Class Notes

Genetics (Traits and Reproduction)

I. Deoxyribonucleic acid (DNA) 

A. DNA is passed from parents to offspring and contain instructions for building proteins, which cells use to grow, live, and perform other tasks.

B. It is in the shape of a double helix which contains four types of nitrogen bases, a deoxyribose sugar, and a phosphate molecule.  These parts combined are called a nucleotide. 

C. Strands are connected by a hydrogen bond and are paired up in the following way: Adenine (A) bonds with Thymine (T), Cytosine (C) bonds with Guanine (G).

D. If you know the order of nitrogen bases on one strand, then you should be able to identify the bases present in the complimentary (connected) strand.

II. Genes and Proteins

A. The section of DNA on a chromosome that codes for a protein or a trait (characteristic) is called a gene.  

B. Proteins are made of units called amino acids that are linked together in a certain order.  If the order of the amino acids changes, then protein that is made may change.

C. If a change occurs in a gene or chromosome, then it is called a mutation (which may affect the traits of an organism).

III. Modern Genetics

A. Selective breeding produces organisms with desired traits

B. Cloning produces copies of cells, tissues, organs, or organisms

C. Genetic engineering transfers genes between organisms

D. Analyzing genomes allows all genes within organisms to be identified (example=Human Genome Project)

Microscopes and Cells

I. Compound Light Microscopes Basics

A. Magnifies objects or organisms using light and 2 lenses

B. The lenses include: eyepiece lens, scanning power objective lens, low power objective lens, and high power objective lens

C. To calculate the total magnification, multiply the eyepiece lens by whichever objective lens is being used at the time.

D. The field of view is the diameter across the area that is being observed and is often measured in millimeters (it will allow you to estimate the length of an organism)

II. Microscope Parts and Use

A. The lenses magnify images and the light source is plugged in to produce light

B. The stage is where the slide is placed for viewing (stage clips can be used if needed).

C. The diaphragm (under the stage) adjusts the amount of light and can darken or lighten the image.

D. Adjustment knobs are used for focusing

      *Coarse adjustment is larger and used to quickly bring something into focus (should only be used under scanning and low power)

      *Fine adjustment is smaller and used to sharpen the image (can be used under all objective lenses)

III. Cell Theory and Cell Basics

A. Cell theory states that living organisms are made of cells (the units of life) that come from other living cells.

B. Prokaryotic cells (bacteria) are unicellular organisms without a nucleus.  Eukaryotic cells do have a nucleus where the DNA is contained (they can be unicellular or in multicellular organisms).

C. Examples of eukaryotic organisms include plants, animals, fungi (yeast, mushrooms), and protists (algae, amoebas).

D. Order of organization from smallest to largest in multicellular organisms:

Cells→ Tissues→ Organs→ Systems→ Organisms

IV. Eukaryotic Cell Organelles and Plant vs. Animal Cells

A. Organelles are smaller parts of cells that have specific functions (roles they play).

B. Key organelles or cell parts include:

*Nucleus: control center (contains DNA)

*Cytoplasm: gel like material that holds organelles

*Cell Membrane: protects and allows materials in and out

*Ribosomes: makes proteins (protein synthesis)

*Vacuoles: stores water, food, and waste

*Mitochondria: powerhouse of the cell (breaks down food)

C. Plant Cells contain the following (which animal cells do not): Cell Walls (protection), Chloroplasts (which have chlorophyll for photosynthesis), and large central vacuoles.  

V. Cell Cycle (Cell Division)

A. One parent cell produces two identical new daughter cells with the same number of chromosomes (pieces of DNA) as the parent cell.

B. Interphase is 90% of the cell’s life and is when DNA is copied. Then mitosis occurs (prophase, metaphase, anaphase, telophase).  Cytokinesis is when the two cells finally  separate. 

C. During cell division, centrioles are only present in animal cells and cell plates are only present in plant cells. 

VI. Meiosis and Reproduction

A.  Meiosis forms gametes (male sperm cells and female egg cells) within an organism.

B. 2 divisions take place so that the cells that are produced have half the number of chromosomes as the body cells of the organism. 

C. Fertilization occurs when a sperm cell and egg cell combine to form a zygote.

D. The zygote will form more cells and grow over time through the cell cycle and mitosis.

Matter and Energy in Ecosystems

I. Ecosystems

A. Ecosystems include all the living and nonliving things interacting in a particular area.

B. Everything that makes up an ecosystem (organisms, air, water, soil) is matter.  

C. Abiotic matter is matter that makes up the nonliving parts of an ecosystem (air, water, rocks) and biotic matter is matter that makes up the living and dead organisms in an ecosystem. 

