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Chapter 21
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Nucleic Acids
Molecules that store information for cellular growth and reproduction
Deoxyribonucleic Acid and Ribonucleic Acid
Large molecules consisting of monomers and nucleotides
Nucleotides
A monomer that cossets of:
-a pentose sugar
-nitrogen containing base
-phosphate ester with C5 OH group of sugar
Pyrimidines
Cystine
Thymine
Uracil
Purines
Adenine
Guanine
DNA Contains:
Cystine
Adenine
Guanine
Thymine
RNA Contains:
Cystine
Adenine
Guanine
Uracil
The DNA pentose sugar
Deoxyribose
The RNA pentose sugar
Ribose
Nucleosides
Nitrogen base linked by C1 glycosidic bond of sugar
Diphosphate
1 phosphate
a nucleotide
Triphosphate
diphosphate
1 nucleotide
Structure of nucleic acid
Joined by phosphodiester bonds
Has free 5' phosphate group and 3' OH free at other end
Double helix of DNA
Has 12 strands of nucleotides
Hydrogen bonds between A-T and G-C
Bases complement each other
Complementary base of Adenine
2 Hydrogen bonds to Thymine
Complementary base of Guanine
3 Hydrogen bonds to Cytosine
DNA Replication
Pair bases in strand with new basest form new complementary bonds
Produce 2 new DNA strands
Exactly duplicate original DNA
Hydrolysis Energy
Energy from hydrolysis of each nucleoside triphosphate adding to the complementary strand
Used to form phosphodiester bond
DNA Replication
Enzyme
Helicase unwinds parent DNA
at several sections
At each replication fork
DNA polymerase
catalyzes the formation of ester bind of leading strand 5'3'
Lagging strand
growing in 3'5' direction
Onazaki Fragments joined by DNA ligase
to from single DNA strand
RNA
Transmits information from DNA to make proteins
Messenger RNA
mRNA
Carries genetic information from DNA to ribosomes
5-10%
Transfer DNA
tRNA
Brings amino acids to ribosomes to make proteins
10-15%
Ribosomal DNA
rRNA
Make up 75% of ribosomes where protein synthesis takes place
RNA structure
A triplet called anitcodon that complements a codon in mRNA
Bonds to a specific amino acid on the receptor stem
Protein Synthesis
Transcription
: mRNA formed from gene on DNA strand
Translation
: tRNA molecules bring amino acids to mRNA to build protein
Transcription
A section of DNA containing the gene unwinds
One strand of DNA is copied starting at initiation point & has sequence TATAAA
mRNA synthesized using complementary base pairing with U replacing T
Moves from nucleus to ribosomes in cytoplasm
RNA Polumerase
During transcription the polymerase moves along DNA in 3-5 direction to synthesize mRNA
Released at termination point
Regulation of Transcript
A specific mRNA synthesized when the cell requires particular protein
Feedback Control
End products speed up or slow down synthesis of RNA
Enzyme Induction
High levels of reactant induce transcription process to provide enzymes headed for reactant
Genetic Code
Sequence of amino acids in a mRNA that determines the order for a protein
Consists of consists of sets of 3 bases along mRNA codon
Different codon for all amino acids to build protein
Start of codon
AUG
Stop of codon
UAG
UAA
UGA
Advantage of genetic Code
Helps reduce error
Somewhat mutation resistant
Protein Synthesis
Activation/Initiation
Translocation
Termination
Mutation
Alter nucleotide sequence in DNA
Normal DNA
Produce mRNA that provides instructions for correct series of amino acids in a protein
Substitution
Different base substitutes for the proper base in DNA
Change in codon in mRNA
Wrong amino acid in polypeptide
Frame Shift
Base added of detected from normal DNA sequence
All codons in mRNA and Amino Acids are wrong
Recombinant DNA
DNA fragment from one organism combined into DNA of another
Mixed with plasmids and joined by ligase to produce protein
DNA Fingerprinting
Restriction enzyme at DNA sample into small fragments
Radioactive isotope that adheres to certain base sequence to produce X pattern
Polymerase chain reaction
Produce multiple copies of DNA in shirt time
Separate DNA by heating and repeated many times
Viruses
Small particles of DNA/RNA require host cell to replicate
Reverse Transcription
A retrovirus that contains only RNA enters cell
Uses reverse transcription to produce DNA strand
Author:
Anaa_n
ID:
272341
Card Set:
Chapter 21
Updated:
2014-04-29 12:39:43
Tags:
chem
Folders:
Chemistry 106
Description:
Cummulative
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