Unit Topic Rationale:
INTRODUCTION
The unit topic chosen is called Chemistry of Life. DNA is the genetic material and basis
of all life. All living things possess DNA, must be able to replicate it properly and pass genetic
material off to offspring in order to be considered living. It covers several topics addressed in the
state standards under life science and also the nature of science.
SEQUENCE OF CURRICULAR EVENTS
This unit must be accurately placed within the school year because it discusses difficult
and abstract concepts that have not yet be introduced to students in great detail. The students
have already been exposed to units covering the basics and nature of science, ecology, botany,
and cytology. The course has been designed to start broad and slowly get more specific, so
students will be able to better grasp these concepts. Under the nature of science unit students
learned about the scientific method students learn how to conduct controlled experiments, and
about the characteristics of life. By placing this unit at the beginning of the school year students
are able to conduct and analyze experiments through the rest of the semester while also
demonstrating the nature of science. Students also understand DNA is the genetic basis that
makes up all life.
The second unit covered was Ecology. Ecology is a rather broad topic covering nutrient
cycles, relationships among living organisms, and relationships between living and nonliving
objects. By covering nutrient cycles students understand without the recycling of carbon,
hydrogen, oxygen, phosphorous, and nitrogen life would cease to exist. All of these compounds
make up DNA, RNA, and proteins which on non-living objects that make up living objects. The
next unit covered was Botany in which students learned about photosynthesis and respiration.
Respiration provides useable energy for a cell to undergo cellular processes such as DNA
replication, RNA replication and protein synthesis.
The unit covered before Chemistry of Life is cytology. Cytology is the study of the cell.
Students learn about cell parts and their functions. Students have learned about cell parts like the
nucleus where DNA is stored and replication and about ribosomes where protein synthesis
occurs. Students must know the function of these organelles before they learn about the
chemistry of life. In the cytology unit students also learn about cell processes such as cell
transport and cell division. In cell division DNA is replication and identical strands of DNA are
passed down to a daughter cell. Students understand prior the Chemistry of Life unit that a cell
must replicate its DNA before it can divide and produce another cell. After the units Nature of
Science, Ecology, Botany, and Cytology students will have enough background knowledge to
begin studying the Chemistry of Life.
The unit placed after Chemistry of Life is Genetics. In the genetics unit students learn
about how DNA helps a cell function and what happens when DNA is damaged or improperly
replicated. It students will be able to see how the genetic make-up of DNA is the instruction for
all living organisms and also that DNA is the basis for evolution and change in species over time.
By placing the units in this order students will be able to connect among the content addressed in
the curriculum and state standards.
The majority of the unit is spent addressing DNA replication, RNA synthesis, and protein
synthesis to emphasize the central dogma of life. The beginning of the unit is briefly spent
covering basic chemistry to ensure students understand the types of bonds present in DNA, RNA,
and protein synthesis and how those bonds are made. The unit also covers the structure of water
and how without water life would cease to exist. The unit also covers macromolecules and their
functions. After students know the function of macromolecules they will be able to learn some
macromolecules make up DNA and protein. Most of the lessons in this unit are spent in a
cohesive nature covering DNA replication, transcription, and translation because these concepts
refer to the central dogma which a key concept to understand in Biology. The central dogma
relates to how organisms survive, are considered living, how abiotic and biotic factors interact
with one another, how DNA is passed down from generation to generation, and how DNA is the
foundation of evolution.
STANDARDS ADDRESSED
Two standards and several benchmarks under the Colorado Department of Education’s Science
state standards are met in the Chemistry of Life Unit. In the following table standard one and
standard three are listed along with the benchmarks met in the unit under grades 9-12
STANDARD
ADDRESSED
Benchmark
met under
standard
STANDARD 1: Students apply the
processes of scientific investigation and
design, conduct, communicate about, and
evaluate such investigations.
STANDARD 3: Life Science:
Students know and understand the
characteristics and structure of living
things, the processes of life, and how
living things interact with each other
and their environment. (Focus:
Biology-- Anatomy, Physiology,
Botany, Zoology, Ecology)
Benchmark 1: ask questions and state
Benchmark 3: there is a purpose of
hypotheses using prior scientific knowledge to
help design and guide development and
implementation of a scientific investigation
synthesis and breakdown of
macromolecules in an organism (for
example: carbohydrates, lipids, amino acids
serve as building blocks of proteins; carbon
dioxide and water are the basic materials for
building sugars through photosynthesis)
Benchmark 9: cellular organelles have
specific functions (for example: the
relationship of ribosomes to protein, and the
relationship of mitochondria to energy
transformation)
Benchmark 11: DNA has a general
structure and function and a role in heredity
and protein synthesis (for example:
replication of DNA and the role of RNA in
protein synthesis)
Benchmark 5: construct and revise scientific
explanations and models, using evidence, logic,
and experiments that include identifying and
controlling variables
Benchmark 6: communicate and evaluate
scientific thinking that leads to particular
conclusions
SIGNIFICANCE OF THE CHEMISTRY OF LIFE
The significance of this topic globally is simple. Biology is the study of life and without the
genetic information stored in DNA all life would lose all of its instruction and lose the ability to
function, evolve, adapt, pass on genetic information, and reproduce. If cells in living organisms
are unable to undergo the processes of DNA replication, RNA transcription, and protein
synthesis properly cells will eventually die. Errors in DNA replication that may be created by
mutations are essential for scientists and doctors in studying genetic disorders. By understanding
the process of DNA replication, RNA transcription, and protein synthesis doctors and scientists
may better understand ways to genetically modify organisms, cure diseases, and invent new
medicines to help those with genetic disorders. DNA is the basis of evolution. The earth has
existed for billions of years. The organisms first present on Earth were small, simple
microorganisms only one cell big. Over billions of years the process of natural selection has
acted on the DNA and genetic material of living organisms. Today, in special thanks to DNA and
evolution, humans and other large, intellectual, functioning species make up the world as known
to all. In the big picture of Biology DNA is the basis for life, for genetics, and for evolution.
Personally, this topic has always been intriguing. When I was younger I always looked at
everything around me and observed it scientifically. More than anything, I wanted to know why
do we look the way we look and how does this happen. Little did I know, molecules and
compounds like DNA and proteins within my cells are the reason for people’s appearance,
actions, decisions, movements, and existence of life. When I pursue my master’s degree in
graduate school I plan on study Biochemistry and these processes present in this unit. While
studying Biochemistry I hope to study what goes wrong within these chemical processes and
how scientists may be able to fix them.