#Genetic drift and gene flow how to
#Genetic drift and gene flow code

This explains why some traits such as color-blindness are more common in males. This means the allele contributed by the mother (on the X chromosome) is the only one that impacts phenotypes for some traits. These are known as sex-linked genes, and males (with their X and Y chromosome) only have one copy of each gene. The X chromosome contains some genes that are not found on the Y chromosome. In humans males possess an X and Y chromosome, and females possess two X chromosomes. These chromosomes partially determine the sex of offspring.

In humans, for example, the 23rd chromosome pair consists of the sex chromosomes. In addition to allele interactions determining the traits we observe in organisms, some genes are only found in the chromosomes contributed by one parent.

For example, allele interactions can help explain why some traits appear to 'skip' generations, why children can have different traits than either parents, and why some rare diseases are more common to appear in matings between closely-related individuals or in small populations. Interactions among alleles explain multiple things people have observed in natural populations. While the simulation we will study today focuses on a gene that only has two alleles, one being dominant and the other recessive, it should be noted that in nature most genes have multiple alleles, interactions may be more complex than simple dominance/recessiveness, and that most traits are impacted by multiple genes. This means that traits associate with recessive alleles are only observed in organisms that are homozygous recessive (or that have two copies of the recessive allele). If one allele is dominant and the other is recessive, the phenotype (trait we can observe in the organism) will be the same in organisms that are heterozygous and those that are homozygous for the dominant allele (have two copies of the dominant allele). In heterozygous individuals, interactions among alleles can impact what traits organisms display. This also means mutations can only be passed on if they impact sex cells. Unless mutations occur, genes do not change across an organism's lifespan. If they receive different alleles from each parent, the organism is heterozygous. If an organism receives the same allele from both parents, we consider the organism to have a homozygous genotype (genetic constitution) at that locus.

#Genetic drift and gene flow code

Different versions of a gene originally arise due to mutations, or accidental changes that occur in the DNA code when a cell is replicated.

There are often multiple forms, or versions, of a gene with-in a population. These genes are located on matching chromosomes (e.g, humans have 23 pairs of chromosomes). Humans have 46 total, while fruit flies have 8.ĭiploid organisms, or those that are formed by the meeting of sex cells ( gametes), like sperm and eggs, contain two copies of each gene (one from each parent). The number of chromosomes varies among organisms. Genes are located at a specific spot (a locus) on a chromosome (a long structure composed of DNA). Morphological, development, and behavioral traits can all be influenced by genes. Genes, along with environment, determine the traits (or phenotypes) an organism displays.

#Genetic drift and gene flow how to

A gene is a section of DNA that provides instructions on how to make molecules, typically proteins. Why do organisms look different from each other? And why do offspring resemble their parents? Understanding genetics provides parts of the answers to these questions.Įvery somatic (body) cell in an adult (or any post-fertilization) organism contains the information that acts a blueprint for that organism how that information is expressed determines how each cell operates.