Set up Cornell Notes on pg. Topic: 6.4 Genes, Traits, Alleles Essential Questions: Explain why an organism’s genes may be homozygous dominant, homozygous recessive, but never heterozygous recessive. 6.4 Genes, Traits, Alleles 2.1 Atoms, Ions, and Molecules Explain why an organism’s genes may be homozygous dominant, homozygous recessive, but never heterozygous recessive.

KEY CONCEPT Genes encode proteins that produce a diverse range of traits.

X Y X X X Y X X X X X Y 50% Girl 50% Boy An allele is a gene occurring at a specific locus on a chromosome. Each parent donates one allele for every gene. Alleles are represented using letters. X Y X X X Y X 50% Girl 50% Boy X X X X Y

A gene is a piece of DNA that directs a cell to make a certain protein. Each gene has a locus, a specific position on a pair of homologous chromosomes. *homo =same

Punnett Square Vocabulary Review

Dominant J A B P H

Recessive j a b p h

Dominant vs. Recessive n b A j K L r Z

(aa) (AA or Aa) Alleles are represented using letters. A dominant allele is expressed as a phenotype when at least one allele is dominant. (AA or Aa) A recessive allele is expressed as a phenotype only when two copies are present. (aa)

Homozygous AA oo LL bb jj aa ww

Heterozygous Aa Oo Ll Bb Jj Mm Ww

Heterozygous vs. Homozygous Aa Oo LL Bb JJ Mm ww Pp

Homozygous Dominant JJ MM KK DD NN YY GG

Homozygous Recessive jj mm kk dd nn yy oo

Heterozygous Dominant? Tt Mm Pp Zz Yy Mm Jj

Heterozygous Recessive? Yy No such thing as heterozygous recessive. Why?

Homozygous describes two alleles that are the same at a specific locus. AA or aa. *homo=same Heterozygous describes two alleles that are different at a specific locus. Aa *Hetero=different

*Both homozygous dominant (AA) and heterozygous (Aa) genotypes yield a dominant phenotype. Most traits occur in a range and do not follow simple dominant-recessive patterns.

Genotype Tt Mm Pp Zz Yy Mm Jj

Phenotype

Genotype: BB or Bb Genotype: bb Genotype CODES FOR Phenotype!!!!!!!!! A genotype refers to the makeup (alleles) of a specific set of genes. Genotype: BB or Bb Genotype: bb Genotype CODES FOR Phenotype!!!!!!!!!

Phenotype: Brown Eyes Phenotype: Blue Eyes A phenotype is the physical expression of a trait. You can see it! Phenotype: Brown Eyes Phenotype: Blue Eyes

Genes influence the development of traits. All of an organism’s genetic material is called the genome.

Hh FF KK Jj LL mm Aa AA aa PP Pp Rr WW qq Dd Which of these are Heterozygous? Hh FF KK Jj LL mm Aa AA aa PP Pp Rr WW qq Dd

Hh FF KK Jj LL mm Aa AA aa PP Pp Rr WW qq Dd Which of these are Heterozygous? Hh FF KK Jj LL mm Aa AA aa PP Pp Rr WW qq Dd

Hh FF KK Jj LL mm Aa AA aa PP Pp Rr WW qq Dd Which of these are Homozygous? Hh FF KK Jj LL mm Aa AA aa PP Pp Rr WW qq Dd

Hh FF KK Jj LL mm Aa AA aa PP Pp Rr WW qq Dd Which of these alleles codes for a Dominant trait? Hh FF KK Jj LL mm Aa AA aa PP Pp Rr WW qq Dd

Hh FF KK Jj LL mm Aa AA aa PP Pp Rr WW qq Dd Which of these alleles are Dominant? Hh FF KK Jj LL mm Aa AA aa PP Pp Rr WW qq Dd

Hh FF KK Jj LL mm Aa AA aa PP Pp Rr WW qq Dd Which of these allele pairs are recessive? Hh FF KK Jj LL mm Aa AA aa PP Pp Rr WW qq Dd