At the beginning of the school year, students will need the following in addition their normal individual school supplies.
A Composition Notebook (see link). You must be able to write your name on the front, and they must be non-removable sheets of paper (no spiral notebooks or perforated pages that can be torn out.
The Planbook link below, which is in red has been created especially for you! Planbook contains what was covered in class for that day, and is a valuable resource, which should be used regularly. When possible, I will attach any handouts as well.
CLICK THE LINK BELOW TO PLANBOOK FOR DAILY AGENDAS, HOMEWORK AND CLASS HANDOUTS!!!!!!
https://www.planbook.com/planbook.html?t=1106395&k=Hasley&v=W&y=1385419
Click the link below to access the online textbook which you created your own username and password for in class
https://www.hmhco.com/one
Great for review of topics covered in class Amoeba Sisters Boezman Science Crash Course Biology
Important Information of many topics we will explore!!!!
Videos
Intro To Biology https://www.youtube.com/watch?v=VgTPg99V_JM&feature=channel&list=UL
Characteristics of Life video https://www.youtube.com/watch?v=juxLuo-sH6M&feature=channel&list=UL
Intro to Water https://www.youtube.com/watch?v=nSENolWbyYQ&feature=channel&list=UL
Reflections of life Biochemistry http://www.youtube.com/watch?v=skdO7yGETdI
Various topics reviewed here http://learn.genetics.utah.edu/
Cells alive (website great for review) http://cellsalive.com/index.htm
Cell Theory video https://www.youtube.com/watch?v=4OpBylwH9DU
10 facts about cells http://biology.about.com/od/cellbiology/a/cells-facts.htm
Surface area to volume ratio (why cells are small) http://www.youtube.com/watch?v=jw0ZHLJGVTY
Surface area to volume ratio calculatorhttp://esminfo.prenhall.com/science/BiologyArchive/lectureanimations/closerlook/cellsurface.html
Osmosis animation (hyper, iso, hypo) http://www.glencoe.com/sites/common_assets/science/virtual_labs/LS03/LS03.html
Diffusion animation http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter3/animation__how_diffusion_works.html
diffusion osmosis lab simulator http://classes.midlandstech.edu/carterp/Courses/bio101/labquiz2/ss8.htm
facilitated diffusion http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_facilitated_diffusion_works.html
Intro to Photosynthesis https://www.youtube.com/watch?v=zEgIO9Kq2_Y&feature=channel&list=UL
Cell Respiration song http://www.youtube.com/watch?v=3aZrkdzrd04&feature=autoplay&list=UL4dbkAGcQ8mM&playnext=1
Polymers Monomers and Macromolecules (gangnam style) https://www.youtube.com/watch?v=4dbkAGcQ8mM&feature=channel&list=UL
Cell Parts/ Organelles Rap https://www.youtube.com/watch?v=jqUhWDp73bM&feature=channel&list=UL
Photosynthesis Rap https://www.youtube.com/watch?v=Wi60tQa8jfE
Photsynthesis and Respiration by seed https://www.youtube.com/watch?v=QMgCziQgrus&feature=related
Photsynthesis and Respiration song https://www.youtube.com/watch?v=65qBlnUTO3k&feature=related
Photosynthesis and Respiration Lecture https://www.youtube.com/watch?v=0IJMRsTcwcg&feature=related
photsynthesis water weed simulator http://www.saddleworth.oldham.sch.uk/science/simulations/waterweed.htm
light dependent reaction simulator http://www.mhhe.com/biosci/genbio/biolink/j_explorations/ch09expl.htm
Light dependent reaction simulator lab instructions http://www.biologycorner.com/worksheets/photosynthesis_sim.html
water weed report handout http://www.biologycorner.com/worksheets/waterweed_sim.html
Cell Division and Mitosis https://www.youtube.com/watch?v=Q6ucKWIIFmg
Cell Cycle Animation http://www.cellsalive.com/cell_cycle.htm
real live cell going through division http://www.youtube.com/watch?v=_pvj8Ai0j7A
