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A. The living world is a hierarchy, with each level of biological structure building on the level below it

A characteristic of life is a high degree of order. Biological organization is based on a hierarchy of structural levels, with each level building on the levels below it

  • Emergent Property = Property that emerges as a result of interactions between components

- With each step upward in the biological hierarchy, new properties emerge that were not present at the simpler organizational levels

- Life is difficult to define because it is associated with numerous emergent properties that reflect a hierarchy of structural organization

Some of the emergent properties and processes associated with life are the following:

1. Order - Organisms are highly ordered, and other characteristics of life emerge from this complex organization

2. Reproduction - Organisms reproduce; life comes only from life (Biogenesis)

3. Growth and Development - Heritable programs stored in DNA direct the species-specific pattern of growth and development

4. Energy Utilization - Organisms take in and transform energy to do work, including the maintenance of their ordered state

5. Response to Environment - Organisms respond to stimuli from their environment

6. Homeostasis - Organisms regulate their internal environment to maintain a steady state, even in the face of a fluctuating external environment

7. Evolutionary Adaptation - Life evolves in response to interactions between organisms and their environment

Because properties of life emerge from complex organization, it is impossible to fully explain a higher level of order by breaking it into its parts

Holism = The principle that a higher level of order cannot be meaningfully explained by examining components parts in isolation

  • An organism is a living whole greater that the sum of its parts
  • EX - A cell dismantled to its chemical ingredients is no longer a cell

It is also difficult to analyze a complex process without taking it apart

Reductionism = the principle that a complex system can be understood by studying its component parts

  • Has been a powerful strategy in biology
  • EX - Watson and Crick deduced the role of DA in inheritance by studying it molecular structure

C. Cells are an organism's basic units of structure and function

Cell - basic unit of structure and function

- Lowest level of structure capable of performing all activities of life

- All organisms composed of cells

- May exist singly as unicellular organisms or as subunits of multicellular organisms

The invention of the microscope led to the discovery of the cell and the formulation of the cell theory

- Robert Hooke (1665) - reported a description of his microscopic examination of cork. Hooke described tiny boxes which he called "cells"(really cell walls)

- Antonie van Leeuwenhok (1600's) used the microscope to observe living organisms such as microorganisms in pond water, blood cells, and animal sperm cells

- Matthias Schleiden and Theodor Schwann (1839) reasoned from their own microscopic studies and those of others, that all living things are made of cells. This formed the basis for the cell theory

The cell theory has since been modified to include the idea that all cells come from preexisting cells

Over the past 40 years, use of the electron microscope has revealed the complex ultrastructure of cells

- Cells are bounded by plasma membranes that regulate passage of materials between the cell and its surroundings

- All cells, at some stage, contain DNA

Based on structural organization, there are two major kins of cells: prokaryotic and eukaryotic

- Prokaryotic cell - cell lacking membrane-bound organelles and a membrane-enclosed nucleus

- Found only in archaebacteria and bacteria

- Generally much smaller than eukaryotic cells

- Contains DNA that is not separated from the rest of the cell, as there is no membrane-bound nucleus

-Almost all have tough external walls

Eukaryotic cell - cell with membrane-enclosed nucleus and membrane-enclosed organelles

- Found in protists, plants, fungi, and animals

- Subdivided by internal membranes into different functional compartments called organelles

- Contains DNA that is segregated from the rest of the cell. DNA is organized with proteins into chromosomes that are located within the nucleus, the largest organelle of most cells

- Cytoplasm surrounds the nucleus and contains various organelles of different functions

- Some cells have a tough cell wall outside the plasma membrane (plant cells). Animal cells lack cell walls

D. Continuation of Life is Based in the Form of DNA

Biological instructions for an organism's complex structure and function are encoded in DNA

- Each DNA molecule is made of four types of chemical building blocks called nucleotides

- The linear sequence of these four nucleotides encode the precise information in a gene, the inherit unit from parent to offspring

- An organism's complex structural organization is specified by an enormous amount of coded information

Inheritance is based on:

- A complex mechanism for copying DNA

- Passing the information encoded in DNA from parent to offspring

All forms of life use essentially the same genetic code

- A particular nucleotide sequence provides the same information to one organisms as it does to another

- Differences among organisms reflect differences in nucleotide sequence

E. Structure and function are correlated at all levels of biological organization

There is a relationship between an organism's structure and how it works. Form fits function.

- Biological structure gives clues about what it does and how it works

- Knowing a structure's function gives insights about its construction

*This correlation is apparent at many levels of biological organization

F. Organisms are open systems

Organisms interact with their environment, which includes other organisms as well as abiotic factors

- Both organism and environment are affected by the interaction between them

- Ecosystem dynamics include two major processes:

1. Nutrient cycling

2. Energy flow

G. Regulatory Mechanisms

Regulation of biological processes is critical for maintaining the ordered state of life

Many biological processes are self-regulating: that is, the product of a process regulates that process (=feedback regulation)

- Positive feedback speeds process up

- Negative feedback slows process down

Organisms and cells also use chemical mediators to help regulate processes

- The hormone insulin, signals cells in vertebrate organisms to take up glucose. As a result, blood glucose goes down

- In certain forms of diabetes, insulin is deficient and cells do not take up glucose as they should, as a result glucose levels remain high

