Test 2 (Pp16-19) Vandenburg Usf Microbiology

Front 1

How many genes does E. coli have?

Back 1

3,000 to 4,000

Front 2

Polycistronic

Back 2

more then one cistron or gene coded for. One mRNA will results in many diff proteins

Front 3

1928 griffith exp with S. pneumoniae

Back 3

Smooth strains were virulent. Rough strains were not. Mouse exp with dead virulent DNA and live non virulent bac killed mouse

Front 4

1944 Avery, MacLeod and McCarty

Back 4

transformed recipients - discovered DNA could be taken from other bac

Front 5

How long are okazaki fragments?

Back 5

1,000 to 2,000 bps, lagging strand still replicates 5' to 3'

Front 6

E coli has how many DNA polymerases?

Back 6

3 - I,II, and III

Front 7

DNA polymerase III

Back 7

can go up to 30,000 bps/minute

Front 8

DNA polymerase I

Back 8

also called Kornberg enzyme. Does excision-repair of UV damage

Front 9

RNA polymerase is large

Back 9

one of the largest enzymes known

Front 10

How long does mRNA live?

Back 10

a few minutes in bac

Front 11

Lactose operon

Back 11

unit of transcription on the chromosome. 1+ structural genes for 3 enzymes under control of one operator. repressor on i gene

Front 12

Lactose operon structure

Back 12

i o p z y a. Repressor, then operator, promoter, structural genes z,y,a

Front 13

What does repressor do for lactose operon?

Back 13

repressor attaches to operator site and prevent RNA polymerase binding. repressor can be inactivated by an inducer, lactose, that will bind to promoter and chang eit's configuration - then RNA polymerase can go

Front 14

B galactosidase in lactose metabolism

Back 14

B galactosidase makes lactose into glucose. cAMP reptor protein, CRP, is positive regulator for the lac operon.

Front 15

Constitutive Enzymes

Back 15

produced in constant amounts at all time. constantly transcribed

Front 16

Inducible

Back 16

enzymes that can be turned on or off. on operons and feedback systems

Front 17

Trp operon has what kind of control?

Back 17

negative control system - repressor is normally inactive and can only bind when trytophan is present. Trytophan is absent then operon is on

Front 18

What does trp operon control?

Back 18

5 structural genes - trpA, B, C, D, E and are regulated by TrpP, O, R (promoter, operator and repressor)

Front 19

TrpL

Back 19

trp leader controls the expression of genes. contains a stop signal, an attenuator. When trp is high then leader slows it down

Front 20

Catabolite Repression

Back 20

a positive control sys. if cell grows in lactose and glucose. glucose will be used and lactose will be turned off. When lactose is only option it will use it. Causes two phases of exponential growth

Front 21

Mutants

Back 21

have undergone mutation and have phenotypic change in organism

Front 22

induced mutants

Back 22

result of chemical or radiation impact on genes to increase mutation rate

Front 23

Missense mutations

Back 23

in position 1 or 2 of codon. consequences vary from protein to protein

Front 24

Nonsense mutation

Back 24

mutation results in the formation of a nonsense codon (won't code). this can result in premature termination of protein syn

Front 25

Deletions

Back 25

mutations when segments are missing

Front 26

insertions

Back 26

one or more bases are added to the DNA

Front 27

Reading frameshift

Back 27

result from insertion or deletions. this could completely change the aa sequence

Front 28

Back mutation

Back 28

mutated base is changed back

Front 29

Suppressor mutatins

Back 29

overcome or suppress effects of the initial mutation w/o alteration in original gene Ex. codon changed from GCU to ACU, change aa but if the the aanticodon -tRNA is also changed aa

Front 30

UV radiation

Back 30

cause the formation of a pyrimidine dimers in chromosomes. distort the helix and cause bulges. inference with DNA replication and transcription

Front 31

Base analogs

Back 31

chemicals. 5-bromouracil substitutes for thymine and binds with guanine

Front 32

transistions

Back 32

replacement of a purine by a diff purine, or pyrimidine for a diff pyrimidine

Front 33

transversions

Back 33

a purine for a pyrimidine

Front 34

NTG

Back 34

an alkylatinf agent that acts as a DNA replication fork causing crosslinking of DNA strands and errors

Front 35

Excision repair

Back 35

bad part cut out and filled by DNA polymerase and closed by ligase

Front 36

Photoreactivation

Back 36

light activated enzyme, photolyase, cleave linkages pyrimidines. then glucosylases detect and remove unnatural base. Gives hole or AP site.