Mitosis Video http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__mitosis_and_cytokinesis.html
Cell Cycle Video http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_the_cell_cycle_works.html
Mitosis and Meiosis with beads simulation https://www.youtube.com/watch?v=zGVBAHAsjJM
Intro to Meiosis https://www.youtube.com/watch?v=mKWxeMMFTEU&feature=bf_next&list=ULFpfAZaVhx3k
Meiosis Video http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter28/animation__how_meiosis_works.html
Comparing reproduction strategies read with animation http://www.nhm.ac.uk/print-version/?p=/nature-online/evolution/sexual-reproduction/index.html
ETERNA RNA molecule building game http://eterna.cmu.edu/game/puzzle/13375/
Intro to Genetics https://www.youtube.com/watch?v=B_PQ8qYtUL0&feature=channel&list=UL Mendel genetics overview clip https://www.youtube.com/watch?v=Mehz7tCxjSE
good genetics review starting with medel http://library.thinkquest.org/28751/review/heredity/1.html
medel genetics good review of topics and practice quizzes http://anthro.palomar.edu/mendel/mendel_1.htm
genetics, dihybrid cross with law of independent assortment and law of segregationhttp://www.bbc.co.uk/bitesize/higher/biology/genetics_adaptation/dihybrid_cross/revision/1/
Various Topics including DNA and genetics reviewed http://learn.genetics.utah.edu/
DNA What is it? http://www.youtube.com/watch?v=zwibgNGe4aY
Transcription (making mRNA) http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter3/animation__mrna_synthesis__transcription___quiz_1_.html
Translation Making Protein) http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter3/animation__how_translation_works.html
Protein synthesis http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter3/animation__protein_synthesis__quiz_3_.html
Intro to the origin of life https://www.youtube.com/watch?v=XvMgoelauLQ&feature=channel&list=UL
Brief overview of th 6 kingdoms of classification http://www.ric.edu/faculty/ptiskus/six_kingdoms/index.htm
Intro to Evolution https://www.youtube.com/watch?v=FpfAZaVhx3k&feature=channel&list=UL
What Is Evolution? http://www.youtube.com/watch?v=GhHOjC4oxh8
Evolution PBS series with questions http://www.biologycorner.com/worksheets/evolutionVIDEO.html
Evolution PBS Nova http://www.youtube.com/watch?v=AYBRbCLI4zU
What is Natural Selection? http://www.youtube.com/watch?v=0SCjhI86grU
Evolution of life on Earth in a day https://www.youtube.com/watch?v=H2_6cqa2cP4
What makes us human? Nova http://www.pbs.org/wgbh/nova/evolution/what-makes-us-human-pro.html
Intro to Protists https://www.youtube.com/watch?v=0-6dzU4gOJo&list=UUWxJwdNjOFOUvKAhsYo41lg&index=1&feature=plcp
Symbiosis Rap https://www.youtube.com/watch?v=xNm7dg3BiyU&feature=relmfu
Intro to Viruses https://www.youtube.com/watch?v=UEKS4w9bfJg&feature=channel&list=UL
Themes of Biology, Characteristics of Life, and Scientific Methods (Scientific Investigations)
Science is a way of understanding nature. Scientific research may begin by generating new scientific questions that can be answered through
replicable scientific investigations that are logically developed and conducted systematically. Scientific conclusions and explanations
result from careful analysis of empirical evidence and the use of logical reasoning. Some questions in science are addressed through
indirect rather than direct observation, evaluating the consistency of new evidence with results predicted by models of natural processes. Results from investigations are communicated in reports that are scrutinized through a peer review process.
The integrity of the scientific process depends on scientists and citizens understanding and respecting the “Nature of Science.”
