Looks like no one added any tags here yet for you.
Friedrich Miescher
First isolated DNA from white blood cells
Albrecht Kossel
Determined that DNA has 4 nitrogenous bases
Phoebus Levene
Discovered DNA is made of nucleotides (phosphate group, sugar and a base) and proposed that tetra-nucleotide structure of DNA
Griffth
Demonstrated the phenomenon of transformation, but did not identify transforming principle
Avery, Macleod, and McCarthy
Identified DNA as a transforming principle
Hershey and Chase
Identified DNA as the genetic material in bacteriophages
Heinz Fraenkel-Conrat and Bea Singer
Discovered that RNA is the genetic material of Tobacco Mosaic Virus
Yanofsky
Established that changes in DNA and protein were collinear (similar in location of changes)
Rosalind Franklin and Maurice Wilkins
Used x-ray diffraction to conclude that DNA was helical
Erwin Chargaff
Determined that DNA for yeast consisted of an equal amount of purines and pyrimidines - therefore concluding the base compositions and that A=T and G=C
James Watson and Francis Crick
Published the structure of DNA
Francis Crick
Proposed non-overlapping code
Brenner and Crick
Established codon consisted of 3 non-overlapping nucleotides
Meselson and Stahl
Grew E. Coli in heavy nitrogen for many generations to the transfer the cells to light nitrogen to replicate and determined DNA replicates through semiconservative replication
Fire and Mello
Learned that genes with nucleotide sequence that was same as injected dsRNA in worms had decreases expression, allowing them to determine that RNAi limits invasion of foreign genes and censors the expression of cell’s own growth
Charpentier and Doudna
Were first to use CRISPR as a “cut and paste” tool to edit gene sequences
Nirenberg and Matthaei
Were first to determine that a specific RNA sequence coded for a specific amino acid by using Poly-U, cell-free extracts, and 20 amino acids where 1 is radioactive. By determining if the protein is radioactive, they could conclude that the labeled amino acid was in the protein and the codon codes for that
Nirenberg and Leder
Used tri-nucleotide, ribosome, and 20 charged tRNA’s (1 radioactive amino acid) to identify 61 different codons
Nucleoside
Sugar and Base
Nucleotide
Sugar, Base, Phosphate
Euchromatin
Lighter staining parts of the chromosome during interphase
Actively transcribed gene
Condenses and relaxes
Heterochromatin
Darker staining parts of chromosome
Fewer Genes
Usually condensed
Usually not involved in crossing over
Replicated in S phase
Constitutive vs Facultative Heterochromatin
Constitutive: always heterochromatin
Facultative: May be Euchromatic sometimes (X chromosome that is Barr Body)
Histones
Basic proteins that are composed of positively charged amino acids (highly conserved)
Nucleosome
Nucleosome core + ~53 base pairs linker DNA
Nucleosome Core
Core histones + ~147 base pairs DNA
Core Histones
Composed of 2 each of H2A, H2B, H3, H4
Positive Supercoiling
Over-rotated in same direction as DNA so left-handed supercoil compensates
Negative Supercoiling
Under-rotated in same direction as DNA so right-handed supercoil compensates
Topoisomerase
Alters torsional stress in DNA by cutting DNA backbone to rewind
Endopolyploidy
Several rounds of DNA replication without separation of replicated chromosomes
Puffs
Areas where the DNA is loosely coiled so that transcription can occur
Theta Replication
Common in bacteria and other circular DNA molecules where Replication proceeds in both directions from origin (bidirectional).
Rolling Circle Replication
the F factor and some viruses (lambda) where Replication continues around many times producing many strands that are used as templates to synthesize many double stranded circular DNA molecules
Linear Eukaryotic Replication
For Eukaryotic Chromosomes which have multiple origins for replication (bidirectional)
In which direction are nucleotides added by DNA Polymerase?
