John Levasseur Springfield Central High School

Central Concepts: Genes allow for the storage and transmission of genetic information. They are a set of instructions encoded in the nucleotide sequence of each organism. Genes code for the specific sequences of amino acids that comprise the proteins characteristic to that organism. 3.1 Describe the basic structure (double helix, sugar/phosphate backbone, linked by complementary nucleotide pairs) of DNA, and describe its function in genetic inheritance. 3.2 Describe the basic process of DNA replication and how it relates to the transmission and conservation of the genetic code. Explain the basic processes of transcription and translation, and how they result in the expression of genes. Distinguish among the end products of replication, transcription, and translation. 3.3 Explain how mutations in the DNA sequence of a gene may or may not result in phenotypic change in an organism. Explain how mutations in gametes may result in phenotypic changes in offspring. 3.4 Distinguish among observed inheritance patterns caused by several types of genetic traits (dominant, recessive, codominant, sex-linked, polygenic, incomplete dominance, multiple alleles). 3.5 Describe how Mendel’s laws of segregation and independent assortment can be observed through patterns of inheritance (e.g., dihybrid crosses). 3.6 Use a Punnett Square to determine the probabilities for genotype and phenotype combinations in monohybrid crosses.

GeneticsGenetics is the study of genes, sections of DNA that determine the production of proteins and heritable traits of organisms from one generation to the next. We studied molecular genetics when we introduced the Central Dogma, how DNA' s coded message is used as a blueprint for protein production. v=MvuYATh7Y74

As you recall the proteins produced by cells can differ slightly due to mutations in the DNA. These mutations allow for variety in any trait that we find in organisms. We will now look at how these proteins determine organisms' traits (appearances or behavior). We will see how Father Gregor Mendel discovered the laws of how traits are passed from one generation to the next in sexually reproducing organisms. Mendel used peas in his experiments, but the laws of how peas inherit traits hold true for the other sexually reproducing organisms. We will also discuss and learn the mathematical basis for understanding genetics

The Central Dogma of Biology: How DNA make us related to all living things and how DNA determines who we are and how living things interact with their environment. The Central Dogma Of Biology: Central Dogma Of Biology DNA is Replicated into more DNA DNA is Transcribed into RNA RNA is Translated into Proteins Molecular Genetics Molecular genetics (the study of DNA) and the central dogma of biology: How DNA makes us related to all living things and how DNA determines who we are and how we interact with our ecosystem. Gene Expression Animation

DNA, (Deoxyribonucleic Acid), is the molecule of heredity. Deoxyribonucleic Acid DNA is in the group of organic molecules called nucleic acids. DNA stands for DeoxyriboNucleic Acid Nucleic Acids are macromolecules made up of subunits called nucleotides. GenesGenes are sections of a long DNA molecule that encode the directions for a particular protein. Genes are coded messages of how, when and where to make proteins.

In eukaryote cells DNA is found in the nucleus either in chromatin or in chromosomes. This DNA replicates itself before the cell divides.eukaryote Chromatin is DNA unraveled in the nucleus; a chromosome is DNA wrapped around protein spools in the nucleus. chromosome During S- Phase of a cell's life, DNA is replicated for new cells.S- Phase DNA makes more DNA The information stored in DNA's chemical code is transcribed into RNA, (ribonucleic acid)ribonucleic acid RNA delivers the DNA's information to the site of protein synthesis RNA stands for: RiboNucleic Acid RNA delivers the DNA’s information to the site of protein synthesis. There are two types of RNA that we'll discuss: messenger RNA, (mRNA) is a strand of nucleic acid with the DNA's information on the order of amino acids for a certain protein encoded on it transfer RNA, (tRNA) has an anti-codon The DNA’s info on the RNA is translated into protein from nucleic acid. Proteins are chains of amino acid links. There are 20 different amino acids. Different proteins have a different order of their amino acids. So what kind of protein is determined by the amino acid order?

Mutations during DNA replication cause changes to DNA nucleotides’ base order, changes the mRNA codons, which changes amino acid order, which changes protein’s form and function. All of the phenotype variations seen in organisms are caused by changed in DNA, which cause changes to proteins.phenotype These changes (mutations) in DNA also cause the variations between organisms as well. Some phenotypes variations are going to be more successful or less successful in a particular environment.

