Traits, Genes, Variations Flashcards
Alleles
The variants of a locus; for autosomal loci, each diploid individuals has two alleles.
Autosomes
The chromosomes that are not different between sexes. In humans there are 22 pairs of autosomes.
Chromosomes
Linear molecules of DNA packaged with proteins.
Codominant
Alleles that are fully expressed in the heterozygote.
Continuous, metric, or quantitative
Phenotypic traits that do not show distinguishable forms but a continuous gradation in the population. These traits are also inherited, but they are multifactorial characters controlled by multiple genes (polygenic characters) and affected to varying degrees by the environment and epigenetic modifications.
Discrete or discontinuous
Traits that are often encoded by only one gene (monogenic traits) with two different alleles in the population, resulting in alternative forms of the trait.
Dominant
An allele that is fully expressed either in the homozygote or in the heterozygote.
Intermdediate dominance
One of the alleles is not completely recessive, or the other is not completely dominant.
Epistasis
A type of gene interaction. Some traits are affected by more than one gene so that the effect of one gene (epistatic) masks or modifies the effect of another gene (hypostatic).
Expressivity
Reflects the degree in which a trait is expressed among individuals with identical genotype.
Gene
A segment of the genome that contains the instructions for a functional product. It is considered the molecular unit of heredity.
Genome
The heritable material that is transmitted from parents to offspring confers the biological identity of an individual. It is composed of large molecules of nucleic acids, whose sequence contains the instructions to build other functional molecules such as ribonucleic acid (RNA) or proteins.
Genotype
The genetic makeup of an organism, the whole set of genes. For a given gene, the genotype is the combination of alleles in a particular individual.
Hemizygous
Are males for the genes located in the X chromosome because they only have one copy.
Heterozygote
An individual with two different alleles (in sequence or function) at a locus.
Homologous Chromosomes
A pair of chromosomes that carry the same gene but are inherited from a different parent. A diploid individual (2n) harbors a number n (haploid) of pairs of homologous chromosomes.
Homozygote
An individual with two identical alleles (in sequence or function).
Linkage
Is due to the fact that alleles are located along chromosomes and end to being inherited in the same combination that is present in parental chromosomes. Linkage is broken by recombination during meiosis, which creates novel combinations of alleles in the chromosome.
Locus
(plural loci) A position (place) in a chromosome; the physical region occupied by a gene, a marker, or any genetic element.
Mendelian
Traits that display Mendelian inheritance typical of diploid organisms.
Penetrance
The proportion of individuals that show the typical phenotypes associated with a genotype.
Phenotype
The collection of observable characteristics of the organism. It is determined by the genotype but also by environmental factors and epigenetic modifications (both inherited and non-inherited)
Quantitative trait locus (QTL)
A locus controlling a quantitative trait.
Recessive
An allele that is fully expressed only in the homozygote.
Sexual chromosomes
The chromosomes that are different in each sex. In humans, females have two X chromosomes, whereas males have one X and one Y chromosome.
SNPS (Single-nucleotide polymorphisms)
Polymorphic sites at single nucleotides
Structural variants (SVs)
Polymorphisms that affect relatively large segments of the genome (from Kb to Mb).
Copy number variation (CNVs)
Regions that are repeated at different number of times in different individuals in the population.
DNA
Deoxyribonucleic acid is made up of four different monomers (adenine, guanine, cytosine, and thymine).
Traits
The observable characteristics of the organism. These characteristics range from biochemical and physiological properties to morphology or behavior.
Nuclear genome
Most of the genome is in the nucleus. Accounts for 99.9995% of genetic information. 37 protein-coding genes maily involved in oxidative phosphorylation.
Extranuclear genome
Located in the organelles like mitochondria and chloroplasts (in plants). Accounts form 0.0005% genetic information.
