Chapter 2 –Biology as a Science

and Tools of the trade

The Nature of Matter

• Pg 40-52• Story of the discovery of oxygen

Brief summaries you should be writing down as you read:early Greek beliefsphlogiston theoryPierre Bayen experimentJoseph Priestley experimentLavoisier experimentWho then discovered oxygen?

Spontaneous Generation vs. Biogenesis

• Pgs 52-60• Living vs. non-living

experiments summaries to write down while you

are readingspontaneous generation theory componentsbiogenesis theory componentsJohn Needham’s experimentLazarro Spallanzani experimentLouis Pasteur’s classic experiment

I. Characteristics of Living Things• We can state with some

confidence that all living things– Are made up of one or more units

called cells– Reproduce– Grow and develop– Obtain and use energy– Respond to their environment

Living things are made up of cells• Cell- basic unit of structure and

function in living things• Organisms are of two types

– Unicellular-an organisms 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

Living things reproduce

• Reproduction- producing new organisms of the same type

• Two different types of reproduction:– Asexual – a single organism produces

new organisms 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

Living things grow and develop• Growth can be accomplished in two

ways:– Increase in cell size– Increase in cell number (at least for

multi-cellular organisms)

• Development involves maturation

• A butterfly goes through a metamorphosis to change from 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

Living Things Obtain and Use Energy

• Real science terms:• Autotroph- organism that makes

it’s own food (consumer)– Photosynthetic autoroph- uses

sunlight as its energy source to make food

– Chemotrophic autotroph- uses the energy from chemical reactions as its source of energy to make food

• Heterotroph- organisms that get their food from an outside source – cannot make it themselves- Chemotrophic heterotroph-

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

- Phototrophic heterotroph- organisms that is able to use sunlight for energy but also requires organic compounds for nutrition

Terms that are important here• Metabolism- the sum total of all

the chemical reactions in the body – the balance of anabolism and catabolism– Anabolism- any process in a living

thing that involves putting together , or synthesizing, complex substances from simpler substances

– Catabolism- the final breakdown of complex substances into simpler ones, usually resulting in the release of energy

Living things 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

• Homeostasis- an organism’s ability to maintain constant or stable conditions that are necessary for life- sweating

Biology: The Study of Life• Biologist- anyone who uses the

scientific method to study life• Branches of biology

– Zoology- study of animals– Botany- study of plants– Microbiology- study of small

microscopic organisms– Paleontology- study of extinct organisms– Ethology- study of animal behavior– Cytology- study of cells

Levels of Organization

• Look at pgs 58-59

Tools of a biologist

• Compound light microscope– Lab on its parts and use– Limitations: as magnification

increases, resolution decreases; the limit of resolution is the point at which the specimen is too blurry to see

– Uses light and two mirrors to reflect through a thin specimen

– Must stain many specimens to see

Electron microscopes

• Electromagnets used to bend streams of electrons like lenses bend light

• Much more powerful- can magnify millions of times without loss of resolution

• Several different types: TEM, SEM, scanning probe

Types of electron microscopes• Transmission electron microscope

(TEM)– Thin specimens in vacuum –must be

dead– 2D view (like compound light only more

magnification)• Scanning electron microscope

(SEM)– Beam of electrons around specimen – in

a vacuum – dead– 3D can see outside surfaces

• Probe microscopes- scanning probe microscopes– can be alive- probes the outside- 3D

Biology lab techniques

• Staining- for visibility• Centrifugation-separates

particles by mass- spins at high speed moving heavy particles to bottom of the test tube

• Micromanipulation- using a microscope to do microdissection or insertion of material into a cell

Chapter 3 intro atoms and molecules

II. Matter

• All things around us are made up of matter

• Matter- anything that has mass and takes up space (volume)

Properties of Matter

• Physical properties- a property that can be observed and measured without permanently changing the identity of the matter– Color– Texture– Odor– State its in- solid, liquid, gas- and the

points at which it changes- boiling point, freezing point, etc.

– Density– Hardness

• Chemical properties- a substance’s ability to change into another substance as a result of a chemical change– Burning coal, wood– Digesting food– Tarnishing silver

Composition of Matter

• Atom- the basic unit of matter– 115 + types of elements- 92 are

naturally occurring– Human body contains about 20.

• Most notable: carbon, nitrogen, oxygen, hydrogen, sodium, phosphorus, fluorine, silicon, sulfur, magnesium, potassium

Atomic Structure

• All atoms are made up of a central nucleus that contains positively charged protons, and neutral neutrons.

• Orbiting the nucleus in energy levels are negatively charged electrons.

Chemical Compounds

• When atoms combine they form substances known as compounds.

• These compounds are made up of two or more elements that chemically join to form new substances that no longer possess the properties they once had, but now have new properties.

Interaction of Matter

• Matter forms compounds in two ways:– Ionic bonds

• bonds formed when two or more elements gain or lose electrons becoming charged particles (ions)

• These ions are then held together by their opposite charges (ionic bonds)

– Covalent bonds• Bonds formed when two or more

atoms share electrons

III. The Chemical Basis of Life• Mixtures- two or more

substances that mix together but are not chemically bound. – can be separated by physical

means– Retain the properties of the

components– Can form solutions, suspensions or

colloids– Solutions are the most important

and water is usually the solvent in living organism solutions

Solutions

• A homogeneous mixture in which one substance is dissolved in another with the particles evenly distributing themselves throughout the mixture.– Ex salt and sugar can form

solutions with water, pepper cannot.

Suspensions & Colloids

• Suspension & colloids- mixtures containing non-dissolved particles distributed within a solid, liquid or gas