genetics

• Mendel's 1964 study on attachment:

  • Aim: identify stages of attachment / find a pattern in the development of an attachment between infants and parents
  • Participants: 60 babies from Glasgow
  • Procedure: analysed interactions between infants and carers
  • Findings: the babies of parents/carers who had ‘sensitive responsiveness’ - (who were more sensitive to the baby’s signals) - were more likely to have formed an attachment
• Attachment is a strong reciprocal emotional bond between an infant and a primary caregiver
• The law of segregation states that during gamete formation, the two copies of each gene separate and end up in different gametes, ensuring each gamete contains a unique set of genes
• Self-pollination is when pollen from the same flower is transferred to the stigma of the same flower, while cross-pollination is when pollen from one flower is transferred to the stigma of a different flower
• In a monohybrid genetic cross between two pea plants, the parental generation (P) consists of two pure-breeding pea plants, one with yellow peas and one with green peas. The first filial generation (F1) shows all plants with yellow peas, demonstrating the dominance of the allele for yellow peas over green peas. The second filial generation (F2) shows a 3:1 ratio of yellow peas to green peas
• Genotype is the genetic makeup of an organism, determining its physical characteristics or phenotype

  
• Genotype is represented by a pair of letters, with the first letter from the mother and the second from the father
• The Punnett square is used to show possible genotypes of offspring from a particular cross
• In a Punnett square, the cross between two heterozygous individuals for the T/t gene results in four possible genotypes for the offspring: TT, Tt, tT, and tt

  
• TT and tt each have a 25% probability of occurring, while Tt and tT each have a 50% probability
• In a Punnett square, a cross between two individuals heterozygous for the A gene results in three possible genotypes for the offspring: AA, Aa, and aa

  
• AA and aa each have a 25% probability of occurring, while Aa will occur 50% of the time
• Probability is the likelihood that a specific event will occur, expressed in words, decimals, fractions, or percentages
• In a test cross, an individual with a dominant phenotype but unknown genotype is crossed with a homozygous recessive individual to determine the unknown genotype
• If all offspring show the dominant trait, the unknown parent must be homozygous; if some offspring show the recessive trait, the unknown parent must be heterozygous
• In a heterozygous cross, the expected outcome is a 3:1 ratio of dominant to recessive traits
• Homozygous Dominant is represented as AA, Homozygous Recessive as aa, and Heterozygous as Aa
• Selective Breeding


  Desired traits of certain plants and animals are selected and passed on to future generations
• Hybridization


  Crossing parent organisms with different forms of a trait to produce offspring with specific traits
• Liger


  Hybrid of a male lion and a female tiger
• Tigon


  Hybrid of a male tiger and a female lion
• Wholphin


  Hybrid of a male false killer whale and a female dolphin
• Zorse


  Hybrid of a male zebra and a female horse
• Growler Bear


  Hybrid of a male grizzly bear and a female polar bear
• Pizzly Bear


  Hybrid of a male polar bear and a female grizzly bear
• Zonkey


  Hybrid of a male zebra and a female donkey
• Beefalo


  Hybrid of a male bison and a female cow
• Cama


  Hybrid of a male camel and a female llama
• Geep


  Hybrid of a male goat and a female sheep
• Inbreeding

  Two closely related organisms are bred to have desired traits and to get rid of negative traits
• Pedigrees

  • A diagrammed family history used to study inheritance patterns of a trait through several generations and predict disorders in future generations
• Pedigrees

  • Males are represented by squares and females by circles
• Pedigrees

  • Individuals being studied are represented by dark or filled squares or circles
• Pedigrees

  • Individuals without the studied trait are represented by empty circles or squares
• Pedigrees

  • Carriers/heterozygous individuals for a trait are filled halfway
• Pedigrees

  • Roman numbers denote generations, birth order is shown from left to right
• Pedigrees

  • Used to determine the mode of inheritance of a disease, disorder, or trait for both x-linked and autosomal traits
• Pedigrees

  • Heterozygous carriers are not always marked, but Punnett Squares can help determine them
• Inferring Genotypes

  By looking at the phenotypes of family members, genealogists can determine the genotypes
• Inferring Genotypes: Example

  The trait in this pedigree is recessive. Filled shapes have a heterozygous recessive genotype