleobases leading to base substitutions.

What is Glycosylase?

Removes the damaged nucleobase during base excision repair.

What is Photoreactivation (light repair)?

Enzyme uses energy from light to break covalent bonds of thymine dimer; only found in bacteria.

What is Nucleotide Excision (dark repair)?

Enzyme removes damage, DNA polymerase makes a new strand, and DNA ligase fills and seals the gap.

What is Bacterial transformation?

Recipient cell takes up naked DNA, which is then integrated into the chromosome

What is Transduction?

Recipient cell acquires donor DNA from the bacterial DNA-containing phage coat.

What is Conjugation?

Recipient cell acquires donor DNA during cell-to-cell contact.

What is Transformation?

Uptake of naked DNA.

What is required for transformation?

Recipient cell must be competent.

What is Transduction?

Transfer of bacterial genes through bacteriophages (phages).

What is Conjugation?

Requires contact between donor and recipient cell.

What is conjugative plasmid?

Direct their own transfer from donor to recipient cell; an example is the F plasmid (F = fertility) of E.coli.

What are F+ cells?

Cells with F plasmid.

What are F- cells?

Cells without F plasmid.

What are Hfr cells (high frequency of recombination cells)?

F-plasmid is integrated into chromosome.

What is F’ plasmid?

When a small piece of chromosome is removed with F plasmid DNA.

What do Restriction Enzymes do?

Cut DNA sequences at specific sequences (recognition sequence) and generate restriction fragments.

What are palindromes referring to restriction enzymes?

They are the same in both strands when reading in the 5’ – 3’ direction.

What is DNA Gel Electrophoresis?

Current causes DNA to migrate through gel to positive (+) electrode – small fragments move faster.

What is Genetically Engineered Bacteria for Protein Production?

Safer and cheaper protein production.

What is DNA Cloning?

Isolate the DNA, cut the DNA of interest and vector molecules, join genomic factors to the vectors to generate a recombinant molecule and introduce the recombinant into the host where it will replicate.

What is Genetically Engineered Bacteria and DNA Production?

Help in research and allows easier production of DNA for study.

What is Complementary DNA (cDNA)?

Synthetic DNA that has many uses in research and biotechnology.

What is a Vector?

Has origin of replication, carries cloned DNA and contains recognition sequences of several restriction enzymes

What is Selectable marker?

Gene encoding resistance to an antibiotic.

What is a Second genetic marker?

Encodes obervable characteristics that allows to distinguish colonies of cells with recombinant molecules.

How can you differentiate colonies with vector pUC18 selecting for cells with vector and differentiates those with recombinant plasmids?

Cells with intact vector (no insert) have functional lacZ’ gene – form blue colonies when grown on X-gal, while cells with the recombinant molecule form white colonies.

What is DNA Sequencing?

Process of determining the order of nucleotides in DNA molecule.

What are the Sager Method requirements for DNA sequencing?

Template DNA, DNA polymerase, Primer, Deoxynucleotides (dNTPs) and Dideoxynucleotide (ddNTP).

What is Polymerase Chain Reaction (PCR) used for?

Amplify DNA.

What is required for PCR?

DNA template (dsDNA), Taq DNA Polymerase, Primers and Deoxynucleotides (dNTPs).

What are the 3 steps of PCR?

Denaturation (95oC), Annealing (50oC) and Synthesis (72oC).