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Protein Synthesis

Protein Synthesis. DNA  RNA  Protein Transcription Translation. DNA. · Basis for heredity from parents to offspring. Located in nucleus of cell. · Regulates synthesis of proteins . Tells what particular polypeptide chain to make.

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Protein Synthesis

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  1. Protein Synthesis • DNA  RNA  Protein Transcription Translation

  2. DNA ·Basis for heredity from parents to offspring. Located in nucleus of cell. ·Regulates synthesis of proteins. Tells what particular polypeptide chain to make. *Proteins are important in structure of organelles, plasma membrane, enzymes and hormones.

  3. ·Contains DNA which is a long twisted (double helix) molecule composed of nucleotides. DNA never leaves the nucleus. Nucleotides have a sugar group, phosphate group (PO4-2), and 1 of 4 nitrogen groups. These are adenine, thymine (uracil in RNA), cytosine, or guanine. ·The sugar and phosphate group make up the uprights and the nitrogen bases make up the rungs. (see diagram) Nitrogen groups pair up. Adenine with thymine and cytosine with guanine. This is called a nitrogen-base pair. Genetic Code

  4. DNA

  5. ·When three base pairs are together, they form a triplet code which makes an amino acid. There are 20 amino acids altogether. (see diagram on board). ·When 10 or more amino acids are formed, these form a gene. A gene is a section of DNA that contains all the triplet base pairs to code for one complete polypeptide chain. ·The genetic code is the message the gene provides to make a polypeptide chain. ·When 50 amino acids are formed, these form a protein. Examples are alanine, valine, cysteine and glycine. Genetic Code

  6. Genetic Code

  7. Protein Synthesis • 2 processes of protein synthesis 1.Transcription 2.Translation

  8. ·Process by which RNA is formed. DNA regulates protein synthesis and ribosomes are where proteins are manufactured. ·DNA needs amino acids so we need breakdown of protein to get amino acids. So go to where proteins are manufactured which is the ribosome. During transcription, triplet code of DNA is transcribed (copied) onto an RNA molecule. 1. Transcription

  9. Transcription

  10. Transcription 1 of 3 types of RNA is formed • A.messenger RNA (mRNA) • B.transfer RNA (tRNA) • C.ribosomal RNA (rRNA)

  11. A. mRNA • Exits nucleus through pores. Passes into cytoplasm and associates with ribosomes.

  12. B. tRNA • ·Different structure then mRNA. It is a folded structure. • ·Exits nucleus and passes into cytoplasm • Transports free amino acids to ribosomes

  13. C. rRNA • ·Still a different structure. It is spherical. • ·Combines with proteins in nucleolus to form a ribosome. • ·Exits into cytoplasm and remains as free ribosome or anchors to endoplasmic reticulum. • Look at p. 68 fig. 3-17

  14. Transcription DNADNA Cytosine Guanine Thymine Adenine Adenine Thymine Each triplet is an amino acid. This is a double helix. The mRNA comes in and “unzips” the double helix.Then you get the following.

  15. Transcription DNA RNADNARNA Cytosine Guanine Guanine Cytosine Thymine Adenine Adenine Uracil Adenine Uracil Thymine Adenine The triplet formed by the mRNA is called a codon.

  16. 2. Translation • The interpretation of the codon message in mRNA to a specific sequence of amino acids.Entirely done in the cytoplasm on the ribosomes.

  17. A.mRNA attaches to ribosomes B.tRNA brings free amino acids. Only 2 tRNA at a time on mRNA. tRNA has triplet base called anticodon. C. Anticodon combines with complementary codon on mRNA D.Continues on down ribosome and peptide bonds are formed E.Sequence is stopped when stop codon is reached F.New protein is then formed Translation

  18. Look at p.69 fig. 3-18 Questions 136-156

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