Molecular Genetics Flashcards
mtDNA
Mitochondrial DNA
- found in mitochondria, but most other DNA is found in the cell nucleus
- inherited solely from mother
Hershey and Chase
conducted experiments using bacteriophages to show that DNA was hereditary material that gets passed on from parent cell to daughter cell
Watson and Crick
Determined structure of DNA
-DNA consists of 2 strands of nucleotides
DNA Contains
Backbone: alternating deoxyribose sugars and phosphates
- nitrogenous bases stick out from the backbone connecting to the deoxyribose sugars
- nucleotides twist clockwise to form the double helix
Purines
Double Ring Structure
- Adenine (A)
- Guanine (G)
Pyramidine
Single Ring Structure
- Cytosine (C)
- Thymine (T) *only found in DNA
- Uracil (U) *only found in RNA
Complementary Base Pairing
(A-T) by 2 hydrogen bonds
(C-G) by 3 hydrogen bonds
-causes helical shape
Original Strand
Template Strand
Replicated Strand
Complementary Strand
Helicase
Unzips DNA strands (breaks H-bonds)
Primase
Adds primers which attach to template strand. (act as starting point for nucleotide addition)
DNA Polymerase III
attaches to primers and begins added nucleotide 5’ to 3’ direction
-proofreads
DNA Polymerase I
Removes primers and replaces them with nucleotides.
-proofreads
Ligase
Glues fragments together.
Restriction Enzymes
Scissors
DNA read/built in what direction
Reads in 3’ to 5’
Builds in 5’ to 3’
Gel Electrophoresis
Used to separate DNA based on size and charge.
- DNA removed from organism, cut by restriction enzymes
- DNA put into wells in a sheet of gel
- Gel is attached to a battery with a positive and negative end
- Electric current is applied, negatively charged DNA moves to positive end
- large particles move slower than small particles
- MAKES DNA FINGERPRINT
PCR
copies DNA
Transformation
Taking foreign DNA, adding another DNA and using PCR to replicate it to clone.
Transcription
Process of converting DNA into mRNA.
- RNA polymerase binds to DNA at the promoter region, opens double helix
- RNA polymerase builds from 5’ to 3’
- similar to DNA replication but does not need primers
mRNA
Messenger RNA
- uracil instead of thymine
- mRNA sequence is complementary (opposite) to DNA
- codon codes for amino acid
Translation
Synthesis of a protein which occurs under the direction of mRNA.
- mRNA is read in groups of 3 called codons
- codon = amino acid
Start Codon
AUG (methionine) where translation begins
Stop Codon
UAA, UAG, UGA do not code for amino acids, where translation ends.
tRNA
Transfer RNA gets the ribosome the corresponding amino acid it is reading
- anticodon binds to complementary codon on mRNA
- other end has corresponding amino acid
P site
Peptidyl Site - where first tRNA enters to attach to start codon
Releasing Factor
Recognizes ribosome has stopped and helps release polypeptide chain.
Silent Mutation
Nucleotide sequence changes but still codes for the same amino acid.
Missense Mutation
Base substitution changes one amino acid in a sequence, resulting in a different protein.
Nonsense Mutation
Normal codon is changed to a stop codon.
-often lethal
Frameshift Mutation
Addition or deletion of codon causing reading frame of codons to change.
