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

Every Living thing… 1.Can be classified in one scheme 2.Is modular – composed of a few simple molecules 3.Is made of cells – lifes chemical factories 4.Uses the same genetic code 5.Evolved from a first cell by natural selection 6.Lives in ecosystems of many interdependent organisms

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

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

The Characteristics of Life High degree of order and complexity High degree of order and complexity Part of larger systems of matter and energy Part of larger systems of matter and energy Life depends on chemical reactions in cells Life depends on chemical reactions in cells Life requires liquid water Life requires liquid water Organisms grow and develop Organisms grow and develop Regulate energy use Regulate energy use Share same genetic code, code is heritable Share same genetic code, code is heritable All living things are descended from a common ancestor All living things are descended from a common ancestor

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

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

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

Why is Taxonomy Important? AB C

Classifying Life Kingdoms Kingdoms Monera Monera Protista Protista Fungi Fungi Plants Plants Animals Animals

Taxonomy of Animals

Classifying Human Beings Kingdom: Animals Kingdom: Animals Phylum: Chordates Phylum: Chordates Subphylum: vertebrates Subphylum: vertebrates Class: Mammals Class: Mammals Order: Primates Order: Primates Family: Hominid Family: Hominid Genus: Homo Genus: Homo Species: sapiens Species: sapiens

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

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

Strategies of Fungi Growth Growth Filaments Filaments Decomposers Decomposers Structure Structure Mass of filaments Mass of filaments Many forms Many forms Reproduction Reproduction Break filaments Break filaments Spores (usually asexual) Spores (usually asexual) Lichens Lichens Fungi + Algae Fungi + Algae Two interdependent species Two interdependent species

The Simplest Plants Phylum: Bryophytes Phylum: Bryophytes Structure Structure No roots No roots Photosynthetic Photosynthetic Reproduction Reproduction Sexual Sexual Asexual Asexual

Vascular Plants Phylum: vascular plants Phylum: vascular plants Structure Structure Roots, stems, leaves Roots, stems, leaves Control water loss Control water loss Reproduction Reproduction Spore = fertilized egg Spore = fertilized egg Cone = holds egg or sperm Cone = holds egg or sperm Seed = egg plus nutrients Seed = egg plus nutrients Pollen = sperm Pollen = sperm Strategies Strategies Seedless (Ferns - spores) Seedless (Ferns - spores) Seeds but no flowers (Gymnosperms - cones) Seeds but no flowers (Gymnosperms - cones) Seeds and flowers (Angiosperms) Seeds and flowers (Angiosperms)

Angiosperms

Invertebrates No backbone No backbone Most diverse animals Most diverse animals Arthropods Arthropods 70% of known animal species 70% of known animal species Structure Structure Exoskeleton Exoskeleton Jointed legs Jointed legs

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

Key Ideas about the molecules of life Based on Carbon (Organic chemistry) Based on Carbon (Organic chemistry) Six main elements (CHNOPS) Six main elements (CHNOPS) Modular; built from simple units Modular; built from simple units Molecular shapes determine their function Molecular shapes determine their function

Nutrition Facts Lipids Lipids Sugars Sugars Amino acids Amino acids Energy Energy

Carbohydrates (sugars) Carbon Hydrogen Oxygen

Cellulose and Starch

Lipids

Saturated and Unsaturated Lipids

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

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

Proteins Structural role Structural role

Proteins – Enzymes

Dietary Amino Acids