Microbiology Chapter 13

What is DNA the template for

DNA replication and transcription

What carries out DNA replication

DNA polymerase

What carries out transcription

RNA polymerase

What is mRNA the template for

proteins

What carries out translation

ribosomes

What does reverse transcriptase do

RNA into DNA (makes cDNA)

Who did the transformation test

Griffith

What did the transformation test show

the change of nonvirulent organisms into virulent ones via transformation

What traits did the transformation show

S strain and R strain

S strain

smooth, pathogenic, has capsule

R strain

rough, not pathogenic, no capsule

What did Avery-Macleod-McCarty do

identify DNA as the transforming factor (when DNA was destroyed, transformation did not occur)

What did Hershey-Chase experiment prove

that DNA is the genetic material

What did the Hershey-Chase experiment use as a model

bacteriophage T2 (DNA virus)

Details of the Hershey-Chase experiement

DNA was labeled with P
Protein coat was labeled with S
Only the labeled DNA entered the cell

Why did only DNA enter the bacterial cell

because phages leave the coat outside

What would’ve happened if the Hershey-Chase experiment was conducted with a mammalian virus

both the protein coat and DNA would’ve entered the cell

What are nucleic acids

polymers of nucleotides

What are nucleic acids linked by

phosphodiester (covalent) bonds

How do DNA and RNA differ

RNA: Uracil, OH on C2, single-stranded
DNA: Thymine, H on C2, double-stranded

What are the purines

adenine and guanine
double ring

Pyrimidines

cytosine, uracil, and thymine
single ring

What holds together the double-stranded helix

H-bonds

DNA strands are…

anti-parallel and complementary

What direction do nucleotides get added to

5’ to 3’

What holds together the back bone of DNA

phosphodiester (covalent) bonds

How many bonds do A-T have

2 H-bonds

How many bonds do C-G have

3 H-bonds

Major Groove

contains the most information and you can read the nucleotides

What is a ribozyme

an RNA enzyme

Most RNA molecules are…

single sstranded

What virus contains double-stranded RNA

rotavirus

What are polypeptides built from

amino acids (monomer)

What bond holds together polypeptides

peptide bonds (covalent)

How are polypeptides synthesized

Amino-terminus (N) to carboxyl-terminus (C)

4 levels of structure of proteins

Primary, Secondary, Tertiary, and Quaternary

Primary proteins

covalent bonds between amino acids

Secondary proteins

alpha helix and beta sheets, H-bonds

Tertiary proteins

noncovalent bondss + disulfide bridge

Quaternary proteins

Noncovalent bonds + disulfide bridge
ex. Insulin

What does methionine have

sulfur and is the 1st amino acid added (AUG)

What does cysteine have

sulfhydryl group

What allows disulfide bond/bridges to be made

sulfhydryl group on cysteine

Two cysteines on the same polypeptide

tertiary

Two cysteines on different polypeptide

quaternary

What direction is the complimentary strand in in DNA replication

5’ to 3’

Leading strand

continuous

Lagging strand

discontinuous with Ozaki fragments

What does DNA polymerase do

fix mutations

What does semi-conservative mean

one old strand and one new strand

How many times is the whole genome replicated during cell division

once

What DNA are in bacteria

circular

Replisome

a complex that binds to OriC and moves in both directions

What does the replisome include

DNA polymerase III, dNTP, topoisomerases, and xerCD

What does DNA polymerase III do

synthesize new DNA

What is dNTP

building blocks

What does topoisomerase do

relieve DNA supercoiling

What does xerCD do

allows separation of two chromosomes in ter

What is the basic unit of genetic information

genes

Transcription has…

a fixed start and end point

What are the three types of RNA

mRNA, tRNA, and rRNA

What does mRNA do

carry the message for protein synthesis

What does tRNA do

carries amino acids to the codon during protein synthesis

What is rRNA

a component of ribosomes

What type of RNA is not translated

tRNA and rRNA

What does the RNA polymerase function as

a holoenzyme

What are the components of a holoenzyme

core enzyme and sigma factor

What is contained in the core enzyme

2 a subunits, b, b’, and omega (w)

What does the b and b’ of a core enzyme do

allows binding to DNA

Sigma factor

recognizes nucleotide sequence
identify promoter and then detach
not necessary for elongation or termination

What are non-protein coding genes

genes that do not code for proteins (tRNA and rRNA)

What do non-protein coding genes consist of

promoter, leader, coding region, trailer, and terminator

What are spacers

non-coding sequences of RNA that are located between tRNA and rRNA

Spacers are

removed after transcription

What removes spacers

ribozymes or ribonucleases

What is an example of posttranscriptional modification

removal of spacers

What does RNA polymerase recognize

the promoter

What direction does RNA polymerase read DNA

3’ to 5’

What direction does RNA polymerase make mRNA

5’ to 3’

What are protein coding genes

structural genes that encode polypeptides

What directs mRNA synthesis

DNA template strand (anti-sense)

What has the same nucleotide sequence as mRNA

complementary DNA (sense) strand

How does RNA polymerase recognize the promoter

with the help of sigma factor

What does the promoter contain

-35 and -10 sequences

What sequence is rich in A-T

-10

What is the -10 sequence rich in

AT

What does the leader sequence include

the Shine-Dalgarno sequence/RBS

What does the ribosome recognize

the Shine-Dalgarno sequence

What does the shine-dalgarno sequence do

align the ribosome to the start codon

The leader sequence is…

not translated

What does RNA polymerase use

the anti-sense

What organisms have monocystronic mRNA

eukaryotes

What organisms have polycistronic mRNA

prokaryotes

What does the operon have

a single promoter and multitude of genes downstream

What happens when the sigma factor binds to the promoter

transcription/translation of all genes

What direction does the ribosome read mRNA

5’ to 3’

What direction does the ribosome make polypeptide

N to C

What directions do DNA and RNA polymerase read

3’ to 5’

What is the start codon

AUG

What does AUG code for

methionine