Day_15
Upcoming SlideShare
Loading in...5
×
 

Day_15

on

  • 509 views

 

Statistics

Views

Total Views
509
Views on SlideShare
509
Embed Views
0

Actions

Likes
0
Downloads
5
Comments
0

0 Embeds 0

No embeds

Accessibility

Categories

Upload Details

Uploaded via as Microsoft PowerPoint

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

Day_15 Day_15 Presentation Transcript

  • ASTR-3040:Astrobiology Day 15 The Nature of Life on Earth Chapter 5
  • Molecular Components
    • Carbohydrates – energy sources
      • Sugars and starches
    • Lipids – energy stores, barriers
      • Fats
    • Nucleic Acids – DNA and RNA
  • Molecular Components
    • Proteins – structure & chemistry
      • Structural materials
      • Enzymes – catalysts for reactions
      • Amino Acids (20 used in most life forms)‏
      • Left-handed in biological entities.
  • Major Groupings
    • Leeuwenhoek – 1674 – microscope
    • 5 Kingdoms
      • Plants
      • Animals
      • Protista
      • Monera
      • Fungi
    • Is there a biochemical classification?
  • Microscopic Life
    • Plants and Animals are different
    • Cell walls (plants)‏
    • Cell Nucleus
      • Prokaryotes
      • Eukaryotes
    • All prokaryotes are
    • single celled. They
    • lack a cell nucleus.
    • Eukaryotes – single or multi-celled.
  • Domains of Life
    • Based on biochemistry and genetics:
    • Bacteria
    • Archaea
    • Eukarya
    • Tree of life.
    Kingdom – Phylum – Class – Order – Family – Genus – Species
  • The Tree of Life
    • Extremely valuable organizational tool.
    • 3 key ideas
      • 1. Domains based on biochemistry & genetics is fundamentally different from the older KPCOFGS based on structural & physiological differences.
      • 2. New and fundamentally different view of microbes - lipid structure of cell membranes.
      • 3. True diversity almost entirely in microbes.
  • Metabolism: Chemistry of Life
    • Metabolic needs:
      • 1. Source of raw materials.
      • 2. Source of energy.
    • ATP: adenosine triphosphate
      • Used by every living cell for internal energy.
      • Outside energy needed only to produce ATP.
    • Carbon sources – form basic materials.
    • Energy sources – run the metabolism.
  •  
  • Classification by Metabolism
    • To obtain carbon:
    • 1. Heterotrophs: Consume preexisting organic compounds (i.e. eating).
    • 2. Autotrophs: Direct uptake from the environment (self-feeding, plants)‏
  • Classification by Metabolism
    • To obtain energy:
    • 1. Photosynthesis: sunlight
    • 2. chemosynthesis: chemical energy
      • Ingested food
      • Inorganic reactions
  • 4 Metabolic Classifications
    • Based on energy and carbon acquisition.
    • 1. Photoautotrophs
    • 2. Chemoautotrophs
    • 3. Photoheterotrophs
    • 4. Chemoheterotrophs
  • Liquid Water on Earth
    • All living cells on Earth depend on liquid water because metabolism requires:
    • 1. Organic chemicals are readily available for reactions.
    • 2. A means of transporting chemicals to and within cells; waste products away.
    • 3. Water plays a role in many of the reactions.
  • DNA and Heredity
    • 3 key features of life on Earth
      • 1. structural units – cells
      • 2. metabolic processes – energy production
      • 3. owner's manual – data storage for how a cell is constructed, how it works, and how to build another one, and pass it on to the next generation - heredity.
  • DNA Structure
    • Double helix
    • DNA bases – 4
      • Adenine
      • Guanine
      • Thymine
      • Cytosine
    • Pair as AT & CG
  • Replication
    • Unzip & each strand acts as a template.
    • Use RNA in the rebuild process.
  • Genome
    • Humans have ~3 X 10^9 bases
    • 46 chromosomes (23 pairs)‏
    • Sequences for individual instructions are called genes .
    • Most of DNA is “noncoding” (junk 95%)‏
    • Complete sequence – genome.
      • Some bacteria – 10^5 bases, few 10^2 genes
      • Humans – 20,000 – 25,000 genes
      • Rice – 37,000 genes (smaller DNA sequence)‏
  • Genetic Code
    • Words consist of 3 DNA bases.
    • Sequence has a start and stop word.
    • Used to build proteins.
    • Redundancy (64 codes, 20 amino acids)‏
    • Most amino acids are coded with the first 2 base letters only (16). Does this give a clue to evolution of complex organisms?
    • Nearly all living organisms have mostly similar genetic code.
  •  
  • RNA
    • Uses ACG & Uracil
    • mRNA – transcription (carries the instr.)‏
    • tRNA – transfer (gathers the AAs)‏
    • rRNA – backbone of building structure.
    • Mutations - <1:10^9, but can have dramatic consequences.
    • Provide the basis for evolution.
    • Genetic Engineering.
    • RNA was probable precursor.
  • Extreme Life - Extremophiles
    • Thermophiles – heat lovers
    • Hyperthermophiles
      • Black smokers (350 ˚ C)‏
      • Hot springs
  • Extreme Life - Extremophiles
    • Psychrophiles – cold lovers
      • Antarctica ice pack (-20 ˚ C)‏
      • Also very dry
    • Radiation hardened
  • Extreme Life - Extremophiles
    • Endoliths – within rocks
      • Up to several km below ground
    • Endospores (resting) – found on moon
      • Could these survive interplanetary journeys?