Genetics Chapter 15 Genomics and Gene Mapping

Genomics

The field of genetics that attempts to understand the content, organization, function, and evolution of genetic information contained in whole genomes

Structural genomics

Concerns the organization and sequence of genetic information contained within a genome

What are the first steps in characterizing a genome

Preparing a genetic and physical map of its chromosomes

What information do genetic and physical maps provide

Provides information about the relative locations of genes, molecular markers, and chromosome segments of an individual organism, population, or species

Genetic maps

(also called linkage maps) provide a rough approximation of the locations of genes relative to the locations of other known genes

Physical maps

are based on the direct analysis of DNA sequence, and they place genes in relation to distances measured in number of base pairs, kilobases, or megabases.

What is a common type of physical map

One that connects isolated pieces of genomic DNA that have been cloned in bacteria or yeast.

Genetic marker

a gene or DNA sequence with a known location on a chromosome that can be used to identify individuals or species.

What is needed to generate a genetic map

Genetic markers

What are the three reasons genetic markers are used

1. Landmarks for gene mapping

2. To mark genome differences between organisms, population, and species

3. As markers for disease

Genetic markers

Patterns in DNA that individuals with a disease/characteristic has that aren’t present in the DNA of the individuals who don’t have the disease/characteristic

Genetic polymorphism

A difference in DNA sequence among individuals, groups, or populations.

Restriction fragment length polymorphism

Changes in DNA fragment length produced by presence or absence of the cleavage sites in DNA molecules

Simple-nucleotide polymorphism

A single base pair difference

Restriction endonucleases sequences

(Also known as recognition sites) are usually six-base pairs longs

What happens if there is the absence of new appearance of recognition sites

Makes restriction fragments longer/shorter which presents differences between two individuals (restriction fragment length polymorphism)

What do differences in DNA sequences (DNA polymorphisms) do to recognition sequences and thus specific restriction enzymes

It generates different recognition sequences and DNA cleavage sites for specific restriction enzymes. Thus, two different alleles may produce different fragment patterns when cut with the same restriction enzyme due to differences in DNA sequence

What is the density of SNPs in the human genome

About one per 1,000 bp

What do most SNPs present within a population arise from

A single mutation that occurred on a particular chromosome and subsequently spread throughout the population

How does genomics analyze genes or genetic elements

All at the same time by massively parallel approaches