Microbio Chapter 9 - Genetics - Set 2

Front 1

Repressible operons have the same basic components as inducible operons:

Back 1

Repressible operons have the same basic components as inducible operons:

 promotor (binds RPo)

 operator (binds only trp/repressor complex)

 structural genes (codes for enzymes used to synthesize tryptophan)

Front 2

Trp Operon

Back 2

Trp Operon - carries genes which code for the enzymes in the biosynthetic pathway which makes tryptophan (an amino acid)

Front 3

In repressible operons, the structural genes are transcribed until they are turned off or

____________ by product (tryptophan)

Back 3

In repressible operons, the structural genes are transcribed until they are turned off or

REPRESSED by product (tryptophan)

Front 4

How does the Trp Operon work?

Back 4

Trp Operon

1. Normally transcription proceeds - enzymes produced - Trp synthesized

2. Once tryptophan is produced, excess tryptophan binds to the repressor (Regulatory) protein;

 Tryptophan = co-repressor

3. Repressor + Trp ---- binds to the operator, blocking transcription

Front 5

Summary of the Lac operon

Back 5

Inducible

Starts as off

controls enzymes for catabolic path

Front 6

Summary of TRP operon

Back 6

Repressible

Starts as On

Controls enzymes for an anabolic path

Front 7

Mutations are _________

Back 7

Mutations are changes in the base sequence of the DNA molecule

Front 8

What are the 3 types of mutations?

Back 8

1. Point mutations - a single base is changed (aka base substitution)

2. Nonsense Mutations - these mutations occur when changes in the DNA base sequence result in the formation of a STOP CODON; protein synthesis then halts when that codon is reached

3. Missense Mutations - these mutations occur when a change results in the wrong amino acid

Front 9

Point mutations - a single ______ is changed (aka ______________)

Back 9

Point mutations - a single base is changed (aka base substitution)

Front 10

Nonsense Mutations - these mutations occur when changes in the DNA base sequence result in the formation of a _____________; protein synthesis then _______________________

Back 10

Nonsense Mutations - these mutations occur when changes in the DNA base sequence result in the formation of a STOP CODON; protein synthesis then halts when that codon is reached

Front 11

Missense Mutations - these mutations occur when a change results in the _______________

Back 11

Missense Mutations - these mutations occur when a change results in the wrong amino acid

Front 12

Give me an example of a disease that is caused by a missense mutation

Back 12

Missense Mutations - these mutations occur when a change results in the wrong amino acid

 Ex: sickle cell anemia is caused because a single base change results in a different amino acid being inserted into hemoglobin

Front 13

Tell me general info about the transformation experiments, when they were done and who did them

Back 13

Griffith's transformation experiments were done (in 1928) to determine what type of molecule was the heritable material (scientists knew it was either DNA or protein)

These experiments used Streptococcus pneumonia which causes pneumonia in mice

Conclusion: the mixture of bacteria in the fourth setup, allowed the "R" strain to transform into the "S" strain, by picking up DNA

Front 14

Explain the details of the transformation experiment

Back 14

There were 2 strains of Streptococcus pneumonia (the bacterium)

 R strain - unencapsulated - harmless

 S strain - encapsulated - causes pneumonia

 Injected the bacteria into mice:

a. Injected "R" (no capsule) - mice ok

b. Injected "S" (had the capsule) - mice died of pneumonia

c. Injected heat killed "S" - mice ok

d. Injected a mix of live unencapsulated & heat killed encapsulated - mice died!

Front 15

what is the definition of transformation?

Back 15

Transformation - the ability of a cell to pick up foreign pieces of DNA from the surrounding environment

Front 16

what is the definition of Conjugation ?

Back 16

Conjugation: the process whereby one bacterial cell transfers a plasmid to a recipient cell

Front 17

PLASMIDS are

Back 17

PLASMIDS are circular double-stranded DNA molecules that exist independent of the bacterial chromosome. Plasmids contain at least one gene, but often have several genes although none of the genes are essential for the growth of the cell under normal conditions.

Front 18

Prokaryotic cells contain a single _____________. In E. coli, that ________________ contains approximately 4.7 x 106 bp of DNA. However, some _____________ in prokaryotic cells is encoded on considerably smaller structures commonly called ___________________.

Back 18

Prokaryotic cells contain a single chromosome. In E. coli, that chromosome contains approximately 4.7 x 106 bp of DNA. However, some genetic information in prokaryotic cells is encoded on considerably smaller structures commonly called plasmids.

Front 19

Plasmids are capable of _____________________________; (they are able to begin their own replication)

Back 19

Plasmids are capable of autonomous replication; (they are able to begin their own replication)

Front 20

Plasmids are classified according to _____

Back 20

Plasmids are classified according to the genetic information they contain.

Front 21

The F PLASMID is a special plasmid that confers

Back 21

The F PLASMID is a special plasmid that confers fertility and is essential for transfer of genetic information between cells by conjugation.

The F Plasmid is present in a single copy per cell and is one of the largest plasmids - 94 kbp

Front 22

R plasmids carry genes that confer __________________

Back 22

R plasmids carry genes that confer resistance to specific chemicals, usually antibiotics.

Front 23

Most R-Plasmids consist of two components:

Back 23

Most R-Plasmids consist of two components:

 The RTF (Resistance Transfer Factor): contains the genetic information that is needed to transfer the plasmid between bacteria.

 The r-determinants are the genes whose products confer the antibiotic resistance.

