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Chapter 3A: Nucleic Acids - Coggle Diagram
Chapter 3A: Nucleic Acids
Key chemical concepts
organisms consists mostly of the small molecule WATER and many different large organic molecules (CARBOHYDRATES, LIPIDS, NUCLEIC ACIDS, PROTEINS)
many large molecules are POLYMERS (consists of simpler subunits)
Subunits of polymer are bound by strong COVALENT chemical bonds
polymers interact with OTHER chemical via weak (HYDROGEN, IONIC) chemical bonds and VAN DER WAALS interactions
different part of a molecules can be polar/charged (HYDROPHILIC) or nonpolar/neutral (HYDROPHOBIC)
for SHAPE and ACTIVITY of molecule
pH and temperature can affect the charge and stability of weak chemical bonds
for structure and activity
Central dogma
DNA ---> transcription --> mRNA --> translation --> protein
Evidence that DNA is the genetic material
Properties of genetic material (3)
controls production of specific traits
if genetic material for a trait is present, trait is present and vice versa
heritable
transmitted from one generation to the next
mutable
can be CHANGED to produce NEW traits
example of mutability: the mutagenetic effectiveness of UV light matches the absorption spectrum of DNA (DNA is absorbed most strongly at the most mutagenetic wavelength)
do the observations that: 1) DNA absorbs UV light, 2) UV light causes mutations, 3) materials that absorb UV light reduce skin cancer (which is caused by mutations) PROVE that DNA is the genetic material?
NO, it DOES NOT PROVE it because it's a CORRELATION not a causation. Maybe there's something else that absorbs UV light that is unknown to us
The phenomenon of transformation
Virulent and nonvirulent strains of bacteria in mice
virulent strain --> mouse dies
nonvirulent strain --> mouse lives
heat-killed virulent strain --> mouse lives
dead virulent strain + live nonvirulent strain --> mouse dies
living virulent strain was present in the dead mouse. Why??
Use enzyme to destroy one of the three types of molecules (DNase, RNase, protease to kill DNA, RNA, protein)
treat dead virulent with
RNase --> still turned nonvirulent bacteria into virulent
protease --> still turned nonvirulent bacteria into virulent
DNase --> nonvirulent bacteria STAYED nonvirulent
shows that DNA is responsible for transforming nonvirulent bacteria into virulent bacteria
The subunit of DNA is a nucleotide
Parts
Ribose carbons are numbered starting at the C attached to base: 1'-5'
Deoxyribose (minus oxygen), NO hydroxyl group at 2' position
Phosphate(s) are linked to 5'C
Phosphate group carries a negative charge (Ionized hydroxyl groups are attached to the phosphate, negative charge makes DNA a mild acid because a molecule loses protons to the aqueous environment)
3 covalently linked parts: phosphate(s), deoxyribose sugar, base
Nucleotides are linked by covalent PHOSPHODIESTER bonds to form SUGAR-PHOSPHATE BACKBONE
Bases (purines vs. pyrimidines)
Pyrimidines (single ring): Pyramids are There for YOU to SEE (Uracil - RNA, Thymine -DNA, Cytosine)
Purines (double ring): Pure As Gold (Adenine, Guanine)
ends of a DNA strand are different so the strand is POLARIZED
5'-AGCT-3'
Base pairs form through HYDROGEN BONDING
A and T held together by TWO bonds
G and C held together by THREE bonds
hydrogen bonding between base pairs can only form in one orientation
if DNA strands are oriented in OPPOSITE directions (Anti-parellel)
Structure of a nucleotide
nucleoside + phosphate = Nucleotide
Nucleoside + 2 phosphate = Nucleoside diphosphate
Nucleoside +3 phosphate = nucleoside triphosphate
Structure of DNA
MAJOR/MINOR GROOVES: important because proteins that interact with DNA recognizes a particular SEQUENCE of bases by making contact with bases by the major and/or minor groove
double helix is RIGHT-HANDED
DNA REPLICATION depends on the WEAK association between DNA strands
Chromatin: DNA is wrapped around histone proteins to form nucleosome
DNA is the template for the production of RNA
Structure of RIBONUCLEOTIDE: Phosphate group, ribose sugar (WITH OXYGEN, HAS HYDROXYL ON 2' POSITION), Base
Diiferences between RNA and DNA
RNA has RIBOSE sugar
no thymine, RNA has URACIL
synthesized as a SINGLE strand, but CAN FOLD on itself
Different types of RNA
protein production
messenger
mRNA
protein coding
transfer
tRNA
translation
ribosomal
rRNA
translation (catalytic activity)
small nuclear
snRNA
splicing (catalytic activity)
small nuceolar
snoRNA
RNA biogenesis
telomerase
TER
DNA replication
micro
miRNA
regulation of gene expression/repress activity of other RNAs
long noncoding
lncRNA
regulation of gene expression
Non-coding RNAs
enzymatic activity: ribozymes cleave RNA messages
target sequence recognition: RNA bound to a protein can direct that protein to a specific DNA or RNA sequence that's complementary, protein then acts on
RNA WORLD HYPOTHESIS
RNA forms from inorganic sources
RNA self-replicates (via ribozymes)
RNA catalyses protein synthesis
Membrane formation changes internal chemistry, allows new functionality
RNA codes both DNA and protein
proteins catalyse cellular activities
DNA becomes master template