Download Biology - Zanichelli online per la scuola

David Sadava, David M. Hillis,
H. Craig Heller, May R. Berenbaum
La nuova
biologia.blu
Le cellule e i viventi
Studying Life
What Is Biology?
Biology is the
scientific study of living
things (organisms).
What Is Biology?
Genome: the sum total of all the DNA in a cell.
DNA consists of repeating subunits called
nucleotides.
Gene: a specific segment of DNA that contains
information for making a protein.
All the cells of a multicellular organism have the
same genome, yet different cells have different
functions and structures.
Different cells are expressing different parts of
the genome.
DNA Is Life’s Blueprint
The Hierarchy of Life (part 1)
Cells became specialized in multicellular organisms;
a biological hierarchy emerged:
• differentiated cells are organized into tissues;
• different tissue types form organs (e.g., a heart);
• organs are grouped into organ systems.
The Hierarchy of Life (part 2)
A group of individuals of the same species is a
population.
Populations of all the species that live and interact in a
defined area are called a community.
Communities together with their abiotic (nonliving)
environment constitute an ecosystem.
Characteristics of living organisms (part 1)
Characteristics of living organisms:
•
Made of a common set of chemical
components: carbohydrates, fatty acids,
nucleic acids, amino acids
•
Most are made of cells enclosed by plasma
membranes
•
Convert molecules from their environment
into new biological molecules
•
Extract energy from the environment and use
it to do biological work
Characteristics of living organisms (part 2)
•
Contain genetic information that uses a
universal code to specify proteins
•
Share similarities among a fundamental set
of genes, and replicate this genetic
information when reproducing
•
Exist in populations that evolve through
changes in frequencies of genetic variants
over time
•
Self-regulate their internal environment,
maintaining conditions that allow them to
survive
Organisms need of nutrients
Organisms acquire nutrients from their environment.
Nutrients supply energy and materials for biochemical reactions.
Some reactions break nutrient molecules into smaller units,
releasing energy for work.
Energy can be used immediately or stored.
The Mechanism of Homeostasis
Organisms must regulate their internal
environment, made up of extracellular fluids.
Maintenance of the narrow range of
conditions that support survival is known as
homeostasis.
The Natural Selection of Life
Evolution is the major unifying
principle of biology.
Charles Darwin compiled factual
evidence for evolution.
He argued that differential survival
and reproduction among individuals
in a population (natural selection)
could account for much of the
evolution of life.
The Many Faces of Life (Part 1)
Three domains of life:
•Bacteria
(prokaryotes)
•Archaea
(prokaryotes)
•Eukarya
(eukaryotes)
Eukaryotic cells have internal membranes
that enclose specialized organelles within
their cells, including the nucleus, which
contains the genetic material.
The Many Faces of Life (Part 2)
How Do Biologists Investigate Life?
Scientific investigations are based on
observation, data, experimentation, and logic.
Observation has been improved by new
technologies.
Information, or data, must be quantified using
mathematical and statistical methods.
Scientific Methodology
How Do Biologists Investigate Life?
Model systems: using one type of organism
to understand others.
This is possible because all life is related by
descent from a common ancestor, shares a
genetic code, and consists of similar building
blocks—cells.
Adapted from
Life: The Science of Biology, Tenth Edition, Sinauer Associates, Sunderland, MA, 2014
Inc. All rights reserved