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NEU Microbiology Spring 2011 Lec 7
These flashcards cover all review material from the book at the end of the chapter and from the review question slide for lecture 7
30
Microbiology
Undergraduate 1
02/13/2011

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Cards

Term
Which steps in the central dogma of DNA are only found in virus?
Definition

RNA can be made into more RNA and RNA can be made into DNA using reverse transcriptase

Term
What is supercoiled DNA?
Definition

Supercoiled DNA is DNA that is compressed to save space within the cell. Negatively supercoiled DNA is DNA which is somewhat unwound whereas positively supercoiled DNA is overwound

Term
What is relaxed DNA?
Definition

Relaxed DNA is a segment of DNA that has the amount of turns in it that is predicted by the number of base pairs in the sequence

Term
What is the difference between chromosomes and plasmids?
Definition

Chromosomes and plasmids can both encode relevent genetic information but plasmids are typically smaller and encode for things like resistance to various environmental factors like antibiotics

Term
What does DNA helicase do?
Definition

DNA helicase unwinds the DNA and enables better access for things like replication

Term
Why is there a need for an RNA primer during replication?
Definition

RNA primers cap the lagging strans present on the 3'-5' strand. Replication lags somewhat and Okazaki fragments are left behind which need to be capped. DNA polymerase and then DNA ligase then come in and fix these gaps

Term
What part of the RNA polymerase recognizes the promoter?
Definition

The sigma factor of RNA polymerase recognizes the promoter

Term
What is the pribnow box?
Definition

The pribnow box is the area located about 10 base pairs away from the start of translation

Term
What is the reading frame?
Definition

The reading frame means that a triplet codon is needed for translation to begin at the correct site

Term
What is aminoacyl-tRNA synthase?
Definition

Aminoacyl-tRNA synthase is an enzyme that catalyzes attachment of an amino acid to its cognate tRNA

Term
What is an anticodon?
Definition

An anticodon is a sequence of three bases in a tRNA molecule that base pairs with a codon during protein synthesis

Term
What is chaperonin (or simply a molecular chaperone)?
Definition

Chaperonin is a protein that helps other proteins fold or refold from a partly denatured state

Term
What is codon bias?
Definition

Codon bias is the nonrandom usage of multiple codons encoding the same amino acid

Term
What is DNA gyrase?
Definition

DNA gyrase is an enzyme found in most prokaryotes that introduces negative supercoils in DNA

Term
What is DNA polymerase?
Definition

DNA polymerase is an enzyme that synthesizes a new strand of DNA in the 5'-3' direction using an antiparallel DNA strand as a template

Term
What is a genetic element?
Definition

A genetic element is a structure that carries genetic information such as a chromosome, a plasmid or a viral genome

Term
What is a genome?
Definition

A genome is the total complement of genes contained in a cell or virus

Term
What is an informational macromolecule?
Definition

An informational macromolecule is any large polmeric molecule that carries or comes from genetic information such as DNA, RNA and proteins

Term
What is a lagging strand?
Definition

A lagging strand is the new strand of DNA that is synthesized in short pieces during DNA replciation and then joined together later

Term
What is the leading strand?
Definition

The leading strand is the strand of DNA that is synthesized continuously during DNA replication

Term
What is a nonsense codon?
Definition

A nonsense codon is just another name for a stop codon. A nonsense mutation is a mutation where a stop codon is put in place of another codon but a nonsense codon simply refers to any of the 3 stop codons

Term
What is an open reading frame (ORF)?
Definition

And open reading frame is a sequence of DNA or RNA that could be translated to give a polypeptide

Term
What is an operon?
Definition

An operon is a cluster of genes that are co-transcribed to give a single messenger RNA

Term
What is a primer?
Definition

A primer is an oligonucleotide to which DNA polymerase can attach the first deoxyribonucleotide during DNA replication

Term
What is a promoter?
Definition

A promoter is a site on DNA to which RNA polymerase binds to commence transcription

Term
What is a replication fork?
Definition

A replication fork is the site on the chromosome where DNA replication occurs and where the enzymes replicating the DNA are bound to untwisted ssDNA

Term
What is RNA polymerase?
Definition

RNA polymerase is an enzyme that synthesizes RNA in the 5'-3' direction using a complementary and antiparallel DNA strand as a template

Term
What is semiconservative replication?
Definition

Semiconservative replication is DNA which yields new double helicases each consisting of one parental and one progeny strand of DNA

Term
What is a signal sequence?
Definition

A signal sequence is a special N-terminal sequence of approximately 20 amino acids that signals that a protein should be exported across the cytoplasmic membrane

Term
What is wobble?
Definition

Wobble is a less rigid form of base pairing allowed only in codon-anticodon pairing

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