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Ch16-17 (DNA (Order of DNA (Nucleosome- beads of DNA wrapped around a…
Ch16-17
DNA
Deoxyribonucleic acid
Nucleic Acid
Sugar Phosphate backbone
Nitrogenous bases
Guanine and Cytosine
RNA has Uracil
Adenine and Thymine
Phosphates link up vertically and the nitrogenous bases link up to create the double helix
Double Helix
Model made by James Watson and Francis Crick 1953
Inherited from parents
Genetic material used to code for protiens
Proteins are what cause the traits to be expressed
DNA has many genes that code for different traits
roughly 20500 genes
Creates own monomers
Copied during DNA replication
Hydrogen bonds are broken between nitrogen bases
Strands are separated
Strands used as templates for replication
two new identical DNA strands are made
proteins
Topoisomerase-breaks swivels and rejoins parent DNA
Helicase-separates parent strands
primase-uses parent DNA to synthesize RNA primers
single stranded binding proteins- stabilize unwound strands
DNA polymerase
catalyze synthesis of new DNA
adds nucleotides to the pre-existing chain
11 different DNA polymerases
Semi conservative model
Order of DNA
Lowest-DNA double helix simple model of stranded DNA
Nucleosome- beads of DNA wrapped around a histone
Histone is a protein used for packing DNA
30nm fiber comes from histone tail interactions
fiber loops into looped domains
looped domains arrange themselves into chromosomes
Separated sides of a chromosome are called cromatids
Gene to protein
Gene expression
how DNA causes genes to make specific proteins
Transcription
Synthesis of RNA from DNA
DNA parent used as template similar to replication
instead codes for RNA a protein coding gene
Messenger RNA
Carries Message from DNA to protein factories
Re-written from DNA to RNA
occurs in the nucleus
Original transcription is called the primary transript
RNA polymerase
strips DNA apart
Joins striped DNA with complementary RNA
Uracil goes with Adenine
gene that marks transcription beginning is the promoter
gene that ends transcription is the terminator
Phases
enlongation
termination
Initiation
Translation
synthesis of polypeptides from mRNA
Translates RNA to amino acid sequences
Like translating English to Chinese
Done in ribosomes
Facilitate linking of amino acids into polypeptide chains
the translator is called transfer RNA tRNA
transfer an amino acid from the cytoplasmic pool of amino acids into a polypeptide
Cells store all 20 amino acids
tRNA creates a cloverleaf like 3D structure
the end of the cloverleaf loke loop is called the anticodon
anticodon decides which protein is made
matching of amino acid and anti codon is done by
aminoacytl-tRNA synthetases
RNA processing
ends of RNA altered
modified guanine added to 5' end after 20-40 nucleotides
Called 5' cap
Poly-A tail
at the end 50-200 adenine nucleotides are added
both ends
facilitate transport
protect from degredation
help ribosomes attach to the 5' end
RNA splicing
Non coding sections are called Introns
Intervening sequences
Sections coded into amino acids are called exons
spliceosome
binds to sequences along the introns releasing them allowing them to degrade
Joins together exons
led to discovery of ribzymes
ribosymes
RNA molecules that function as a ribosome
self splicing ribosomal RNA
not all biological catalysts are proteins