5’ to 3’
DNA Polymerase I
5’-3’ exonuclease activity to remove and replace RNA primers, proofreads with 3’ to 5’ exonuclease activity
DNA Polymerase II
DNA repair and restates replication after damage halts synthesis
DNA Polymerase III
Elongates DNA and restates replication after damage halts synthesis, proofreads with 3’ to 5’ exonuclease activity, adds nucleotides to the primer
DNA Polymerase IV
DNA repair
Okazaki Fragments
Fragments of newly synthesized DNA created on the lagging strand
Initiator Protein
Binds to the origin of replication causing local unwinding and short stretch of single-stranded DNA
Helicase
Attaches at replication fork and moves into the fork breaking H-bonds
Single-Stranded Binding Proteins
Coat single-stranded DNA to protect it, stabilize it, and prevent double-strand DNA (hairpins)
Gyrase
A topoisomerase that releases supercoiling ahead of replication fork as it unwinds
RNA Primers
Made by Primase (an RNA polymerase)
Primosome
Helicase and Primase
DNA Ligase
Seals the nicks (missing sugar-phosphate bond)
Replication Licensing Factor
Attaches to each origin of replication early in cell cycle
Telomerase
Ribonucleoprotein that contains RNA which it uses to make several repeats of DNA to extend the 3’ end of the telomere
RNA Polymerase I
large rRNA
RNA Polymerase II
mRNA, snRNA, snoRNA, miRNA
RNA Polymerase III
small rRNA, tRNA, snRNA
Ratl Exonuclease
Chews up RNA (exonuclease) and removes nucleotides from DNA
Cap on 5’ to prevent it from chewing up mRNA that is needed
RNAi = RNA interference
Mechanism not RNA type
Shuts off gene expression using dsRNAs in eukaryotes
hnRNA
Heterogenous RNA, Pre-mRNA, Precursor for mRNA, Primary transcript for mRNA
Addition of 5’ cap
3’ Cleavage and addition of Poly-A-tail
RNA splicing
RNA editing
Internal RNA modifications
rRNA = Ribosomal RNA
Most abundant
Structural and functional components of the ribosome
Ribosomes have two subunits and it is not fully assembled until transcription
Precursor rRNA
Contains all rRNAs except 5S rRNA in eukaryotes
snoRNA = Small Nucleolar RNA
Processing and assembly of rRNA
tRNA = Transfer RNA
Help incorporate amino acids into polypeptide chain
Amino acid site is always CCA
Ribthymine: thymine with ribose attached
Pseudouridine: ribose attaches to 5 position of ring instead of 1 position
Inosine: derivative of guanine
A site: Aminoacyl
In P and A sites peptide bond is forming between amino acid
P site: Peptidyl
tRNA releases amino acid
E site: Exit
snRNA = Small Nuclear RNA
Processing pre-mRNA
Regions complementary to exons
snRNPS = Small Nuclear Ribonucleoproteins
Critical in proper positioning for splicing and base-pairing is important in their binding to RNA
gRNA = Guide RNA
Aid in insertion and deletion types of editing
dsRNA = Double Stranded RNA
Can form miRNA and siRNA using enzyme dicer to leave dsRNA
miRNA = MicroRNA
Inhibits translation of mRNA
Transcribed from distinct gene and targets other genes for regulation
siRNA = Small Interfering RNA
Triggers degradation of other RNA molecules
Comes from mRNA, transposons, or viral RNA and targets the genes that it comes from
RISC
miRNA and siRNA bind with proteins to form an RNA induced splicing complex that base pairs with mRNA and either inhibits translation (miRNA) or degrades mRNA (siRNA)
piRNA = Piwi-Interacting RNA
Suppresses the transcription of transposable elements in reproductive cells
Protects germline cells from transposons by silencing transposon RNA
lncRNA = Long Non-Coding RNA
Variety of functions
Decoys to bind regulatory proteins or miRNAs, pair with mRNA to trigger RNAi, Xist RNA recruit proteins to inactive X-Chromosome
crRNA = CRISPR RNA
Only in prokaryotes
Assists destruction of foreign DNA
Cas9 protein is a special enzyme that binds with it to cut the DNA
Aminoacyl Synthetase
Seen in each amino acid and can recognize all tRNAs for that amino acid - helps pair amino acid to its tRNA
Shine-Dalgarno Sequence
Located in the 5’ untranslated region to help with ribosome binding
*translation
Polycristronic mRNA
1 mRNA molecule produced, but contains the information for more than one gene and is translated into more than 1 gene product
mRNA always reads 5’ to 3’ end
Ribosome binds at 5’ end
Eukaryotes are not polycistronic
Peptidyl Transferase Activity
Ribozyme forming peptide bond between amino acids
Polysomes
Multiple ribosomes translating the same mRNA simultaneously
Splicosome
SnRNPs and pre-mRNA complex structure at which introns are removed and exons are joined together
Methylation
Occurs and identifies separate rRNA-to-be molecules
What are some differences in Eukaryotic Replication vs Prokaryotic?
Have many origins
Origin must be approved for replication
Linear chromosomes
Many DNA polymerase molecules (only DNA polymerase I and III in prokaryotes)
Have telomeres which replicate
Nucleosome assembly immediately follows replication
Transcription Unit
A segment of DNA that codes for an RNA molecule and the sequences necessary for its transcription
Consensus Sequence
A sequence that describes the nucleotides most often present in a segment of interest
Y = Pyrimidines
R = Purines
N= Any
Upstream
Sequences prior to the start of transcription
Downstream
Sequences after the start of transcription (+1 and up)
Core enzyme
a2BB’ (core RNA polymerase) (B = beta)
Holoenzyme
a2BB’ o (B = beta and o = sigma)
Rho (p)
Binds to the RNA and moves toward 3’ end and RNA polymerase, its helicase activity causes the DNA-RNA hybrid to unwind and transcription ends
Cis Elements
Same piece of DNA, adjacent to the genes they will regulate; cannot move
Trans Elements
Can move around and interact with many genes, attach to cis-elements or other transcription factors, and recruit RNA polymerase
Core (basal) promoter
Immediately upstream of gene and where the basal transcription apparatus binds (contains TATA box)
Regulatory Promoter
Immediately upstream of core promoter; variety of consensus sequences
3 Types of Processing
Capping of 5’ end
Poly-A-tail added to 3’ end
Removal of introns
Primary Structure
Amino acid sequence
Secondary Structure
Chain of amino acids folding on itself (alpha helix and beta pleated sheet)
Tertiary Structure
Protein folding secondary structure
Quaternary Structure
Protein containing more than one subunit - the joining of subunits
Wobble Effect
Single tRNA can pair with more than one codon
Inosine can pair with U, C, and A
Guanine and Uracil can also pair