Post on 02-Jan-2016
description
10.6-10.16 GENETIC
INFORMATION FROM DNA TO
RNA TO PROTEIN
1. DNA GENOTYPE =PROTEINS= PHENOTYPE=
The central concept in biology is:DNA determines what protein is made
RNA takes instructions from DNA
RNA programs the production of protein synthesis
Proteins determine the phenotype of the organism
Proteins are made into two main stagesTranscription-
the transfer on genetic info from DNA to RNA molecule
Translation- transfer of info in the RNA into a protein
DISCUSS W/ PARTNER: What is a protein? What protein have you eaten
today and/or yesterday? What role do proteins play in
your bodily functions?
2. GENETIC INFO
WRITTEN CODONS
mRNA Codon Chart
Genes are located on molecules of DNA
The language of DNA is the order (sequence) of nucleotides Ex: AAGCTT
The order of the nucleotides determine which genes are made
Transc
riptio
n & Tr
anslatio
n of c
odons
THE GENETIC CODE DNA’s instructions
are based on 3 nucleotides (triplet code)
The 3 nucleotide sequence (codon) are the genetic instructions from DNA to make amino acids; which together make polypeptide chains (proteins)
Each codon specifies for an amino acid
3. TRANSCRIPTION
A close-up view of transcription
During transcription:1. RNA polymerase (an enzyme)binds
to DNA on the promoter region & separates the DNA strands.
Promoter- Region of DNA (a codon) that allows transcription to begin
Terminator- Region of DNA that signals the end of a gene & transcription stops.
• There are 3 main types of RNA:• Messenger RNA (mRNA)– carry
copies instructions from genes for putting together amino acids into proteins. Carry “messages” from DNA to the rest of the cell.
• Ribosomal RNA (rRNA)- makes up a major part of the ribosome (proteins are put together here)
True shape of a functioning ribosome
• Transfer RNA (tRNA)- transfers each amino acid to the ribosome as it is specified by coded messages in mRNA.
4. RNA EDITING
• When RNA molecules are formed, introns and exons are copied from DNA.
• Introns- DNA sequences of nucleotides that do not code for a protein
• Exons- sequences that does code for a protein
• The introns are cut out of RNA molecules.
• The exons are then spliced together to form mRNA.
5. TRANSLATION
• Takes place on the ribosomes• Translation- the decoding of an mRNA
message into a polypeptide chain (protein)
1. Translation begins when an mRNA molecule attaches to a ribosome.
2. As each codon of the mRNA molecule moves through the ribosome, the proper amino acid is brought into the ribosome by tRNA.
3. In the ribosome, the amino acid is transferred to the growing polypeptide chain.
• In the process anticodons are formed• Anticodon- 3 unpaired bases of tRNA that are
complementary to mRNA•
RIBOSOMES Are made of rRNA Have a binding site for mRNA and three
binding sites for tRNA moleculesThe P site holds the tRNA carrying the growing
polypeptide chain
The A site carries the tRNA with the next amino acid
tRNAs leave the ribosome at the E site
STEPS OF TRANSLATION
1)Initiation brings together mRNA, with tRNA Special initiator tRNA carries and attaches to the
start codon
2)Elongation adds amino acids according to the mRNA codonsPeptide bond formation b/w a.a’s During translocation, the ribosome
moves the tRNA with the attached polypeptide from the A site to the P site
Elongation continues codon by codon to add amino acids until the polypeptide chain is completed
3)Termination occurs when one of the three stop codons reaches the A site
SUMMARY OF TRANSLATION
MUTATIONS Errors can occur during DNA
replication, DNA repair, or DNA recombination
These can lead to base-pair substitutions , insertions , or deletions
Can lead to frame shifts, which move the reading frame over slightly and change the primary structure of the polypeptide
MUTAGENS Are chemical or physical agents
that interact with DNA to cause mutations
Physical agents include high-energy radiation like X-rays and ultraviolet light
Chemical agents include carcinogens cause cancer