All forms of life share common properties

Organism

an individual living thing, such as an alligator. All organisms are composed of cells. They occur singly as a great variety of unicellular (single-celled) organisms, such as amoebas and most bacteria. And cells are the subunits that make up multicellular organisms, such as owls and trees. Your body consists of trillions of cells of many different kinds.

Evolution

can be defined as the process of change that has transformed life on Earth from its earliest beginnings to the diversity of organisms living today. The fossil record documents the fact that life has been evolving on Earth for billions of years, and patterns of ancestry can be traced through this record. Their differences reflect the evolutionary changes that occurred within their separate lineages during the history of their existence on Earth. Thus, evolution accounts for life's dual nature of kinship and diversity. The fossil record provides evidence of such diversification of species from ancestral species. The fossil record, along with other evidence such as comparisons of DNA, allows scientists to trace the evolutionary history of life back through time. All of life is connected, and the basis for this kinship is evolution—the core theme that makes sense of everything we

Kingdom Plantae,

consists of plants, which produce their own food by photosynthesis.

population

includes all the individuals of a particular species living in an area.

Growth and Development

inherited information in the form of DNA controls the pattern of the growth and development of all organisms

molecule

is a cluster of small chemical units called atoms held together by chemical bonds

organelle

is a membrane-enclosed structure that performs a specific function within a cell.

organ

is made up of several different tissues, each in turn made up of a group of similar cells that preform a specific function.

Regulation

many types of mechanisms regulate an organism's internal environment, keeping it within limits that sustain life. pictured here is a lizard sunbathing which helps raise its body temperature on cool mornings

Reproduction

organisms reproduce their own kind.

Kingdom Fungi

represented by the mushrooms, is a diverse group whose members mostly de compose the remains of dead organisms and organic wastes and absorb the nutrients into their cells.

organ system

such as the circulatory system or nervous system, consists of several organs that cooperate in a specific function. For instance, the organs of the nervous system are the brain, the spinal cord, and the nerves. For example, an alligator's nervous system controls all its actions.

Taxonomy

the branch of biology that names and classifies species, arranges species into a hierarchy of broader and broader groups: genus, family, order, class, phylum, and kingdom.

domains

there is consensus among biologists that life can be organized into three higher levels and the three domains are Bacteria, Archaea, and Eukarya.

Energy processing

this caterpillar will use the chemical energy store in the plant it is eating to power its own activities and chemical reactions

Order

this sunflower illustrates the ordered structure that typifies life. Living cells make up this complex organization.

Prokaryotic cells

were the first to evolve and were Earth's sole inhabitants for more than 1.5 billion years. Fossil evidence indicates that eukaryotic cells evolved from prokaryotic ancestral cells about 1.8 billion years ago. A prokaryotic cell is much simpler and usually much smaller than a eukaryotic cell. The cells of the microorganisms we call bacteria are prokaryotic.

ecosystem

which consists of all the organisms living in a particular area, as well as the physical components with which the organisms interact, such as air, soil, water and sunlight

DNA

All cells have DNA, and the continuity of life depends on this universal genetic material. DNA is the chemical substance of genes, the units of inheritance that transmit information from parents to offspring. Genes, which are grouped into very long DNA molecules called chromosomes, also control all the activities of a cell. Each DNA molecule is made up of two long chains, called strands, coiled together into a double helix. The strands are made up of four kinds of chemical building blocks. Figure 1.5 (left side) illustrates these four building blocks, called nucleotides, with different colors and letter abbreviations of their names. The right side of the figure shows a short section of a DNA double helix. Each time a cell divides, its DNA is first replicated, or copied—the double helix unzips and new complementary strands assemble along the separated strands. Thus, each new cell inherits a complete set of DNA, identical to that of the parent cell. You began as a single cell stocked with DNA inherited from your two parents. The replication of that DNA during each round of cell divi- sion transmitted copies of the DNA to what eventually became the trillions of cells of your body. The way DNA encodes a cell's information is analogous to the way we arrange letters of the alphabet into precise sequences with specific meanings. The word rat, for example, conjures up an image of a rodent; tar and art, which contain the same letters, mean very different things. We can think of the four building blocks as the alphabet of inheritance. Specific sequential arrangements of these four chemical letters encode precise information in genes, which are typically hundreds or thousands of "letters" long. The DNA of genes provides the blueprints for making proteins, and proteins serve as the tools that actually build and maintain the cell and carry out its activities. A bacterial gene may direct the cell to "Make a yellow pigment." A particular human gene may mean "Make the hormone insulin." All forms of life use essentially the same genetic code to translate the information stored in DNA into proteins. This makes it possible to engineer cells to produce proteins normally found only in some other organism. Thus, bacteria can be used to produce insulin for the treatment of diabetes by inserting a gene for human insulin into bacterial cells. The diversity of life arises from differences in DNA sequences—in other words, from variations on the common theme of storing genetic information in DNA. Bacteria and humans are different because they have different genes. But both sets of instructions are written in the same language. The entire "library" of genetic instruc tions that an organism inherits is called its genome. A typical human cell has two similar sets of chromosomes, and each set contains about 3 billion nucleotide pairs. In an emerging field known as genomics, researchers now study whole sets of genes in a species and then compare genes across multiple species. The benefits from such an approach range from identifying genes that may be implicated in human cancers to revealing the evolutionary relationships among diverse organ isms based on similarities in their genomes. Genomics affirms the unity of life based on the universal genetic material

