Understanding Genes, Alleles, and Phenotypes

Gene

Section of DNA coding for a specific protein.

Chromosome

Long DNA strand containing thousands of genes.

Genetic code

Sequence of bases along a gene.

Amino acids

Building blocks of all proteins, 20 types exist.

Protein

Molecule formed by amino acids, determines function.

Trait

Characteristic of an organism influenced by proteins.

Allele

Alternative version of a single gene.

Genotype

Pair of alleles an individual possesses.

Phenotype

Physical characteristic determined by genotype.

Homozygous genotype

Two identical alleles for a gene.

Heterozygous genotype

One dominant and one recessive allele.

Dominant allele

Causes dominant phenotype in heterozygous individuals.

Recessive allele

Causes recessive phenotype only in homozygous recessive.

Dominant phenotype

Characteristic expressed in heterozygous individuals.

Recessive phenotype

Characteristic expressed only in homozygous recessive individuals.

Environmental influence

Phenotype can be affected by environmental factors.

Gene sequence

Determines amino acid order in proteins.

Protein shape

Final form of protein affects its function.

Allele position

Alleles occupy the same chromosome location.

Phenotype ratio

Proportion of different phenotypes in offspring.

Lego analogy

Genes provide instructions like Lego booklets.

Chromosome pairs

Most cells have two copies of each gene.