### order | series | sequence | gene | allele:

Lethal allele
* are always recessive.
* can be dominant or recessive, but mor often they are recessive
  - either recessive, dominant and can be either autosomal , sex linked
* result in modified ratios among surviving foals.
* violate the rules of Mendelian inheritance.

New allele
* are produced all the time by mutation of existing alleles.
* originate by mutation.
* produced by mutation allow plants and animals to adapt to their new environment.

Defective gene
* Some defective genes are more common in certain ethnic groups.
* can also pass along traits such as hearing loss or speech and language disorders.
* cause inborn errors of metabolism.

Developmental gene
* is isolated from a model organism.
* operate in the womb.

### order | series | sequence | gene:

Different gene
* affect individuals in different ways.
* are active in different cells at different times
  - kinds of cells
  - expressed in different cells
* are responsible for the expression of different characteristics of the organism
  - in different species for specifying the same anatomical features
  - subjected to the environment
  - the best for getting information about different conditions
* cause genetic variation.
* contain the blueprints for different organs, bones, blood vessels, etc.
* determine the different characteristics, or traits, of an organism.
* make up different species.
* operate at different times.

Essential gene
* are the set of genes thought to be critical for an organism's survival.
* produce proteins that are always required by the cell.

Eukaryotic gene
* Many eukaryotic genes contain large numbers of exons
  - have two stop codons located close to each other at the end of the gene
* show colinearity between genes and gene products.

Gene amplification
* form of genomic instability , a hallmark of cancer cells.
* is another frequently found aberration in human tumor cell genomes
  - important because it is the first step in the formation

### order | series | sequence | gene:

Gene flow
* allows different genes to mix with others.
* appears to be biased towards males, but overall populations are matrilineally structured.
* can increase genetic variability by bringing in alleles from other populations
  - introduce new alleles and maintain diversity in populations
* describes changes in gene frequency due to small population size.
* increases genetic variation within a population
  - the divergence of populations
* is caused by individuals from one population interbreeding with another population
  - important when it comes to lasting viability of populations
  - impossible between two species
  - interrupted when a population is divided into geographically isolated subpopulations
  - possible in the Far East where soybean originated and wild related plants exist
  - random among populations
  - restricted by distance, geographic barriers, and local adaptation
* is the addition or subtraction of alleles from a population due to migration
  - great homoginizing agent
* is the movement of alleles in or out of a population
  - into and out of a population as a result of a. fertilization
  - genes from one population to another
  - genetic information into or out of a population
* is the result of migration between populations with different gene frequencies
* largely neglected, but potentially important, factor in evolution.
* occurs when individuals migrate between populations.
* plays a crucial role in all three stages.
* refers to introduction of genes from outside the local breeding population.
* relational process involving dispersal into a reference population.
* tends to decrease differentiation
  - homogenize allele frequencies among populations
  - reduce differences between populations

Homologous gene
* can be identified in many species, however their function is yet to be elucidated.
* function in fly and fish segmentation.