Chapter 7 Microbial Genetics

Front 1

Define Transposons

Back 1

transposons are segments of DNA, 700-40,000 bp in length
they move from one location to another in a dna molecule or move to another molecule

Front 2

Charactertistics of Transposons

Back 2

the action of a transposon is transposition the frameshift insertion and recombination that needs no specific region.

Front 3

importance of transposons

Back 3

transposons are found in all prokaryotes,eukaryotes, and viruses. they vary in their nucleotide sequences but have palindrome sequence at end

Front 4

types of transposons

Back 4

Insertion sequences, complex transposons

Front 5

Transposons:
insertion sequences

Back 5

the simplest transposons consist of no more than two inverted repreats and has the gene that encodes the enzyme transposase that splits the dna molecule at the site and inserts the transposon and produces duplicate copy of the target site

Front 6

Transposons: complex transposons

Back 6

contain one or more genes not connected with transposition such as genes for antibiotic resistance r factors-plasmids that resist antibiotics often contain transposons

Front 7

Plasmids definition

Back 7

small, circular molecules of DNA that replicate independently of the chromosome.

Front 8

Plasmid characteristics

Back 8

circular and 1 to 5% the size of a bacterial chromosome each plasmid carries information required for its own replication

Front 9

Factors of plasmids

Back 9

Fertility, resistance, bacteriocin, virulence, cryptic

Front 10

Plasmid- fertility factor

Back 10

carry instruction for conjugation -transferting gentes from one bacterial cell to another

Front 11

Plasmid- resistance factor

Back 11

carry genes for restiance to antimicrobial druggs

Front 12

Plasmid-bacteriocin factors

Back 12

carry genes for proteinaceous toxins called bacteriocins which kill bacterial cells fo the same or similar species

Front 13

Plasmid-Virulence plasmids

Back 13

carry instructions for structures enzymes or toxins that enable a bacterium to become pathogenic

Front 14

Plasmid- cryptic

Back 14

no one knows

Front 15

Bacterial genome

Back 15

the genome of a cell or virus is its entire genetic complement including genes and nucleotide sequences that connect genes to one another

Front 16

structure of nucleic acids

Back 16

they are polymers of nucleotides that contain pentose sugar Deoxyribose and ribose, a phosphate, and one of the 5 nitrogenous bases gc at or u

Front 17

dna replication process

Back 17

an anabolic polymerization proces allows a cell to pass copies of its genome to descendants

Front 18

dna replication require

Back 18

they require monomers(building blocks) and energy triphosphate and deoxyribonucleotides 3 phosphate groups linked by two high energy bonds are functions in dna replication

Front 19

structures in dna synthesis

Back 19

guanosine triphosphate nucleotide (dGTP
in dATP it stores energy like ATP but with an RNA molecule

Front 20

key to dna replication

Back 20

complementary structure of the two strands
AG TC

Front 21

initial process in dna replication

Back 21

begins at specific sequence of nucleotides called origin. removes chromosomal proteins exposing DnAhelix
2. dna helicase unzip dna molecule by breaking the hydrogen bonds between complementary nucleotide bases.

Front 22

next process in dna replication

Back 22

after helicase untwist and expose replication fork other rpotein molecules stablizie single strands to prevent rejoining - dna polymerase binds to strands

Front 23

5 kinds of dna polymerase

Back 23

they synthesize dna by bonding to hydroxyl group at 3 prime and replicating 5 prime

Front 24

strands

Back 24

leading strand continuously synthesized while lagging strand is synthed in short segments latter joined

Front 25

synthesis of leading strand

Back 25

1. enzyme called primase synthesizes shor tna molecule and provides a 3 prime hydroxyl group to dna
2. triphosphate deoxyribonucleotides form hydrogen bonds with complements in parental strand
3 use energy in high energy bonds of triphosphate deoxyribonucleotides
4. dna polymerase proofreads removes incorrect pairs
5. another enzyme replaces rna primer with dna

Front 26

Synthesis of the Lagging strand

Back 26

1. primase sythezises rna
2. nucleotide pairs with complement at cg
3. dnapolymerase joins neighboring nucleotides and rpoffreads
4. another type of dna polymerase replaces rni primer with dna
5. dna ligase seals gaps btw ozaki frags(discontinuous segmentsin the lagging strand) and form a continuous dna strand

Front 27

helicase

Back 27

untwists dna

Front 28

primase

Back 28

synthesizes rna primer

Front 29

DNA polymerase

Back 29

joins neighboring nucleotides and proofreads

Front 30

DNA ligase

Back 30

seals gap btween adjacent okazaki fragments to form continuous dna strand

Front 31

Polymerase chain reaction

Back 31

is a scientific technique that produces a large number of identical molecules of DNA in vitro - for epidemiologists,