Openness to new ideas, skepticism, and honesty are attributes required for good scientific practice. Scientists must use logical reasoning
during investigation design, analysis, conclusion, and communication. Science can produce critical insights on societal problems from a personal and local scale to a global scale. Science both aids in the development of technology and provides tools for assessing the costs,
risks, and benefits of technological systems. Scientific conclusions and arguments play a role in personal choice and public policy
decisions. New technology and scientific discoveries have had a major influence in shaping human history. Science and technology continue to offer diverse and significant career opportunities.
The basis of all scientific investigation is observation. Scientists assure the accuracy of their observations by carefully using scientific tools. Observations are often used to make inferences. An inference is an attempt to explain or interpret observations or determine the cause of what was observed.
A hypothesis is a proposed solution to a scientific problem. A hypothesis is tested through experimentation using controls and variables. Controls are the parts of an experiment which are not allowed to change and are used as standards of comparison. Variables (independent and dependent) are the parts of an experiment which are allowed to change. Independent variables are the elements of the experiment that are manipulated by the scientist. Dependent variables are the observable changes that result from the manipulation of the independent
variable.
A control group serves as a standard of comparison for testing the results of a scientific experiment on an equivalent experimental group.
In an experimental group, one or more variables are manipulated to determine the effect on another variable. The dependent variable (responding variable) is the factor a scientist observes or measures in the control group and in the experimental group to determine what
changes occur as a result of the experiment. The independent variable (manipulated variable) is the presumed cause of a change in the dependent variable. Variables can be plotted to show relationships.
Use of multiple replicates of both experimental and control groups should be done so that results can be considered valid (free from systematic error). The number of replications will depend upon resources of the scientist or school and the nature of the study. Generally, as the number of replications increases, the validity of the study
increases.
Science and technology have made it possible to deal in new ways with issues involving life and nature. These advancements have a price, and individuals and society must weigh the pros, cons, and ethical implications of decisions that are made concerning these
issues.
As scientific and technological advancements accelerate, the need for sound decision making processes concerning bioethical issues has also accelerated and will continue to increase. This need for sound decision making applies to individuals, families,
governments, and society as a whole. Accurately and effectively communicating procedures and processes allows members of the scientific community to share their work and prompts others in the field to verify and build on others’ findings. This information can then be used by society in making bioethical decisions.
Biochemistry
Living organisms are composed of cells.Water is
the primary substance in them.In addition to water, compounds
containing carbon compose the bulk of organic matter.These
carbon-containing compounds include proteins, lipids, carbohydrates, and nucleic
acids.These organic macromolecules contain subunits which include
simple sugars in carbohydrates, fatty acids in lipids, amino acids in proteins
and nucleotides in nucleic acids.
Each macromolecule is polymer composed of monomers that
include monosaccharides, fatty acids, nucleotides and amino
acids.These molecules include the elements Carbon, Hydrogen,
Nitrogen, Oxygen, Phosphorus, and Sulfur.
Polymers are produced from monomers by dehydration and
polymers can be broken down into monomers by hydrolysis.
Energy is stored in the bonds within the organic
molecules. Adenosine triphosphate (ATP) is a stored energy source. Removing a
phosphate from the molecule to form adenosine diphosphate (ADP) releases large
amounts of energy.
Proteins serve many biochemical functions in living
organisms.One of those is as enzymes, or biological
catalysts.The sequence of amino acids and the shape of the protein
affect its ability to act as a catalyst.
Living things are made up of complex molecules (carbohydrates,
lipids, proteins and nucleic acids) and their subunits. These subunits include simple sugars in carbohydrates, fatty acids in lipids, amino acids in proteins
and nucleotides in nucleic acids.
Carbohydrates are a biochemical class made up of simple sugars
which consist of a general atomic ratio of carbon (C) to hydrogen (H) to oxygen (O) of 1:2:1 (CnH2nOn). They also include polymers of simple sugars.
Carbohydrates function as short-term energy storage in the form of simple sugars and as intermediateterm energy storage as polysaccharides, specifically as starches in plants and glycogen in animals. Polysaccharides are also structural components in cells as cellulose in the cell walls of plants and many protists and as chitin in the exoskeleton of insects and other arthropods.
