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1. Truebreeding (homozygous); self pollinating
2. Dominant- “stronger” allele, will be expressed over a recessive allele, represent dominance using a
Capital letter. Recessive- “weaker” allele will hide in the presence of a dominant allele, must have to
have 2 (homozygous) alleles for the recessive trait to show in the phenotype, represent using a lower
case letter.
3. Co-dominance- both alleles expressed together in phenotype. Ex. Red parent crossed with a white parent
offspring would be Red and white in the same flower.
Incomplete dominance- offspring is in-between that of the parents. Ex. Cross between Red and white
makes a Pink flower.
Complete dominance – One allele will be completely dominant over the recessive. Ex. Red parent
crossed with a white parent and the offspring is Red.
4. Law of segregation- alleles separate or segregate during gamete (egg & sperm) formation. This is what
we are doing when we set up crosses.
Law of independent assortment- alleles of different genes assort independently of each other. Ex. hair
color does not determine your eye color they are separate.
5. Dominant; recessive
6. Test crosses are used to determine the genotype of a dominant phenotype. Remember: Dominant = RR
or Rr so you would cross your unknown with a known (homozygous recessive rr) If your unknown was
heterozygous then the offspring would be half and half . If the unknown is homozygous then all the
offspring will be dominant.
7. Monohybrid- 1 trait, uses 4 squares, 2 alleles per parent, with one allele in each gamete. Ex. Rr
Dihybrid- 2 traits, uses 16 squares, 4 alleles per parent and two alleles per gamete. Ex. RrTt
8. Genotype determines phenotype. Genotype= Genes or alleles, letters Ex. Rr
Phenotype = physical traits, red, blue, tall, short Ex. Red
9. 500 or 100%
10. Cross pollination- 2 different plants, new genes introduced. Self pollination- within the same plant, no
new genes introduced.
11. BbRr = BR, Br, bR, br
12. Different choices in a gene. Ex. Blue, brown, green eyes.
13. Heredity: Passing of traits from parent to offspring. Genetics: the study of how traits are passed from
parent to offspring ex. dominant, recessive, sex-linked, autosomal etc.
14. True Breeding: One that is homozygous for a trait (self pollinating) purebreeding
Hybrid: one of each allele, heterozygous Ex. Hh
15. Male and female parts are located in the same plant, multiple offspring, fairly short generation times,
traits are easy to tell apart.
16. Autosomal traits- found on autosomes which are chromosomes 1-22, appear in both sexes equally.
Sex-linked- usually appear more in males than females, inherited on X or Y chromosomes, usually X
17. A chart that traces a trait throughout a family. Remember always ask yourself if there are carriers and if
so are there any male carriers. If there is a male carrier then you know it can NOT be sex-linked it must
be autosomal.
18. Sex-linked recessive because there are male carriers
19. 25% or 1 out of 4 2 heterozygous gives the 1:2:1 ratio of genotypes.