Heredity

Genes

  • Genes are small units of information inside our cells that contain instructions for how our bodies develop and function

  • they code for their traits life eye color, hair and height

  • segments of DNA located in structures called chromosomes

  • chromosomes carry DNA

DNA

  • A molecule that carries genetic information in living organims

  • looks like a twisted ladder (double helix)

  • found inside the nucleus of our cells

  • DNA stands for deoxyribonucleic acid

Nucleotides

  • All genetic code is made up of 4 chemical units

  • A- adenine

  • T- thymine

  • c- cytosine

  • g- guanine

  • A, T, C, and G occurs in different combinations to code for a specific amino acid

  • our DNA code for different proteins that perform specific functions in our body

Trait

  • observable charactiristic that is inherited from a living thing to its offspring

  • eye color, hair color, tongue curling, blood type

  • trait information is located within an organisms genes

Trait Variation

  • natural differences in traits (observable qualities and chractaristics) between individuals of the same species

  • ex. some cats, are active/laid back, has different hair length and eye color

Genetics

  • branch of biology that deals with the study of heredity and variation

Gregor Mendel

  • father of genetics

  • responsible for the laws governing inheritanceof traits

Genetic Terminology

  • Alleles- 2 forms of a gene (dominant and recessive)

  • dominant- the stronger of 2 genes expressed in the hybird represented by a capital letter

  • recessive- genes that shows up less often in a cross represented by a lowercase letter

  • Genotype- gene combination of a trait

  • homozygus genotype- gene combination involving 2 dominant or 2 recessive genes; also called pure (rr, RR)

  • heterogenus genotype- gene combination of 1 dominant or 1 recessive alleles (Rr); called hybrid

Phenotypes

  • The expression or manifestation of an organisms genotypes

  • ex. red, white

Law of dominance

  • some alleles are expressed or seen and others are hidden

Law of segregation

  • during the formation of genetics (egg or sperm) the 2 alleles responsible for a trait separate from each other

  • Alleles for a trait are then “recombned” at fertilization producing the genotype for the traits of the offspring

Law of independent assortment

  • the separation of factors of one trait does not influence the separation of other factors of the other traits

  • this law can be illustrated using dihybrid crosses

Punnet Square

  • used to help solve genetics problems

Monohybrid cross

  • only 1 trait is involved

dihybrid cross

  • 2 traits are involved

Determining Phenotypes

  • A phenotype of an individual is based on its genotype

Law of Dominance

  • the dominant allele will always mask the recessive allele

Assigning Symbols

  • First letter of the dominant trait will be used at the symbole uppercase for dominant and lowercase for recessive

Homozygous dominant

  • containing 2 dominant alleles (HH)

Homozygous Recessive

  • containing 2 recessive alleles (hh)

heterozygous

  • containing 2 different alleles (Hh)