Download BIOLOGY STANDARD 4

Understanding of the following terms are needed for mastery of the
Genetics and Biotechnology Unit
BIOLOGY STANDARD 4.0 GLOSSARY
Allele - one form of a gene having two or more alternate forms, that occupy corresponding positions
on homologous chromosomes
Autosome - any chromosome other than the sex chromosome
Carrier - an individual who is heterozygous for a recessive trait, and therefore will not express the
trait, but may pass the trait on to its offspring. (Example is carrier of Sickle Cell anemia)
Chromosomes - long coiled strands of deoxyribonucleic acid and protein that comprise the genetic
material
Co-dominant - a genetic pattern where the pair of alleles is equally expressed in the offspring for
example a black chicken mated with a white chicken produce speckled offspring
Cystic fibrosis - a genetic disorder caused by a recessive trait carried on the autosomes that caused
mucus build up in the pancreas, lings, digestive tract, and other organs
Diploid - referring to a cell having two sets (2N) of chromosomes, one inherited from each parent.
DNA - deoxyribonucleic acid; the genetic material that contains information to code for proteins
within the nucleus of the cell
Dominant - the term used to describe the gene that is expressed when a single allele is present. In
Mendel's experiments with peas, tallness was a dominant trait.
Gamete - a cell that has the potential to combine with another cell for sexual reproduction; this cell
contains only half the chromosome number of the organism (In) and has been formed by the process
of meiosis
Gene - the basic unit of heredity that codes for a particular protein
Genotype - the genetic make-up of the organism represented by letters
Haploid - cells that contains a single set of chromosomes (N)
Heterozygous — the genetic condition of an organism with one dominant and one recessive allele
for a particular trait
Homologous chromosomes - a matching pair of chromosomes that possess genes for the same traits;
one of the pair is inherited from the organism's father, and one comes from the mother
Homozygous - the genetic condition of an organism that has two identical alleles for a given trait
Hybrid - an organism that receives different genetic information from each parent for a particular
trait
Hybridization - the crossing of two breeds to obtain an offspring with characteristics of both
Inbreeding - the technique of crossing two individuals with similar genotypes
Incomplete dominance - the pattern of inheritance the produces offspring with a phenotype showing
a blend of both parents for example the pink flowered offspring from red and white flowed phlox
Karyotype - a photograph of a cell's chromosomes, arranged in homologous pairs, this picture can be
used to detect problems originating in the chromosomes of an individual, even before birth
Law of dominance - an inheritance pattern where the offspring will express a particular trait even if
only receiving a single allele for that trait.
Law of independent assortment — Mendel's second law, stating that each allele pair segregates
independently during gamete formation
Law of segregation - Mendel's first law, stating that each pair of alleles separate during the
formation of gametes.
Linkage group — genes that are found close together on the same chromosome
Meiosis - the type of cell division that forms cells containing only half the chromosomes of the
original cell. This is required to form gametes for sexual reproduction.
Mendel - Gregor Mendel (1822-1884) established the basic principles of heredity by breeding garden
peas in an Augustinian monastery
Multiple alleles - three or more different alleles for a single gene found in a population that control a
particular trait, like blood type alleles.
Mutation - spontaneous change in a gene or chromosome
Pedigree - a chart showing how a trait is inherited in a family
Phenotype - the physical appearance of an organism
Polygenic - a pattern of inheritance that involves many genes controlling a trait such as eye color,
skin color, and height
Protein synthesis — the process of putting together amino acids to form proteins; controlled by
DNA
Punnett square - a chart used to predict all possible genotypes from all the gametes of a given set of
parents
Recessive - the allele that is not expressed in the phenotype unless the organism in homozygous for
that allele
Replication - the process of making exact copies of DNA for the production of new cells
RNA - ribonucleic acid aids DNA in the production of proteins; there are three forms of RNA,
messenger, ribosomal, and transfer
Sex chromosome - chromosome containing the genetic information to code for the sex of the
organism
Sex-linked - genes found on the X or Y chromosomes
Sickle cell anemia - genetic disorder caused by recessive autosomal inheritance; the red blood cells
are sickle-shaped and unable to transport oxygen efficiently
Synapsis - the pairing of homologous chromosomes during meiosis
Tay - Sachs - a genetic disorder that causes complex lipids to collect in the brain, leading to death in
early childhood
Test cross - breeding of an organism of unknown genotype with a homozygous recessive individual
to determine the genotype of the unknown individual. The ratio of phenotypes in the offspring
determines the unknown genotype.
Transcription - the process of copying the DNA code onto a strand of mRNA
Translation - the process of synthesizing amino acids into proteins with the aid of RNA