II. Evolution, Unity, and Diversity

A. Diversity and Unity

Biological diversity is enormous

- Estimates of total diversity range from 5 million to over 30 million species

- About 1.5 million species have been identified and named, including approximately 260,000 plants, 50,000 vertebrates, and 750,000 insects

To make this diversity more comprehensible, biologist classify species into categories

Taxonomy = branch of biology concerned with the naming and classifying organisms

-Taxonomic groups are ranked into a hierarchy from the most to least inclusive category:

domain

kingdom

phylum

class

order

family

genus

species

The three domain are:

Archaea

Bacteria

Eukarya

- The kingdoms of life recognized in the traditional five-kingdom system are:

Monera

Protista

Plantae

Fungi

Animalia

There is unity in the diversity of forms at the lower levels or organization. Unity of life form is evident in:

- A universal genetic code

- Similar metabolic pathways

- Similarities of cell structure

B. Evolution is the core theme of Biology

Evolution is the one unifying biological theme:

- Life evolves. Species change over time and their history can be described as a branching tree of life

- Species that are very similar share a common ancestor at a recent branch point on the phylogenetic tree

- Less closely related organisms share a more ancient common ancestor

- All life is connected and can be traced back to primeval prokaryotes that existed more that three billion years ago

In 1859, Charles Darwin published On the Origin of Species in which he made two major points

1. Species change, and contemporary species arose from a succession of ancestors through a process of "descend with modification"

2. A mechanisms of evolutionary change is natural selection

Darwin synthesized the concept of natural selection based upon the following observations

- Individuals in a population of any species vary in many inheritable traits

- Populations have the potential to produce more offspring than will survive or the environment will support

- Individuals with the best suited traits will leave a large number of offspring which increases the proportion of inheritable variations in the next generation

Organism's adaptations to their environments are a product of natural selection

- Natural selection does not create adaptations; it merely increases the frequency of inherited traits by chance

- When exposed to environmental pressures, certain traits might favor reproductive success

Darwin proposed that cumulative changes in a population over long time spans could produce a new species from an ancestral one

- Similarities between two species may be a reflection of their descent from a common ancestor

- Differences may be the result of natural selection modifications

III. Science is a Process

A. Hypothesis must be Testable

Science is a way of knowing. It is a human endeavor that emerges from our curiosity about ourselves, the world, and the universe

Good scientists are people who:

  • Ask questions about nature and believe those questions are answerable
  • Are curious, observant, and passionate in their quest for discovery
  • Are creative, imaginative, and intuitive
  • Are generally skeptics

Scientific method = process which outlines a series of steps used to answer questions

- It is not rigid

- Based on the conviction that natural phenomena have natural causes

- Requires evidence to logically solve problems

The key ingredient of the scientific process is the hypothetico-deductive method, which is an approach to problem-solving that includes:

1. Asking a question and formulating a tentative hypothesis by inductive reasoning

2. Making hypothesis and then testing the validity of those predictions

Inductive reasoning = making an inference from a set of observations to reach a conclusion

Deductive reasoning = making an inference from general premises to specific consequences, which logically follow if the premises are true

- If... then logic

- Usually involves predicting experimental results that are expected if the hypothesis is true

Usefully hypothesis have the following characteristics:

- Are probable causes

- Reflect past experience

- Multiple hypotheses should be proposed whenever possible

- Must be testable via the hypothetico-deductive method

- Can be eliminated, but not confirmed with absolute certainty

Another feature of the scientific process is the controlled experiment

Control group = the group in which all variables are held constant

- Necessary for comparison with experimental group which has been exposed to a single changed variable

- Allows conclusions to be made about the effect of experimental manipulation

- Good controls = good experimental design

Variable = condition of an experiment that is subject to change and that may influence an experiments outcome

Experimental group = the group in which one factor is varied

Science is a never ending process that is a self-correcting way of knowing. Scientists:

- Build on prior knowledge

- Try to replicate observations and experiments of others to check their conclusions

- Share information

B. Science and Technology are functions of society

Science and technology are interdependent

- Technology extends our ability to observe and measure, which enables scientists to work on new questions that were previously unapproachable

- Science in turn, generates new information that makes new technological inventions possible

We have a love/hate relationship with technology

- Technology has improved our standard of living

- Technology has also created new problems

A better understanding of nature must remain the goal of science. Scientists should:

- Try to influence how technology is used

- Help educate the public about the benefits and hazards of technology

C. Biology is Multidisciplinary

- Includes chemistry, physics and mathematics

- As well as humanities and the social sciences

Ch.1 - Introducing Advanced Biology

I. Life's Hierarchical Order

  • Atoms
  • Complex biological molecules
  • Subcellular organelles
  • Are ordered into
  • Cells
  • In multicellular organisms similar cells are organized into
  • Tissues
  • Organs
  • Organ systems
  • Complex organism

There are levels of organization beyond the individual organism:

Population = Localized group of organisms belonging to the same species

Community = Populations of species living in the same area

Ecosystem = An energy-processing system of community interactions that include abiotic environmental factors such as soil and water

Biomes = Large scale communities classified by predominant vegetation type and distinctive combinations of plants and animals

Biosphere = The sum of all the planet's ecosystems

B. Each level of Biological Organization Has Emergent Properties

The study of biology balances the reductionist strategy with the goal of understanding how the parts of cells, organisms, and populations are functionally integrated

Though structurally different, eukaryotic and prokaryotic cells have many similarities, especially in their chemical processes

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