Chapter 3 Flashcards
Which carbon do the nitrogenous bases attach to?
1’
Which carbon do the phosphate groups attach to?
5’
Phosphodiester Bond
the chemical linkages between nucleotides
What gives DNA its polarity?
phosphodiester bonds
-one end differs from other
How many base pairs are there in a complete turn?
10
central dogma
the usual flow of genetic info in a cell is from DNA to RNA to protein
-DNA –> Transcription –> Translation
Differences of RNA and DNA
1. RNA sugar = ribose
DNA sugar = deoxyribose
2. Uracil in RNA
Thymine in DNA
3. RNA molecules are shorter than DNA
4. RNA is single stranded / DNA is double strandedRNA World Hypothesis
RNA was the original info-storage molecule
RNA Transcript
complementary to the template according to base pairing rules
RNA Polymerase
enzyme that carries out polymerization
-adds successive nucleotides to the 3’ end of the growing transcript
nontemplate strand
not transcribed by RNA
Intiation
- First stage of transcription
- RNA polymerase and other proteins are attracted to DNA, DNA strands are separated, and transcription begins
Elongation
- Second stage of transcription
- Successive nucleotides are added to the 3’ end of the RNA transcript as RNA polymerase proceeds along template strand
Termination
- Third stage of transcription
- RNA polymerase encounters a sequence in the template that causes transcription to stop and the RNA transcript to be released
Direction and growth of RNA transcript
5’ to 3’
TATA Box
common promoter sequence
Sigma Factor
a protein which associates with RNA polymerase and facilitates binding to specific promoters
General Transcription Factors
assemble at the promoter of a gene
-necessary for transcription to occur
Transcriptional Activator Protein
each binds to specific DNA sequence known as the enhancer
Mediator Complex
recruits the RNA polymerase complex to the promoter
Primary Transcript
the RNA transcript that comes off the template DNA
-for protein making: includes info needed to direct ribosome to produce the protein corresponding gene
mRNA
RNA molecule that combines with the ribosome to direct protein synthesis
-carries the genetic “message” from DNA to ribosome
Polycistronic mRNA
molecules of mRNA that code for multiple proteins
RNA processing
complex chemical modifications of the primary transcript
