Genetic Inheritance

• What causes different development of the same trait?

  Different alleles of a gene
• Where do alleles of a gene occupy on chromosomes?

  Same loci on homologous chromosomes
• Do alleles controlling the same character contain the same genetic information?

  No, they do not necessarily contain the same genetic information
• What is an allele?

  Alternative forms of a gene that occupy the same locus on homologous chromosomes

  
• How many alternative alleles does a gene usually have?

  Two alternative alleles
• Give an example of a gene and its alleles.

  Gene for flower color; alleles for purple and white flower

  
• How are alleles usually represented?

  By the same alphabet
• What does allele P represent?

  Dominant allele for purple flower

  
• What does allele p represent?

  Recessive allele for white flower

  
• How many alleles must an individual have for each gene?

  Two alleles
• What is a genotype?

  The combination of alleles an individual has for a specific gene
• How does genotype affect phenotype?

  It determines the observable traits of an organism
• What is a phenotype?

  Observable traits of an organism
• What is a homozygous organism?

  An organism with two identical alleles for a gene at a given locus

  
• What are the genotypes of a homozygous organism?

  PP or pp

  
• What is a heterozygous organism?

  An organism with two different alleles for a gene at a given locus
• What is the genotype of a heterozygous organism?

  Pp

  
• What is a dominant allele?

  An allele that is fully expressed in the phenotype of a heterozygous organism

  
• What is a recessive allele?

  An allele whose phenotypic effect is not observed in a heterozygote
• What is a self cross?

  A cross between male and female parts of the same flower or individual
• What is the consequence of a self cross?

  Self-fertilization
• What is a test cross?

  A cross between a homozygous recessive individual and an organism of dominant phenotype but unknown genotype

  
• What does a test cross determine?

  The genotype of an organism with a dominant phenotype

  
• What is a character in genetics?

  A heritable feature that varies among individuals
• What is a trait?

  A variant for a character of individuals
• What does true breeding refer to?

  Organisms that produce offspring of the same variety over many generations of self-pollination
• What is the P generation in genetic diagrams?

  The parental generation

  
• What is the F1 generation?

  The first filial generation produced from a cross between individuals of the P generation
• What is the F2 generation?

  The second filial generation produced from a cross between F1 individuals

  
• Who was Gregor Mendel?

  An Austrian monk who studied the inheritance of garden peas
• Why did Mendel study genetic inheritance in pea plants?

  Because they are easy to grow in large numbers and have many observable characters

  
• What are the characteristics of Mendel's pea plants that made them suitable for genetic studies?

  • Easy to grow in large numbers
  • Short life cycle
  • Many easily observable characters
  • Pollination could be easily controlled
  • Have both male and female parts
• What is Mendel's first law of inheritance?

  The Law of Segregation states that two alleles for heritable characters segregate during gamete formation
• What does the Law of Segregation involve?

  Crossing between two individuals with different phenotypes
• What is a monohybrid cross?

  A cross between two true breeding individuals with different phenotypes

  
• What are the steps of Mendel's monohybrid cross experiment?

  1. Produce P generation (true breeding)
  2. Produce F1 generation
  3. Produce F2 generation

  
• What is the genotypic ratio of the F2 generation in Mendel's monohybrid cross?

  1. 2:1

  
• What is the phenotypic ratio of the F2 generation in Mendel's monohybrid cross?

  1. 1

  
• What is a Punnett Square?

  A diagram used to predict the allele composition of offspring from a genetic cross

  
• How are possible gametes represented in a Punnett Square?


  Written in the green colored grid