Front 37

SOS response

Back 37

if DNA damage is SEVERE - like large gaps in helix. involves 17 genes in excision repair of DNA damgae. expression is controlled by lexA or REcA

Front 38

Replica plating

Back 38

method used to detect auxotroughs from prototroughs (wild type strain) - like stamping bacteria

Front 39

3 ways that genetic material is transferred in bacteria

Back 39

tranformation (insertion of naked DNA), transduction (bacteriophage is vector) and conjugation (contact btw donor and recipient)

Front 40

transformation

Back 40

cells are transformable in late log phase. small portion of DNA in tranferred. recipient takes DNA then it's competent

Front 41

Natural transformation

Back 41

a cell lyses and a closely related recipient takes up DNA when it's competent

Front 42

Artificial transformation

Back 42

DNA is extracted chemically. recipients are treated with CaCl2 to make them competent

Front 43

transfection

Back 43

involves introduction of bacteriophage DNA into cell. treat cells with CaCl2

Front 44

Ames Test

Back 44

bacterial test to screen for carcinogens. measures reversion in Salmonella typhimurium. Feed carcinogens to rats then remover livers and feed bac liver. mutation will allow iS. typhimurium to grow without histidine in medium

Front 45

initiation codon establishes the _____ for the mRNA

Back 45

reading frame

Front 46

The purine rich region that precedes the AUG codon

Back 46

3-9 bases. Shine Delgarno sequence

Front 47

IF3

Back 47

catalyzes the dissociation of the 70S ribosome into individual subunits. also binding of the 30S subunit to appropriate site on mRNA

Front 48

IF2 and GTP

Back 48

Involved in the positioning of the th fmet-tRNA to the correct codon

Front 49

IF1

Back 49

assist IF3 in binding 30S subunit to the mRNA

Front 50

Elongation

Back 50

binding of aminoacyl-tRNA to complimentary codon on mRNA. Recognition requires EF-Ts and EF-Tu (elongation factors heat stable and unstable). Using GTP hydrolysis to power aa matching

Front 51

What is translocation?

Back 51

new aa attached at p site to ribome then moved to a site as ribosome moves and aa peptide bond is made with last aa simultaneously as the ester linkage btw the aa and the tRNA breaks

Front 52

Negative regulation

Back 52

an inhibitor (also called repressor) prevents transcription. an inducer can reverse this

Front 53

Positive regulation

Back 53

an effector molcule activates promotor. no inhibition involved

Front 54

polycistronic mRNA

Back 54

one mRNA can carry aa sequence for many aa chains

Front 55

leader

Back 55

in mRNA the sequence of 5-20 bases that is untranslated on the 5' end

Front 56

spacer

Back 56

in polycistronic mRNA the spacer is 10 bp long section that lies btw the separate codon sequences

Front 57

What is the smallest RNA molecule?

Back 57

tRNA

Front 58

What DNA sequences are promotors?

Back 58

Pribnow box (TATAAT) is the -10. TTGACA is the -35

Front 59

Five stages of RNA Synthesis

Back 59

1. promotor recognition (-10,-35) 2. local unwinding (RNA polymerase forms an open promotor complex) 3. Chain initiation 4. chain elongation 5. chain termination

Front 60

Rho dependent and independent

Back 60

rho protein unwinds RNA and DNA at the terminator. Rho independent is a poly U sequence that results in a hairpin in the RNA - this stops synthesis