Chapter 22 part 1 The Basic Unit of Life – the Cell

The Big Idea- All living things are made up of one or more units called cells

Biology: the study of Life

Biology is the study of life and living things

A biologist is anyone who uses the scientific method to study life

An organism is an individual living thing such as a plant or an animal.

Branches of Biology- most of these overlap with other

fieldsZoology- study of animals

Botany- study of plants

Microbiology- study of small microscopic organisms

Paleontology- study of extinct organisms

Cytology- study of cells

Genomics- study of the total hereditary content of various organisms

There are a lot more branches and sub-branches

But what exactly makes a living thing alive?

https://www.youtube.com/watch?feature=player_embedded&v=juxLuo-sH6M#t=0

Characteristics of Living Things

Are made up of one or more units called cells

Are based on a universal genetic code

Obtain and use energy

Grow and develop

Maintain a stable environment

Reproduce

Respond to their environment

Evolve

1. Living things are made up of cells

Cell- basic unit of structure and function in living things; though small in size, cells are complex and highly organized

Organisms are of two types:Unicellular- an organism consisting of a

single cell; bacteria, protists, some fungiMulticellular- an organism consisting of

many cells; some of which are typically specialized for particular functions

2. Living things are based on a universal

genetic codeAll organisms store the complex information

they need to live, grow and reproduce in a genetic code written in the molecule DNA (deoxyribonucleic acid)

That information is copied and passed from parent to offspring

With a few minor variations, life’s genetic code is almost identical in every living organism on earth

3. Living things obtain and use energy

the energy is conserved and changed from one type of energy to another

Autotroph- organism that makes it’s own food for energy (producer)Photosynthetic autotroph- uses sunlight as

its energy source to make food (photosynthesis)

Chemosynthetic autotroph- use the energy from chemical reactions as its source of energy to make food ( obscure group)

Heterotroph- organisms that get their food from an outside source- cannot make it themselves- use the processes of cellular respiration and fermentation to release energy from food (consumer)Chemotrophic heterotroph- organisms

that can obtain energy by taking in organic molecules and then breaking them down

Phototrophic heterotroph- organisms that are able to use sunlight for energy but also require organic compounds for energy (obscure group)

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Other important terms here:

Metabolism- the sum total of all the chemical reactions in the body – the balance of catabolism and anabolism

Catabolism- the final breakdown of complex substances to simpler substances

Anabolism- any process in a living organism that involves putting together, or synthesizing complex substances from simpler substances

4. Living things grow and develop

Growth can be accomplished in two ways:Increase in cell size (baby cell grows

bigger)Increase in cell number (for multi-

cellular organisms)

Development involves maturationA butterfly goes through a

metamorphosis to change from a egg, to larva, to pupa to butterfly

Female egg cells mature during menstruation

Organisms have some type of life cycle that takes them from birth to death- some are more complicated than others but all living things have them

5. Living things maintain themselves- they maintain a

stable environmentThey make structures and repair damaged structures

They maintain their internal environment

Using energy to keep conditions inside their cells within certain limits is called homeostasis

More on maintaining environment

Def- homeostasis- an organism’s ability to maintain constant or stable conditions that are necessary for lifeEx- sweating or shivering to

maintain temperature; blood pressure, etc.

6. Living things can reproduce as a species

Reproduction- producing new organisms of the same typeAsexual reproduction- a single organism

produces new organisms that are genetically identical to itself- bacteria, protists, fungus, plants, some animals

Sexual reproduction- a process in which two cells, normally from different organisms unite to produce the first cell of a genetically different organism – bacteria (simple) protists, fungus, plants, animals

7. Living things can respond to their

environmentResponses can be rapid or slow

Stimulus- anything in the environment that causes an organism to react

Irritability- no, not grumpiness!- it’s the ability of an organism to respond to stimuli (plural of stimulus)

8. Taken as a group, living things evolve

Over generations, groups of organisms evolve, or change over time

Evolutionary change links all forms of life to a common origin more than 3.5 billion years ago

Evidence of this shared history is found in all aspects of living and fossil organisms, from physical features to structures of proteins to sequences of information in DNA.

More on evolution

Any structure, behavior or internal process that enables an organism to respond to environmental factors and live to produce offspring is called an adaptation

Adaptations are inherited from previous generations

The gradual change in a species through adaptations over time is evolution

Review

Are made up of one or more units called cells

Are based on a universal genetic code

Obtain and use energy

Grow and develop

Maintain a stable environment

Reproduce

Respond to their environment

Evolve

http://www.mybigcampus.com/library/108935