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eva chapter 7 microbial genetics
Terms in this set (45)
the detection of the critical mass. requires receptors proteins on the surface of the bacterial cell that binds to molecules from the neighbors. when the critical mass is detected using the receptors, the bacteria change their gene expression. turn on new and different genes so that they can secrete matrix. the entire number of genes that come in response. 10% of the total genes are regulated by this.
horizontal gene transfer
the way bactere gives genetic information to their neighbors
three types of gene transfer
dna is taken up from the enviroment by bacteria that are said to be competent treated with calcium chloride. bacteria can acquire new characteristics from the environmental dna. comes from dead bacteria.
discovered that genes for anitibiotic resistance can be passed to new bacteria through transformation. he worked with the bacteria that caused pneumonia steptococcus pneumoniae. mixed non pathogenic bacteria with dead pathogenic bacteria of the same type and the resulting bacteria was very pathogenic. killed mice
a bacterial virus phages takes up some dna from its host bacterial cell. then the virus transmits it to its new host bacterial cell. so, the new bacterial cell has new dna. one example is clostridium diphtheria- gets its toxin gene from a phage beta
requires a plasmid f plasmid that encodes a pilus that brings two separate bacteria together. then, once thy are together, the f plasmid moves into the new cell. leaves a copy in the old cell. f plasmid can insert into the chromosome if it does this can move the entire chromosome into the new cell the partner cell
a small genetic element. stretch of dna. encode transposas enzymes that cause the tranposons to jump around the dna. also found in eukaryotes. disc in plants, corn.
what transposons have at their edges.
transposons jumping itself
bacteria have a single chromosome
attached to the cytoplsmic membrane, in gram negaives inner membrane, made out of dna. made out of necleotides. made out of bases, sugars, and phosphates.
double stranded. strands are NOT parallel.
protein associated with a bacterial chromosome
has no histones
must be copied. a copy must bve put in the new cell.
dna dependent dna polymerase
enzyme that copies the dna
is used because the template for copying is dna itself
it is forming new dna using free nucleotides to produce that dna.
if a mistake is mad and not corrected
regulation of gen expression in eukaryotes
gene are individually regulated with respect to tissue type, time on during fetal development, others could be on in adult. and external stimuli neural transmitter or hormones
regulation of gene expression in prokaryotes
genes are regulated in groups called operons. each operon has several proteins and strings of bases that control that operon
to be on
need a polymerase on the promoter need the operator to be open. there cannot be a repressor on the operator because the repressor would interfere with the polymerase. polymerase reads down to make the mRNA with three genes on it that will be translated.
operons that are not inducible instead they are on all the time.
you do this so that they are transcribed faster than usual. involves a CAP protein. catabolite activator protein. so this CAP actually helps the RNA polymerase attach to the promoter. the result is more mRNA and more of the protein that is encoded by these genes
is a permanent change in the base sequence in the dna.
1. nonsense mutation
2. missence mutation
3. silent mutation
ecodes methionine within rna
encodes methionine within dna
this is a stop codon. causes the translation to stop. so the resulting protein would be shorter than normal.
so that instead of methionine another amino acid would be placed in the protein. so the protein is the same length, but there is an amino acid substitution.
change the nucleic sequence, but the amino acid remaind the same. not detectable
these involve either an insertion or a deletion within the dna
change dna. radiation/chemicals/uv light/ x rays/ heat of the body
enzymes involved in repair
2. base excision repair
3. mismatch repair
4. sos response
cleaves pyrmidine dimers are t,u, a
base excision repair
removes the wrong base, added in the correct base
only in bacteria. ocurs when the dna is so damaged that it cannot be copies during dna replication. so the baterial cell cannot reprouce dead. so in the sos response, proteins come to the rescue, and they make the dna polymerase error prone, so that is can move over the damage and start up agian. problem is that is error prone, so many mutations occur.
a test for the capacity of chemical to cause mutation
example of ames test
1. have salmonella his negative- means that salmonella cannot grow without histidine amino acid. to grow scientists add histidine to the agar.
2. give the mutagen to the salmonella cells, and then plate the bacteria on media without histidine
3. if colonies form, then a mutation occurred- these bacteria are now histidine positive
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