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Chapter 10 How proteins are made.

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1 Chapter 10 How proteins are made

2 10-1 From Genes to protein Objectives
Compare the structure of DNA and RNA Summarize the process of transcription Outline the major steps of translation SCS:B-4.4

3 Proteins are made by decoding the information in DNA
Traits are determined by proteins that are built according to the instructions found on DNA Proteins are not built directly from DNA but from RNA (ribonucleic acid) Copy of the DNA that is decoded

4 RNA – the facts Single stranded string of nucleotides Different bases
Has uracil instead of thymine Different sugar – ribose


6 Gene expression – protein synthesis
A gene’s instructions for making a protein are coded in the sequence of nucleotides in the gene Instructions are transferred from DNA to RNA in a process called transcription The instructions are then decoded to make a protein in a process called translation

7 Transcription Takes place in the nucleus of eukaryotic organisms and in the cytoplasm of prokaryotic organisms

8 Steps of transcription
RNA polymerase binds to the DNA molecule at the specific sequence that needs to be translated RNA polymerase unwinds and separates strands RNA polymerase adds nucleotides and links complimentary base until it reaches a “stop” signal. RNA detaches then it leaves the nucleus to be translated.


10 Genetic code is written in 3 nucleotide “words”
3 types of RNA are made during transcription Messenger RNA (mRNA) – copy of the DNA Transfer RNA (tRNA) – carries nucleotides to the ribosome Ribosomal RNA (rRNA) – part of the ribosome


12 Each codon codes for an amino acid or a start or stop signal
RNA instructions are written as a series of 3 nucleotide sequences of mRNA called codons Each codon codes for an amino acid or a start or stop signal the sequence can be decoded using the a genetic code Specifies the amino acid, so it tells you what protein is being made Nearly universal

13 Genetic Code

14 Translation Takes place in the cytoplasm
mRNA, tRNA, and rRNA are involved Ribosomes are the site of protein synthesis Translation can take place at multiple places on the mRNA

15 Steps of translation mRNA leaves the nucleus; ribosome attaches at the start codon (AUG) tRNA brings the complimentary anticodon with a amino acid attached A peptide bond forms after another tRNA brings a second amino acid The ribosome continues the above process until a stop message is reached in the mRNA. The newly made protein detaches and the ribosome break apart.


17 10-2 Gene regulation and Structure
Objectives Summarize how protein synthesis is regulated Describe the types of mutations that can occur during translation SCS:B-4.4

18 Protein synthesis is controlled by “on” and “off” switches
This switch is called an operator Controls the access of RNA polymerase to the sequence of DNA A protein (repressor) binds to the DNA to keep RNA polymerase from binding to the promoter site (the group of genes that codes for a specific protein)

19 Regulation is more complex in eukaryotic organisms
Regulated in many ways

20 Most of your DNA does not code for anything useful
Introns – non coding region Are “cut” out during translation Exons – regions that actually code for proteins

21 Mutations result in nonfunctional proteins
Types of point mutations (occur in only a few nucleotides) Substitution Insertion Deletion

22 Mutations can result in no protein being made, a nonfunctional protein, or have no affect at all
Many genetic disorders are a result of a single nucleotide mutation

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