Unit 6 ap bio

inducible

default off, able to be expressed, needs an added protein to be turned on; ex. Lac

repressible

default on, able to be unexpressed, needs an added protein to be turned off; ex. Trp

operon

prokaryotic gene control mechanism; operator region, repressor comes from regulatory gene

regulatory gene

makes a repressor, always “on”

operator

where the repressor binds

promoter

allows RNA polymerase to bind

structural gene

makes proteins for a trait

active repressor

blocks RNA polymerase, the gene is turned off

corepressor

attaches to an inactive repressor to activate it

gene is off

operator + repressor = RNA polymerase is blocked

histone acetylation

DNA is unraveled and usable; attachment of acetyl groups and AAs to histones

DNA methylation

DNA is condensed and unusable, the gene is shut down; addition of methyl group to DNA bases

epigenetics

inheriting life experiences, long term control from generation to generation

enhancer

regions of DNA before the gene that controls transcription rate

repressor

protein that slows or stops transcription

transcription factor

controls the speed of transcription; tells the RNA polymerase where to go

differential gene expression

one gene is expressed and another is not

pre-mRNA

mRNA strand with introns and exons, before splicing

alternative RNA splicing

exons can be spliced together in alternative ways, thus allowing for the production of multiple protein versions from the same mRNA transcript

modifications of RNA

protective mechanism for the mRNA strand on the way to ribosomes; 5’ cap, poly-A tail, splicing

5’ cap

protective barrier against digestive enzymes on the front of an mRNA strand

poly-A tail

excessive adenines on the back of an mRNA strand acting as a buffer for protection against digestive enzymes

RNA splicing

removal of non-protein coding regions of RNA, coding regions are spliced together

spliceosome

cuts out introns and joins exons together

translation control

mRNA degradation, availability of initiation factors, availability of tRNAs, AAs, and other protein synthesis factors

RNAi

interacts with RNA to destroy it or block translation, a tool to track a gene target

activator

protein that speeds up transcription

central dogma

DNA > transcription > mRNA > translation > protein > phenotypes

replication

the process of making more DNA from DNA; A-T, C-G

semiconservative replication

each strand of DNA is half old and half new

prokaryotic replication

replication runs in both directions from the ONE origin site, CIRCULAR DNA

eukaryotic replication

replication bubbles fuse to form new DNA strands, MANY origin sites

DNA elongation

DNA polymerase III, matches A to T and C to G, for REPLICATION, ONLY happens in 5’-3’ direction

priming

nucleotide bases attach to a primer, done through primase

leading strand

assembled continuously, TOWARDS helicase, happens in 5’-3’ direction

lagging strand

assembled in okazaki fragments, AWAY from helicase

transcription

copying DNA into RNA strands; initiation, elongation, termination, post-transcriptional modifications

initiation

transcription factors bind to the DNA at the TATA box, signals for RNA polymerase to bind there

elongation

once RNA polymerase is attached it copies the DNA into an RNA strand continuously; T-A, A-U, C-G

termination

once RNA polymerase reaches the end of the gene a terminator sequence tells RNA polymerase to detach

pre-mRNA

raw RNA, RNA with both INTRONS and EXONS, not yet spliced

translation

building proteins from a RNA code, done by ribosomes

tRNA

carries AA for polypeptide synthesis

point mutation

changes in one or a few nucleotides in the genetic code

silent

a base pair is changed for another one, but it has no effect on the AA; no effect anywhere

missense

a base pair is changed for another one, AND it changes the AA; shortens proteins

nonsense

a base pair is changed for another one, AND it changes the AA to a stop codon

insertion

the addition of a base in the DNA

deletion

the loss of a base in the DNA

DNA polymerase III

enzyme responsible for adding DNA base pairs to a growing strand

DNA polymerase I

enzyme responsible for replacing RNA primers with DNA

primase

enzyme responsible for adding RNA primers to start a strand

ligase

enzyme responsible for gluing fragments of DNA together

helicase

enzyme responsible for separating strands of DNA

TATA box

binding site for transcription factors