MODULE 4: Microbial Metabolism and Genetics

Question 1

Topoisomerase

Answer 1

Enzyme that alters the supercoiled form of a DNA molecule

Question 2

DNA gyrase

Answer 2

Inserts negative supercoils into DNA

Question 3

Transposable Elements

Answer 3

DNA that are inserted into other DNA molecules that can move from one site to another

Question 4

Operon

Answer 4

A cluster of genes transcribed to form a single mRNA strand

Question 5

6 Functions of Ribosomes

Answer 5

1. Antibiotic Resistance
2. Virulence Factors (ability to attach to host / produce invasive toxins are plasmid-encoded sometimes)
3. Bacteriocins (inhibit closely related species for decrease in competition)
4. Nodule Formation
5. PCB degradation (Polychlorinated Biphenyls; degradation of toxic pollutants)
6. Conjugation (gene transfer)

Question 6

4 Enzymes in DNA replication

Answer 6

Primase
Helicase
DNA Polymerase
Ligase (produces the last phosphodiester bond)

Question 7

Replication in Bacterial and Archaeal Chromosomes (2 Major differences than with Eukarya Chromosomes)

Answer 7

1. Bidirectional Replication (2 replicating forks; Theta structures formed)
2. Replisome - aggregation of replication proteins (PRIMOSOME - unwinds and applies RNA primer)

Question 8

TATA Box

Answer 8

Sequence on operons that act as “promoters” indicating to the RNA polymerase WHERE to start transcription

Question 9

TATA-binding proteins

Answer 9

Transcription FACTORS that bind to TATA boxes to initiate transcription

Question 10

Sigma Factor

Answer 10

Protein that binds to RNA polymerase to recognize promoter and initiation site in Transcription

Question 11

Operon

Answer 11

Genes that encode several enzymes of a

Question 12

Polycistronic mRNA

Answer 12

The product of transcription; contains multiple open-reading frames

Question 13

Open-reading frames

Answer 13

Portions of mRNA that encodes amino acids

Question 14

Stem loop

Answer 14

Intrastrand base pairing for transcription termination

Question 15

3 Methods of Transcription Termination in Bacteria

Answer 15

1. Transcription termination region is reached
2. Stem loop
3. Terminator Protein Rho (binds tightly to RNA and moves down the chain towards RNA polymerase; causes RNA polymerase to be released)

Question 16

Spliceosome

Answer 16

Protein complex containing both RNA and protein does performs the splicing (removal of introns)

Question 17

70s Ribosomes breakdown (Svedberg units and protein #)

Answer 17

30s -> 16s rRNA & 21 proteins
50s -> 5s and 23s rRNA & 31 proteins

Question 18

3 sites of a Ribosome

Answer 18

1. A site (first initial accepting site)
2. P site
3. E site (Exit site)

Question 19

Polysome

Answer 19

Complex of ribosomes that perform translation much faster

Question 20

Bacterial Chaperones

Answer 20

Proteins that catalyze a variety of macromolecular folding events

Question 21

Bacterial Chaperones (6 events)

Answer 21

1. Folds proteins that do not fold spontaneously
2. Refolds partially denatured proteins
3. Assembles multiprotein complexes
4. Prevents improper aggregation of proteins
5. Untangles RNAs
6. Incorporates cofactors into enzymes

Question 22

SEC and TAT systems

Answer 22

1. SEC translocase system - exports UNFOLDED proteins and inserts integral membrane proteins into the cytoplasmic membrane
2. TAT translocase system - transports FOLDED proteins through the cytoplasmic membrane

Question 23

6 Types of Protein Secretion of GRAM-NEGATIVE systems

Answer 23

Type I: ABC transport systems
Type II: Transport of proteins from periplasm to extracellular environment
Type III: Secrete toxic proteins that inject directly into eukaryotic host cells
Type IV: Bacteria and Archaea’s delivery of secreted proteins into other cells
Type V: Structurally simple autotransporter
Type VI: Cytoplasmic & forms needle-like proteins

Question 24

4 Methods of Manipulating DNA

Answer 24

1. Polymerase Chain Reaction
2. Electrophoresis
3. Nucleic Acid Hybridization
4. Molecular Cloning