Lipids are involved mainly with long-term energy storage. Lipids
make up such molecules as fats, oils and waxes and also contain carbon,
hydrogen and oxygen. They are generally insoluble in polar substances such as
water. Other functions of lipids are functional, as in the case of phospholipids as the major building block in cell membranes and some kinds of hormone messengers that have a role in communications within and between cells.
Proteins are very important in biological systems as control and structural elements. Control functions of proteins are carried out by enzymes and some
kinds of hormones. Enzymes are biochemicals that act as organic catalysts to speed up the rate of a chemical reaction. These proteins are
folded in intricate ways that produce shapes that “fit” corresponding features of specific substrates. Structural proteins function in the cell as parts of
the cell membrane, muscle tissue, and connective tissue types. Proteins
are polymers of amino acids and contain, in addition to carbon, hydrogen and oxygen, also nitrogen and sometimes sulfur.
Nucleic acids are composed of very long chains of subunits called nucleotides, which contain carbon, hydrogen, oxygen, nitrogen and phosphorus. The two chief types of nucleic acids are DNA (deoxyribonucleic acid) which contains the hereditary information in all living organisms and RNA
(ribonucleic acid) which delivers the instructions coded in a cell’s DNA to its protein
manufacturing sites.
Organisms make the molecules they need or obtain them from their
diet. Specific proteins, for example, are required for specific
cellular processes. Without these proteins, or with non-functioning proteins,
certain processes may not be carried out at all.
Dehydration links smaller subunits into larger units by removing
water and forming covalent bonds. Hydrolysis is a chemical reaction in
which a compound reacts with water. This type of reaction is used to break down
larger organic molecules into smaller subunits. Dehydration and hydrolysis are
essentially the reverse of each other.
Energy is involved in the formation of chemical bonds. The
breaking and reforming of new bonds by living things often involves a transformation of
energy from higher energy bonds to lower energy bonds, allowing usable energy
to be released for use by the organism. An example of high energy bonds are
the phosphate bonds in ATP. When the third phosphate group of
ATP is removed by hydrolysis, a substantial amount of free energy is
released. For this reason, this bond is known as a “high-energy” bond.
Cell Structure and Function
All living things are made of cells and all functions occur at the cellular level. Cells contain smaller specialized structures (organelles) to carry out particular life functions. Cells replicate themselves by cell division. Cells are continuously breaking down reactants to produce chemical energy needed for all life processes (photosynthesis, respiration, food storage, and transport). Cell theory states that all living things are made of cells, cells are the basic unit of structure and function in living things, and all cells are produced from other cells.
Organisms such as the amoeba or paramecium are unicellular. Other organisms such as plants and animals are multicellular and may have billions of cells.
Multicellular organisms contain specialized cells that perform specific functions of life (e.g., blood cells carry oxygen, nerve cells carry impulses, etc.). The cells in a multicellular organism are often quite different from each other in size and structure. If a specialized cell is removed from an organism, the specialized cell would die because it can not perform all necessary life functions. However, a unicellular organism such as the amoeba can survive on its own because its one cell provides all the necessary life functions.
In multicellular organisms, specialized cells work together as tissues. Various kinds of tissues combine as organs, and different organs work together as organ systems.
Plants and animal cells are very similar in structure, each containing a cell membrane which protects and regulates access into and out of the cell and cytoplasm, living material that contains the organelles and is in constant motion to move food, oxygen, and waste in and out of the cell. Plant cells differ from animal cells in that plant cells have a cell wall for structural strength, and chloroplasts which contain chlorophyll necessary for photosynthesis.
Some organelles are the nucleus, the control center of the cell; vacuolesthat store food, water, and waste materials; chromosomes (in the nucleus) that carry the genes which transmit hereditary information; and mitochondria, considered the “power house” of the cell, the place where food is utilized to release energy.
