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Genetics Vocab Notes

Genetics Vocab Notes. Genetics. The study of heredity, how traits (characteristics) are passed down from one generation to the next Gene – sequence of DNA that codes for a protein & thus determines a trait. Nucleosome. Chromosome. DNA double helix. Coils. Supercoils. Histones/proteins.

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Genetics Vocab Notes

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  1. Genetics Vocab Notes

  2. Genetics • The study of heredity, how traits (characteristics) are passed down from one generation to the next • Gene – sequence of DNA that codes for a protein & thus determines a trait

  3. Nucleosome Chromosome DNA double helix Coils Supercoils Histones/proteins

  4. Chromosomes Thread-like structures located inside the nucleus Each chromosome is made of protein and a single molecule of DNA. Passed from parents to offspring, DNA contains the specific instructions that make each type of living creature unique.

  5. Karyotype • A picture or display of all the pairs of chromosomes in numerical order based on size & shape

  6. Homologous chromosomes • Chromosomes that pair up and code for same genes, are the same size and shape. • One from mother & one from father.

  7. Autosomes • Contain genes for all traits except for sex • Chromosome pairs 1-22

  8. Sex Chromosomes • Chromosome pair #23 • XX – 2X’s will make female • XY – will make male

  9. Traits A genetically determined characteristic or condition.  Traits may be physical, such as hair color or leaf shape, or they may be behavioral, such as nesting in birds and burrowing in rodents.

  10. Alleles • Different forms of the same gene for a specific trait. • Ex. Trait – eye color Alleles – blue, brown, green

  11. Genotype • The genetic makeup • Refers to the alleles inherited for a particular gene • Made up of 2 alleles

  12. Phenotype • Physical appearance of the alleles • Ex. Blue eyes, tallness, being colorblind **Lots of misconceptions about dominant & recessive**

  13. Phenotype

  14. Talk to a Partner: Determine the genotype and phenotype of each flower

  15. Recessive • An allele expressed only when paired with another recessive allele. • Written as a small letter. • EX: b ~ blue eyes

  16. Dominant • An allele that is expressed when present • Written as a capital letter • EX: B ~ Brown eyes

  17. Homozygous • Having 2 identical alleles for a specific trait • Purebred • Can be dominant (BB) or recessive (bb)

  18. Heterozygous • Having 2 different alleles for a specific trait (Bb) • Hybrid or carrier

  19. Which gene is heterozygous?

  20. Which gene is heterozygous?

  21. Which gene is heterozygous?

  22. Talk to a Partner: Determine which are Homozygous & Heterozygous

  23. What would be the phenotypes of the 4 individuals below? R = Red r =white

  24. Talk to a Partner: Use the following terms: Homologous chromosomes, genes, alleles, heterozygous, homozygous, dominant, recessive, genotype, phenotype

  25. Which of these are genetically identical? A) Homologous chromosomes B) Sister Chromatids C) Neither

  26. Which of these will pair up to form chromosomes during mitosis? A) Homologous chromosomes B) Sister chromatids C) Chromatids pair at random, so it’s impossible to predict

  27. How would you answer?

  28. An allele is: a) another word for a gene b) a homozygous genotype c) a heterozygous genotype d) one of several possible forms of a gene

  29. Phenotype refers to the ______________ of an individual a) genetic makeup b) actual physical appearance c) recessive alleles

  30. When the genotype consists of a dominant and a recessive allele, the phenotype will be like _________________ allele a) the dominant b) the recessive c) neither

  31. Patterns of Gene Expression– 6 types 1. Dominant 2. Recessive

  32. 3. Codominance • Two different alleles of the same trait are fully expressed • Ex: Human blood types - A, B, AB, O • Alleles: IA, IB, i • IA & IB - codominant • i - recessive (ii=type O blood)

  33. Genotype IA IA orIAi IB IB orIBi IA IB ii Phenotype

  34. Examples

  35. 4. Incomplete Dominance • Two different alleles of same trait combine (BLEND) to form a new expression of alleles • Ex: Colors in flowers, red + whitepink

  36. Comparison Codominance Incomplete dominance

  37. 5. Polygenic traits • Trait produced from many alleles on more than one chromosome • Ex. Hair color, skin color, eye color, height

  38. 6. Sex linked traits • Traits carried on the sex chromosomes (mostly the x chromosome)

  39. Ex. Colorblind, hemophilia Summary – 3-4 sentences

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