Genetic Exam 1 terms

Consanguinity

A close family relationship between two individuals, such as first cousins.

Cystic fibrosis

An often fatal recessive genetic disorder associated with abnormal secretions of the exocrine glands.

Marfan syndrome

An autosomal dominant genetic disorder that affects the skeletal system, the cardiovascular system, and the eyes.

X-linked

The pattern of inheritance that results from genes located on the X chromosome.

Y-linked

The pattern of inheritance that results from genes located only on the Y chromosome.

Hemizygous

A gene present on the X chromosome that is expressed in males in both the recessive and dominant condition.

Color blindness

Defective color vision caused by reduction or absence of visual pigments, including red, green, and blue blindness.

Muscular dystrophy

A group of genetic diseases associated with progressive degeneration of muscles.

Huntington disease

An autosomal dominant disorder associated with progressive neural degeneration and dementia.

Penetrance

The probability that a disease phenotype will appear when a disease-related genotype is present.

Expressivity

The range of phenotypes resulting from a given genotype.

Camptodactyly

A dominant human genetic trait that is expressed as immobile, bent little fingers.

Gene

The fundamental unit of heredity.

Dominant trait

The trait expressed in the F1 (or heterozygous) condition.

Recessive trait

The trait unexpressed in the F1, but which is re-expressed in some members of the F2.

Phenotype

The observable properties of an organism.

Genotype

The specific genetic constitution of an organism.

Allele

One of the possible alternative forms of a gene, usually distinguished from other alleles by its phenotypic effects.

Homozygous

Having identical alleles for one or more genes.

Heterozygous

Carrying two different alleles for one or more genes.

Segregation

The separation of members of a gene pair from each other during gamete formation.

Independent assortment

The random distribution of genes into the gametes during meiosis.

Genetics

The scientific study of heredity.

Locus

The position occupied by a gene on a chromosome.

Pedigree

A diagram listing the members and ancestral relationships in a family; used in the study of human heredity.

Proband

First affected family member seeking medical attention for a genetic disorder.

Incomplete dominance

Expression of a phenotype that is intermediate between those of the parents.

Codominance

Full phenotypic expression of both members of a gene pair in the heterozygous condition.

Multiple alleles

Genes that have more than two alleles.

Epistasis

A form of gene interaction in which one gene prevents or masks the expression of a second gene.

Macromolecules

Large cellular polymers assembled by chemically linking monomers together.

Carbohydrates

Macromolecules including sugars, glycogen, and starches composed of sugar monomers linked and cross-linked together.

Lipids

A class of cellular macromolecules including fats and oils that is insoluble in water.

Proteins

A class of cellular macromolecules composed of amino acid monomers linked together.

Nucleic acids

A class of cellular macromolecules composed of nucleotide monomers linked together.

Molecules

Structures composed of two or more atoms held together by chemical bonds.

Organelles

Cytoplasmic structures that have specialized functions.

Endoplasmic reticulum (ER)

A system of cytoplasmic membranes arranged into sheets and channels whose function is to synthesize and transport gene products.

Ribosomes

Cytoplasmic particles that aid in the production of proteins.

Golgi complex

Membranous organelles composed of a series of flattened sacs that sort, modify, and package proteins synthesized in the ER.

Lysosomes

Membrane-enclosed organelles that contain digestive enzymes.

Mitochondria

Membrane-bound organelles that are the sites of energy production within the cells.

Nucleus

The membrane-bound organelle in eukaryotic cells that contains the chromosomes.

Nucleolus

A nuclear region that functions in the synthesis of ribosomes.

Chromatin

The DNA and protein components of chromosomes, visible as clumps or threads in nuclei.

Chromosomes

The thread-like structures in the nucleus that carry genetic information.

Sex chromosomes

In humans, the X and Y chromosomes that are involved in sex determination.

Autosomes

Chromosomes other than the sex chromosomes.

Cell cycle

The sequence of events that takes place between successive mitotic divisions.

Interphase

The period of time in the cell cycle between mitotic divisions.

Mitosis

Form of cell division that produces two cells, each with the same complement of chromosomes as the parent cell.

Cytokinesis

The process of cytoplasmic division that accompanies cell division.

Prophase

A stage in mitosis during which the chromosomes become visible.

Chromatid

One of the strands of a duplicated chromosome.

Centromere

A region of a chromosome to which microtubule fibers attach during cell division.

Sister chromatids

Two chromatids joined by a common centromere.

Metaphase

A stage in mitosis during which the chromosomes move and become arranged near the middle of the cell.

Anaphase

A stage in mitosis during which the centromeres split and the daughter chromosomes begin to separate.

Telophase

The last stage of mitosis, during which the chromosomes of the daughter cells decondense.

Meiosis

The process of cell division that produces four haploid cells.

Diploid (2n)

The condition in which each chromosome is represented twice.

Haploid (n)

The condition in which each chromosome is represented once.

Homologous chromosomes

Chromosomes that physically associate during meiosis.

Assortment

The result of meiosis I that puts random combinations of maternal and paternal chromosomes into gametes.

Crossing over

A process in which chromosomes physically exchange parts.

Spermatogonia

Mitotically active cells in males that give rise to primary spermatocytes.

Spermatids

The four haploid cells produced by meiotic division of a primary spermatocyte.

Oogonia

Mitotically active cells in females that produce primary oocytes.

Primary oocyte

The cell produced from oogonia that will begin meiosis.

Secondary oocyte

The large cell produced by the first meiotic division.

Ovum

The haploid cell produced by meiosis that becomes the functional gamete.

Polar bodies

Cells produced in female meiosis that contain little cytoplasm and will not function as gametes.

Translational Medicine

The union of research and medicine that seeks to translate research findings into methods for diagnosis and treatment of diseases.

Immunotherapy

A method for treating diseases by enhancing an immune response.

Transmission genetics

The branch of genetics concerned with how genes are transferred from parent to offspring.

Pedigree analysis

The construction of family trees to follow transmission of genetic traits.

Cytogenetics

The study of the organization and arrangement of genes and chromosomes.

Karyotype

A complete set of chromosomes from a cell arranged in a standard sequence.

Molecular genetics

The study of genetic events at the biochemical level.

Recombinant DNA technology

A series of techniques in which DNA fragments are linked to create recombinant DNA molecules.

Clones

Genetically identical molecules, cells, or organisms derived from a single ancestor.

Gene therapy

Procedure in which normal genes are transplanted to treat genetic diseases.

Genome

The set of genetic information carried in the DNA of an individual.

Genomics

The study of the organization, function, and evolution of genomes.

Population genetics

The branch of genetics that studies inherited variation in populations.

Eugenics

The attempt to improve the human species by selective breeding.

Hereditarianism

The idea that human traits are determined solely by genetic inheritance.

Single nucleotide polymorphism (SNP)

Single nucleotide differences between individuals in a population.

Haplotype

A set of genetic markers located close together on a single chromosome.

Genome-wide association study (GWAS)

Analysis of genetic variation across an entire genome to find associations between variations and specific phenotypes.

Biotechnology

The use of recombinant DNA technology to produce commercial goods and services.