D. One way ecologists (scientists who study the environment) make sense of ecosystems is by tracking the cycling of matter over time. 

II. Photosynthesis

A. Producers are organisms that can make their own energy storage molecules (such as glucose) during the process of photosynthesis.

B. During photosynthesis light energy (from the sun) and carbon (from carbon dioxide) are used to make energy storage molecules.  This moves carbon from abiotic to biotic matter.

C. The amount of carbon and sunlight in an ecosystem will affect the amount of energy storage molecules that are available. This will impact the number of organisms that can survive.  

III. Cellular Respiration

A. Producers, consumers, and decomposers release carbon dioxide and water through cellular respiration. 

B.The process moves carbon (in form of carbon dioxide) from biotic matter (living things) to abiotic matter (air and water).

C. It is this chemical reaction between oxygen and energy storage molecules, such as glucose, that releases energy into cells.

IV. The Carbon Cycle

A. Earth is a closed system, so the amount of carbon stays relatively constant over time.

B. Carbon moves naturally through the processes of photosynthesis, which transfers carbon from abiotic to biotic, and cellular respiration, which transfers carbon from biotic to abiotic. 

C. When organisms die they decay. When this happens, the carbon in their body can be released into abiotic matter.

Chemical Reactions

I. Atomic Structure and Periodic Table

A. Atoms are made of subatomic particles called protons, neutron, and electrons.  Protons (1 amu)  are positive, Neutrons (1 amu) are neutral, and electrons (0 amu) are negative. 

B. Elements (made of 1 type of atom) are identified on the Periodic Table and are arranged in order of Atomic Number (the number of protons or electrons).  Atomic mass is the number of protons and neutrons in an atom. When elements combine they form compounds (example: H2O)

*Groups are vertical (up and down) and periods are horizontal (across) in the periodic table.

C. Atomic Theory states that all matter is made of atoms, and that different elements are made of different types of atoms. Many scientists have contributed to this theory over time through experimentation.  

II. Chemical Properties

A. Chemists observe substances in order to identify their properties (examples include boiling point, melting point, color, texture, smell)

B. Different substances have different properties because they are made of different types and numbers of atoms that repeat.

C. Scientists can use properties to help them distinguish (tell the difference) between different substances. 

III. Physical and Chemical Changes

A. A physical change occurs when a material changes without a chemical reaction (change in shape, phase, color).  Examples: cutting objects, boiling/freezing/melting water, painting an object a different color

B. A chemical change occurs when a new substance forms through a chemical reaction.  It can be shown as a formula: 

Reactants→ Products (Example:  CH4   +      2O2          →          CO2      +      2H2O)   

                                               Methane +  Oxygen     yields   Carbon Dioxide + Water

Examples: burning, cooking/baking, creating gas by mixing chemicals, digesting food, rust forming, food rotting/spoiling

C. The Law of Conservation of Mass states that the total number of each atom has to be the same before and after a reaction (matter is not created or destroyed)           

Organisms and Scientific Method

I. Observations and Inferences

A. Observations are made using the senses (sight, taste, touch, smell, hearing) 

B. Observations can be quantitative (numbers or measurements) or qualitative (colors, texture).

C. Inferences are conclusions based on observations.

II. Characteristics of Organisms (living things)

A. Includes the following: made of cells, use energy, maintain homeostasis, genetics (DNA), grow and develop, evolve (have adaptations), reproduce, respond to stimuli

B. Key terms include:

Homeostasis: the maintenance of a stable internal environment (examples: body temperature, heart rate) 

Adaptations: behaviors or structures that help organisms survive (examples: hibernating, gills, fur) 

Stimuli (stimulus): may cause a response

(examples: a hot stove, cold air, light)

Metabolism: converting food into energy 

III. Scientific Method

A. Series of steps taken to investigate a question or problem

B. Usually includes identifying a problem, researching, testing a hypothesis

-A hypothesis (if, then, because statement) is an educated prediction that can be tested by conducting an experiment. 

C. The last step is often to “form a conclusion” based on the data (information collected).

IV. Experiments (collecting data)

A. Contain only 1 independent variable (the difference between the groups or trials)

B. Contain a dependent variable (the observation that is measured)

C. Contain multiple control variables (stay the same in all groups or trials)

D. Valid (reliable) if they can be duplicated (repeated) by others, and the same result is found to occur.

V. Organizing Data (charts and graphs)

A. Charts list data or information in a logical order.

-On a chart, the independent variable is usually on the left and the dependent variable is usually on the right

B. Graphs show trends visually (in science line graphs and bar graphs are common) 

-On a graph, the independent variable is on the X axis and the dependent variable is on the Y axis 

-If the graph shows something occurring “over time”, then time goes on the X axis.