1 / 22

GENE EXPRESSION

GENE EXPRESSION. TRANSCRIPTION, TRANSLATION AND MUTATIONS. HOW DOES DNA, AS A GENE, GET EXPRESSED?. DNA codes for specific proteins to be made proteins are assembled from amino acids amino acids are selected based on the genetic code.

courtney-mclean
Download Presentation

GENE EXPRESSION

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. GENE EXPRESSION TRANSCRIPTION, TRANSLATION AND MUTATIONS

  2. HOW DOES DNA, AS A GENE, GET EXPRESSED? • DNA codes for specific proteins to be made • proteins are assembled from amino acids • amino acids are selected based on the genetic code

  3. Amino Acids will be bonded together to form long chains. These long chains are proteins. • There are 20 different amino acids • The DNA code dictates the sequence of acids

  4. DNA to Proteins • The process of making the proteins from DNA instructions is called PROTEIN SYNTHESIS • Protein Synthesis has 2 major steps: • Transcription • Translation

  5. TRANSCRIPTION Trans= Across Script= writing Writing across= RNA is being made (or written) using DNA Starts in the nucleus with the chromosome which contains the gene that will be expressed.

  6. As with replication-- • DNA unzips, but this time only in the gene location • mRNA forms instead of another piece of DNA • Uracil is substituted for Thymine • only one strand is transcribed- called the “sense” strand- other strand is called the “nonsense” strand

  7. WHAT IS A GENE? A gene is a section of a chromosome which codes for a specific trait

  8. After the DNA code is copied into the mRNA language, Transcription ends with the mRNA leaving the nucleus. (DNA is too big)

  9. RNA • needed to assist in the synthesis of proteins • 3 types • Messenger RNA (mRNA) • Transfer RNA (tRNA) • Ribosomal RNA (rRNA)

  10. RNA STRUCTURE & Differences from DNA • 1.) Uracil instead of Thymine • 2.) Single stranded • 3.) Sugar is a Ribose Sugar

  11. The strand of mRNA that forms is set up in 3-base code words. Formed from nitrogen bases These are called CODONS

  12. Transcribe This DNA • DNA • ACTCAGACTATGACCTAGGATCAT • TGAGTCTGATACTGGATCCTAGTA • Consider bottom row as sense strand • What will the 8 codons be in mRNA?

  13. TRANSLATION • Translating RNA into proteins • Where are proteins made?? • RIBOSOMES • Begins when mRNA travels to and enters the ribosomes • Transfer RNA (tRNA) is out in the cytoplasm searching for amino acids • Ribosomal RNA (rRNA) is in the ribosomes, helping place the mRNA in position

  14. Each codon (mRNA) indicates which amino acid the tRNA is suppose to bring to the ribosomes. Scientists use a chart like this to translate the protein. Example: codon = ACA AA = threonine Fig. 14.11, p. 230

  15. anticodon codon in mRNA anticodon amino acid attachment site amino acid OH tRNA MOLECULE amino acid attachment site Fig. 14.12, p. 231

  16. C G anticodon 1 A U G anticodon 2 C C U anticodon 3 C G A anticodon 4 A G C anticodon 5 C U C anticodon 6 G A U anticodon 7 C Once mRNA is at the ribosome, tRNA matches amino acids to the codons using ANTICODONS **Each tRNA carries a different amino acid

  17. Amino acid chain tRNA ribosome anticodon codons mRNA

  18. Binding site for mRNA P (first binding site for tRNA) A (second binding site for tRNA) Fig. 14.14a, p. 232

  19. Fig. 14.14b, p. 233

  20. Because there are only 20 amino acids, they are often called by their first three letters mRNA codons AUG CCG GAU UAG amino acids Met Pro Asp stop *not all codons will code for an AA, some will be stop codons to tell translation to stop start codon

More Related