Understanding DNA, Chromosomes, and Genetic Variation

DNA Deoxyribonucleic Acid Forming Chromosomes

Stores genetic info DNA wounded to histones which becomes nucleosome loops onto chromatin

Codes for protein twisted into chromatid looped and packed into chromosome

Nucleotide Chromatin fibers are coiled and condensed to form chromosomes

consisting of a nitrogen-containing base Histones are proteins that help package and organize DNA in the nucleus of

(a, g, t, c.) or uracil in RNA eukaryotic cells by forming nucleosomes around which DNA is wrapped.

- phosphate group nucleosome is a basic unit of DNA packaging in eukaryotic cells

- sugar chromatid is one of the two identical copies of a replicated chromosome

Homologous Chromosomes chromosome is a long, coiled-up strand of DNA that contains genetic information

chromosomes with same sequence DNA sequences for genes which code for making protein

same size shape and location Mutations - Permanent change in genetic materials; source of new genetic variation

same type of genetic info Natural Selection - certain heritable traits become more or less common in a population over time

traits and punnet square

Dominant - allele is expressed regardless of other allele Selective advantage - genetic advantages that improve chance

Recessive - allele expressed when only two of them are present Phenotype - physical description of trait Adaptation - organism becomes better suited to its environment

Genotype - combination of alleles through genetic or behavioral changes.

codominance - both alleles are dominant and are equally expressed as traits

Incomplete dominance - neither alleles gain dominance and shows intermediate traits

Adaptive radiation - a single ancestral species gives rise to multiple new species that adapt to a variety of different ecological niches

Effects of mutations: Positive: Creation of new genetic variations (new alleles, increases genetic diversity)

Development of new traits (new and improved) Evolutionary innovation (gives a rise to new biological improvements)

Neutral: no effect on function of genes Negative: Loss of function (can disrupt the normal functioning of genes)

Increased susceptibility to disease (mutations in the BRCA1 or BRCA2 genes increase a person's risk of developing breast and ovarian cancer)

Genetic disorders , Reduced fitness | Natural selection: important driving force of evolution, has impact on populations

four main components of natural selection: variation, heritability, differential reproduction, and selection pressure