Melanin Unit Vocab

Adaptation

A trait that helps an organism survive and reproduce

allele

Different forms of a gene

base pairing rule

the rules stating that cytosine pairs with guanine and adenine pairs with thymine in DNA, and that adenine pairs with uracil in RNA

carrier

A person who has one recessive allele for a trait, but does not have the trait.

Codon

A specific sequence of three adjacent bases on a strand of DNA or RNA that provides genetic code information for a particular amino acid

Deletion

A change to DNA in which a fragment of the chromosome is removed.

DNA

A complex molecule containing the genetic information that makes up the chromosomes.

dominant allele

An allele whose trait always shows up in the organism when the allele is present.

double helix

Shape of DNA

frameshift mutation

mutation that shifts the "reading" frame of the genetic message by inserting or deleting a nucleotide

Gene

A segment of DNA on a chromosome that codes for a specific trait

Genetics

the study of heredity

Genotype

genetic makeup of an organism

Heredity

Passing of traits from parents to offspring

Heterozygous

Having two different alleles for a trait

Homozygous

Having two identical alleles for a particular gene

Hybrid

Offspring of crosses between parents with different traits

incomplete dominance

Cases in which one allele is not completely dominant over another, heterozygous phenotype is a blend

Insertion

A mutation involving the addition of one or more nucleotide pairs to a gene.

missense

A base-pair substitution that results in a codon that codes for a different amino acid.

monohybrid cross

A cross between individuals that involves one pair of contrasting traits

Mutation

change in a DNA sequence that affects genetic information

nitrogenous base

A molecule found in DNA and RNA that encodes genetic information in cells. EX: adenosine, adenine, thymine, cytosine

nonsense

changes a normal codon into a stop codon

Nucleotide

monomer of nucleic acids made up of a 5-carbon sugar, a phosphate group, and a nitrogenous base

Phenotype

physical characteristics of an organism

Purebred

the offspring of many generations that have the same traits

Recessive

An allele that is masked when a dominant allele is present

sex-linked traits

Traits controlled by genes located on sex chromosomes.

Pedigree

A diagram that shows the occurrence of a genetic trait in several generations of a family.

Punnett Square

A chart that shows all the possible combinations of alleles that can result from a genetic cross

point substitution

change in a single base pair

silent mutation

alters a base but does not change the amino acid and thus has no effect

Codominance

A condition in which both alleles for a gene are fully expressed, heterozygous phenotype may for example show spotted or speckled colors