Name____________________
Science 9 Genetics Vocabulary
Date:____________
Genetics Vocabulary
characteristic
Definition: A distinguishing quality
Context: A pair of factors determines each inherited characteristic.
chromosomes
Definition: Rod-shaped structures contained in a cell made up of a molecule of DNA threaded around
proteins
Context: In females, the gene responsible for red eyes on one of the X chromosomes might be overshadowing
the gene for white eyes on the other chromosome.
dominant
Definition: An allele that produces the same phenotype whether inherited with a homozygous (pure
dominant) or heterozygous (hybrid) allele; exercising the most influence or control.
Context: Certain genes are dominant and others are recessive.
recessive
Definition: An allele that produces a recessive trait phenotype. It can only be homozygous (pure recessive)
because heterozygous (hybrid) alleles only show the dominant trait .
Context: The genotype for all recessive traits is pure recessive.
enzymes
Definition: Any of several complex proteins produced by cells that act as catalysts in specific biochemical
reactions
Context: Genes direct the production of enzymes.
genes
Definition: Basic, functional units of heredity, each occupying a specific place on a chromosome. Genes are
represented by a pair of letters. Heterozygous or Homozygous
Context: In 1909 a Danish botanist coined the term “genes” to describe Mendel’s factors in inherited traits.
heredity
Definition: Genetic transmission of characteristics from parent to offspring
Context: Fixed laws of nature govern heredity.
Transcription:
Definition: Copying individual DNA strands to create
RNA (a genetic blueprint for a single DNA strand)
Translation:
Definition: Used with the ribosome the mRNA(messenger
RNA) is then used to create a protein, which is the building
block for most organisms. The mRNA carries specific
codes each form certain types of proteins.
Codon
Definition: A sequence of three nucleotides in messenger RNA that codes for a single amino acid (the
building blocks of life for most organisms).
Context: This codon sequence will produce a certain protein that will form a specific amino acid
Heterozygous
Definition: A genotype consisting of two different alleles for the same gene on a pair of chromosomes. The
individual has received a different allele for the given gene from each parent.
Homozygous
Definition: A genotype consisting of two identical alleles for the same gene on a pair of chromosomes. The
individual has received the same allele for the given gene from each parent.
Allele
Definition: One of the alternate forms of a single gene. Different traits
Genotype
Definition: The genetic makeup of an organism. Often used to refer to a specific genetic allele which is
responsible for specific observable trait (phenotype). A set of alleles which is responsible for a particular
phenotype.
Phenotype
Definition: An observable, measurable characteristic of an organism. The physical manifestation of the
genotype as a particular trait. For example, some peas can have a phenotype of roundness while others have
a phenotype of roughness.
Hybrid:
Definition: An offspring of two pure recessive parents, containing two different alleles, though only one may
be seen in the organism.
Trait:
Definition: visible characteristic based on genetic make-up.
Co-dominant
Definition: a gene that causes the homozygous form to look different than the wild-type and the
heterozygous form to have traits of both.