Lecture 8 Flashcards
What is genetics?
Science of hereditary
Total DNA is a genome (chromosomes and plasmids)
What is a DNA broken down?
Macromolecule composed of nucleotides
What are the nucleotides of DNA?
Nitrogenous base -> A,G,T,C
Deoxyribose sugar
Phosphate group
What is the structure of DNA?
Two strands held together by covalent bonds forming a helix held together by hydrogen bonds b/w bases
How many hydrogen bonds are b/w A-T vs G-C?
2 weak hydrogen bonds forming
3 weak hydrogen bonds but more strong than A-T
What are nucleotides linked together by?
Phosphodiester bonds
What direction is DNA read?
5’ to 3’
What are the different ways to use DNA?
Expression - using it to make proteins through transcription and translation
Recombination - transfer to cells via pili of the same generation
Replication - replicating DNA to daughter cells
What are the characteristics of DNA replication?
5’ - 3’ strand is the leading strand because direction is right to left
3’ - 5’ strand is the lagging strand because DNA polymerase only goes 5’ to 3’ away from replication fork causing Okazaki fragments and DNA ligase to connect
What are the characteristics of the daughter DNA?
50% 50% semi conservative replication
Anti parallel to each other 5’- 3’ / 3’ - 5’
What is the role of DNA gyrase and helicase?
Unwind and separate two DNA strands
Gyrase - only found in bacteria not eukaryotic cells (antibiotic target)
What is the role of RNA primer and DNA polymerase?
RNA - attaches to form new strand. Frees 3’ C-OH for DNA to start
DNA - joins the respected nucleotide with phosphodiester bonds
What is the role of DNA ligase?
Fills in gaps once RNA primer are removed to join all Okazaki fragments together
What are the 3 types of RNA?
Messenger RNA - carry coded info for proteins
Ribosomal RNA - part of ribosomes for protein synthesis to occur
Transfer RNA - carry amino acids to ribosomes for protein creation
What are the 3 transcription requirements?
Enzyme - RNA polymerase
A supply of RNA nucleotides
DNA template
What are the steps to transcription?
RNA polymerase binds to start nucleotide assembles new chain -> moves along template -> reaches end codon -> single strand RNA is released
RNA polymerase binds to start codon to assembles new chain -> moves along template -> reaches end codon -> single strand RNA is released
What are the steps to translation?
mRNA sticks to ribosome -> tRNA with amino acids bind to mRNA -> amino acids are joined by peptide bond -> ribosome moves 5’ - 3’ -> reach stop codon -> mRNA and protein are released from ribosomes
What is mutation?
A change in nucleotide DNA sequence
What are the two types of mutation?
Point mutation (substitution) - single nucleotide is replaced by another causing an incorrect base and amino acid in protein AKA missense mutation
-May not cause a change in amino acids AKA redundant code
-Cause premature stop codon AKA truncated proteins
Frame shift - insertion/ deletion. Causes change to the end of reading frame of mRNA
What are the causes mutations to occur?
Spontaneously - occasional mistake. No mutagen.
Mutagen - agent causes mutation. Ex. UV light, radiation
What happens when a mutation occurs?
Incomplete truncated protein (non functional)
Protein with new sequence (new function or normal function)
Silent mutation with no effect on protein (functional protein)
What are plasmids?
Self replicating double DNA strands with non essential genes (AKA autonomous replication)
What are the 3 types of plasmids?
F-plasmid - carry genes to make F pili found in bacterial conjunction (mating) and transfers DNA
R plasmids - carry antibiotic resistance genes
Vir plasmids - carry genes for toxin production
