Unit 4 Vocabulary Review

Nucleic Acids Organic molecules that serve as the blueprint for proteins and, through the action of proteins, for all cellular activity.

Deoxyribonucleic Acid (DNA) Hereditary traits that codes for the synthesis of proteins.

Ribonucleic Acid (RNA) Transport system for hereditary information to make proteins.

Nucleotides Basic structure of nucleic acids consisting of a base, a sugar, and a phosphate group.

Complementary Bases Nitrogenous bases that bond together.

Chromosomes A structure in the nucleus of a cell consisting essentially of one long thread of DNA that is tightly coiled

Gene A specific location on a chromosome, consisting of a segment of DNA, that codes for a particular protein.

Genetic Code DNA, which comprises the organism’s chromosomes that contains the code for each protein that the organism needs.

Sex Chromosomes A pair of chromosomes in an organism determines the sex (male, female) of the organism.

Autosomal Chromosomes (Autosomes) These are all chromosomes, except the chromosomes that determine the sex of the organism.

DNA Replication The process of making an exact copy of DNA.

Protein Synthesis The process of making proteins that the cell needs in order to function properly.

Transcription The process by which a portion of the molecule of DNA is copied into a complementary strand of RNA.

Messenger RNA (mRNA) Nucleotides of RNA that form complementary strands to the DNA.

Codons Each three-base nucleotide sequence on the mRNA.

Transfer RNA (tRNA) Nucleotides of RNA that assemble amino acids into the correct sequence for the required protein by transferring amino acids to the ribosomes when needed.

Anticodon site Each three-base nucleotide sequence at the end of each tRNA.

Peptide Bond The bond formed by the ribosome between the amino acids, where the amino acid chain begins to form.

Stop Codon A codon that signals the end of protein synthesis.

Law(Principle) of Dominance States that some alleles are dominant whereas others are recessive.

Law (Principle) of Segregation States that alleles are separated during meiosis and that each gamete has the same chance of receiving either one of the alleles for each trait.

Law (Principle) of Independent Assortment States that the segregation of the alleles of one trait does not affect the segregation of the alleles of another trait.

Dominant The trait that will more than likely be expressed in the offspring.

Recessive The trait that will probably not be expressed in the offspring unless two alleles are present for that trait.

Homozygous When an organism has two identical alleles for a particular trait.

Heterozygous When an organism has two different alleles for a particular trait.

Genotype Genetic makeup of an organism.

Phenotype Physical characteristics of an organism.

Linked genes Genes that are located on the same chromosome and will be inherited together.

Punnett Square Chart that is used to predict the probable genetic combinations in the offspring that result from different parental allele combinations that are independently assorted.

Monohybrid Cross A cross that examines the inheritance of one trait.

Dihybrid Cross A cross that examines the inheritance of two different traits.

P 1 Generation The parents in a cross.

F 1 Generation The 1 st set of offspring in a cross.

F 2 Generation The 2 nd set of offspring in a cross.

Chromosome Theory of Inheritance States that genes are located on chromosomes and that the behavior of chromosomes during meiosis accounts for inheritance patterns.

Gene Linkage The process of genes being inherited together because they are located on the same chromosome.

Crossing Over A process in which alleles in close proximity to each other on homologous chromosomes are exchanged.

Incomplete Dominance A condition in which one allele is not completely dominant over another.

Codominance A Condition in which both alleles for a gene are completely expressed.

Multiple Alleles A condition in which more than two alleles exist for a trait; however, only two alleles are inherited.

Polygenic Traits Traits that are controlled by two or more genes.

Sex-linked traits Traits that are carried on either the X or the Y chromosome.

Sex-Linked Genes Genes that are carried on sex-linked chromosomes.

Pedigree A chart constructed to show an inheritance pattern (trait, disease, disorder) within a family through multiple generations.

Mutations The alteration of an organism’s DNA.

Mutagen A physical or chemical agent that may cause a malfunction during the process of meiosis.

Mutant Cell An alteration of a cell that may have adverse or beneficial effects on the cell, the organism, and future generations.

Gene Mutation A mutation that affects a single gene.

Chromosomal Mutation A mutation that affects a group of genes or an entire chromosome.

Nondisjunction A condition that is expressed due to an abnormal number of chromosomes, usually occurring during meiosis.

Beneficial Mutations Changes that may be useful to organisms in different or changing environments.

Genetic Engineering The process of replacing specific genes in an organism in order to ensure that the organism expresses a desired trait.

Gene Map A chart that shows the relative location of each known gene on a chromosome.

Genome Refers to all the genetic material in an organism.

Cloning An identical copy of a gene or an entire organism.

Gene Therapy The insertion of a normal gene into an absent or abnormal gene to produce the correct protein or enzyme, eliminating the cause of a disorder.

Selective Breeding The method of artificially selecting and breeding only organisms with a desired trait to produce the next generation.

Inbreeding The process of crossing individuals who are closely related.

Hybridization The process of breeding organisms that show strong expression for two different traits in order to produce offspring that express both traits.