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DNA and other Nucleic Acids

DNA and other Nucleic Acids. DNA. Deoxyribonucleic acid Complex molecule found in the nucleus of cells and in small quantities in mitochondria and chloroplasts. DNA structure.

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DNA and other Nucleic Acids

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  1. DNA and other Nucleic Acids

  2. DNA • Deoxyribonucleic acid • Complex molecule found in the nucleus of cells and in small quantities in mitochondria and chloroplasts

  3. DNA structure • DNA is made of nucleotides that bond together in long chains and across to matching chains that will twist into a double helix (twisted ladder)

  4. DNA structure • DNA nucleotides are made of a phosphate, a deoxyribose (sugar), and a base

  5. DNA Nucleotide bases • DNA nucleotides contain 1 of 4 possible bases • Bases are adenine thymine guanine cytosine

  6. DNA Nucleotide bases • Adenine and guanine are larger molecules • Thymine and cytosine are smaller molecules

  7. DNA Nucleotide bases • Adenine and thymine always bond together • Cytosine and guanine always bond together

  8. DNA Nucleotide bases • Base pairs • A – T or T – A • G - C or C – G • Base pairs are connected with hydrogen bonds

  9. DNA Structure - connections • Base pairs form the rungs of the DNA ladder • Phosphate and deoxyribose form the sides of the ladder • Deoxyribose connects to 1 or 2 phosphates and a base

  10. Replicating DNA • During the S stage of interphase, before mitosis or meiosis, the DNA in the cell nucleus replicates itself • DNA unzips by breaking hydrogen bonds that connect the base pairs

  11. Replicating DNA • Nucleotides are brought and connect to form new base pairs • Phosphates and deoxyriboses connect to each other to make new side to DNA ladder • Two identical DNA molecules are formed

  12. DNA Function • Makes up the chromosomes of cells • Chromosomes are made of DNA molecules wrapped around proteins called histones

  13. DNA controls everything about an organism through coded instructions • DNA provides the instructions for life

  14. DNA must be interpreted and changed into molecules with biological activity – proteins (particularly enzymes) • Enzymes are proteins that control all chemical reactions that happen in cells

  15. Decoding DNA • DNA interpretation involves the following steps: • DNA is copied into mRNA (messenger RNA) in a process called transcription (in the nucleus)

  16. Decoding DNA, cont. • mRNA is copied into amino acids in a process called translation (at the ribosomes) with the help of rRNA (ribosomal RNA) and tRNA (transfer RNA)

  17. Decoding DNA, cont. • Amino acids are bonded together to make proteins (at the ribosomes and in the cytoplasm)

  18. RNA structure • Ribonucleic acid, similar in structure to DNA but only one strand • RNA is made of nucleotides that bond together in long chains

  19. RNA structure • RNA nucleotides are made of a phosphate, a ribose (sugar), and a base

  20. RNA Nucleotide bases • RNA nucleotides contain 1 of 4 possible bases • Bases are adenine uracil guanine cytosine

  21. RNA Nucleotide bases • Adenine and guanine are larger molecules • Uracil and cytosine are smaller molecules

  22. RNA Nucleotide bases • Adenine and uracil always bond together • Cytosine and guanine always bond together

  23. Phosphate and ribose form the side of the RNA chain • Ribose connects to 1 or 2 phosphates and a base

  24. Types of RNA • Three types of RNA • mRNA – messenger RNA made in nucleus and moves to cytoplasm • rRNA – ribosomal RNA, found at the ribosomes • tRNA – transfer RNA found in the cytoplasm

  25. Transcription (DNA to mRNA) • DNA unzips and mRNA nucleotides connect to one of the unzipped sides, DNA is copied into mRNA • mRNA goes to ribosomes

  26. Transcription (DNA to mRNA) • Every three DNA bases translate into a code for a particular amino acid or other protein building signal

  27. Translation (mRNA to amino acids) • mRNA attaches to a ribosome • tRNA brings amino acids and carries them to mRNA

  28. Translation (mRNA to amino acids) • tRNA attaches to mRNA at the ribosome, the amino acids they carry attach to the next amino acid to link together and form proteins • Process repeats until the entire protein molecule is made

  29. Genes • DNA controls color of eyes, hair, etc • Controls all our characteristics: traits • Genes are sections of DNA that code for the proteins that build cells and tissues and work as enzymes

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