chapter 11 dna and genes section 2 from dna to protein
TRANSCRIPT
Chapter 11DNA and Genes
Section 2
From DNA to Protein
Genes and Proteins
• The sequence of nucleotides in DNA are a code for building proteins.
• Proteins are important because they– make up some structures in organisms.
– make up enzymes that all chemical reactions in organisms
RNA
• RNA is an nucleic acid that helps the cell build proteins.
• www.biologycorner.com/bio1/DNA.html
RNA Structure
• RNA is made up of a single strand of nucleotides.
• RNA nucleotides differ from DNA nucleotides in 2 ways–Ribose sugar instead of
deoxyribose sugar
–Uracil instead of thymine
Difference Between DNA and RNA
• DNA–Deoxyribose
sugar
–Thymine
• RNA–Ribose sugar
–Uracil
Three Types of RNA
• Messenger RNA (m-RNA)
• Ribosomal RNA (r-RNA)
• Transfer RNA (t-RNA)
Messenger RNA
• Copies DNA’s instructions for making proteins and brings those instructions from the nucleus to the cytoplasm.
• www.accessexcellence.org/AB/GG/rna.html
Ribosomal RNA
• Makes up the ribosome. The ribosome binds to mRNA and uses the instructions to hook together amino acids into long chains that will become proteins.
Transfer RNA
• Brings amino acids to the ribosomes.
• ghs.gresham.k12.or.us/.../chpt15/chpt15.htm
Transcription
• Transcription is what happens when m-RNA makes a copy of DNA
Steps of Transcription• DNA molecule unzips.• RNA nucleotides form base pairs
with DNA nucleotides. RNA nucleotides bond together to form an m-RNA molecule
• m-RNA leaves the nucleus and enters the cytoplasm.
Science at a Distance
© 1997, 1998, 1999, 2000 Professor John Blamire
The Genetic Code
• When m-RNA enters the cytoplasm, it has instructions for how to build proteins. These instructions are written in a nitrogenous base language and must be translated into a language that proteins understand.
Genetic Code
• On m-RNA, a sequence of 3 nucleotides is called a codon.
• Each codon codes for a specific amino acid.
• www.answers.com/topic/genetic-code
http://www.biology.arizona.edu
All contents copyright © 1996. All rights reserved.
Translation
• Translation is when the message in the nitrogenous base sequence of m-RNA is changed into an amino acid sequence in proteins.
Proteins
• Proteins are made up of 20 different amino acids. The sequence of the amino acids determines the function of the protein.
Role of t-RNA
• Each t- RNA can bond to a specific amino acid on one side of the t-RNA molecule.
• The other side of the t-RNA molecule has 3 nitrogenous bases called anticodons.
• Anticodons base pair with codons during translation
Steps of Translation
• The codon AUG is a start codon. This codon is the first step in the building of proteins.
• staff.jccc.net/.../translation/steps.html
Steps of Translation
• m-RNA attaches to ribosome
• t-RNA brings an amino acid to the ribosome.
• t-RNA anticodons form base pairs with m-RNA codons.
• © 2006 The Board of Regents of the University of Wisconsin System.
Steps of Translation
• t-RNA anticodons form base pairs with m-RNA codons.
• Amino acids form peptide bonds to one another and break away from t-RNA.
Translation• Amino acids will
continue to bond together until a stop codon is encountered. At this point, the amino acid chain will enter the cytoplasm for further processing.
• Brooklyn College
City University of New York
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