Materials (water, salts, sugar, and nutrients) are moved into and out of cells through passive transport by osmosis and diffusion. The direction and speed at which the movement occurs depends on the concentration gradient, temperature, and size of molecules. Active transport requires energy to move large molecules across cell membranes by ectocytosis and endocytosis.
Cellular structures include: cell membranes, cell walls, chloroplasts, cytoplasm, Golgi apparatus, mitochondria, nucleus, ribosomes, and vacuoles.
“Endosymbiotic theory, which proposes the chloroplasts and mitochondria were once free-living prokaryotes that developed such close relationships with early cells and that they were eventually taken in as substructures, represents a major step in the evolution of eukaryotes, since it couples energetic processes to cell function. Evidence for the theory is striking:
• chloroplasts and mitochondria both contain circular DNA, similar to prokaryotes
• their cell membrane structures are similar to prokaryotes
• they reproduce by binary fission, as do prokaryotes
• their ribosomes are similar in structure to prokaryotes
Cell Websites
http://www.cellsalive.com/cells/3dcell.htm (Cell structure and Function models and animations)
http://micro.magnet.fsu.edu/cells/bacteriacell.html (Bacterial cell structure)
http://facstaff.gpc.edu/~pgore/students/w96/joshbond/symb.htm (Endosybiosis)
Photosynthesis and Respiration
Living organisms obtain and use energy. They are continually converting
energy and matter. Plants are producers. They convert the energy from the sun
(using water and carbon dioxide) into sugars. With the energy from the sun and
nutrients from the soil, they also produce fats and proteins. Animals are
consumers. They use the energy from the plants to sustain life.
Cells transform energy from one form to another through the processes of
photosynthesis and respiration. The mitochondria are the organelles in animal
cells responsible for energy transformation. In plants, both Chloroplasts and
Mitochondrion fill that role.
Photosynthesis takes place in the chloroplasts and cellular respiration
occurs in the mitochondria. Both are important to the production of ATP. ATP are
molecules containing high-energy phosphate bonds whose energy is released to
perform various functions in the organism.
Photosynthesis is the process by which ATP (as harnessed through the
sunlight) combines with carbon dioxide and water is converted into glucose and
oxygen. Cellular respiration is the reverse reaction, where glucose and oxygen
are converted into ATP, carbon dioxide and water.
Respiration and photosynthesis are components of the oxygen-carbon cycle,
enabling organisms to carry on life functions. Photosynthesis is a basic
cellular process by which the Sun’s energy is converted and stored as chemical
energy. Respiration is a process by which chemical energy is released for
cellular activities.
Adenosine triphosphate (ATP) is a stored energy source. Removing
a phosphate from the molecule to form adenosine diphosphate (ADP)
releases large amounts of energy
Students should identify the reactants and products in the process of
photosynthesis and respiration.
Anerobic vs. Aerobic Respiration
Compare and contrast the energy needs of unicellular organisms vs the energy
needs of multicellular organisms and explain why unicellular organisms can
survive on 2 ATPs vs. mulitcellular organisms requiring 38 ATPs to survive. Do
multicellular organisms go through a process of anaerobic respiration? (Yes)
Students should know that anaerobic respiration initiates the mitochondria to
start the process of aerobic respiration and the storage of energy via ADP to
ATP (the bonds in the compound). This makes a connection to B2.4f. (Consider
using the metaphor of kick-starting a Harley Davidson motorcycle to the
initiating of the mitochondria.)
