inheritance 2

• What is a gene?

  Sequence of DNA bases coding for protein
• What are alleles?

  Different versions of a gene
• What is a genotype?

  Genetic constitution of an organism
• What is a phenotype?

  Expression of genotype and environment interaction
• What is meant by a dominant allele?

  Needs one copy to be expressed
• When is a recessive allele expressed?

  When two copies are present
• What happens with codominant alleles?

  Both alleles are expressed
• What is a locus?

  Location of a gene on chromosome
• What does homozygous mean?

  Two copies of the same allele
• What does heterozygous mean?

  Two different allele copies
• What is a carrier?

  Carrying allele not expressed but passed on
• What is monohybrid inheritance?

  Inheritance of one gene
• What does monohybrid inheritance help identify?

  Possible offspring genotypes and phenotypes
• What is dihybrid inheritance?

  The inheritance of two genes
• What does dihybrid crosses allow you to work out?

  Offspring genotype, phenotype and ratio
• What happens when codominant alleles are present together?

  Both are expressed
• How does a codominant allele act when alone?

  As a normal dominant allele
• What are autosomal chromosomes?

  Any chromosomes except sex chromosomes
• What might homologous pairs of autosomal chromosomes contain?

  Same genes but different alleles
• What is autosomal linkage?

  Two or more genes on same autosome
• What genotypes do gametes from heterozygotes show during autosomal linkage of two genes?

  Two types of genotypes
• What is the first step in determining possible offspring genotypes?

  Write parental genotype
• How can linked genes get separated?

  Via crossing over
• What genotypes do gametes from heterozygotes show during crossing over?

  Four types of genotypes
• After writing parental genotypes, what's the next step in an autosomal linked gene cross?

  Determine genotypes of gametes produced
• Where are sex linked genes located?

  On a sex chromosome
• What does allele expression depend on for sex linked genes?

  The sex of the individual
• What is a carrier in the context of sex-linked genes?

  Parent carries allele, doesn't express trait
• Which types of alleles can be affected by sex linkage?

  Recessive, dominant, or codominant
• What can pedigree analysis diagrams determine?

  Dominance/recessiveness and sex linkage of allele
• In pedigree diagrams, what do squares and circles represent?

  Males and females
• In a pedigree, if an allele is recessive, what must be true for a child to have the phenotype?

  Neither parent has the phenotype
• What is epistasis?

  One gene affects another's expression
• Why are males more likely to express recessive sex linked genes?

  They cannot be carriers
• What do pedigree analysis diagrams show?

  Inheritance of phenotype over generations
• What does a shaded box in a pedigree analysis diagram indicate?

  Individual shows the phenotype
• In a pedigree, if an allele is dominant, what must be true for a child to have the phenotype?

  At least one parent has phenotype
• In a cross with autosomally linked genes and crossing over, after determining parental genotypes and gametes, what is the final step to determine possible offspring?

  Writing out possible genotypes of offspring