Foundations of Biology Exam 4: Making Proteins Overview and Transcription

the central dogma of biology

DNA replication only occurs in cells in S phase prior to mitosis or meiosis

protein synthesis

__________ _________ is occuring almost all the time in almost all cells

amino acids

the monomers of proteins

nucleotides

the monomers of nucleic acids

nucleus

transcription occurs in the _________

cytoplasm

translation occurs in the __________

transcription

mRNA "copies" of genes are made by RNA polymerase

translation

the process of converting the information of mRNA nucleotides into amino acids to build proteins

RNA

a nucleic acid that mediates protein synthesis during transcription and translation

mRNA

a nucleic acid that carries protein-encoding information; helps to make proteins; catalyzes some reactions

the four steps to make a transcript

- initiation

- elongation

- termination

- processing

RNA polymerase

on enzyme that makes polymers of RNA using DNA as a template

promoter

the DNA address for a gene; upstream of a gene

gene

the recipe for a protein

chromatin

DNA + histones

histones

protein complexes responsible for packing DNA; determine 'open' or 'closed' state of DNA ( w/ associated proteins)

euchromatin

copied or used region of DNA; open

heterochromatin

not copied or used region of DNA; closed

transcription factors (TFs)

proteins that bind to DNA and regulate gene expression

actiavtor

transcription factor that binds to DNA to promote transcription

repressor

transcription factor that binds to DNA to stop or prevent transcription

general transcription factors (GTFs)

proteins that bind to DNA and regulates gene expression. These bind upstream of EVERY gene that needs to be transcribed at a TATAA box; act like a beacon to call over RNA polymerase to transcribe a gene

TATAA box

a region of DNA upstream of a gene where GTFs bind to regulate gene expression

steps to eukaryotic transcription initiation

1. the chromatin are open a able to be read

2. transcription factors bind to DNA to regulate expression

3. general transcription factors bind to DNA and call over RNA polymerase

4. RNA polymerase binds and begins to assemble an mRNA strain using DNA as a template

3'; 5'

RNA polymerase reads DNA in the ___ to ___ direction

5'; 3'

RNA polymerase builds mRNA in the ___ to ___ direction

eukaryotic transcription elongation

DNA unwinds and RNA polymerase moves along using template strand of gene as a template for mRNA; RNA pol reads template strand 3' to 5' and makes antiparallel, complimentary mRNA transcript 5' to 3'

eukaryotic transcription termination

the DNA termination sequence is reached, and RNA pol falls off DNA and mRNA dissociates from enzyme

transcription in prokaryotes

- instead of GTFs, a sigma factor (protein) binds to the promoter DNA region to guide RNA polymerase to the correct location

- RNA polymerase opens up to DNA and starts transcription

- once transcription has begun, the sigma factor is released, and RNA polymerase continues transcribing

- a hairpin forms in mRNA due to sequence of transcribed base that hydrogen bond together

- hairpin structure if followed be a long stretch of Uracil bases leading to RNA polymerase separation, terminating transcription