microbio chapter 7

Question 1

genetics

Answer 1

the study of inheritance and inheritable traits as expressed in an organisms genetic material

Question 2

genome

Answer 2

the entire genetic complement of an organism
- includes genes and nucleotide sequences

Question 3

DNA

Answer 3

• 5’ end terminates in a phosphate group attached to a 5’ carbon
• 3’ end terminates in a hydroxyl group where more can be added in DNA replication
• strands run antiparallel to each other

Question 4

prokaryotic chromosomes

Answer 4

• each bacteria cell has a single copy of their genome
• they are haploid cells
• typical chromosome consists of circular DNA localized by the nucleoid
• DNA is folded into loops that are 50-100K base pairs long
• chromosome is the main portion of DNA with associated proteins and RNA

Question 5

plasmids

Answer 5

• small molecules of DNA that replicate independently
• non-chromosomal DNA, non-essential genes
• each plasmid carries genes necessary for its replication
• only contain bonus genes

Question 6

what are the bonus genes that can be found on plasmids

Answer 6

1. fertility factors
2. resistance factors
3. bacteriocin factors
4. virulence factors

Question 7

fertility factors

Answer 7

• allows for production of pili
• allows for conjugation

Question 8

resistance factors

Answer 8

• cells carry genes for antimicrobial drugs
• cells can transfer resistance factors and create resistance in new cells

Question 9

bacteriocin

Answer 9

• carry genes for proteinaceous toxins called bacteriocins
• bacteriocins kill bacteria cells of same/similar species that lack plasmids with this factor
• bacteria cells are killing their competitors

Question 10

virulence factors

Answer 10

carry structures, enzymes, or toxins that enable bacterium to become pathogenic
- increased levels = more ill
- help bacteria survive internal body environment

Question 11

DNA replication

Answer 11

• theta replication
• bacteria only have one ORI site
• DNA-A binds to ori site to initiate replication
• replication is bidirectional
• each strand of DNA has a leading and a lagging strand

Question 12

DNA-A

Answer 12

• enzyme that recognizes and binds to ORI site of a bacteria’s DNA
• when it binds it creates a replication bubble

Question 13

Helicase

Answer 13

• helicase enzyme comes in and unwinds the DNA strands from each other

Question 14

single stranded porteins

Answer 14

• bind to DNA strands to prevent them from reconnecting after helicase has unwinded them

Question 15

primase

Answer 15

• lays down RNA primers in order for replication to occur
• provides the 3’ hydroxyl group for DNA polymerase to begin replication

Question 16

DNA polymerase

Answer 16

• only synthesizes 5’ to 3’
• follows behind helicase to synthesize DNA
• can utilize its exonuclease function to take out mismatched pairs and place correct ones from 3’ to 5’; this is the only time it will go in that direction
• this is called proofreading

Question 17

topoisomerase

Answer 17

• also called DNA-gyrase
• periodically cuts DNA strand to unwind it and reseals it
• this is to avoid knots in the DNA strand
• what we want antibiotics

Question 18

leading strand

Answer 18

• replicates at open 3’ end of DNA template
• replicated from 5’ to 3’
• one RNA primer is needed to replicate

Question 19

lagging strand

Answer 19

• replicates at open 5’ end of DNA template
• replicates still only from 5’ to 3’
• multiple RNA primers are needed for replication
• replicates on fragments called okazaki fragments
• replicates away from the replication fork

Question 20

Plasmid DNA replication

Answer 20

• large plasmids utilize theta replication
• some small plasmids utilize rolling circle replication

Question 21

Rolling circle replication

Answer 21

• utilized by some small plasmids
• allows for conjugation through pili
• can pass on resistance and other plasmid factors to other cells
• ORI site is different from theta replication

Question 22

Rep-A

Answer 22

• protein that binds to the ORI site of plasmids that use rolling circle replication
• cleaves one strand of DNA and holds onto its 5’ end
• allows for DNA polymerase to start replication without a primer being needed