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 fields Zoology- 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 fungi Multicellular- an organism consisting of many cells; some of which are typically specialized for particular functions

2. Living things are based on a universal genetic code All 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)

US THEM

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 maturation A 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 environment They 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 life Ex- sweating or shivering to maintain temperature; blood pressure, etc.

6. Living things can reproduce as a species Reproduction- producing new organisms of the same type Asexual 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 environment Responses 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