Chapter 9

Spliceosome

________: recognizes exon- intron junctions and enzymatically cuts through them and joins the exons.

Primer

________: the length of RNA that is inserted initially during replication.

Anticodon

________: found at the bottom of cloverleaf, designates the specificity of the tRNA that complements the mRNA codon.

AUG

________ is the stop code for: prokaryotes not eukaryotes.

Introns

________: intervening sequences of bases that do not code for a protein.

Codons

________: a series of triplet bases that hold the message of the transcribed mRNA.

Cotranslational

________ only occurs in: bacteria and archaea.

RRNA

________: long polynucleotide molecule that contributes to the structure of the ribosome, ________ and protein create the subunits of the ribosome.

Allosteric

________: change in shape or activity of an enzyme.

Mutation

________: any change to the nucleotide sequence in the genome, in microbes very obvious.

Ames test

________: rapidly detects chemicals with carcinogenic potential, uses bacteria to mutate their DNA to monitor gene expression.

Translocation

________: shifting the ribosome down the mRNA strand to read new codons.

Operons

________: found only in bacteria and archaea, coordinated set of genes regulated a single unit.

Plasmids

________: extrachromosomal DNA that can replicate on their own and move between cells, found in bacteria and fungi, not essential but can have advantageous traits.

Eukaryotic

________ proteins only code for one protein while bacterial mRNAs: often code form several genes.

Posttranslational modifications

________: proteins begin to fold, cofactors may be added, tertiary and possible quaternary structures formed.

RNA

________: single stranded molecule that exists in helical form and can have secondary and tertiary levels of complexity.

Central dogma

________: DNA makes RNA which makes proteins which creates the function.

Transcription

________: DNA synthesized into RNA.

Redundancy

________: certain amino acids are represented by multiple codons.

deoxyribose sugar

Structure of a nucleotide: phosphate, ________, nitrogenous base.

transduction horizontal gene transfer

Generalized ________: random fragments of disintegrating host DNA are taken up by a phage during assembly.

Excess nutrients

________ can serve as a to block the action of the operon: corepressor.

Repressible operons

________ are usually in on mode but will turn off when: a nutrient is no longer required.

Okazaki fragments

________: short segments of DNA synthesized in the 5 to 3 direction which are sealed in the opposite direction.

amino acid

Wobble: only the first two nucleotides are required to encode the correct ________, permit mutation without altering the message.

MRNA

________: transcript of a structural gene or genes of DNA.

Lac

________ operon structural locus: made up of three genes each coding for a different enzyme needed to catabolize lactose.

Translation

________: RNA produces proteins.

Termination of translation

________: the ribosome reaches the stop codon (nonsense codon) and an enzyme breaks off the amino acid chain.

TRNA

________: contains sequences of bases that form hydrogen bonds with complementary sections of the same tRNA strand.

Transposons Transposable elements

________: ‘ jumping genes that can shift from one part of the genome to another.

absence of lactose

In ________ for the lac enzyme the repressor: binds to the operator blocking the transcription of structural genes.

Principle of translation

________: mRNA nucleotides are read in codons in groups of 3, the codon dictates the amino acids, this is universal for archaea, bacteria, and viruses.

DNA

Lagging strand: strand of new ________ that is sealed in the 3 to 5 direction.

Replication fork

________: the place where the DNA helix is unwound and replication begins.

Point mutations

________: small mutations that affect only a single base on a gene.

Lac operon regulator

________: composed of the gene that codes for the repressor, a protein capable of repressing the operon.

Missense mutation

________: any change in the code that leads to different amino acids.

Structure of a nucleotide

phosphate, deoxyribose sugar, nitrogenous base

DNA polymerase 3

synthesizes new daughter strand of DNA but the DNA molecule must be unwound first, can only add nucleotides onto existing chain, and can only add in the 5 to 3 direction

Replication fork

the place where the DNA helix is unwound and replication begins

Circular DNA will have replication forks

two

Primer

the length of RNA that is inserted initially during replication

Leading strand

strand of new DNA that it synthesized in the 5 to 3 direction

Lagging strand

strand of new DNA that is sealed in the 3 to 5 direction

Okazaki fragments

short segments of DNA synthesized in the 5 to 3 direction which are sealed in the opposite direction

