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DNA

Deoxyribonucleic acid. DNA. DNA carries genetic information. DNA determines an organism’s traits How does DNA achieve its control? By producing proteins(enzymes) Enzymes are important because the control the chemical reactions needed for life. Structure of DNA. Very long molecule

brielle-macdonald
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DNA

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  1. Deoxyribonucleic acid DNA

  2. DNA carries genetic information • DNA determines an organism’s traits • How does DNA achieve its control? • By producing proteins(enzymes) • Enzymes are important because the control the chemical reactions needed for life

  3. Structure of DNA • Very long molecule • Made of repeating subunits called nucleotides:

  4. Composition of Nucleotide • Simple sugar- deoxyribose • Phosphate group – PO4 • Nitrogen base- A carbon ring structure that contains one or more Nitrogen’s • guanine(G), Adenine(A) • Cytosine(C) Thymine(T) • 4 possible DNA nucleotides depending on nitrogen bases

  5. Nucleotides Cont • Nucleotides join together to form long chains • The phosphate group of one nucleotide bonding to the deoxyribose sugar of an adjacent nucleotide. This form the backbone of DNA • The nitrogen bases stick out

  6. DNA Nitrogen Bases • In DNA, the amount of adenine is always equal to the amount of thymine • The amount of guanine is always equal to the amount of cytosine

  7. Base Pair Rules • Adenine always pairs with thymine • Guanine always bonds with cytosine • A-G-T-C-C opposite strand would be • T-C-A-G-G

  8. James Watson and Francis Crick double helix is like a long zipper that is twisted

  9. How can organisms be so different from each other if their genetic material Is made of the same four nucleotides

  10. The differences result from the sequence of the 4 nucleotides

  11. DNA Replication • DNA is copied before cell division • Without replication, new cells would only have half of DNA from their parents • When a DNA molecule replicates, 2 molecules are formed • Each molecule has 1 original strand and one new strand

  12. Steps of DNA Replication 1) Two nucleotide strands separate at their base pairs. Hydrogen bonds between are broken 2) Free nucleotides base pair with exposed nucleotides 3) The sugar and phosphate parts of adjacent nucleotide strands bond together to form backbone of new strand 4) The process of replication produces 2 molecules of DNA. Each new molecule has been newly synthesized from free nucleotides in the cell

  13. DNA Transcription DNA encodes the instructions for making proteins thereby controlling the cells

  14. RNA • Ribonucleic acid • Different from DNA in 3 ways • 1. RNA is single stranded • 2. Ribose-sugar • 3. Uracil takes the place of thymine

  15. RNA’s JOB RNA take instructions from the DNA on how a protein should be assembled. They then assemble the protein, amino acid by amino acid until the protein is made.

  16. Three types of RNA • mRNA- messenger RNA -Brings information from the DNA in the nucleus to the cell’s cytoplasm • rRNA- ribosomal RNA- Ribosome's made of ribosomal RNA clamp onto the mRNA and use its information to assemble the amino acids in the correct order • tRNA- transfer RNA- transports amino acids to the ribosome to be assembled into a protein

  17. Transcription- takes place in Nucleus 1) The process of transcription begins as enzymes unzip the molecule of DNA, just as they do during DNA replication 2) As DNA unzips, free RNA nucleotides pair with complementary DNA nucleotides on one of the DNA strands 3)When the process of base pairing is completed, the mRNA molecule breaks away as the DNA rejoins. 4)The mRNA leaves the nucleus and enters cytoplasm

  18. The Genetic Code

  19. What is the genetic code? A code is needed to convert the language of mRNA into the language of proteins

  20. Amino Acids • Building blocks of proteins • 20 amino acids • For every 1 amino acid there are 3 nucleotides • Each set of 3 nucleotides makes a codon (triplet) • There are 64 codons in the genetic code

  21. Genetic Code Continued • Some codons do not code for amino acids, they provide instructions for assembling proteins • UAG is a start codon UAA is a stop codon • Genetic code is universal

  22. Translation: From mRNA to Protein The process of converting the information in a sequence of nitrogen bases in mRNA into a sequence of aminoacids that make up protein

  23. Translation • Takes place in ribosomes in the cytoplasm • mRNA- made in nucleus, ribosomes attach to them • tRNA- bring the amino acids to the ribosomes • Correct translation-depends on the joining of each mRNA codon with the correct tRNA molecule

  24. Codon and Anticodon • Group of three amino acids-CODON • Anti-codon- opposite code • A-C-A codon • anticodon is U-G-U

  25. Steps of Translation 1) the starting end of the mRNA strand attaches to the ribosome 2)tRNA which are carrying a specific amino acid , approach the ribosome 3) The tRNA anticodon pairs with the first mRNA codon and temporarily join

  26. Steps of Translation 4) The first code from mRNA is AUG, this signals the start of protein synthesis 5) The ribosome slides along the mRNA to the next codon 6) A new tRNA molecule carrying amino acid pairs with the 2nd mRNA codon 7) When the first and 2nd amino acids are in place, an enzyme joins them by forming a peptide bond between them

  27. Steps of the Translation 8) As the process continues, a chain of amino acids is formed until the ribosome reaches a stop codon on the mRNA strand

  28. tRNA--

  29. Types of Mutations Any change in the DNA sequence that also changes the protein it codes for

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