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44 terms

DNA

STUDY
PLAY
Frederick Griffith
proved heredity occurs at the molecular level and bacterial transformation
Bacterial Transformation
uptake and expression of foreign DNA
Oswald Avery
first to prove that DNA NOT protiens carries information
Hershey and Chase
second to prove indefinitely that DNA was the genetic material
Erwin Chargaff
Found that the % of Adenine almost = the % of Thymine and that the % of Cytosine almost = the % of Guanine
Rosalind Franklin
proved that DNA was a double helix
Watson and Crick
proved DNA structure, Purines to Pyrimidine, Adenine and Thymine have 2 H bonds & cytosine and guanine had 3 H bonds
DNA Structure
composed of two separate single strands of nucleotides held together by H bonding between nitrogenous bases.
The phosphate of a strand is its ___' and the sugar end is its ___' end.
3' and 5'
DNA Replication
production of 2 exact copies of ds DNA from 1 original ds DNA
"Semi-Conservative"
each of the 2 new replicate "daughter strands" contains Y2 of the original nucleotides and Y2 new nucleotides.
Origin Site
Is the site where replication can begin and progress in both directions.
Step 1 to DS DNA replication
Helicases attatch to the DS DNA origin sites and can move in either direction breaking H bonds
Step 2 to DS DNA replication
Single Stranded Binding Protiens (SSB's) follow the helicase and keep the H bonds from bonding back up.
Step 3 of DS DNA replication
Primase adds small segments of single stranded RNA to act as a "primer" and get the additional nucleotides started.
Step 4 of DS DNA replication
The leading strand is where the enzyme DNA polymerase links to the primer and adds new nucleotides in the direction of replication.
Step 5 of DS DNA replication
The lagging strand is the strand in which dna polymerase must work away from the actual direction of replication, and DNA ligase links okazaki fragments so that there is a continuous double stranded DNA.
The enzyme that makes a mistake every 1 in 10 billion
DNA Polymerase
Excision
cut out a mistake and replace it with new nucleotides by DNA polymerase.
Building Blocks for Nucleic acids
Nucleotides
Gene
sequence of DNA nucleotides that codes for the building of a specific protein
RNA
single stranded, Ribos sugar instead of Deoxyribos, no Thymine but Uracil instead.
Types of RNA
mRNA, tRNA, rRNA
mRNA
messenger RNA that carries info from DNA to ribosomes
tRNA
transfer RNA that brings amino acids to ribosomes
rRNA
ribesomal RNA that is not for coding but part of ribosome structure with protein.
DNA to RNA to Protein inbetween steps
Transcription then Translation
Translation
converting info of mRNA into an amino acid sequence (protein)
Genetic Code
based on mRNA nucleotides, Triplet code-3 bases required to specify one of 20 possible amino acids
Ribesomes Structure
Large Subunit, Small subunit
tRNA structure
single stranded RNA with numerous loops
Mutations
a change in DNA
How mutations occur
Replication
Levels of mutation
Nucleotide, Gene, Chromosome
Point Mutations
involving a single base up to 3 bases (codon) [will affect 1 amino acid]
"Silent Substitution"
change a base but still code for the same amino acid
"Missense Substitution"
Base change causes a codon to code for a different amino acid
"Nonsense"
substitution changes a codon to a stop codon [can be very harmful]
Frameshifts
base is either inserted or deleted from a gene. Every codon downstream gets altered. (very damaging)
Mutagen
a chemical that causes mutation
Carcinogen
mutagen that causes cancer
Introns
sequences in genes that don't code for anything
Exons
sequences in genes that code for amino acids
Satallite DNA
outside of genes codes for nothing