Transcription

DNA synthesized into RNA

Translation

RNA produces proteins

Participants in transcription and translation

mRNA, tRNA, rRNA, ribosomes, enzymes, raw materials

Central dogma

DNA makes RNA which makes proteins which creates the function

RNA

single stranded molecule that exists in helical form and can have secondary and tertiary levels of complexity

mRNA

transcript of a structural gene or genes of DNA

Codons

a series of triplet bases that hold the message of the transcribed mRNA

tRNA

contains sequences of bases that form hydrogen bonds with complementary sections of the same tRNA strand

Anticodon

found at the bottom of cloverleaf, designates the specificity of the tRNA that complements the mRNA codon

rRNA

long polynucleotide molecule that contributes to the structure of the ribosome, rRNA and protein create the subunits of the ribosome

Initiation of the transcription

it is initiated when RNA polymerase recognizes the promoter region, the template strand is copied by RNA polymerase

Elongation of transcription

proceeds in the 5 to 3 direction the mRNA is assembled

Termination of transcription

the polymerases recognize a code that signals the separation and release of the mRNA strand

Principle of translation

mRNA nucleotides are read in codons in groups of 3, the codon dictates the amino acids, this is universal for archaea, bacteria, and viruses

Start codon

AUG (f-Methionine)

Stop codon

UAA, UAG

Redundancy

certain amino acids are represented by multiple codons

Wobble

only the first two nucleotides are required to encode the correct amino acid, permit mutation without altering the message

Stages of translation

initiation, elongation, termination

Initiation of translation

the ribosome encounters the start codon and tRNA come with the compliment amino acid

Elongation of translation

tRNA 2 enters the A site and form peptide bonds between amino acids and this process continues by translocating to the next mRNA

Termination of translation

the ribosome reaches the stop codon (nonsense codon) and an enzyme breaks off the amino acid chain

Translocation

shifting the ribosome down the mRNA strand to read new codons

Posttranslational modifications

proteins begin to fold, cofactors may be added, tertiary and possible quaternary structures formed

Cotranslational only occurs in

bacteria and archaea

AUG is the stop code for

prokaryotes not eukaryotes

Eukaryotic proteins only code for one protein while bacterial mRNAs

often code form several genes

Introns

intervening sequences of bases that do not code for a protein

Exons

coding regions

Spliceosome

recognizes exon-intron junctions and enzymatically cuts through them and joins the exons

Operons

found only in bacteria and archaea, coordinated set of genes regulated a single unit

lac operon regulator

composed of the gene that codes for the repressor, a protein capable of repressing the operon

lac operon control locus

promoter and operator (on/off switch of transcription)

lac operon structural locus

made up of three genes each coding for a different enzyme needed to catabolize lactose

Allosteric

change in shape or activity of an enzyme

In absence of lactose for the lac enzyme the repressor

binds to the operator blocking the transcription of structural genes

Repressible operons are usually in on mode but will turn off when

a nutrient is no longer required

Excess nutrients can serve as a to block the action of the operon

corepressor

Drugs that inhibit protein synthesis in bacteria

Rifamycin and Actinomycin D

Drugs that interfere with the ribosome of bacteria

Erythromycin, Spectinomycin, Chloramphenicol, Aminoglycosides

Recombination of DNA

one bacterium donates DNA to another bacterium

Plasmids

extrachromosomal DNA that can replicate on their own and move between cells, found in bacteria and fungi, not essential but can have advantageous traits

Recombinant organism

any organism that contains and expresses genes that originated in another organism

Horizontal gene transfer and types

any transfer of DNA that results in organisms acquiring new genes that did not come from parents, conjugation, transformation, transduction

Transformation horizontal gene transfer

bacterial cell accepts small fragments of soluble DNA from the surrounding environment

If a cell can accept genetic material through transformation then the cell is

competent

Generalized transduction horizontal gene transfer

random fragments of disintegrating host DNA are taken up by a phage during assembly

Specialized transduction horizontal gene transfer

a highly specific part of the host genome is incorporated into the virus

Transposons/ Transposable elements

‘jumping genes that can shift from one part of the genome to another

General effects of transposable elements

scramble genetic language and can be beneficial or adverse depending on where, what genes relocated, and the type of cell

Effects of transposable elements on bacteria

changes in morphology, pigmentation and antigenic characteristics, replacement of damaged DNA, transferred drug resistance

Mutation

any change to the nucleotide sequence in the genome, in microbes very obvious

Wild type microbe

a microbe exhibits natural characteristic which is in the majority of the population