Molecular Genetics Part Ii

Front 1

transcription

Back 1

the synthesis of RNA by RNA polymerase using DNA as a template

Front 2

promoter

Back 2

dna sequence preceding the gene

Front 3

closed complex

Back 3

when polymerase is bound to the promoter but the dna has not yet been opened.

Front 4

transcription bubble

Back 4

the region of dna where the strands are separated

Front 5

the transcription start site (TSS)

Back 5

is the first base to be transcribed

Front 6

rna polymerases

Back 6

are large multi-subunit enzymes

Front 7

bacterial holoenzyme

Back 7

the core enzyme and the sigma factor complex

Front 8

pro-sigma factor

Back 8

sigma factor that has inhibitory domains that have not been cleaved

Front 9

anti-sigma factors

Back 9

are proteins that bind to sigma factors, inactivating them

Front 10

open complex

Back 10

rna polymerase bound to an open region of dna

Front 11

abortive initiation

Back 11

release of short rna's

Front 12

transcriptional pausing

Back 12

when rna polymerase pauses due to physical obstructions

Front 13

rho

Back 13

is an hexameric atp-ase with a ring structure, it binds to c-rich areas of rna.

Front 14

polyadenylation

Back 14

poly-A tail

Front 15

repressors

Back 15

regulatory proteins that decrease the level of transcripts for certain genes

Front 16

activators

Back 16

proteins that increase transcription

Front 17

operator sites

Back 17

sequences recognized by regulators, typically overlapping or close to the promoter

Front 18

enhancers

Back 18

eukaryotic genes controlled by distant regulatory sequences

Front 19

allosteric effectors

Back 19

small molecules that can bind directly to the regulatory proteins and change their conformation

Front 20

helix-turn helix

Back 20

common and found in many protein folds

Front 21

homeodomain

Back 21

a common eukaryotic dna binding domain

Front 22

coiled-coils

Back 22

are alpha helices that wind round each other

Front 23

negative regulation

Back 23

a repressor protein binds to an operator to prevent a gene from being expressed

Front 24

positive regulation

Back 24

a transcription factor is required to bind at the promoter in order to enable rna polymerase to initiate transcription.

Front 25

inducible regulation

Back 25

the gene is regulated by the prescence of its substrate

Front 26

repressible regulation

Back 26

the gene is regulated by the product of its enzyme pathway.

Front 27

operon

Back 27

genes located together, regulated together and transcribed together to make a product

Front 28

mitogens

Back 28

are extracellular signals (hormones) that promote entry into mitosis

Front 29

combinatorial control

Back 29

refers to the response of a gene to multiple signals and regulatory proteins

Front 30

two-compartment systems

Back 30

have a sensor kinase (detects signal) and response regulater (activated when phosphylated by the sensor kinase).

Front 31

anti-termination

Back 31

genes transcribed only when transcription termination is actively prevented

Front 32

attenuation

Back 32

is regulation of bacterial operon expression by controlling termination at the sequence before the first structural gene.

Front 33

riboswitches

Back 33

portions of a transcript that can directly bind a small molecule that controls the rna secondary structure, regulating transcription or translation

Front 34

imprinting

Back 34

when one or both parental gens are methylated at the insulator control region, the gene is silenced.

Front 35

pre-rnas

Back 35

non functional molecules, need to be modified to make functional rna

Front 36

ribonucleases

Back 36

cleave the rans into smaller parts

Front 37

self-splicing

Back 37

catalyze their own removal

Front 38

exons

Back 38

encode protein

Front 39

introns

Back 39

precursor rna

Front 40

cis splicing

Back 40

where exons in the smae molecule are joined together

Front 41

trans slicing

Back 41

is unusual, and joins exons from different rna molecules

Front 42

cryptic slice sites

Back 42

the sequences defining intron-exon junctions

Front 43

exon definition model

Back 43

the splicing machinery identifies exons for inclusion into the mature transcript.

Front 44

splicing enhancers

Back 44

rna sequence elements that positively affect splicing

Front 45

siRNAs

Back 45

are generated from random cleavage of double-stranded rnas

Front 46

ribosomes

Back 46

carry out translation

Front 47

translation factors

Back 47

associate with ribosomes and help with translation

Front 48

wobble pairing

Back 48

allows non watson-crick interactions, like g-u

Front 49

codon bias

Back 49

when some codons are used more infrequently than others, this rare codons, and these tend to be decoded by rarer trnas

Front 50

aminoacylation

Back 50

attaches amino acids to trnas

Front 51

cognate amino acid

Back 51

the correct amino acid for a trna

Front 52

polysomes

Back 52

many ribosomes on a mrna

Front 53

GTPase facots

Back 53

catalyze gtp hydrolysis, providing energy and undergoing conformational changes.

Front 54

polycistronic

Back 54

having several open reading frames

Front 55

shine-delgarno sequence

Back 55

polypurine tract, upstream of initiator aug

Front 56

monocistronic

Back 56

encode only 1 protein