DNA and RNA

what is the function of DNA?

stores and transmits genetic information

what is the function of RNA?

helps convert genetic information into proteins

what sugar is found in DNA?

deoxyribose

What sugar is found in RNA?

ribose

which base is found in DNA but not RNA?

thymine

which base replaces thymine in RNA?

uracil

which bases are purines?

Adenine and Guanine. rememeber PURE is GOLD

which bases are pyrimidines in DNA?

cytosine and thymine

What does it mean that DNA strand are antiparallel?

They run in opposite directions

in what direction is DNA synthesized?

5' (phosphate) to 3' (hydroxyl (OH))

what is the purpose of dna replication?

to make identical copies of DNA before cell division.

What enzyme unwinds and separates DNA strands?

Helicase

what proteins keep DNA strands apart from helicase acts ?

Single strand binding proteins (SSBs)

what are enzymes synthesizes RNA primers?

primase

what enzyme synthesizes most of the new DNA strand in bacteria?

DNA polymerase III

what enzyme removes RNA primers and replaces them with DNA?

DNA polymerase I

what enzyme seals breaks between DNA fragments?

DNA ligase

what enzyme relieves supercoiling during DNA replication?

Topoisomerase (DNA gyrase)

what is a replication fork?

The Y shaped region where DNA is being copied

Which strand is synthesized continuously?

leading strand

what strand is synthesized discontinuously?

lagging strand

What are Okazaki fragments?

Short DNA fragments synthesized on lagging strands

why is the lagging strand synthesized in fragments?

because DNA can only synthesize 5' to 3'

what are mutations?

A permanent change in the DNA sequence

Can proteins be mutated?

no, only DNA is mutated

what is spontaneous mutation?

a mutation that occurs naturally

what is an induced mutation?

a mutation caused by external mutagens

what is a point mutation?

a mutation involving a single nucleotide change

what is a silent mutation?

a mutation that does not change the amino acid

what is a missense mutation?

a mutation that changes one amino acid into another

what is nonsense mutation?

a mutation that creates a stop codon

what is a frame shift mutation?

a mutation that shifts the reading frame.

what is the ames test used to detect?

mutagens

what bacteria are commonly used in ames test?

Histidine auxotrophin salmonella

what does a high number of revertant colonies indicate?

the substance is highly mutagenic

what are the three mechanisms of horizontal gene transfer?

transformation, transduction, and conjugation

what is transformation?

uptake of free DNA from the environment

what is transduction?

transfer of bacterial DNA by a bacteriophage

what is conjugation?

firect transfer of dna from one bacterial cell to another

what structure is used during conjugation?

sex pilus

what type of genes are transferred during generalized transduction?

random bacterial genes

what type of genes are transferred during specialized transduction?

specific genes located near the phophage insertion site

what is an operon?

a group of genes controlled by a single promoter

what is the function of a promoter?

it is the DNA sequence where RNA polymerase binds

what is the function of an operator?

it is the DNA sequences where a repressor binds

what is the function of a repressor?

it blocks transcription

what is an inducible operon?

an operon that is normally OFF but can be turned ON

which operon is inducible?

the lac operon

what turn the lac operon on?

lactose

what is a repressible operon?

an operon that is normally on but can be turned off

which operon is repressible?

the trp operon

what turn the trp operon off?

tryptophan