Front 32

PCR is a repetitive process that separates and relpicates two strands of dna alternately

Back 32

1. Denaturation - exposure to heat
2. priming- as temps cool dna will bind to primers to prevent rebinding
3. extension raising temp to 72 to increase rate of dna polymerase replicates each strand

Front 33

required chemical compounds in polymerase chain reaction

Back 33

DNA plymerase, primiers, and triphosphate deoxynucleotides

Front 34

gel electrophoresis- purpose

Back 34

isolates fragments of dna molecules that can be inserted into vectors and multiplied by pcr or preserved in library

Front 35

gel electrophoresis- principle

Back 35

dna molecules with negative charge are drawn through a gel(retards dna movement) by electric current towards positive electrode in chanber

Front 36

components of rna nucleotides

Back 36

transcription- copy dna info as rna nucleotide sequences - ribomes in rna synthesize polypeps called translation
dna is transcribed to rna that translates to form polypeptides

Front 37

cells transcribe three types of rna from dna

Back 37

messengerrna- carry genetic info from chromosomes to ribosomes
ribosomal rna- combine with ribosomal polypeps to form ribosomes -organelles that synthesize polypeps
transferrna- deliver amino acids to ribosomes

Front 38

transcription occurs

Back 38

in nucleoid region of cytoplasm in prokaryotes in eukaryotes it offurs in nucleus, mitochondria, and chloroplasts

Front 39

steps in rna transcription

Back 39

initiation of transcription
elongation of the rna transcript
termination of transcription

Front 40

rna polymerase

Back 40

enzyme that synthesizes rna

Front 41

stages of translation: initiation

Back 41

initiation
1. smaller ribosomal subunit attaches to mRNA at ribosomal recognition sequence with start codon at psite
2. tRNA attaches to ribosome 's p site, GTP supplies the energy required for binding
3. larger ribosomal subunit attaches to form complete initiation complex

Front 42

stages of translation: elongation

Back 42

1. transfer rna is escorted by elongation factor along with GTP to stabilize trna as it is added to A site
2. ribozyme formes peptide bond by dehydration synthesis and attaches polypeptide to tRNA occupying the A site
3. using energy supplied by moreGTP the ribosome moeves one codon down the mRNA moving trna down
4. ribosome releases empty trna from e site and it gets recharged
5. cycle repreats

Front 43

stages of translation: termination

Back 43

involves proteins called release factors to halt elongation

Front 44

replication

Back 44

duplicate cells genome

Front 45

transcription

Back 45

synthesize rna

Front 46

translation

Back 46

to synthesize polypeptides

Front 47

mutation

Back 47

a change in nucleotide base sequence of a genome in the genes

Front 48

types of mutation

Back 48

point mutation

frameshift mutation

Front 49

point mutation

Back 49

just one or a few nucleotide base paires are affected
substitution, insertion deletion

Front 50

frameshift mutation

Back 50

deletion or insertion that causes new sequences of codons altering polypeptide sequences dramatically

Front 51

mutagen

Back 51

mutations induced by physical or chemical agents

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spontaneous mutation

Back 52

error in replication and repari also recombination error

Front 53

thimine dimers

Back 53

nonionizing radiation from uv light causing adjacent tyhmine bases to bond with one another

Front 54

horizontal gene transfer

Back 54

prokaryotes acquire genes from other microbes of the same generation - a donor cell contributes part of its genome to recipient cell

Front 55

3 types of horizontal gene transfer: transformation, transduction, bacterial conjugation

Back 55

transformation- a recipient cell gets dna from environment
tranduction- transfer dna from one cell to another via replicating virus (bacteriophages)

Bacterial conjugation: donor cell remains alive- unlike other two,requires physical contact btw two cells- like sex
Bacterial

Front 56

making cells competent for transformation

Back 56

altering temp and salt content

Front 57

competent

Back 57

ability of cells to take up dna of their environment

Front 58

Cojugation pili

Back 58

sex pili are protenaecous rodlike structures

Front 59

F+ F-
HFR and F-

Back 59

gene coding for conjugation pili f plasmid- or f factor- cells with are F+ and give to F-
HFR moves around too much and is in the dna so F- doesnt get all info

Front 60

compare transducing phage and normal phage

Back 60

normally phages assmble around dna phage to form new phage particles but some mistaknly incormporat remaining fragments of bacterial dna to form transducing phages
transducing phage injects donor dna into host cell