Chapter 5 Bacteria Transformation and Polymerase Chain Reaction

What is the clinical significance of bacterial transformation in biotechnology?

It explains antibiotic resistance spread and allows genetic engineering such as insulin production and gene therapy

When did Griffith discover transformation?

1928

How did the mouse die in Station 1?

It died from pneumonia caused by live encapsulated S-strain bacteria

What did the S-strain contain?

A polysaccharide capsule that allows immune evasion

How was the R-strain different from the S-strain?

It lacked a capsule and was non-virulent

What happened in Station 3 of Griffith’s experiment?

Heat-killed S-strain was injected and the mouse survived

What happened in Station 4?

The mouse died and R-strain was transformed into virulent S-strain

How did the bacteria demonstrate genetic variation?

The R-strain acquired capsule genes and became virulent

What happens during DNA release and uptake in the transformation process?

DNA from dead S-strain is released and taken up by a competent R-strain bacterium

What happens during DNA integration?

S-strain DNA replaces the matching region of R-strain DNA

What happens during bacterial division in the transformation process?

Transformed DNA is replicated and passed to daughter cells

What is the clinical significance of bacterial conjugation?

It rapidly spreads antibiotic resistance

What are the different bacterial mating types?

F+ donor and F− recipient

What is the Fertility Factor?

A plasmid that allows a bacterium to donate DNA

What is the conjugation bridge?

A sex pilus connecting donor and recipient bacteria

How are genes transferred during conjugation?

Through a pilus using rolling-circle plasmid replication

What is high frequency recombination?

When the F factor is integrated into the chromosome allowing chromosomal gene transfer

What is bacterial transduction?

Transfer of bacterial genes by bacteriophages

What happens during bacteriophage attachment?

The phage binds to specific receptors on the bacterial surface

What happens during phage DNA replication?

Phage DNA directs synthesis of new phage DNA and proteins

What happens during packaging and phage release?

Bacterial DNA may be packaged and released during cell lysis

What are the steps of generalized transduction?

Attachment DNA injection fragmentation packaging error and lysis

What happens during prophage integration and excision?

Phage DNA integrates and excises with nearby bacterial genes

What is hybrid DNA formation?

DNA containing both phage and bacterial genes

How is DNA transferred to the recipient?

Through bacteriophage infection

What is the pre-integration state?

Recipient chromosome before donor DNA integrates

What is the post-integration state?

Donor DNA is recombined into the host chromosome

What is the clinical significance of bacterial transduction?

It spreads virulence and antibiotic resistance genes

How did genetic engineering revolutionize medicine?

It allowed bacteria to produce human proteins like insulin

What is the donor plasmid?

A small circular DNA molecule used as a vector

What are restriction enzymes?

Enzymes that cut DNA at specific sequences

What are DNA ligases?

Enzymes that join DNA fragments together

Where does foreign DNA come from?

Other bacteria animal cells or human cells

What is a chimera?

A recombinant plasmid containing foreign DNA

What does CaCl₂ solution do to cells?

It opens cell membranes to allow plasmid entry

How does the host bacteria reproduce quickly?

By binary fission

How can recombinant proteins be used?

For insulin hormones vaccines and enzymes

How did PCR revolutionize medicine?

It enabled rapid DNA detection and diagnosis

What are primers?

Short DNA sequences that start DNA synthesis

What are dNTPs?

DNA building blocks used to make new strands

What is Taq DNA polymerase?

A heat-stable enzyme that builds DNA during PCR

What are the three steps of PCR?

Denaturation annealing and elongation

What temperature does denaturation occur at?

About 95°C

What happens during the denaturation phase?

DNA strands separate

What temperature does annealing happen?

About 55°C

What happens during annealing phase?

Primers bind to the template DNA

What temperature does elongation happen at?

About 72°C

What occurs during elongation stage?

DNA polymerase synthesizes new DNA strands

How does PCR multiply?

By doubling each cycle using the formula 2ⁿ

How many cycles of PCR are typical?

25 to 40 cycles