Inherritance

• Who is known for his work in genetics through pea plant experiments?

  Gregor Mendel
• What did Mendel's experiments on pea plants reveal about inheritance?

  Characteristics are not blended during inheritance
• What are genes?

  Sections of DNA on a chromosome
• How do alleles differ from genes?

  Alleles are different versions of a gene
• What is an example of a dominant allele mentioned in the text?

  The allele for purple pea flowers
• What is an example of a recessive allele mentioned in the text?

  The allele for cystic fibrosis
• What did Mendel conclude about the relationship between characteristics like pod shape and flower color?

  They are determined independently of each other
• What term did Mendel use to describe the inherited units that determine characteristics?

  Units
• Why was Mendel's work not recognized during his lifetime?

  Many scientists believed in the blending theory of inheritance
• When was Mendel's work rediscovered?

  In the late 1800s
• How did scientists in the early 1900s relate Mendel's units to chromosomes?

  They realized Mendel's units behaved similarly to chromosomes
• What term replaced "Mendel's units" in the early 1900s?

  Genes
• What significant discovery about DNA was made in the mid-1900s?

  The structure of DNA and how genes function
• What are the key contributions of Gregor Mendel to genetics?

  • Conducted breeding experiments on pea plants
  • Discovered that characteristics are inherited independently
  • Introduced the concept of dominant and recessive alleles
  • Established that inherited units (genes) do not change when passed on
• What were the misconceptions about inheritance before Mendel's work?

  • Characteristics were believed to be blended during inheritance
  • Many scientists did not recognize the significance of Mendel's findings
• What was the timeline of the recognition of Mendel's work?

  1. Mendel published his research
  2. His work was forgotten due to prevailing blending theory
  3. Rediscovery occurred in the late 1800s
  4. Connection to chromosomes established in the early 1900s
• What do genetic diagrams show us?

  They show all the different combinations of alleles from two parents.
• What does the dominant allele represented by a capital 'A' code for in the example?

  It codes for normal amounts of average muscle.
• What does the recessive allele represented by a lowercase 'a' code for?

  It codes for a muscular mass.
• How do we represent alleles in genetic diagrams?

  Using uppercase for dominant and lowercase for recessive alleles.
• What is a typical question regarding genetic diagrams?

  Draw a genetic diagram for the cross between a homozygous normal mouse and a homozygous muscular mouse.
• What are the five main steps to draw a genetic diagram?

  1. Identify the parents' phenotype and genotype.
  2. Determine the gametes' genotypes.
  3. Combine the gametes to find offspring's genotypes.
  4. Determine the offspring's phenotypes.
  5. Present the results in a genetic diagram.
• What is the genotype of a homozygous normal mouse?

  Capital A, capital A.
• What is the phenotype of a homozygous muscular mouse?

  Muscular.
• Why is the muscular allele expressed in a homozygous muscular mouse?

  Because it has two lowercase a alleles.
• How do you find the gametes from the parents' genotypes?

  By splitting the two letters in each parent's genotype into separate circles.
• What do you do to find the offspring's genotypes?

  Combine all possible combinations of the two parents' gametes.
• What is the result of combining a capital A gamete with a lowercase a gamete?

  The genotype will be capital A, lowercase a.
• What does it mean for offspring to be heterozygous?

  They have one allele of each type.
• What phenotype do all heterozygous offspring have in this example?

  Normal phenotype.
• What is a Punnett square and its benefits?

  • A diagram used to predict the genotype and phenotype combinations.
  • Benefits:
  • Simpler to draw than genetic diagrams.
  • Shows the same information as genetic diagrams.
• How do you set up a Punnett square for two heterozygous normal mice?

  Place capital A and lowercase a gametes on the top and left of the square.
• What are the possible genotypes of the offspring when two heterozygous normal mice mate?

  One homozygous dominant, two heterozygous, and one homozygous recessive.
• What is the phenotype ratio of the offspring from two heterozygous normal mice?

  Three normal to one muscular.
• What is the probability of having muscular offspring from two heterozygous normal mice?

  One in four or twenty-five percent.
• What factors influence traits beyond single genes?

  • Multiple genes interact.
  • Environmental factors play a significant role.
• What is an important consideration regarding traits determined by single genes?

  Many different genes interact and the environment can also influence traits.
• What are inherited disorders?

  Conditions that can be passed on through certain alleles from parents
• Name two examples of inherited disorders discussed in the video.

  Polydactyly and cystic fibrosis
• What is polydactyly?

  • A condition where a baby is born with extra fingers or toes
  • Usually does not cause other problems
  • Caused by a dominant allele