Unit 5

Genetic information is stored in DNA. DNA is copied into RNA, which has many functions in the cell.

Proteins are essential tools in the structure and function of an organism; they can function as structural elements, enzymes, signals, or receptors. Some RNA molecules serve as templates for proteins.

Mutations are changes in the genetic information of an organism—they are the ultimate source of heritable genetic variation, the raw material essential for evolution. Offspring can inherit germline mutations from their parents. Mutations can affect the product of a gene, such as a protein, or the levels of expression of that gene product.

Mutations are rare, but they arise at a roughly steady rate.

Mutations can have harmful or beneficial effects; most mutations are neutral or mildly deleterious.

Sexual reproduction adds genetic variation within a population. During meiosis, genetic recombination and independent assortment separate, mix, and combine alleles, resulting in siblings from the same parents inheriting different characteristics.

The phenotype is the manifestation of the genotype, but the relationship is not always straightforward. Some phenotypic polymorphisms exist because of a mutation to a single gene. Some genotypes can produce multiple phenotypes, depending on the environment.

Quantitative traits can reflect the simultaneous effects of multiple genes and the environment, so it is misleading to speak of a gene “for” a trait.

An example of a quantitative traits: the “height gene.”, any particular gene that affects height probably accounts for only a small amount of variation among the heights of individuals in a population. Other complex traits are also affected by numerous genes and in some cases environmental circumstances as well.

The environment can produce large variations in the expression of a trait.

Phenotypic plasticity is the result of interactions between genotypes and environments.

Animo Acids are the building blocks of Proteins

• there are 20 different amino acids that are used in different combinations to make proteins of different uses

DNA is made up of nucleotides and at the end of a nucleotide, is a base

Eukaryotes have DNA that is tightly wound around histone proteins

Proteins land on a DNA molecule near the beginning of the gene sequence: promoter region

RNA polymerase: assembles a string of nucleotides whose sequence matches the template DNA

Transcription: process of RNA polymerase reading the template DNA and creating mRNA (messenger RNA)

Translation: mRNA is read to create proteins

repressor: binds to a silencer area of a sequence of DNA or RNA and inhibits the expression of one or more genes

A transcription factor regulates gene expression by binding to a specific DNA sequence called an enhancer which activates gene expression

noncoding DNA is removed via RNA splicing and is called introns and coding DNA is joined together after they are spliced and is called exons

Germ-line mutations are mutations that occur in egg or sperm cells (inherited)

Somatic mutations happen in all other cells besides egg or sperm cells

point mutation: substitutes a nucleotide

insertion: inserts a segment of DNA in an already existing one

Deletion: removal of a DNA segment

Frameshift mutation: a mutation that inserts or deletes one or two bases that leads to a shift of the 3 group codons

Duplication: repetition of copied a second time

Inversion: a segment of DNA flipped and inserted backward

Aneuploidy: chromosomes duplicated or lost

Chromosome fusion: two chromosomes joined together as one

Genome duplication: entire genome is duplicated; leads to the increase of ploidy