Response to the environment

All organisms respond to environmental stimuli. This Venus flytrap closed its trap rapidly in response to the stimulus of a damselfly landing on it.

Eukarya.

All the eukaryotes, organisms with eukaryotic cells, are grouped in domain Eukarya. The three remaining groups within Eukarya are distinguished partly by their modes of nutrition. Three the groups in Eukarya are Kingdom Plantae, Kingdom Fungi and Kingdom Animalia

Kingdom Animalia

Animals obtain food by eating other organisms.

Bacteria

Bacteria and Archaea both consist of prokaryotes, organisms with prokaryotic cells. Bacteria are the most diverse and widespread prokaryotes.

Archaea

Bacteria and Archaea both consist of prokaryotes, organisms with prokaryotic cells. Many of the prokaryotes known as archaea live in Earth's extreme environments, such as salty lakes and boiling hot springs. Each rod-shaped or round structure in the photos of the prokaryotes

natural selection

Darwin's second point was to propose a mechanism for evolution, For example, an imaginary beetle population has colonized an area where the soil has been blackened by a recent brush fire. Initially, the population varies extensively in the inherited coloration of individuals, from very light gray to charcoal. ➋ A bird eats the beetles it sees most easily, the light-colored ones. This selective predation reduces the number of light-colored beetles and favors the survival and reproductive success of the darker beetles, which pass on the genes for dark coloration to their offspring. ➌ After several generations, the population is quite different from the original one. As a result of natural selection, the frequency of the darker-colored beetles in the population has increased. Darwin realized that numerous small changes in populations as a result of natural selection could eventually lead to major alterations of species. He proposed that new species could evolve as a result of the gradual accumulation of changes over long periods of time. This could occur, for example, if one population fragmented into subpopulations isolated in different environments. In these separate arenas of natural selection, one species could gradually divide into multiple species as isolated populations adapted over many generations to different sets of environmental factors. The fossil record provides evidence of such diversification of species from ancestral species.

eukaryotic cells

Fossil evidence indicates that eukaryotic cells evolved from prokaryotic ancestral cells about 1.8 billion years ago. Plants, animals, fungi, and protists (mostly unicellular organisms) are all composed of eukaryotic cells. a eukaryotic cell is subdivided by membranes into various functional compartments, or organelles. These include a nucleus, which houses the cell's DNA.

Darwin started with two observations, from which he drew two inferences

OBSERVATION #1: Individual variation. Individuals in a population vary in their traits, many of which are inherited from parents to offspring. OBSERVATION #2: Overproduction of offspring. All species can produce far more offspring than the environment can support. Competition for resources is thus inevitable, and many of these offspring fail to survive and reproduce. INFERENCE #1: Unequal reproductive success. Individuals with heritable traits best suited to the local environment are more likely to survive and reproduce than are less well-suited individuals. INFERENCE #2: Accumulation of favorable traits over time. As a result of this unequal reproductive success over many generations, a higher and higher proportion of individuals in the population will have the advantageous traits.

Organisms interact with their environment, exchanging matter and energy.