Front 24

The F plasmid encodes numerous genes including:

Back 24

The F plasmid encodes numerous genes including:

 F+ x F- -------> F+ x F+

 F+ integrates plasmid -------> HFr

 HFr x F- -------> HFr x F- but with SOME genetic recombination

Front 25

Hfr for high-frequency recombination. Hfr strains behave genetically as _______cells and thus are a type of ________cell.

Back 25

Hfr for high-frequency recombination. Hfr strains behave genetically as donor cells and thus are a type of F+ cell.

Front 26

Transduction is __________

Back 26

 Transduction is the transfer of genetic information from one host cell to another via bacteriophage (phage). (Phages are viruses that infect only bacterial cells.)

 This genetic exchange occurs when phage mistakenly PACKAGE HOST CHROMOSOMAL DNA.

 The infected cell becomes a genetic donor for the recipient cell

Front 27

tell me about insertion sequences and transposons

Back 27

insertion sequences and transposons

 These are sequences of DNA that are able to shift from one part of the genome to another.

 The formal name is transposable elements and their movement is called transposition.

Front 28

There are two major classes of bacterial transposable elements:

Back 28

insertion sequences and Complex transposons

Front 29

insertion sequences

Back 29

insertion sequences (IS) only contain the genetic information needed to catalyze their own transposition.

Front 30

Complex transposons

Back 30

Complex transposons (usually shortened to transposons) contain additional genetic information that is not essential for transposition, such as antibiotic resistance genes.

Front 31

Important point - unlike plasmids and bacteriophage, transposons are not capable of ______________________.

Back 31

Important point - unlike plasmids and bacteriophage, transposons are not capable of autonomous replication. Replication of a transposon can only occur when it is integrated into the host chromosome or a plasmid.

Front 32

Transposons are identified by

Back 32

Transposons are identified by the presence of inverted terminal repeat (IR) sequences. Each type of a transposon has its own unique inverted repeat. On either side of the inverted repeat is a short (less or equal to 10bp) direct repeat.

Front 33

Inverted Repeat (I.R.)

Back 33

Inverted Repeat (I.R.) - the sequence is repeated in the reverse left to right order in the OPPOSITE strand

Front 34

Direct Repeat (D.R) -

Back 34

Direct Repeat (D.R) - is repeated in the same order, in the same strand

Front 35

The _________ are not part of the transposon. Rather, they originate from the chromosome and will be dependent on the precise site of insertion. The ____________ are a part of the transposon and thus will be the same at each insertion site.

Back 35

The direct repeats are not part of the transposon. Rather, they originate from the chromosome and will be dependent on the precise site of insertion. The inverted terminal repeats are a part of the transposon and thus will be the same at each insertion site. (I.R. = part of the transposon)

Front 36

What is the ring structure in the purines?

Back 36

Two rings

Front 37

The site of protein synthesis is the:

Back 37

Ribosome

Front 38

The name for the model describing the replication of DNA whereby the new molecules are half old and half new.

Back 38

Semi-conservative

Front 39

What are the subunits (building blocks) of nucleic acids?

Back 39

Nucleotides

Front 40

Base triplets found on mRNA are known as:

Back 40

Codons

Front 41

The name of the enzyme which assembles new nucleotides to growing DNA strands during replication.

Back 41

DNA Polymerase

Front 42

The name of the process which makes DNA from a DNA template.

Back 42

Replication

Front 43

What would the base pairs of DNA be that would pair with the sequence: 5'-CGTTA-3' ; put the answer with 5' on the left side.

Back 43

What would the base pairs of DNA be that would pair with the sequence: 5'-CGTTA-3' ; put the answer with 5' on the left side.

5'-TAACG-3'

Front 44

The process which makes RNA from the DNA template.

Back 44

Transcription

Front 45

The enzyme which pieces together the short DNA segments on the lagging strand during replication.

Back 45

Ligase

Front 46

The name of the enzyme which assembles new nucleotides to growing RNA strands during transcription.

Back 46

RNA Polymerase

Front 47

In DNA, the base Adenine pairs with:

Back 47

Thymine

Front 48

Base triplets found on tRNA are known as:

Back 48

Anti-codons

Front 49

The region on the DNA to which RNA polymerase binds.

Back 49

Promoter

Front 50

What would the DNA bases be that would pair with: T C A G ?

Back 50

What would the DNA bases be that would pair with: T C A G ?

A G T C

Front 51

Thymine is substituted by _____ in RNA.

Back 51

Uracil

Front 52

The process that produces protein from the message contained on the mRNA.

Back 52

Translation

Front 53

What are the anti-codons that would base pair with these codons? GCA - AUA

Back 53

What are the anti-codons that would base pair with these codons? GCA - AUA

CGU - UAU

Front 54

The type of RNA capable of carrying an amino acid and has an anti-codon.

Back 54

tRNA

Front 55

The purines found in DNA are:

Back 55

Guanine and Adenine

Front 56

In DNA & RNA, the base Cytosine pairs with:

Back 56

Guanine

Front 57

What would the RNA bases be that would pair with: T C A G ?

Back 57

What would the RNA bases be that would pair with: T C A G ?

A G U C

Front 58

In RNA, the base Adenine pairs with:

Back 58

Uracil

Front 59

The type of RNA which carries the message (has codons)?

Back 59

mRNA

Front 60

The name of the strand in DNA replication that is made as small pieces that are later put together.

Back 60

Lagging

Front 61

What is the ring structure in the pyrimidines?

Back 61

A single ring

Front 62

The name of the strand in DNA replication that is made as one continuous piece.

Back 62

Leading

Front 63

The pyrimidines found in DNA are:

Back 63

Cytosine and Thymine

Front 64

What direction is DNA polymerase able to make new strands?

Back 64

5' to 3'