1 / 19

DNA/RNA & Molecular Basis of Evolution

DNA/RNA & Molecular Basis of Evolution. ASTR 1420 Lecture 4 Sections 5.2, 5.4. Organic Building Blocks. Cells. Typical Eukaryotic Cell. All living organisms are made of cells Adult human body have 10-50 trillion cells!. Components of Cell.

adora
Download Presentation

DNA/RNA & Molecular Basis of Evolution

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. DNA/RNA&Molecular Basis of Evolution ASTR 1420 Lecture 4 Sections 5.2, 5.4

  2. Organic Building Blocks

  3. Cells Typical Eukaryotic Cell • All living organisms are made of cells • Adult human body have 10-50 trillion cells!

  4. Components of Cell • Carbohydrates (= carbs) : providing energy to cells and make cellular structures  sugars, starches, cellulose, etc. • Lipids (aka fats) : store energy, make cell membranes • Proteins : versatile, essential molecules of cells • Nucleic acids : handling heritable information of cells – DNA and RNA

  5. DNA  Proteins • All Earth life have DNA, and DNA is the backbone of heredity. • Heredity  DNA replication • function of DNA (genes)  protein synthesis • What’s protein? • organic compound made of amino acids in a folded chain • essential part of organisms and participate in every process within cells • enzymes involved in matabolism • make cell stucture • cell signaling, immune responses, etc.

  6. http://www.youtube.com/watch?v=qy8dk5iS1f0 DNA structure

  7. http://www.youtube.com/watch?v=hfZ8o9D1tus DNA replication

  8. http://www.youtube.com/watch?v=XO-2Z933AzM Protein synthesis

  9. RNA world? • In the beginning of Earth life, the very first life could not be based on DNA. DNA is way too complicated to be created by mere “lucky” chemical reaction. • early life must have used a simpler molecule (e.g., RNA) • or, DNA was introduced externally?!? Although we do not expect DNA or RNA to appear in life on other worlds, molecules with similar function are well expected!

  10. Amino Acids • Most important monomer! • Basic building blocks of proteins, nucleotides, and sugars • Typically, few hundred amino acids form a protein polymer. There are about 70 different amino acids in the nature, but only ~20 are used in living organisms. A strand of amino acids, part of a protein

  11. Monomer/Polymer • Glycogen: the carbohydrate that animals use to store energy is a polymer made of glucose molecule contains 22 atoms Most life forms consist of small number of simple molecule types called monomers, which can join together in a repetitive sequence to become larger and more complex molecules called polymers. glucose

  12. Chirality of Amino Acids • Chirality (handedness) For a given amino acid, there are two geometricalshapes: left-handed & right-handed • In non-biological environ: two types are equally found • In living organisms: only left-handed amino acids are found! • All Earth life forms were originated from an ancestral life using only left-handed amino acids!

  13. Genes • a distinct portion of DNA strand representing any single function (e.g., instruction for one protein)

  14. Small difference in genes • Different human races • Any possible distinct genetic differences are now disappeared by inter-racial breed. • Genetic difference b/w races < b/w two individuals from one race! • Astrobiological Implication? • Small genetic difference  huge difference (e.g., Chimpanzee vs. Human) ; Chimpanzee and human share 98% of the same genes • Is advanced intelligence an inevitable evolutionary outcome?

  15. Genetic code : a set of rules for reading DNA Codes for most amino acids really depend on just two letters  in the past, genetic codes were two letter based… • Genetic “words” consist of three DNA bases in a row. For the purpose of protein building, each word represents either a particular amino acid or “start reading” or “stop reading”. • Genetic code is same for nearly ALL living organisms on Earth! common ancestor of all life on Earth!

  16. Mutation • Replicating the whole ~3 billion bases for human DNA takes only a few hours • About 1 replication error in billion chances • wrong base • deleted base • extra base • etc. • Most of these errors have no effect Why? about 95% of human DNA bases are “non-coding DNA” Most significant change is from “deleted base”. • Due to this “error”, every individual living organism differ each other. • Mutation = molecular engine of the evolutionary adaption! • Any change in the base sequence of DNA

  17. Sickle-cell disease • Just one base change in one gene (Adenine  Thymine) • Most mutations are harmful, but occasional good mutations are being picked up by “natural selection”

  18. Another evidence of the common ancestor • ATP (Adenosine TriPhosphate). • Cells recyleATP. • The ATP molecule gives up energy when it splits into ADP and a phosphate group. • ATP/ADP are like battery • ATP : fully charged • ADP : fully discharged • There are many other possibilities of different molecular pairs (i.e., different batteries), but all Earth life use ATP as the energy reservoir. common ancestor of all Earth life.

  19. In summary… Important Concepts Important Terms amino acids / proteins chirality genes, genetic code mutation • Common ancestor of all Earth Life (chirality of amino acid, common genetic code, and use of ATP among all living organisms on Earth) • Some non-DNA based life forms in the beginning? • DNA replication • Chapter/sections covered in this lecture : 5.2 & 5.4

More Related