1. Great Ideas in Science Lecture 10 - Living Things
Prof. Robert Hazen
PROV-301

2. Every Living thing… Can be classified in one scheme
Is modular – composed of a few simple molecules
Is made of cells – life’s chemical factories
Uses the same genetic code
Evolved from a first cell by natural selection
Lives in ecosystems of many interdependent organisms

3. Ways of Thinking About Living Things
Biosphere
Ecosystem
Community
Population
Organism
Anatomy & physiology
Cellular
Molecular

4. What is Life?
Encapsulation: All life is separated from the environment by a membrane.
Metabolism: All life obtains energy and atoms from the environment.
Reproduction: All life reproduces via genetics.

5. The Characteristics of Life
Life has a high degree of order & complexity.
Life is part of larger systems of matter & energy.
Life depends on chemical reactions in cells.
Life requires liquid water.
Organisms grow and develop.
Organisms carefully control their use of energy.
All life shares the same genetic code, which can be passed from parent to offspring.

6. Great Idea: Living things use many different strategies to deal with the problems of acquiring and using matter and energy.
Linnaean classification
Hierarchy
Kingdom
Phylum
Class
Order
Family
Genus
Species

7. Why is Taxonomy Important?
Think about how to describe a tree.
Names are essential for accurate communications
But taxonomy can be rather
arbitrary
Lumpers versus splitters
Local variations in species

8. Why is Taxonomy Important?
Dracorex (top left) and Stygimoloch (top right),
as growth stages of Pachycephalosaurus (bottom).

9. Why is Taxonomy Important?C A B

10. Classifying Life
Kingdoms
Monera
Protista
Fungi
Plants
Animals

11. Taxonomy of Animals

12. Classifying Human Beings
Kingdom: Animals
Phylum: Chordates
Subphylum: vertebrates
Class: Mammals
Order: Primates
Family: Hominid
Genus: Homo
Species: sapiens
Homo sapiens is the only surviving member of the Hominid family

13. A New View: Three Domains of Life
Bacteria
Archaea
Eukarya

14. Implications of Linnaean Classification
You can use genetic material to classify.
Similarities depend on time and change.
Classification results from real events.
“Nothing in biology makes sense except in the light of evolution.”

15. Vascular Plants
Phylum of vascular plants: They have roots, stems, and leaves that control water movements.
Strategies
Seedless plants (Ferns: spores are fertilized eggs)
Seeds but no flowers (Gymnosperms: cones hold egg or sperm)
Seeds and flowers (Angiosperms: The seed is an egg plus nutrients, while pollen is sperm)

16. Invertebrates These diverse animals have no backbone.
Arthropods include 70% of known animal species.
Their structures include an exoskeleton and jointed legs

17. The Molecules of Life
All life is modular – composed of a few simple molecules.

18. Four key Ideas about the molecules of life
Life’s molecules are based on Carbon (the topic of organic chemistry).
Six main elements (CHNOPS) are dominant.
Biomolecules are modular; they are built by arranging lots of smaller molecules.
Molecular shapes determine their function.

19. Nutrition Facts
Energy
Lipids
Sugars
Amino acids

20. Carbohydrates (sugars)
Carbon
Hydrogen
Oxygen

21. Cellulose and Starch

22. Cellulose and Starch

23. Lipids

24. Saturated and Unsaturated Lipids

25. Amino Acids Amino group Carboxyl group
Side-group (20 different things)

26. Protein – sequence of amino acids
Primary – chain of amino acids
Secondary – folding of chain
Tertiary
Quaternary

27. Proteins
Some play a structural role, as in hair, fingernails, spider webs, tendons, muscle fibers, and in bones.

28. Proteins Act As Enzymes

29. Dietary Amino Acids