DNA has a role in making Proteins that determine organism traits 

• The structure and function of DNA are intimately linked.
• DNA is a double helix molecule containing a specific sequence of nitrogenous bases which create a code for making proteins.
  
  • Proteins are used to build cells, tissues, organs, and to perform life processes.
• Chromosomes are strands of tightly wound DNA.
  • Genes are sections of a chromosome that carry the code for a particular protein.
  • Each gene controls the production of specific proteins, which in turn affects the traits of the organism.

• Proteins carry out most of the work of cells to perform life functions .
• DNA provides the code that tells the cell exactly which proteins to make.
  • The sequence of the bases A, T, C, and G along a section of DNA forms a code to make each protein .
  • The sugar and phosphate molecules on the sides of the DNA molecule are always the same for all living things, so when scientists write out the DNA code, they write only the sequence of the pairs of nitrogenous bases in the center (i.e., on the rungs) of the ladder-like DNA molecule.
• A series of contributions and discoveries has led to our current understanding of DNA, genes, chromosomes, and traits.
  • This process illustrates the nature of science.

You should be able to:
• describe the structure and function of DNA  
• explain the relationship among genes, chromosomes, and alleles  
• explain that DNA contains coded instructions that store and pass on genetic information from one generation to the next

Meiosis - to transfer traits to the the next generation

• A complex system functions to pass characteristics (traits) from one generation to the next.
• The interaction of heredity mechanisms and the environment creates both stability from one generation to the next and drives the changes that produce the diversity of life on our planet.
• Living organisms must reproduce to continue the existence of their species.

• Through reproduction, new individuals that resemble their parents are formed.
• All the organisms alive today arose from preexisting organisms.
• Reproduction is a life process (system) by which living things transfer genetic information to their offspring.
• Sexual reproduction involves the production of sex cells through meiosis.
• Sex cells each carry half the parent's genetic material, resulting in variation between parent and offspring .
• During meiosis, chromosome pairs independently become distributed so that each sex cell contains one-half of the chromosomes of the original cell.
• The probability of a sex cell containing either allele from the pair is 50 percent.
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Punnett Squares are mathematical models used to predict the Probability of Traits in offspring

• The Punnett square is one mathematical model that predicts the probability of the genotype (genetic makeup) and phenotype of the offspring of a cross between parents.
  • A Punnett square predicts the probability of the ratios of genotypes and phenotypes among offspring.

• Traits that are expressed through genes can be inherited.
  • Characteristics that are acquired through environmental influences, such as injuries or practiced skills, cannot be inherited.
• The basic laws of Mendelian genetics explain the transmission of most traits that can be inherited.
  • Genotype refers to the specific combination of genes.
  • Phenotype refers to the physical expression of traits.
  
  • Dominant traits mask the expression (phenotype) of recessive traits.

You should be able to:
• describe why asexual reproduction results in offspring with identical genetic information and sexual reproduction results in offspring with genetic variation 
• explain the significance of gametes contributing half of their genetic material through sexual reproduction
• know types of characteristics that can be inherited and those that cannot be inherited 
• distinguish between dominant and recessive traits
• use Punnett squares to predict the possible genetic combinations and phenotype expressions from single trait crosses using dominant and recessive traits