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genes and the genetic basis of metabolism and development (analysis of…
genes and the genetic basis of metabolism and development
storing genetic information
protecting the genes
ways dna is stored safely
dna does not participate directly in protein synthesis
produces messenger rna (mRNA)- carries information from one destination to another
most DNA is stores in the nucleus, protected from the cytoplasm by the nuclear envelope
histone proteins hold most nuclear DNA in an inert resistant form
histones are a special class of proteins
forms aggregates and DNA wraps around them forming a nucleosome
histones bind nucleosomes creating chromatin
the genetic code
codons- nucleotides grouped together in 3's
stop codons- they signal protein synthesis to stop. (UAG, UAA, UGA
star codons- signals the star of protein synthesis (AUG)
the structure of genes
composed of a structural region that codes for the amino sequence
promoter- regulates the synthesis of mRNA
located upstream (5' side)
TATA box- important. if damaged, RNA polymerase 2does not bind well
exons and introns
exons- sequences of nucleotides whose codons are eventually ecpressed
introns- sequence of nucleotides that are not expressed
transcription of genes
creation of RNA
RNA polymerase transcribes both introns and exons
formation of poly (A) tail 3' end
protein synthesis
ribosomes
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reads genetic message in mRNA and synthesizes proteins
composed of two subunits and sides made up of ribosomal rna
small subunit contains one molecule of rRNA and the larger subunit contains three types of rRNA
ribosomes found in the cytoplasm of eukaryotes are 80s (large and dense) ribosomes found in plastids, mitochonfria, and prokaryotes are 70s
tRNA
anticodon- three nucleotide sequence
composed of amino acid attachment and an anticodon
transcribed from tRNA genes
mRNA translation
translation- synthesis of a protein molecule by ribosomes under guidances of mRNA
initiation processes starts with a start codon AUG
frameshift error- reading nucleotides in the wrong sets of three
control of protein levels
transcription factors- proteins that binds to promoters
trans-acting factors: transcription factors that come from somewhere else and bind to DNA
cis-acting factors: promoters, enhancers, and TATA boxes
micro mRNA- controls gene expression
analysis of genes and recombinant DNA techniques
nucleic acid hybridzation
DNA melting/denaturation: speparation of DNA helix via heating
DNA hybridzation/reannealing: the reformation of the DNA helix.
used to determine the relatidness of the two types of DNA
method used to measure the number of copies of a gene that occurs in its nucleus
restriction endonucleases
responsible for cleaving the DNA
palindrome- sequence recognized by a restriction endonucleus that is present in both strands
sequence can be read forwards and backwards
cuts DNA near the end of palindrome
identifying DNA fragments
restriction endonucleus creates DNA fragments
number of fragments reveals number of Pst I sites
restriction fragment length polymorphism
complementary DNA (cDNA)
expression profiling uses cDNA to examine gene expression
DNA cloning
produces identical copies of DNA
plasmid- circular piece of DNA that occurs in bacteria and acts as a bacterial chromosome
plymerase chain reaction
technique of DNA cloning
DNA sequencing
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chain termination method-DNA first cloned to get a large sample then divided into 4 groups
add the enzymes and nucleotides necessary for DNA replication
pyrosequencing method- DNA addes to a solution of all the enzymes
genetic engineering of plants
plants have recieved a gene from bacillus thuringiensis that makes plant toxic to caterpillars
not widely accepted
viruses
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virus structure
contains a protein and nucleic acid
retroviruses- source of reverse transcriptases - single stranded RNA- no DNA- Plant Virus
split genome viruses- plant virus
virus metabolism
must invade a host to reproduce
bacteriophages- viruses that attack bacteria (phages)
to invade plants- viruses rely on on damaging living cells
retroviruses act as mRNA
temperate viruses- produce no symptoms, hidden, dies when plant dies
formation of new virus particles
infected cells go through lysis which spreads the virus particles
origin of viruses
portion of genes of host species or species closely related
mess up with DNA fragmentation
plant diseases caused by viruses
this is an image of a ribosome
this is an image of the end product of DNA synthesis
this is an image of a virus
DNA store genetic information
viruses contain DNA
ribosomes make proteins
