The Tree of Life - PowerPoint PPT Presentation

Loading...

PPT – The Tree of Life PowerPoint presentation | free to download - id: 6e7154-Njk0Y



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

The Tree of Life

Description:

Chapter 26 – PowerPoint PPT presentation

Number of Views:3
Avg rating:3.0/5.0
Date added: 5 December 2019
Slides: 35
Provided by: ISD145
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: The Tree of Life


1
Chapter 26
  • The Tree of Life An Introduction to Biological
    Diversity

2
Overview
  • Geologic events that alter environments change
    the course of biological evolution
  • Example Large lake splitting into several small
    lakes
  • Living things change the planet they inhabit
  • Example Evolution of photosynthetic organisms
    putting oxygen into the atmosphere

3
Photosynthetic Cyanobacteria
4
(No Transcript)
5
26.1
  • Cells produced in 4 stages
  • 1. Abiotic synthesis of AA nucleotides
    (organic compounds)
  • 2. Joining of monomers into polymers
  • 3. Packaging into protobionts droplets with
    membranes that maintained an internal chemistry
    different from the environment.
  • 4. Origin of replication that made inheritance
    possible
  • Evidence for each of these 4 stages discussed

6
1. Synthesis of organic compounds
  • Earth formed about 4.6 billion years ago
  • Conditions on early Earth were very different
    from today
  • Primitive soup experiment of Miller and Urey
  • Strongly reducing atmosphere
  • Hydrogen
  • Methane
  • Ammonia
  • Water vapor
  • Sparks to mimic lightning

7
Conception of Earth 3 billion years ago
8
  • Extraterrestrial Sources of Organic Compounds
  • Amino acids that reached early Earth aboard
    chondrites could have added to the primitive soup
  • Looking to other planets for signs of life
  • Present day Mars no life
  • Billions of years ago it was warm, liquid water,
    and carbon dioxide in the atmosphere

9
2. Abiotic synthesis of polymers
  • Researchers have produced amino acids polymers by
    dripping solutions of amino acid monomers onto
    hot sand, clay, or rock
  • Formed spontaneously

10
3. Protobionts
  • Replication and metabolism are essential for life
  • Protobionts aggregates of abiotically produced
    molecules surrounded by a membrane or
    membrane-like structure.
  • Exhibit some properties of life and could have
    formed from abiotically produced organic compounds

11
4. Origin of replication
  • The first genetic material was probably RNA
  • Had the ability to copy itself and began to
    appear in protobionts
  • RNA could have been the template on which DNA was
    assembled
  • DNA is much more stable and can be replicated
    more accurately so as genomes grew DNA grew
  • RNA world gave way to a DNA world and RNA took
    over its role that we see it in today

12
26.2 The fossil record
  • Fossils are found in sedimentary rocks
  • Index fossils the strata at one location can
    often be correlated with strata at another
    location by the presence of similar fossils known
    as index fossils

13
Radiometric dating
  • Radiometric dating decay of radioactive isotopes
  • Half-life the number or years it takes for 50
    of the original sample to decay

14
  • Carbon-14 has a half life of 5,730 years so it is
    useful for dating fossils up to about 75,000
    years old
  • Potassium-40 used to date much older fossils (530
    million years old)
  • Magnetism of rocks can also provide dating
    information

15
Geologic record
  • 3 Eons
  • Archaean Proterozoic lasted approx. 4 billion
    years
  • These are known as Precambrian
  • Phanerozoic eon the last half billion years is
    most of the time multicellular eukaryotic life
    has existed
  • Divided into 3 eras
  • Paleozoic
  • Mesozoic
  • Cenozoic
  • Boundaries between eras correspond to times of
    mass extinctions seen clearly in the fossil record

16
(No Transcript)
17
Mass Extinctions
  • 2 mass extinctions have received the most
    attention
  • Permian Cretaceous
  • Permian at the boundary between Paleozoic and
    Mesozoic eras claimed about 96 of marine animal
    speices
  • Cretaceous at the boundary between Mesozoic and
    Cenozoic eras doomed more than half of all marine
    species and many families of terrestrial plants
    and animals including the dinosaurs.

18
  • Permian mass extinction caused by volcanic
    eruptions that increased the carbon dioxide and
    warmed the global climate
  • Cretaceous mass extinction caused by an asteroid
    or comet hitting the earth that spewed up dust
    and blocked sunlight for several months.

19
Impact Crater
20
26.3
  • Oldest known fossils
  • Date to 3.5 billion years ago
  • Stromatolites
  • Composed of layers of bacteria and sediment
  • Found today in a few warm, shallow, salty bays

21
Prokaryotes
  • Prokaryotes were Earths sole inhabitants
  • 3.5 to about 2 billion years ago

22
The oxygen revolution
  • Earliest types of photosynthesis did not produce
    oxygen
  • Oxygenic photosynthesis evolved 3.5 billion years
    ago in cyanobacteria
  • When oxygen started to accumulate in atmosphere
  • It posed a challenge for life
  • It provided an opportunity to gain abundant
    energy from light
  • It provided organisms an opportunity to exploit
    new ecosystems

23
26.4 Eukaryotes
  • Oldest fossil eukaryotes date back 2.1 billion
    years
  • Arose from Endosymbiosis and genetic exchanges
    between prokaryotes
  • Endosymbiotic theory states that chloroplasts
    mitochondria were formerly prokaryotic organisms
    living within larger cells.

24
Endosymbiosis
  • Mitochondria and plastids were formerly small
    prokaryotes living within larger host cells
  • Gained entry to the host cell as undigested prey
    or internal parasites
  • The host and endosymbionts would have become a
    single organism
  • Evidence to support theory
  • Similarities in inner membrane structures and
    functions
  • Both have their own circular DNA

25
26.5 - Multicellularity
  • Evolved several times in eukaryotes
  • Oldest fossils of eukaryotes, small algae that
    lived 1.2 billion years ago
  • 1st multicellular organisms were colonies

26
Cambrian Explosion
  • Most of the major phyla of animals appear here

27
Colonization of land by plants, fungi, and animals
  • Occurred about 500 million years ago
  • Adaptations that helped prevent dehydration made
    it possible to move out of water onto land
  • Symbiotic relationships between plants and fungi
    began at this time and exist today

28
Continental Drift
  • Continents are not fixed but drift across our
    planets surface on plates of crust that float on
    a hot underlying mantle
  • Interactions at plate boundaries
  • Convergent boundaries (moving together)
  • Divergent boundaries (moving apart)
  • Transform boundaries (sliding past one another)
  • Volcanoes, Earthquakes, mountain building, and
    subduction occur at plate boundaries

29
(No Transcript)
30
(No Transcript)
31
  • The formation and breakup of the supercontinent
    Pangaea explain many biogeographical puzzles
  • Land bridges
  • Fossils found on 2 continents that cant swim
  • Rock formations
  • Apparent puzzle piece fit of the continents

32
(No Transcript)
33
26.6 Taxonomic systems
  • Old system was 2 Kingdoms (Plant Animal)
  • 5 kingdom system
  • Monera, Protists, Plantae, Fungi, Animalia
  • 3 Domain system has replaced the 5 kingdom system
  • Archaea, Bacteria, Eukarya

34
(No Transcript)
About PowerShow.com