Module 4 (Nucleic Acids and Information Flow) Flashcards
Function of DNA
Storing genetic information, copying itself to transmit the genetic information from one generation to the next
F. Griffith (1928)
Made experiment where a dead virulent bacteria mixed with live bacteria that was non-virulent transformed harmless bacteria into harmful bacteria.
Streptococcus pneumoniae
What type of bacteria did F. Griffith use?
Avery, MacLeod, McCarty
Determined that DNA was responsible for the transfer of genetic information
Deoxyribose
2’ carbon “minus oxygen”
Component of DNA
Nucleoside
Base and a sugar
Nucleotide
Base, sugar and phosphate
What contributes to the stability of DNA?
Hydrogen bonds, and base stacking
Replication
How DNA copies itself to pass along genetic information to the next generation
Fidelity
The degree of exactness with which something is copied
Parental Strands
The original DNA strand
Daughter strand
The strand of DNA that is newly replicated from an existing template strand of DNA
Reverse Transcriptase
Catalyzes the reaction of RNA to DNA
Polarity
Difference between two ends of strands of DNA
Bases can only be added to __________ on the sugar
3’ Carbon
DNA is synthesized in a _______ direction
5’-3’
Watson and Crick
Used other researcher’s data to create a 3D model of DNA
Rosalind Franklin and Maurice Wilkins
Used x-ray crystallography to study DNA structure
Erwin Chargaff
Discovered that DNA composition varies, but the amount of adenine is always the same as thymine and the amount of cytosine is always the same as guanine.
Base stacking
Stabilizing hydrophobic interactions between bases in the same strand of DNA. (non-polar)
Hydrogen bonds in DNA
Create stability in the DNA molecule in numbers
Central Dogma
DNA -> RNA -> Protein
Reverse Transcription
RNA -> DNA
RNA template for the synthesis of DNA
Gene
“The unit of heredity affecting one or more traits of an organism; the DNA sequence that corresponds to a specific protein”
Gene expression
The production of a functional gene produce, such as a protein, is regulated
Nucleus
Transcription occurs here in eukaryotes
Cytoplasm
Where transcription occurs in Prokaryotic cells
The 5’ end of a RNA strand
A triphosphate
Why is RNA less stable?
The -OH group on 2’ Carbon on RNA makes it easier to break down
Transcription
Copying a DNA sequence into an RNA sequence
Why does RNA break down easier?
Because of the OH group on the 2’ carbon, it makes it susceptible to hydrolysis.
5’ of RNA is ….
Typically a triphosphate
5’ end of DNA is …
Typically a monophosphate
Hairpin Turn
The folding of RNA, where RNA bases interact with each other
ex. tRNA
What is the difference between Uracil and Thymine?
Uracil has a hydrogen where Thymine has a methyl (-CH3) group
What is needed for transcription to occur?
- A DNA template
- RNA polymerase (enzyme)
Stages of Transciption
Initiation, Elongation, Termination
Where is Transcription initiated?
The promoter sequence
TATA box
Common promoter sequence in eukaryotes
Sigma factor
A protein that is responsible for promoter recognition in bacteria.
- Works with RNA polymerase
General transcription factors
Proteins that are responsible to initiate transcription in Eukaryotes (at least 6)
- Bind to promoter region
Where do transcriptional activator proteins bind to?
They bind to enhancer sequences on DNA, recruit RNA polymerase complex II
Why does the looping of the DNA do for transcription?
DNA brings activator proteins into contact with the proteins bound at the promoter region, causes transcription to start.
Transcription Elongation
RNA Pol (prokaryotes) and RNA Pol II (eukaryotes) allows for unwinding of DNA
- RNA nucleotide triphosphates can enter via channels
- RNA polymerase detects the ribonucleoside triphosphate, makes sure it pairs properly
- Orients O in OH group to 3’ end of strand, two phosphates cleaved (energy for reaction)
Pyrophosphate group
Phosphate group - phosphate group
Primary Transcript
RNA transcript that comes off the template DNA strand
Location of transcription in prokaryotes
Both occur in the cytoplasm
Polycistronic mRNA
In prokaryotes, primary transcripts may contain information for more than one gene
5’ Cap
7-methylguanosine to the 5’ end of mRNA
- Unique 5’-5’ bond, protects mRNA from exonucleases and stability
- Required for ribosome to recognize mRNA
Poly (A) Tail
Polyadenylation
- Approx 250 A bases to 3’ end of mRNA
- Protection from degradation
- Transcription termination
Alternative Splicing
Removing Introns from mRNA sequence
