DNA, RNA, and Protein Synthesis

Transcription

1 DNA, RNA, and Protein Synthesis

2 DNA base pairs carry the genetic Section 12-1 code for the sequence of the amino acids Nucleotide Structure of DNA Hydrogen bonds Sugar-phosphate backbone Key Adenine (A) Thymine (T) Cytosine (C) Guanine (G)

3 Nucleotides in the DNA strand carry the code for proteins Image by: Riedell

4 Nitrogen bases = Steps of ladder Phosphate group A G Purines (2 rings) Deoxyribose sugar C T Pyrimidines (1 ring) Pearson Education Inc, publishing as Pearson Prentice Hall. All rights reserved

5 Nitrogen bases = Steps of ladder Phosphate group A G ADENINE GUANINE Deoxyribose sugar C T CYTOSINE THYMINE Pearson Education Inc, publishing as Pearson Prentice Hall. All rights reserved

6 CHARGAFF S RULES A = T G = C At time no one knew why now we know its because Adenine always bonds across with THYMINE Guanine always bonds across with CYTOSINE Image from:

7 DNA is safely stored in the nucleus. mrna (messenger RNA) brings a copy of the code out to the cytoplasm. RNA and PROTEIN SYNTHESIS Pearson Education Inc, publishing as Pearson Prentice Hall. All rights reserved

8 Transcription - Making a copy of the DNA code Adenine (DNA and RNA) Cystosine (DNA and RNA) Guanine(DNA and RNA) Thymine (DNA only) Uracil (RNA only) RNA polymerase RNA DNA Enzyme called RNA polymerase separates strands of DNA, then uses one strand as a template to assemble an mrna copy. mrna will carry the script out of the nucleus to the cytoplasm

9 RNA- the Other Nucleic Acid Also made of nucleotides Sugar is ribose instead of deoxyribose. RNA is single stranded, instead of doubled stranded. Contains uracil instead of thymine.

10 MASTER PLAN DNA stays safe in nucleus Pearson Education Inc, publishing as Pearson Prentice Hall. All rights reserved TRANSCRIPTION (DNA RNA) & PROCESSING (remove interons) takes place in nucleus TRANSLATION (RNA proteins) takes place on ribosomes in cytoplasm Blueprints of master plan are carried to building site

11 Translation - Translating the base pair codes into an amino acid sequence mrna the copy of the code sequence of base pairs trna carries the amino acid to the ribosome as coded for in the mrna codons code for specific amino acids.

12 ANTICODON on trna EACH trna carries only one kind of amino acid matches up with CODON on mrna Images modified from Pearson Education Inc, publishing as Pearson Prentice Hall. All rights reserved

13 HOW CAN JUST 4 BASES GIVE DIRECTIONS TO MAKE 20 AMINO ACIDS? Message is read in groups of 3 = CODON UCGCACGGU UCG-CAC-GGU Serine - Histidine - Glycine Codons represent different amino acids

14 The mrna Code 64 possible codons Some amino acids have more than one codon. AUG START= 3 codons for STOP

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16 Translating the base pair codes into an amino acid sequence Translation

17 Translation (continued)

18 Summary of protein synthesis DNA strand in nucleus Occurs in the nucleus RNA message copied from DNA mrna moves out to cytoplasm Occurs in the cytoplasm at the ribosome

19 A graphic to show you translation to sequence the protein carries a specific amino acid depending upon its code codon ribosome

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21 What is Gel Electrophoresis? Gel electrophoresis is a widely used technique for separating electrically charged molecules. It is a central technique in molecular biology and genetics laboratories, because it lets researchers separate and purify the nucleic acids DNA and RNA and proteins, so they can be studied individually. Gel electrophoresis is often followed by staining or blotting procedures used to identify the separated molecules. Read more:

22 Gel Electrophoresis

23 Gel Electrophoresis

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25 Test March 22 and 23 Please Study!