Chapter 17, 18, and 19 Test

Gene Expression

gene expression

the process by which DNS directs protein synthesis which includes transcription and translation

alkaptonuria

hereditary disease in which enzyme is missing to break down alkapton- turns urine black

primary transcript

initial RNA transcript from any gene pior to processing

central dogma

DNA→ RNA → PROTEIN

Pre-mRNA

RNA before splicing

exon

part of DNA expressed

intron

Part of DNA cut out

RNA Polymerase

catalyzes RNA synthesis which pries DNA apart and joins together RnA nucleotides

Initiation

RNA Polymerase finds and bonds to the promoter

Elongation

adds on corresponding RNA transcript

Termination

End signal adn RNA transcript is disconnected

Promoter

where RNA Polymerase attaches

Transcription Unit

Stratch of DNA that is transcribed

Transcription factors

mediate the binding of RNA polymerase and the iniation of transcription

TATA Box

promoter that is crucial to the initiation complex

Modification of Pre-mRNA

5’ recieves a 5’ cap

3’ end gets a poly A tail w/ 50-250 adenines

RNA splicing

removes introns adn joins exons creating an mRNA molecule

spliceosome

variety of protein and snRNPs that recognize the splice sites

Ribozymes

catalytic RNA molecules that function as enzymes and can splice RNA

tRNA

translates the mRNA into protein with the help of this; brings mRNA to the ribosome

anticodon

codes for a codon which codes for specific amino acid

aminoacyl-tRNA synthetase

enzyme that attaches tRNA and an amino acid

wobble

explains how multiple anticodons can code for the same codon due to the flexible base pairing in the third base

rRNA

makes up ribosomal subunits

P site

holds the tRNA that carries the growing polypeptide

A Site

holds the tRNA that carries the next amino acid to be added to the chain

E site

discharged tRNA leave the ribosome

signal-recognition particle (SRP)

particle bound to the ER that ribosomes bind to when transporting polypeptide chain

Polyribosome

multiple ribosomes translating a single mRNA simultaniously

point mutation

chemical changes in just one base pair of a gene

silent mutation

no effect in the amino acid produced

missense mutation

still code for an amino acid but no the correct one

Nonsense mutation

change in amino acid codon into a stop codon leading to a nonfunctional protein

insertion/deletion

additon and deletion of nuclotide pairs

frameshift mutation

shift of the reading frame changing all the amino acids produced off of the mRNA chain

mutagen

physical or chemical agents that can cause mutations

operator

the “switch” positioned usually in the promoter of DNA

operon

the entire stretch of DNA that includes the promoter operator and gene

repressor

prevents gene transcription by binding to the operator and blocking RNA polymerase

corepressor

a molecule that cooperates with a repressor protein the switch off and operon

inducible operon

one that is usually off and the inducer in activates the repressor and turns on transcription (lac)

inducer

inactivates the repressor to turn the operon on

differential gene expression

the expression of different genes by cells with the same genome

histone acetylation

acetyl groups are attached to positively charged lysine in histone tails; loosens chromatin and promotes transcription

DNA methylation

the addition of methyl groups to certain bases in DNA; associated with reduced transcription in some species

virus

infectious particle consisting of genes packaged in a protein coat

capsid

protein shell that encloses the viral genome

capsomeres

monomer of capsid

viral envelopes

surround the capsids of influenza viruses and many other viruses found in animals

bacteriophages

viruses that infect bacteria

obligate intracellular parasites

meaning that viruses can only reproduce in a host cell

lytic cycle

produces new phages and the lyses the cell releasing more of the phages

lysogenic

when the viral DNA is incorporated into the host cell’s chromosome

prophage

integrated viral DNA

temperate phages

phages that use the lytic and lysogenic cycle

retroviruses

use reverse transcriptase to copy their RNA genome into DnA

provirus

viral DNA that is integrates into the host genome

vaccines

harmless derivates of pathogenic microbes that stimulate the immune system to mount defenses against the harmful pathogen

horizontal transmission

plant viruses entering through damaged cell walls

vertical transmission

inheriting the virus from a parent

viroids

small circular RNA molecules that infect plants and disrupt their growth

prions

slow-acting virtually indestructible infectious proteins that cause brain diseases in mammals