Transformation

Question 1

Transformation 101 Basics

Answer 1

(**LYSIS and COMPETENCE)

• involves
  a. LYSIS of some cells (the DONORS)
  b. release of naked DNA (LOTS of nakey around when there is LOTS of bacteria)
  c. UPTAKE of that DNA by other cells (the RECIPIENTS)
• competence=ability to take up DNA from the environment
  
  • encoded by many bacterial chromosomal genes.
  • these genes become active under certain environmental conditions…transformation is NATURAL
• D lyses R preps

Question 2

Transformation 1-Clinical Relevance

Answer 2

The following use transformation to change the appearance of clinically important surface antigens, thereby evading the host immune system:
-G+ Streptococcus pneumoniae (Pneumococcus)
-G NEG Haemophilus influenza and Neisseria gonorrhea
{differences between + and - mechanism but the principle is the same}

Question 3

Transformation 2-Gram POSITIVE bacterium-Streptococcus pneumoniae (A)

Answer 3

How do donor cells release naked DNA into the environment?
-lysis
-trauma
-DEATH
DNA is naked ergo HIGHLY SUSCEPTIBLE to environment factors includinggg DETERGENTS that inhibit binding and NUCLEASES that destroy DNA.

Question 4

Transformation 3-Gram POSITIVE bacterium-Streptococcus pneumoniae (B)

Answer 4

-pneumococcal cells secrete a PROTEIN COMPETENCE FACTOR that induces cells to synthesize special proteins necessary for COMPETENCE.

Question 5

Transformation 3-Gram POSITIVE bacterium-Streptococcus pneumoniae (C)

Answer 5

• a protein located on the cell surface binds the dbl stranded DNA indiscriminately. aka IT BINDS ANY DNA PRESENT in the environment.
• as the DNA passes through the membrane, ONE strand is DEGRADED by NUCLEASE

Question 6

Transformation 3-Gram POSITIVE bacterium-Streptococcus pneumoniae (D)

Answer 6

Remaining SINGLE-strand EXOGENATE: 1 of 3 fates.
{after PMF-uptake energy)
1. DEGRADATION (most of them)-no heritable change in the recipient, lost to nucleases
2. CIRCULARIZATION-if it can replicate, it will be inherited as a plasmid.
-lost by dilution-only one will get the DNA
3. (HOMOLOGOUS) RECOMBINATION into the chromosome, stable retained. permanent alteration

Question 7

Competence

Answer 7

-takes a lot of energy, only want to engage if theres nake d DNA around, ergo when LOTS of neighbors (can count eachother using pheromones-once numbers reach a certain threshold, cells become COMPETENT)
-this method ensures that theres lots of naked DNA in the environment
-COMPLEMENT expresses machinery to get DNA from outside to inside
-Need: proteins on recipient surface to bind DNA (DNA binding proteins)
:DNA nucleases to convert dbl–>single stranded

Question 8

Homologous Recombination

Answer 8

exogenous–> endogenous –> homologus recombinant (Next: selected for OR against)