Categorieën: Alle - transcription - rna - dna - protein

door Matthew Navarrete 2 jaren geleden

147

Concept Map 3

The process of gene expression involves multiple stages including transcription and translation, each regulated by various proteins and enzymes. Transcription is carried out by RNA polymerase, which synthesizes RNA from a DNA template.

Concept Map 3

Floating topic

Experiments

Hershey and Chase

DNA Phosphorus
Settled in pellet
protein Sulfur
Found in supernatum

Subtopic

Griffiths

proved genetic material could be passed through bacteria

DNA Replication

unzipped by Helicase

kept apart by SSB
stress relieved by topoisomerase

replication begins at ORI

5' to 3' direction

leading strand with primase and DNA pol III

lagging strand and DNA pol I

direction of replication goes into fork and ligase seals gaps

semi conservative proved by Messleson and Stahl experiment

short GC rich sequences create mRNA foldiing

without rho factor

Promotes mRNA polymerase dissociation

requires ATP

with rho factor

Vesicle

Golgi Body

Plasma Membrane
Lysosome

Aminoacyl tRNA Synthetase

initiator tRNA scans mRNA for start codon & large subunit joins the translation initiation complex (other proteins called initiation factors may be involved)

in the ER, translation continues and the signaling peptide is cleaved by an enzyme called Signal Peptidase

no tRNA corresponds to a stop codon, so a release factor in the A site disassociates the complex and stops translating the mRNA (a GTP driven process)

in the elongation stage, a polypeptide chain begins as new amino acids are brought to the A site and attached to the previous one. the empty tRNA moves then moves to the P site after the amino acid chain was transferred

Gene Expression

Distal
Enhancers
Proximal
bind general transcription factors

Prokaryotes

Lac operon
Lactose present

repressor binds to Lactose

Glucose present

Adenylyl cyclase is inactive

cAMP levels are low

CAP is inactive

Operon is OFF

Adenylyl cyclase is active

cAMP levels High

CAP is active

Operon is ON

repressor binds to operator

Operon is OFF basil

Binding of RNA to DNA
Promoter

sigma factor of polymerase recognizes promoter region

not transcribed

recognized even in helical double stranded form

Orientation to polymerase

initiation of transcription

RNA polymerase

elongation in 5' to 3' direction

creates phosphodiester bond between NTP and sugar

protein

nucleosomes
DNA
histones

H4

H3

H2B

H2A

histone core

H1

Archae

RNA Polymerase and other transcriptional factors

Specific
changes level of transcription

Repressors

Activators

General
background/basil
three multimeric structures
RNA polymerase III synthesizes small RNA such as tRNA
RNA polymerase I synthesized rRNA
RNA polymerase II primary one

Orientation and facilitates RNA Polymerase Binding

elongation

termination

inactivated by phosphatases

site for addition of poly A tail

poly A tail

methylation

capping

ribonucleotide triphosphates

phosphate group
ribose sugar
sugar phosphate backbone

encodes

Nitrogenous base pair
Pyrimides

Single-ring structure

CTP

purines

GTP

ATP

UTP

Double-ringed structure

DNA template

only one strand of DNA is used as a template
mRNA

Translation/Protein Movement

Proteins in the Endomembrane System

Nucleus

Chloroplasts

Peroxisomes

Mitochondria

Secretory Pathway

Polypeptide synthesis on a free ribosome

Endoplasmic Reticulum

Cytoplasm

Steps in Translation

Prokaryotic

Elongation

Termination

Eukaryotic

Initiation

Ribosomes

Large and Small subunits

codons

tRNA

Binding Sites

E site

P Site

Peptidyl Transferase

A Site

Amino Acids

anticodons

transcription

occurs downstream from +1

promoter found upstream

Eukaryotes

transcription in nucleus

RNA pol II

pre-mRNA

RNA splicing

introns are spliced out

exons remain in final mRNA

5' end cap and 3' poly A tail

prokaryotes

transcription in cytoplasm

RNA pol

Transcetylase

Permease

Beta Galactosidase

rRNA

Each gene can be easily transcribed and translated with different efficiencies and regulation factors

vast array of various proteins in large quantities and or minute quantities with different functions