1. Genes
Subtitle

2. Genes are the basic unit of inheritance by which characteristics are passed on from one generation to another.
DNA-Deoxyribonucleic acid, contains instructions in the form of 4 chemicals which act as code letters.
DNA forms double helix and has 4 bases- Adenine (A), guanine(G), cytosine(C), thymine(T). They form pairs, A and T; G and C.
Chromosomes – long strands of DNA. In each cell, the nucleus has 46 chromosomes, 23 from mother and 23 from father.

3. Trait- Physical characteristics that are passed down / inherited from one generation to next, genes code for specific traits.
Alleles- Different versions of the same gene.
Allele-One version of the pair of genes that appear at a particular location on a particular chromosome and control the same characteristics like eye color.
Organisms typically have two alleles for a trait

4. Dominant- Allele that shows trait whenever it is present.
Recessive- Weaker gene, Eg: Eye color, brown from mom, blue from dad.
Homozygous-When Alleles for a characteristic are same, the organism is homozygous for that characteristic.
Heterozygous- When the alleles are different for a characteristic, then the organism is heterozygous for that characteristic.
Genotype- the information in genes that make up that trait
Phenotype-Actual appearance of organism. .
When allele pairs are the same, they are homozygous. When the alleles of a pair are different, they are  heterozygous. The phenotype of one trait may be dominant and the other recessive. The dominant allele is expressed and the recessive allele is masked.

5. Punnett Square B- Brown eyes (Dominant) b-blue eyes (Recessive)
BB-Homozygous Dominant; Bb-Heterozygous
bb-Homozygous Recessive