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Genetics Vocabulary

Genetics Vocabulary. The field of Biology devoted to understanding how traits are passed from parents to offspring. Gregor Mendel -pioneer in genetics -crossed peas to show how traits were passed on. Genetics. Gregor Mendel (1822-1884). Austrian monk

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Genetics Vocabulary

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  1. Genetics Vocabulary

  2. The field of Biology devoted to understanding how traits are passed from parents to offspring Gregor Mendel -pioneer in genetics -crossed peas to show how traits were passed on Genetics

  3. Gregor Mendel (1822-1884) • Austrian monk • Called the “Father of Genetics" for his study of the inheritance of 7 traits in pea plants.

  4. Gregor Mendel (1822-1884) • The traits that Mendel chose to study were easily observable in 2 distinct forms. • EX.: Stem Height - tall vs. short • Pod Shape - round vs. wrinkled • Flower Color – white vs. purple • Seed Color – green vs. yellow

  5. Gregor Mendel (1822-1884) • The significance of Mendel's work was not recognized until the turn of the 20th century • Its rediscovery prompted the foundation of genetics.

  6. The transmission of traits from parents to their offspring Important for understanding reasons for our appearance and study of genetic diseases Heredity

  7. vocabulary terms INHERITANCE or HEREDITY-The genetic transmission of characteristics from parent to offspring, such as hair, eye, and skin color.

  8. A category within which alternate characteristics can be observed Examples of traits: hair color, eye color, height Trait

  9. A segment of DNA that contains coding for a polypeptide or protein – a unit of hereditary information Found on chromosomes within the nucleus Gene

  10. vocabulary terms HOMOLOGOUS CHROMOSOME- A pair of matching chromosomes in an organism, with one being inherited from each parent.

  11. vocabulary terms AUTOSOME- A chromosome that is not a sex chromosome.

  12. An alternate form of a gene Ex: Everyone has an eye color, but there are different types: blue, brown, etc. Alleles

  13. vocabulary terms • ALLELES- alternative forms of the same gene.  Alleles for a trait are located at corresponding positions on homologous chromosomes called loci. ALLELES Chromosome from MOM A b C d e Chromosome from DAD A B c d E

  14. (P) Chromosome from DAD: P Chromosome from MOM: p (p)

  15. An allele that masks the presence of another allele for the same characteristic -Shown with a capital letter (ex: A, T, G). -Will always be seen if present. Dominant

  16. What are Dominant Genes? • Dominant Genes = one gene overshadows the other • Angus Cattle: black is dominant, red is not Dominant: BB or Bb Recessive: bb ONLY

  17. What are Dominant Genes? Hereford: white face is dominant Dominant: WW or Ww Recessive: ww ONLY

  18. An allele that is masked by the presence of another allele for the same characteristic -Shown with a lower case letter (ex: a, t, g). -Will only be seen if both alleles for a trait are recessive. Recessive

  19. What are Recessive Genes? Black wool is recessive to white wool. Dominant: WW or Ww Recessive: ww ONLY

  20. What are Recessive Genes? • Albinism (Albino) is recessive to pigmented.

  21. Allows each parent to contribute half the chromosomes to produce offspring with the full # of chromosomes. Law stating that pairs of genes separate in meiosis and each gamete receives one gene of a pair Law of Segregation

  22. Law stating that pairs of genes separate independently of one another in meiosis The gene for eye color sorts separately from hair color, and skin color, etc… Law of Independent Assortment

  23. The genetic makeup of an organism Written with the letters of alleles: Aa, TT, bb, etc. Genotype

  24. vocabulary terms GENOTYPE- the genes present in the DNA of an organism.  There are always 2 letters in the genotype because (as a result of sexual reproduction) 1 gene from MOM + 1 gene from DAD = 2 genes (2 letters) foroffspring

  25. vocabulary terms Now, it turns out there are 3 possible GENOTYPES: • TT = homozygous = purebred • Tt = heterozygous = hybrid • tt = homozygous = purebred

  26. The external (physical) appearance of an organism that is determined by the individual’s genotype Written as the Physical Trait: Brown hair, blue eyes, short, etc. Phenotype

  27. vocabulary terms • PHENOTYPE- how the trait physically shows-up in the organism; it is the observable traits present in an organism What the organism LOOKS like • Examples of phenotypes: blue eyes, brown fur, striped fruit, yellow flowers

  28. Referring to a gene pair in which the two alleles code for the same trait Written as: AA or aa Homozygous

  29. Referring to a gene pair in which the two alleles do not code for the same trait Written as: Aa Heterozygous

  30. An organism that is homozygous for a trait Ex: AA or aa Purebred

  31. An organism that is heterozygous for a trait Ex: Aa Hybrid

  32. The number of times an event is expected to happen divided by the number of opportunities of an event to happen Ex: dice, coin-flipping, chance of have blue eyes, etc. Probability

  33. Geneticists apply mathematical principles of probability to Mendel’s laws of heredity in order to predict the results of simple genetic crosses

  34. Mendel’s laws of heredity are based on his mathematical analysis of observations of patterns of the inheritance of traits. • The laws of probability govern simple genetic recombinations. • To see this we use a Punnett Square

  35. Mom’s alleles go together on one side and Dad’s go together on the other. A model used to establish the probabilities of the results of a genetic cross Punnett Square

  36. Punnett Squares • For the pea plant flowers: dominant: purple color = P recessive: white color = p. • If both parents are purebred, then the purple colored parent must be PP and the white colored parent must be pp.

  37. How can we predict these results? Homozygous-dominant We complete the possible combinations. P P p P P p p p P P p p Homozygous-recessive

  38. These results show that all the F1 (1st filial generation) offspring are all purple colored hybrids. 100% purple offspring

  39. We can use another Punnett square to predict the F2 (2nd filial generation) offspring. Heterozygous - hybrid P p Heterozygous - hybrid P P P P p p P p p p

  40. The results are always mathematically the same, a 3:1ratio with 75% purple & 25% white offspring Heterozygous - hybrid P p Heterozygous - hybrid P P P P p p P p p p Phenotypic ratio 3:1 Genotypic ratio 1:2:1

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