Biol 205 Flashcards
What is the coding strand?
Sense strand (+ strand)
Has the same sequence as the mRNA
What is the template strand?
The non coding strand
Used to synthesized mRNA
Opposite of coding and mRNA strand
What is a codon?
Three letter code specific to the genetic code
What is the tRNA?
Type of RNA that assembles peptides from mRNA chain
What effect would a mutation have on the promoter?
Different expression pattern
What effect would a mutation have on the non-coding region?
It would be a silent mutation since the introns get spliced out
What are the types of mutations?
Non-sense, Missense, Frameshift and Silent
What is a non-sense mutations effect?
Premature stop codon
What is a missense mutations effect?
Change to the amino acid sequence
What is a framshift mutations effect?
Insertion or deletion, can lead to entire peptide changes
What is a silent mutations effect?
No change to the protein sequence
What are the ideal parameters for PCR primer?
- Length 18-24 bp
- 40-60% G+C content
- Melting temp (Tm) 50-60 C
- Primers should have a Tm w/in 5 degrees of each other
What is a recombinant DNA?
- A DNA molec. generated in the lab that brings together pieces of DNA from multiple sources
- Usually contain 2 pieces of DNA –> an engineered plasmid (vector) + gene of interest
- Can be inserted into organisms to carry out specific functions
What is the plasmid?
- (aka a vector) are engineered DNA molecs which have defined features for a specific function (protein expression, clonning, ect.)
What components do plasmid contain?
- Promoter sequence (to express inserted gene)
- Origin of replication (to amplify plasmid
- Selectable marker (to select transformed bacteria)
- Multiple cloning sites (MCS)(used to insert gene of interest)
What are restriction enzymes?
- Endonucleases that cleave phosphodiester bonds b/w nucleotides @ sepcific DNA sequences (often palendromic)
Explain cloning by restriction enzymes
- Cleaving both vector + insert w/ one restriction site has no orientation
- Using 2 sites results in only one possible orientation
- Blunt cutters insert w/ no orientation
Explain cloning by PCR
- First we amplify our gene of interest through PCR w/ primers that incorporate RE sites
- After PCR, DNA can be cut w/ RE + subcloned into a vector
What does the proofreading in transc?
DNA polymerase III
Works in the 3 -5 prime direction
What do DNA gyrase, helicase and DNA polym I do respectively?
- Prevent supercoilling
- Unwind
- Declave DNA
Which has more replication origins, DNA or bact?
DNA
- bact has only one and humans have thousands
During what phase of the cell cycle does DNA replicate?
During the S phase of the cell cycle
How does DNA know when to start replicating?
The machinery for replication requires specific proteins and those proteins are made during M and G1 phase
What is the start codon?
AUG
What does telomerase do?
Carries short RNA molecs complementary to 3 prime overhang
Why are caps important?
- “protect” the telomere at the end of a chromosome
Which is more stable RNA or DNA?
- RNA is more reactive because of the “OH” group
- “OH” is more reactive than “H”
Which is more stable Uracil or Thymine?
- Thymine because Uracil lacks a methyl group
List all the reasons RNA is less stable
- Single stranded
- Uracil instead of thymine
- Has an OH instead of an H group
What is the role of mRNA’s?
Intermediary that passes information from DNA to protein
What is the role of functional RNA
They don’t incode info to make protein. Instead the RNA itself is the final functional product
What tells the proteins where to go in the promoter?
Sigma factors
What is sigma 70?
Housekeeping transc factor, binds to promoter of genes that are always on in the cell. Euk have no sigma factors
What are the only aa that have hydroxyl group?
Tyrosine, serine and threonine
What are the internal proteins and why are they internal?
Nonpolar proteins (b/c they are hydrophobic)
What are the externall proteins and why are they internal?
Polar/Uncharged (hydrophillic)
Polar/ post charged (binf DNA b/c DNA has net neg charge)
Polar Charged (reactive + can form w/ other nearby aa)
What deternines how the protein will fold?
The R group
What does determiens the role of the protein?
Its structure
Are codons overlapping?
No they are no overlapping; each nucleotide is part of only one codon
Is the codon continuous?
Yes it is continuous; its read from a fix starting point and continues uniterrupted to the end of the open reading frame
How many letters make up a codon?
3
What is the equation to determine the number pf combinations for a codon?
4^n
n= the number of codons
What are the stop codons?
UAA, UAG, UGA
