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Vocabulary for Genetics

DNA:  nucleic acid that codes for proteins

Nucleotide:  sugar, phosphate and a nitrogenous base (Adenine, Guanine, Cytosine, Thymine, Uracil)

Chromatin:  stringy form of DNA - state DNA is in when the cell is not undergoing mitosis or meiosis

Chromosome:  condensed form of DNA that can be seen under the microscope during cell division

Genome:  one set of chromosomes  (Humans are diploid; We have two sets of chromosomes - one set from mom and one set from dad.)

Gene:  section of DNA on the chromosome that codes for a specific polypeptide

Allele:  an alternate version of a gene - one allele per genome

Genotype:  the allele(s) an organism has for any given physical trait  (For example, a person that has two alleles for blue eyes has two recessive alleles - that person's genotype is bb.)

Phenotype:  the expressed physical trait determined by an organisms collection of alleles  (For example, the person that has two recessive alleles for blue eyes will develop blue eyes that anyone can see by looking at that person.)

Recessive:  A trait that needs to be in its homozygous form to be detected phenotypically, but can still be passed on by a heterozygote.

Dominant: A trait that can be either homozygous or heterozygous and be seen phenotypically.  Dominant traits mask recessive traits.

(Campbell/Reese Biology 6th Ed. Copyright 2002 Pearson Ed. Inc.)