Week 1: Nucleic Acids
What carbon of sugar does nitrogenous base attach to?
"1'"
Oswald Avery
"1944; Identified DNA as ""transforming principle"" (genetic material/substance for heredity)"
What carbon of sugar is different when comparing deoxyribose & ribose?
"2'"
What carbon of sugar is phosphodiester bond made with?
"3'"
What carbon of sugar does phosphate group attach to?
"5'"
Structure of nucleotide
"<img src=""Screen Shot 2022-08-17 at 8.18.00 PM.png"" width=""512"">"
Deoxyribose sugar structure
"<img src=""paste-20af22c3e0e293027d07e58617db387c7e8f10a2.jpg"">"
THYMINE (T) BASE
"<img src=""paste-27c4f7d6150ce1c0a157e677bdaf2fc6dca736fb.jpg"" width=""279""><br><span style=""color: rgb(255, 64, 255);"">PYRIMIDINE</span> <br>Extra methyl group "
ADENINE (A) BASE
"<img src=""paste-47c00c125cf723196fcc65a30a67722b732e857a.jpg""><br><span style=""color: rgb(255, 64, 255);"">PURINE</span>"
GUANINE (G) BASE
"<img src=""paste-9063778d641ebbcfa3dc38c0a23452ba0bc22ded.jpg"" width=""331""><br><span style=""color: rgb(255, 64, 255);"">PURINE</span>"
Ribose sugar structure
"<img src=""paste-a9e8774c944047a5996a35b7fe7a8fc18f604e86.jpg""><br>Hydroxyl group instead of hydrogen "
nucleoside
"<img src=""paste-aa743373a004a0f27d7faffdd9fa2d8896cb352e.jpg"" width=""299""><br><span style=""color: rgb(255, 64, 255);"">Only the base & sugar portion of the nucleotide</span>"
The Central Dogma
"<img src=""paste-acc93030fc1b0558db3c0236b8ae139617d1466d.jpg"">"
CYTOSINE (C) BASE
"<img src=""paste-acee2cf846034df15217cd9afa95a51764b58e93.jpg"" width=""156""><br><span style=""color: rgb(255, 64, 255);"">PYRIMIDINE</span>"
URACIL (U) BASE
"<img src=""paste-e0601564effe663ffa55ca45c79e96126564cdf8.jpg""><br><span style=""color: rgb(255, 64, 255);"">PYRIMIDINE</span>"
polyA polymerase
"Adds polyA tail to 3' end of mRNA"
DNA Polymerase
"Makes new strands in 5'-->3' direction"
Leading strand
"Runs from 3' --> 5' direction"
Template strand
"Runs from 3' --> 5'"
Lagging strand
"Runs from 5' --> 3' direction"
RNA Polymerase
"Works in the 5' --> 3' direction, similar to DNA polymerase"
polyA tail
"at the 3' end, sequence of adenines added to the 3' end after polyadenylation signal<br><br>Protects the mRNA from degradation"
Phosphodiester bond
"formed between 3' hydroxyl on ribose sugar & 5' hydroxyl on phosphate group "
DNA Replication
- each strand serves as a template<br>- occurs during S phase of cell cycle<br>- multiple origins of replication
Identify the structural features of the DNA double helix?
1. Base pairing between two DNA strands<br>2. Strands are antiparallel<br>3. Strands are equidistant<br>4. Strands twist to form a double helix
DNA vs RNA structural differences
1. Double stranded polynucleotide vs. single polynucleotide strand<br>2. deoxyribose sugar vs. ribose sugar <br>3. A, G, C, T vs. A, G, C, U
"DNA's negative charge helps with what? "
1. Stability <br>2. Helps facilitate protein binding <br>3. Helps repel ions
Levene
1919; Discovered nucleic acid is composed of nucleotides & studied the structure of nucleotides
Erwin Chargaff
1950; Discovered base pairing A=T and C=G
Rosalind Franklin & Maurice Wilkens
1952; Photo 51 was an x-ray diffraction image of DNA, allowed the structure of DNA to be illucidated
James Watson & Francis Crick
1953; Published on the complementary structure of DNA
Describe A & T H-bonding
2 H-bonds, 11.1 Angstroms
Describe C&G H-bonding
3 H bonds, 10.8 Angstroms
codon
3 nucleotides which form a unit of genetic code. Translates to a specific amino acid
Purines
A & G
DNA Ligase
Binds any fragments together after DNA polymerase is done copying the parental strand
Pyrimidines
C, T, U
Exons
Coding regions
Phosphate backbone
Consists of the sugar, phosphate groups, and phosphodiester bonds between them. Backbone is always constant <br><br>Gives NAs their negative charge which helps with stability & repels unwanted ions
"5' cap"
Guanine triphosphate added to the end of RNA and then gets mehtylated <br><br>Seals RNA & protects against degradation & allows it to get recognized for translation
Miescher
Isolated white blood cells from bandaid; discovered nuclein (DNA with associated proteins from a cell nuclei)
Where does splicing occur
Nucleus
Promoter region
Region of DNA upstream of a gene where relevant proteins (RNA polymerase & trasncription factors) bind to initiate transcription of that gene
Splicing
Removal of introns during matruation by spliceosome
Topoisomerase
Stabilizes super-coiling (strain caused by helicase unwindind DNA). Does this by breaking and rejoining the phosphodiester bonds
Primase
Synthesizes an RNA primer to give DNA polymerase a place to start from. Is responsible for the Okazaki fragments on the lagging strand
Helicase
Unwainds DNA by breaking H-bonding between 2 DNA strands
Telomerase
When you get to the end of a lagging strand, a primer is removed and you get a shorter strand<br><br>Adds telomeres, short sequences fo repeating bases, to the ends of chromosomes to prevent shortening/lost DNA
gene
coding region in chromsome that generes an RNA/product
Transcription
copying a gene (DNA) to make mRNA