Plants are the producers that provide the food for a typical ecosystem. A tree, for example, absorbs water (H2O) and minerals from the soil through its roots, and its leaves take in carbon dioxide (CO2) from the air. In photosynthesis, a tree's leaves use energy from sunlight to convert CO2 and H2O to sugar and oxygen (O2). The leaves release O2 to the air, and the roots help form soil by breaking up rocks. Thus, both organism and environment are affected by the interactions between them. The consumers of a ecosystem eat plants and other animals. The moose in Figure 1.4 eats the grasses and tender shoots and leaves of trees in a forest ecosystem in Canada. To release the energy in food, animals (as well as plants and most other organisms) take in O2 from the air and release CO2. An animal's wastes return other chemicals to the environment. Another vital part of the ecosystem includes the small animals, fungi, and bacteria in the soil that decompose wastes and the remains of dead organisms. These decomposers act as recyclers, changing complex matter into simpler chemicals that plants can absorb and use.

Cell

The cell has a special place in the hierarchy of biological organization. It is the level at which the properties of life emerge—the lowest level of structure that can perform all activities required for life. A cell can regulate its internal environment, take in and use energy, respond to its environment, and build and maintain its complex organization. The ability of cells to give rise to new cells is the basis for all reproduction and also for the growth and repair of multicellular organisms. All cells share certain characteristics. For example, every cell is enclosed by a membrane that regulates the passage of materials between the cell and its surroundings. And every cell uses DNA as its genetic information. The activities of organisms are all based on cells. For example, your every thought is based on the actions of nerve cells, and your movements depend on muscle cells. Even a global process such as the cycling of carbon is the result of cellular activities, including the photosynthesis of plant cells and the cellular respiration of nearly all cells, a process that uses oxygen to break down sugar for energy and releases carbon dioxide. All organisms are composed of cells. They occur singly as a great variety of unicellular (single-celled) organisms, such as amoebas and most bacteria. And cells are the subunits that make up multicel lular organisms, such as owls and trees. Your body consists of trillions of cells of many different kinds.

the cycling of chemicals and flow of energy in an ecosystem

The dynamics of ecosystems include two major processes— the recycling of chemicals and the flow of energy. These processes are illustrated in Figure 1.4. The most basic chemicals necessary for life—carbon dioxide, oxygen, water, and various. By contrast, an ecosystem gains and loses energy con stantly. Energy flows into the ecosystem when plants and other photosynthesizers absorb light energy from the sun (yellow arrow) and convert it to the chemical energy of sugars and other complex molecules. Chemical energy (orange arrow) is then passed through a series of consumers and, eventually, to decomposers, powering each organism in turn. In the process of these energy conversions between and within organisms, some energy is converted to heat, which is then lost from the system (red arrow). In contrast to chemicals, which recycle within an ecosystem, energy flows through an ecosystem, entering as light and exiting as heat.

Community

The entire array organisms interact, such as air, soil, water and sunlight.

Descent with modification

The first of two main points that Darwin presented in The Origin of Species was that species living today arose from a successor of ancestors that differed from them. It was an insightful phrase, because it captured both the unity of life (descent from a common ancestor) and the diversity of life (modifications that evolved as species diverged from their ancestors).

System biology

The properties of life emerge from the ordered arrangement and interactions of the structures of a cell. Such a combination of components forms a more complex organization that we can call a system. Biologists today often use this approach, the study of a biological system and the modeling of its dynamic behavior by analyzing the interactions among its parts. Biological systems can range from the functioning of the biosphere to the molecular machinery of an organelle. Experience shows you that form generally fits function. A screwdriver tightens or loosens screws, a hammer pounds nails. Because of their form, these tools can't do each other's jobs. Applied to biology, this theme of form fitting function is a guide to the structure of life at all its organizational levels. For example, the long extension of the nerve cell shown in Figure 1.2 enables it to transmit impulses across long distances in the body. Often, analyzing a biological structure gives us clues about what it does and how it works.

The diversity of life can be arranged into three domains

There seems to be a human tendency to group things, such as owls or butterflies, although we recognize that each group includes many different species. And then we cluster groups into broader categories, such as birds and insects. biologists divided all of life into five kingdoms. But new methods for assessing evolutionary relationships, such as comparisons of DNA sequences, have led to an ongoing reevalua tion of the number and boundaries of kingdoms.