Consider the metaphor of a rechargeable battery to the process of storing
energy in the cells. Both plants (carbohydrates) and animals (lipids) store
energy in cells. Why does a marathon runner eat a lot of pasta the day before
the race? Why do elite athletes train at high altitudes? (Increase oxygen
available for respiration) Use the process of respiration to describe how
individual cells break down energy-rich molecules to provide energy for cell
functions. (B2.5D)
Discuss cramping in one’s side when running due to
lack of oxygen in muscle cells. (lactic acid storage following anaerobic
respiration)
Photosynthesis
6CO2 + 6H2O ----> C6H12O6 + 6O2
(in the presence of chlorophyll and sunlight) (In chloroplast)
Respiration
C6H12O6 + 6O2 ---> 6CO2 + 6H2O + energy(ATP)
(IN The Mitochondria)
Function of ATP
Adenosine-P~P + P + energy --> Adenosine-P~P~P
Energy Transfer
Plants are producers, converting energy from sunlight into food. Animals are consumers;
they need to obtain energy by eating other organisms. The variety of organisms
in an ecosystem depends on biotic and abiotic factors. Populations of organisms
are interdependent.
Energy initially obtained from the sun is transformed through the
processes of photosynthesis. Nutrients and water obtained from the soil are
converted by the captured radiant energy into chemical energy which is stored in
the form of sugars.
The opposite reaction, cellular respiration, releases the stored energy.
Energy moves through the ecosystem via food chains. Nutrients are cycled through
the ecosystem.
Organisms can be organized into producers, consumers, and decomposers
according to their role in these cycles.
Foods used by living things are the direct or indirect products of
food-making organisms (plants/autotrophs) and are transferred in ecosystems
through food chains and food webs. Foods are consumables containing usable
organic compounds needed to support life (chemical definition) or the source of
energy and raw materials for cellular functions (biological
definition).
Changing Environments
Succession is a series of predictable changes in an ecosystem community over a long period of
time. Length of time varies depending upon the plant and animal species involved
and many environmental factors which impact the succession. These factors
include climate (temperature, moisture), wind, water, living things,
competition, physical barriers (oceans, mountains, etc.), human activities
(pollution, industry, agriculture, mining, other land uses).
Types of succession:
Primary - establishment of an ecosystem in
a barren environment with initial invasion of pioneer species, e.g., beach or
blown-out dune starting to grow beach grass and other pioneer species. Part of
Drummond Island is an example of the primary succession stage.
Secondary - reestablishment of an ecosystem that was originally
present after a disturbance of an existing ecosystem occurs (e.g., an abandoned
agricultural field eventually reverts to broadleaf trees in deciduous forests)
or the gradual change from a primary environment towards a climax environment
(e.g., intermediate stage when a beach changes to oak/maple/beech forest).
Stages of succession:
Pioneer stage - new species invade sand
or bare rock to begin primary succession.
Intermediate stages follow, leading to the climax community.
Climax community - the endpoint stage of succession in which all
species present reproduce in proportion to one another and no further change
occurs (e.g., hardwood forest, alpine meadow).
Succession results in the disturbance of the status quo in an environment,
with new species moving in and established species moving out or dying out as
conditions change.
Classification
Students should have the opportunity to learn about a wide variety of organisms, both familiar
and exotic, and should become more precise in identifying their similarities and
differences. They should begin to switch their attention from external
characteristics to internal structure and function. Students should develop an
understanding of the classification system used in modern biology, how it was
developed and why certain features are used to classify organisms.
Classification systems are not part of nature but are tools designed by
biologists to aid in describing the immense diversity of living things. In
classifying organisms, scientists consider details of internal and external
structure and function, ribosomal RNA, and genes at the molecular level to be
more important than appearance or behavior (adapted from Benchmarks
for Scientific Literacy). Similarities among organisms are found in
anatomical features, which can be used to infer the degree of relatedness among
organisms. Living things can be classified based on structural, embryological, and
molecular (relatedness of DNA sequence) evidence. Shared characteristics include
physical, biochemical, genetic, and cellular characteristics. Species are
reproductively distinct groups of organisms that can be classified based on
morphological, behavioral, and molecular similarities. The degree of kinship
between organisms or species can be estimated from the similarity of their DNA
and protein sequences.
Swedish botanist Carolus Linnaeus developed the binomial
classification system based on organisms’ structures and functions in which he
placed all organisms into plant or animal kingdoms. Each organism was further
classified into differentiated categories using more precise criteria. The
classification groups form a hierarchy with the largest groups being the most
general and the smallest the most specific.
