BIOLOGICAL SCIENCES HIERARCHICAL ORGANIZATION

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BIOLOGICAL SCIENCESHIERARCHICAL ORGANIZATION

• ECOLOGICAL LANDSCAPE
• ORGANISM
• CELL
• MOLECULES

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ORIGIN EVOLUTION OF LIFE

• Origin of Earth 4 billion years ago.
• Life appeared on Earth 3.8 billion years ago.

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WHAT IS LIFE?LIFES FUNDAMENTAL ATTRIBUTES?

• Store and process information
• Reproduction/replication
• Store and process energy
• Compensatory response
• to environment

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1.3 What Is Life?
Characteristics of life DNA and Information

• Deoxyribonucleic acid is found
• in all organisms, from bacteria to
• whales.
• Instruction guide to construct and
• operate the phenotype
• Each segment of DNA contains
• a set of genes
• When an organism reproduces
• it passes along a copy of its DNA
• to its offspring

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Characteristics of life Growth/Reproduction
When an organism reproduces it passes along a
copy of its DNA to its offspring
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Characteristics of Life Acquire and Use Energy

• What is Metabolism?
• Reactions by which cells
• harness energy and use
• it to drive their activities
• Capacity to (1) obtain and convert energy from
• surroundings and (2) use energy to maintain
  itself,
• grown and make more cells

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Characteristics of Life Respond to Environment

• Light
• Sound
• Heat
• Chemicals
• Touch
• Motion
• Gravity

Daphnia Zooplankton
Vertical Migration Of crab larvae (zooplankton)
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Using his antennae, the male moth finds female
moths by following a trail of airborne chemicals,
called pheromones, upwind to the female producing
them. This is an example of how living things

• acquire nutrients
• respond to stimuli
• grow
• reproduce

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Atom

• Is the smallest unit of matter that still retains
  the properties of an element
• Greek word for indivisible

• Protons () and neutrons
• Are found in the atomic nucleus
• Electrons (-)
• Surround the nucleus in a cloud

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Atomic number the number of protons in the
nucleus is unique for each element
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The chemistry of life

• Although more than 25 types of elements can be
  found in biomolecules, six elements are most
  common.
• These are called the CHNOPS elements the letters
  stand for the chemical abbreviations of carbon,
  hydrogen, nitrogen, oxygen, phosphorus, and
  sulfur.

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How Do Atoms Form Molecules?

• The great variety of substances found in nature
  is constructed from a limited pool of atoms.
• Molecules two or more atoms of one or more
  elements held together by interactions among
  their outermost electron shells
• The results of losing, gaining, or sharing
  electrons are chemical bondsattractive forces
  that hold atoms together in molecules.

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Why Is Carbon So Important To Life?

• Carbon can combine with other atoms in many ways
  to form a huge number of different molecules.
• Molecules that have a carbon skeleton (and
  sometimes hydrogen) are know as organic molecules

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Why Is Carbon So Important To Life?

• A molecule may be depicted in different ways.
• Organic molecules have a carbon skeleton and some
  hydrogen atoms.
• Much of the diversity of organic molecules is due
  to the presence of functional groups.

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Macromolecules 4 Major Classes

• Carbohydrates
• Lipids
• Proteins
• Nucleic acids

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LIFE OCCURS IN WATER
Chemical Structure Attributes
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Why is water so important to life?

• One of the most abundant substances on earth and
  it plays a crucial role in sustaining life
• Life originated in water all living things
  require it
• 60 to 90 of an organism consists of water
• The importance of water stems from properties of
  the molecule

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Why Is Water So Important?

• Water interacts with many other molecules.
• Oxygen released by plants during photosynthesis
  comes from water.
• Water is used by animals to digest food.
• Water is produced in chemical reactions that
  produce proteins, fats, and sugars.

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Water interacts with other molecules

• The water molecule, with a filled outer electron
  shell, is more stable than either the hydrogen or
  oxygen atoms that gave riseto it.
• Properties of water which contribute to Earths
  fitness for life
• Cohesion- tend to stick together
• Solvent properties
• Expansion upon freezing

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Cohesive properties

• Water molecules tend to stick together
• Surface tension water tends to resist being
  broken
• Cohesion water molecules stick together

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Many molecules dissolve easily in water

• Many molecules dissolve easily in water.
• Water is an excellent solvent, capable of
  dissolving a wide range of substances because of
  its positive and negative poles.
• NaCl dropped into H2O
• The positive end of H2O is
• attracted to Cl.
• The negative end of H2O is
• attracted to Na.
• These attractions tend to
• push apart the components
• of the original salt.

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Construction and breakdown of organic molecules
involves water

• In living organisms, complex molecules are
  constructed from smaller ones through a
  dehydration synthesis (ex. carbohydrates are
  chains of simple sugars)
• So, Building molecules gives off water

Thats a bigger organic molecule
And thats water!
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Construction and breakdown of organic molecules
involves water

• Large food molecules must be broken down so
  organism can get energy
• So, breaking down molecules uses water
• Water consuming breakdown reactions are known as
  hydrolysis reactions