1. d. Students know the central dogma of molecular biology outlines the flow of information
from transcription of ribonucleic acid (RNA) in the nucleus to translation of proteins on
ribosomes in the cytoplasm.
DNA, which is found in the nucleus of eukaryotes, contains the genetic inforÂ¬mation for encoding
proteins. The DNA sequence specifying a specific protein is copied (transcribed) into messenger RNA
(mRNA), which then carries this message out of the nucleus to the ribosomes located in the cytoplasm.
The mRNA message is then translated, or converted, into the protein originally coded for by the DNA.
1. e. Students know the role of the endoplasmic reticulum and Golgi apparatus in the
secretion of proteins.
There are two typesâ€”rough and smoothâ€”of endoplasmic reticulum (ER), both of which are systems
of folded sacs and interconnected channels. Rough ER synthesizes proteins, and smooth ER modifies
or detoxifies lipids. Rough ER proÂ¬duces new proteins, including membrane proteins. The proteins to
be exported from the cell are moved to the Golgi apparatus for modification, packaged in vesicles, and
transported to the plasma membrane for secretion.
1. f. Students know usable energy is captured from sunlight by chloroplasts and is stored
through the synthesis of sugar from carbon dioxide.
Photosynthesis is a complex process in which visible sunlight is converted into chemical energy in
carbohydrate molecules. This process occurs within chloroplasts and specifically within the thylakoid
membrane (light-dependent reaction) and the stroma (light-independent reaction). During the light-
dependent reaction, water is oxidized and light energy is converted into chemical bond energy
generating ATP, NADPH + H+, and oxygen gas.â€ During the light-independent reaction (Calvin
cycle), carbon dioxide, ATP, and NADPH + H+ react, forming phosphoglyceraldeÂ¬hyde, which is
then converted into sugars. By using a microscope with appropriate magnification, students can see the
chloroplasts in plant cells (e.g., lettuce, onion) and photosynthetic protists (e.g., euglena).
â€ ATP is adenosine triphosphate, and NADPH is reduced nicotinamide adenine dinucleotide
Students can prepare slides of these cells themselves, an activity that provides a good opportunity to
see the necessity for well-made thin sections of specimens and for correct staining procedures.
Commercially prepared slides are also available. By observing prepared cross sections of a leaf under
a microscope, students can see how a leaf is organized structurally and think about the access of cells
to light and carbon dioxide during photosynthesis. The production of oxygen from photosynÂ¬thesis
can be demonstrated and measured quantitatively with a volumeter, which can collect oxygen gas from
the illuminated leaves of an aquatic plant, such as eloÂ¬dea. By varying the distance between the light
source and the plant, teachers can demonstrate intensities of the effects of various illumination. To
eliminate heat as a factor, the teacher can place a heat sink, such as a flat-sided bottle of water,
between the plant and light source to absorb or dissipate unwanted heat.
1. g. Students know the role of the mitochondria in making stored chemiÂ¬cal-bond energy
available to cells by completing the breakdown of glucose to carbon dioxide.
Mitochondria consist of a matrix where three-carbon fragments originating from carbohydrates are
broken down (to CO2 and water) and of the cristae where ATP is produced. Cell respiration occurs in
a series of reactions in which fats, proÂ¬teins, and carbohydrates, mostly glucose, are broken down to
produce carbon dioxÂ¬ide, water, and energy. Most of the energy from cell respiration is converted
into ATP, a substance that powers most cell activities.
1. h. Students know most macromolecules (polysaccharides, nucleic acids, proteins, lipids) in
cells and organisms are synthesized from a small collection of simple precursors.
Many of the large carbon compound molecules necessary for life (e.g., polysacÂ¬charides, nucleic
acids, proteins, and lipids) are polymers of smaller monomers. Polysaccharides are composed of
monosaccharides; proteins are composed of amino acids; lipids are composed of fatty acids, glycerol,
and other components; and nucleic acids are composed of nucleotides.