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. Chromosome
Supercoils
Coils
Nucleosome
Histones/proteins
DNA
double
helix

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.

8. Autosomes Contain genes for all traits except for sex
Chromosome pairs

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

12. 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.

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

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

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

16. Phenotype

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

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

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

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

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

22. Which gene is heterozygous?

23. Which gene is heterozygous?

24. Which gene is heterozygous?

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

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

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

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

29. 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

30. How would you answer?

31. 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

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

33. a) the dominant b) the recessive c) neither
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

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

35. 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)

36. Genotype IA IA or IAi IB IB or IBi IA IB ii
Phenotype

37. IA IA or IAi A IB IB or IBi B IA IB A and B AB ii none O
Genotypes
Surface Proteins
Phenotypes
IA IA or IAi A
IB IB or IBi B
IA IB
A and B AB ii
none O

38. Examples

39. 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

41. Comparison
Codominance
Incomplete dominance

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

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

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