Classification categories have been disputed ever since
Linnaeus did his original work. For the purposes of this unit, the Six Kingdom
system will be used. Conceptually, this system is more understandable to this
level of student and better achieves the goals of observation and classification
than other systems that could have been used.
Plants can be classified as vascular and non-vascular.
Vascular plants have specialized cells which transport liquids within the plant.
An organism has unique characteristics that enable it to live
in its environment. In response to changes in an environment, organisms evolve,
or change, over time. Organisms whose characteristics are well-suited for their
environment have a tendency to survive and produce offspring. The offspring
inherit these characteristics and pass them to their offspring when they
reproduce. The characteristics that did not prepare them well for survival will
disappear with them. This is survival of the "most fit."
Evolution
Natural selection includes four basic concepts: 1.) the potential for a population to increase its numbers, 2.) the genetic variability
of offspring due to mutation and recombination of genes, 3.) a finite supply of
resources required for life and 4.). The ensuing selection from environmental
pressure leaves some of those organisms better able to survive and leave
offspring. (Michigan Curriculum Framework, 1996 and Michigan Biology Companion
Document, 2007)
Evolution provides scientific explanations for life history on
Earth. Evolution is depicted in the fossil record and in similarities evident
within the diversity of existing organisms. Evolution generally results from
three processes: random mutation to genetic material, random genetic drift, and
non-random natural selection within populations and species. These three
processes result in major consequences, including the diversification of all
forms of life from shared ancestors, and observable changes in the fossil record
over long periods of time. Some examples of modern evolutionary changes in
populations relating to natural selection are evident today (e.g., development
of insect resistance to pesticides, bacterial resistance to antibiotics and
viral strains).
There are many sources of similarities among all living organisms. They are
due to common ancestry and the more closely related organisms share more recent
common ancestors. Molecular evidence, shown by DNA similarity, supports the
anatomical evidence for evolution and provides substantial detail about the
branching of various lines of descent.
Natural selection provides the following mechanism for evolution: some variation in heritable traits exists
within any given species. Some of these characteristics give individuals an
advantage in surviving and reproducing more offspring and those offspring, in
turn, are more likely to survive and reproduce successfully. Over time, the
proportion of these advantaged individuals in the population will increase.
Since mutations occur randomly and are selected for if they help organisms
survive and reproduce more successfully in their environment, the population
changes as a result of this selection. Of course, those individuals that inherit
traits that are selected against, are not as successful reproductively and
eventually these traits may even die out of the population.
Fundamentals of Genetics
Characteristics of living organisms are influenced by both heredity and environment.
Genes are segments of chromosomes that determine the exhibited traits of
individuals.
Chromosomes, which are made of both DNA and protein, are organized as
homologous pairs. The number of pairs is the “n” number. The number of
chromosomes in a non-mitotic somatic cell is “2n.” One chromosome for each pair
is obtained from each parent. A trait is determined by the coordinating genes in
the pair.
A given gene can be dominant, recessive, or codominant. Some traits are
polygenic, determined by more than one gene pair. Sex-linked traits are
determined by genes located on the chromosomes which also determine whether an
organism is male or female.
During meiosis, the production of egg or sperm, an individual’s homologous
pairs are separated, and randomly assorted.
Characteristics of living things are passed on from generation to generation.
Traits (dominant or recessive) are controlled by genes which usually act/occur
in pairs. Dominant genes are expressed or acted upon, while recessive genes are
masked or hidden in gene pairs.
Genetics uses the principles of probability to predict the phenotypes and
genotypes that result from genetic crosses. A graphic device called the Punnett
square can be used to show all possible gene combinations (genotype and
phenotype) from a cross.
Genetic material, DNA, replicates during cell division and is passed
from parent to offspring during sexual and asexual reproduction (see Biology:
Organization and Development of Living Systems - Cells Structure and Function).
