College Bio Chp. 1 & 2

Characters of Life

Made of cells

Reproduce

Grow & develop

Obtain materials and use energy

Respond to environment

Maintain internal environment

Universal genetic code

Change over time

Evolution

Change over time

5 Main Themes of Life

Organization, information, energy and matter, interactions, evolution

Organization

Structure = function ex. hummingbird

Cell

basic unit of structure and function of all living things

Prokaryotic: no nucleus

Eukaryotic: contains nucleus

Levels of Organization

Atom: basic unit of matter

Molecule: chemical structure consisting of two or more atoms

Organelles: “tiny organs” in cells

Cells: basic unit of life; fundamental unit of structure and function

Tissue: group of cells that work together & perform a specific function

Organ: group of tissues

Organ System: group of organs

Organism: individual living thing

Population: group of the same organisms; mate & have offspring

Community: group of different populations living in same area

Ecosystem: living things in a particular area along with NON-LIVING

Biome: group of same ecosystems with same climate

Biosphere: all life on Earth and places where life exists

Information

Expression and Transmission of Genetic Information (DNA)

Chromosomes

Hold DNA (deoxyribonucleic acid)

Genes: section of DNA in the chromosome

*encode info necessary to build all the molecules made in a cell; gives cell its identity and function

DNA Structure

double-helix

4 Types of nucleotides: adenine, guanine, cytosine, thymine

Transfer of Energy and Matter

Input -> Sun Output →Heat

Total Energy Expenditure = Basal metabolism + digestion + physical activity

Interactions

Every organism interacts with other organisms and the environment. Not all interactions are positive

ex. climate change

Evolution

*Core theme of biology

Concept that the organisms living on Earth today are the modified descendants of common ancestors. **Descent with modification

Evolution: Section 2

Evolution accounts for the unity and diversity of life

All organisms fit into one of three domains: bacteria (most diverse; prokaryotic), Archaea (live in Earth’s extreme environments; prokaryotic), eukarya-eukaryotic; 4 Kingdoms (fungi, protista, plantar, animalia)

Domains & Kingdoms

Domain Archaea: kingdom archaebacteria

Domain Bacteria: kingdom eubacteria

Domain Eukarya: kingdom protista, fungi, plantae, animalia

Theory of Natural Selection

1. Species arise from a succession of ancestors that were different from them (decent with modification)

2. “Natural Selection” is the primary cause of descent with modification

3. The environment consistently “selects” for the propagation of certain traits among naturally occurring variant traits in the population

   1. *better inherited traits are suited for environment

Forming & Testing Hypothesis

Science: way of knowing: an approach to understanding the natural world

Inquiry: a search for information and explanation of natural phenomena

Process: make observations, form hypothesis, test

Hypothesis: educated guess

Theory: well-tested hypothesis

Scientific Method

1. Observation/Inference

2. Create hypothesis

3. Run experiment

   1. Control

   2. variable (ind. & dep.)

4. Collect Data

   1. Quantitative

      1. Duration of behaviors

   2. Qualitative

      1. Drawings of chimps

5. Conclusion

6. Repeat

Experiment

Controlled Experiment: on designed to compare an experimental group with a controlled group

Variable: item that varies

Ind. variable: color of the mouse

Dep. variable: factor being measured; amt of predation

Chemical Context of Life

Matter is made up of elements → substances that cannot be broken down to other substances by chemical reactions

92 elements that occur naturally in nature out of 118

Compound

substance consisting of two or more different elements combined in a fixed ratio *sodium & chlorine

Emergent Property

a new characteristic that a complex system has, but which the individual parts do not have on their own *work as a team

4 Elements that make up 96% of living matter

Oxygen (O), Carbon (C), Hydrogen (H), Nitrogen (N)

Remaining 4% - Trace elements: require minimal quantities

3 Subatomic Particles

Protons, Neutrons, Electrons

Nucleus = Positive

Cloud = Negative

Elements

Atomic Number: # of protons

Mass Number: # of protons & # of neutrons added together (mass)

Atomic Mass Number: slightly different from the total mass

Atomic particles are measured in “daltons”

Shell Numbers

1st Shell - 2 electrons

2nd Shell - 8 electrons

3rd Shell - 18 electrons

Isotope

different atomic forms of the same element; atoms that have more neutrons than other atoms of the same type

*Most are stable, some not and some radioactive

Radioactive Isotope

have a nucleus that decays spontaneously, giving off particles and energy

*can date relics/fossils

Formation & Function of molecules

atoms with incomplete valence shells will interact with other atoms

*this forms a chemical bond: interactions that result in atoms staying close together

4 Types of Bonds

Covalent, Ionic, Hydrogen (weak), Van der Waals “interactions”: everchanging

Covalent Bonds

bonds that share valence electrons and become a molecule: two or more atoms held together by covalent bonds

**water is a covalent bond that’s considered polar

Ionic Bond

one atom completely strips an electron from its partner; electron “jumps” or gets “transferred” to the other

Result: the separate atoms now have different charges

Cation: + charge

Anion: - charge

Hydrogen Bonds

*central to the chemistry of life!

hydrogen atom in a covalent bond has a partial positive charge

ex: water and DNA double helix

Van der Waals Interactions

individually weak & occur only when atoms and molecules are very close together **gecko

Adhesion vs. Cohesion

adhesion - water molecules stick to other surfaces (water on leaf)

Cohesion - water molecules stick to each other (water droplets together)

Surface Tension

a measure of how difficult it is to stretch or break the surface of a liquid

*mosquito on water

Solvent vs. Solute

solution: a mixture of two or more substances

solvent - typically water; dissolving agent

solute - substance that is dissolved

*water is the solvent of life

**aqueous solution: any solution in which the solvent is water

Hydrophilic vs. Hydrophobic

Hydrophilic - water loving; cotton

Hydrophobic - water fearing; oil

pH Scale

0-14

0-6 = Acids

7 = Neutral

8-14 = Bases

*Buffer - substance that minimizes the changes in the concentration of H+ and OH- by accepting H+ ions when they are in excess