Living Things Inherit Traits In Patterns Chapter 4.1 Pages

parents and offspring are similar 1.traits 2.some acquired and some inherited 3.sexual reproduction 4.trait combinations differ in parent & offspring 5.DNA affects traits

genes are on chromosome pairs 1.genes are DNA segments of chromosomes 2.each gene codes for a trait 3.genes are inherited 4.heredity 5.homologous chromosomes 6.alleles 7.many alleles for each gene in a species 8.chromosome number 9.X and Y chromosomes determine sex of offspring

Gregor Mendel made some important discoveries about heredity 1.Austrian monk – studied math & science 1800’s 2.detailed notes and observations 3.7 traits of pea plants 4.started experiments with true-breeding plants One Example 1.bred pure tall with pure short – P generation 2.all offspring were tall – F 1 generation 3.bred the F 1 generation together 4.about 25% short and 75% tall – F 2 generation 5.noticed the same pattern in all 7 traits

Gregor Mendel made some important discoveries about heredity Mendel’s Conclusions 1.each plant has 2 “factors” -1 from each parent 2.it only takes 1 factor to show a trait 3.the other factor can be hidden (masked) 4.hidden factor can show up in future generation 5.factors today = genes and alleles

alleles interact to produce traits 1.1 gene = trait? there’s more to it now Phenotype and Genotype 1.alleles and what they do in an organism 2.we all have “hidden” alleles Dominant and Recessive Alleles 1.dominant alleles – 1 copy needed 2.recessive alleles – 2 copies needed 3.multiple alleles 4.environment 5.hair color: blond recessive to brown

Vocabulary Time sexual reproduction a type of reproduction in which male and female reproductive cells combine to form offspring with genetic material from each cell gene the basic unit of heredity that consists of a segment of DNA on a chromosome heredity the passing of genes from parent to offspring allele one form of a gene for a specific trait phenotype the observable characteristics or traits of an organism genotype the genetic make-up of an organism; the actual alleles an organism has dominant a term that describes the allele that determines the phenotype of an organism when two different alleles (copies) are present recessive a term that describes an allele that is not expressed when combine with a dominant allele