Asexual reproduction allows for limited variation in species producing clones of
the parent cell where in sexual reproduction, genes of parents are randomly
distributed in sex cells creating genetic variations within a species. Sexual
reproduction and mutations provide adaptive traits in a species and encourage
evolutionary change through natural selection.
DNA Structure, RNA Structure, DNA Replication, Protein Synthesis (Transcription and Translation)
The biochemical identity of an organism is determined by its DNA, which is characteristic for
each species and sometimes for each individual within that species. DNA contains
the directions for making all the protein types required by individuals to
express their heredity. The function of each protein molecule depends on its
specific sequence of amino acids and the shape of the molecule. These proteins
are characteristic of each species and many of them, enzymes, in particular, are
responsible for allowing individuals to express genetic traits specific to each
species.
DNA duplication in cell division involves the copying of all genetic material
for descendent cells, whereas the process of gamete formation involves the
apportioning of DNA to eggs/sperm with only half the DNA. The processes of DNA
duplication, transcription and translation are very complex, but provide the
basis for the central dogma of biology – that in most cases, DNA information is
copied onto messenger RNA by the process of transcription and proteins are
synthesized using messenger RNA as a template and transfer RNA as delivery
molecules that bring the appropriate amino acids to the ribosome for assembly.
This process is called translation.
When errors occur in any of the processes described above, the results may
be positive, negative or neutral to the organism and/or its offspring. Mutations
may result in changes in structure that render the protein non-functional, or
they may result in insignificant changes that do no harm to the functioning of
the protein and hence its expression in the individual. There are a number of
common diseases that are inherited by offspring of parents who carry faulty
genes. These include: sickle cell anemia which results in the manufacture of
defective hemoglobin by the victim’s red blood cells, phenylketonuria, a disease
that results in the inability of a victim’s liver to metabolize a common amino
acid and cystic fibrosis, a disorder that causes lung damage in affected
people.
Cell division Mitosis and Meiosis
Organisms are made of cells. Multicellular organisms have cells specialized
with regard to function. Cells are organized in tissues, organs and systems to
obtain food, air, and remove waste.
Living organisms reproduce. That reproduction can be either sexual or
asexual. Sexual reproduction takes the genetic information from two parents and
asexual results in an identical copy to one parent.
Cell division occurs due to the cell's needs for materials inside the cell.
The cell needs to maintain a workable ratio of cell volume to surface area of
the cell membrane. If the volume becomes too great, the cell cannot move
sufficient materials in or waste out. The cell then either stops growing, dies
or reproduces to create two cells, each with a smaller ratio of volume to
surface area.
Asexual reproduction (mitosis) creates new exact genetic cell copies of
the parent cell. This process is a disadvantage in that it only allows limited
species variation; change occurs over long time periods. An advantages of
asexual reproduction is that the organism does not put its energy into
maintaining a reproductive system, producing sex cells, finding a mate, and
mating. Another advantage is that isolated individuals
of the species (or the last existing individual) can
reproduce.
Although mitosis is presented as a series of steps, it is actually a
continuous process where the steps blend from one to the next.
In sexual reproduction, new cells are created from the union of two parent
cells, each of which has gone through specific changes (meiosis) to halve the
number of chromosomes it contains (haploid number). The original (diploid)
chromosome number is reestablished when the union of egg and sperm
occurs, with genetic material from each parent being passed along to the
offspring. Human body (somatic) cells contain 46 chromosomes, but
the number of chromosomes in human gametes, or reproductive
cells, is 23. When the human sperm and egg unite, the number of
chromosomes in the new cell is 46. The number of chromosomes in cells differs
from species to species.
Change within a species can take a shorter period of time as a result of
sexual reproduction than asexual reproduction, due to variations in genetic
makeup which occurs in the offspring. This process allows for more mutations and
thus more diversity within the population, which provides greater capacity of
the species to adapt to environmental changes. The need to use energy to produce
sexual organs, offspring, and finding mates is a disadvantage of sexual
reproduction.