Gregor Mendel and the 2 Laws of Heredity : (from: The Law of Segregation: two alleles separate during gamete formation (a Tt parent can produce both T sperm, and t sperm) A punnet square is a representation of this law, showing how gametes separate and then come together during fertilization 2.The Law of Independent Assortment: each pair of alleles segregates independently of other pairs of alleles (this law evidence by dihybrid crosses) Dihybrid Crosses Tutorial on Genetics

Gregor Mendel used pea plants for his experiments to discover the laws of heredity. Pea plants have some good qualities that allowed Mendel to be successful. Mendel crossed pea plants differing in one trait (flower color, pea color, pea shape, pod shape, pod color, etc.). One form of the trait disappeared until the second generation offspring. Mendel formed his Law of Segregation to explain these observations. Step by Step Animation See and hear this animation om/watch?v=Mehz7t CxjSE

Mendel formulated his Law of Independent Assortment to explain that separate traits are inherited independently. Example: Pea shape and pea color are independently inherited. Mendel's principle of independent assortment states that during gamete formation the alleles in one gene segregate and pass into gametes independently of the alleles in other genes. In a dihybrid cross, the F 2 generation will display four phenotypes in a 9:3:3:1 ratio. Independent Assortment Narrated Animation

Genes are sections of DNA strands found on the chromosomes. 1 gene, 1 protein, (usually). Genes may have more than one form. The different forms of a gene are called alleles. Example: a plant may have a flower color gene and that gene may have the allele for white or for purple. Since many organisms have two of every chromosome they have 2 copies of every gene. So sometimes both copies of the gene have the same allele. Other times two copies of the gene have differing alleles. The possible outcomes of differing alleles: One allele dominant One allele recessive Co-dominant An allele can be dominant (seen) or recessive (unseen), or the alleles can be equally dominant.

Events in genetics are governed by the mathematical laws of probability. We can use Punnett Squares (a math matrix) to solve genetics problems. The Bell Curve is also a way to mathematically model events in genetics

Incomplete dominanceIncomplete dominance is a condition when neither allele is dominant over the other. The condition is recognized by the heterozygotes expressing an intermediate phenotype relative to the parental phenotypes. If a red flowered plant is crossed with a white flowered one, the progeny will all be pink. When pink is crossed with pink, the progeny are 1 red, 2 pink, and 1 white.* We will study some genetic crosses that appear not to adhere to Mendel’s laws. Example: Animation of Incomplete dominance

* From Multiple alleles Many genes have more than two alleles (even though any one diploid individual can only have at most two alleles for any gene), such as the ABO blood groups in humans, which are an example of multiple alleles. Multiple alleles result from different mutations of the same gene. Coat color in rabbits is determined by four alleles. Human ABO blood types are determined by alleles A, B, and O. A and B are codominants which are both dominant over O. The only possible genotype for a type O person is OO. Type A people have either AA or AO genotypes. Type B people have either BB or BO genotypes. Type AB have only the AB (heterozygous) genotype. The A and B alleles of gene I produce slightly different glycoproteins (antigens) that are on the surface of each cell. Homozygous A individuals have only the A antigen, homozygous B individuals have only the B antigen, homozygous O individuals produce neither antigen, while a fourth phenotype (AB) produces both A and B antigens.

Polygenic inheritancePolygenic inheritance is a pattern responsible for many features that seem simple on the surface. Many traits such as height, shape, weight, color, and metabolic rate are governed by the cumulative effects of many genes. Polygenic traits are not expressed as absolute or discrete characters, as was the case with Mendel's pea plant traits. Instead, polygenic traits are recognizable by their expression as a gradation of small differences (a continuous variation). The results form a bell shaped curve, with a mean value and extremes in either direction. Skin color and height in humans are both polygenic traits. As you may recall, if you line up the entire class a continuum of variation is evident, with an average height and extremes in variation, very short to very tall. Traits showing continuous variation are usually controlled by the additive effects of two or more separate gene pairs. This is an example of polygenic inheritance. The inheritance of EACH gene follows Mendelian rules. Traits are usually quantified by measurement rather than counting. Two or more gene pairs contribute to the phenotype. Phenotypic expression of polygenic traits varies over a wide range.

There are certain genes that are linked to certain chromosomes. In humans, males have one X Chromosome and one Y chromosome, while females have two X chromosomes. This means that males will be more likely to have the phenotype of the gene’s allele passed on by the mother’s X Chromosomes. Examples of Sex Linked genes: Male Pattern Balding Hemophilia Color Blindness

What is the basic structure of DNA? What the basic process of DNA replication? What is genetics? What is molecular genetics? What is incomplete dominance? How is human blood type inherited? What are some examples of polygenic inheritance? How do mutations in the DNA sequence of a gene effect results in phenotypic change of an organism ? What are sex linked genes? What is Mendelian genetics? Who was Gregor Mendel? What are genes? How does math help explain genetics? What are the two laws of genetic inheritance?