Final Flashcards
Step 1: P gen
Produced a “true breeding” population called the P generation by self-pollinating plants with the desired trait. R: PP and pp
Step 2: F1 gen
Produced a F1 generation by cross-pollinating the p generation. T: PP X pp / R: Pp
Step 3: F2 gen
Produced a F2 generation by self-pollinating the F1 generation.
T: Pp x Pp / R: PP, pp, Pp, Pp
P gen= Phenotypes + Phenotypic ratio
P: White, Purple
PR: 1:1
F1 gen= Phenotype + Phenotypic ratio.
P: 100% purple
PR: 1:0?
F2 gen= Phenotype + Phenotypic ratio
P: White, Purple
PR: 3:1
Allele
One of two (or more) forms of a gene.
-Each individual has two or more alleles per trait.
-Each parent will pass an allele to an offspring.
-The F2 genwration will produce a ratio of 3:1.
Phenotype
-The physical apperance of an organism
-Word descriptions (blue eyes and black hair)
Genotype
-The genetic makeup of an organism.
-Letters (BB, Bb, bb)
Monohybrid Cross
-Mono means one
-A monohybrid cross is a cross between individuals reguarding only one trait.
Phenotypic ratio
The ratio of phenotypes that appear in the offspring.
(Dominant) : (Recessive)
Genotypic ratio
The ratio of genotypes that appear in the offspring.
(AA) : (Aa) : (aa)
Test cross
Process used to determine the genotype of an unknown genotype of an organism.
To perform a cross test
To perform: Cross the individual with unkown genotype with a homozygous recessive individual. Analyze the phenotype ratios of the offspring.
Results of the test cross
If the offspring is 100% dominant, then the unknown is probably homozygous dominant.
If any of the offspring is recessive, then the unknown is heterozygous.
Complete Dominance
One allele is completely dominant.
Ex. Aa (A dominates a)
Incomplete Dominance
Two or more alleles influence the phenotype. Often the phenotype is a blending or mixing of the other phenotypes. Only heterozygous is affected.
Codominance
Both alleles for a gene are expressed in the heterozygous individual. Neither allele is dominant ir recessive. Nor do the alleles blend in the phenotype. Only the heterozygous if affected.
Incomplete Dominance example
Ex. When you cross a red flower and a white flower, you get a pink flower.
Codominance example
Ex. When you cross a red horse with a white horse you get a ROAN horse.
- 3 Phenotypes
- Heterozygote mix
- Expresses both alleles
- Incomplete or Codominance
- Incomplete dominance
- Codominance
Multiple Alleles (Blood Types)
More than two types of alleles (not just B or b) but each person only gets two alleles that are equally dominant and recessive third allele
Ex. Human bloodtype
Human Bloodtype Geneotype
Antigens (protein) [A-antigens, B-antigens, O-no antigens]
I is equally dominant to other I.
Type A: I^A I^A or I^A i
Type B: I^B I^B or I^B i
Type AB: I^A I^B
Type O: ii
Dihybrid
Crossing two traits simultaneously.
Solving Dihybrid Crosses: Step 1
Step 1: Determine the genotypes of the parents.
a. Two traits involved
b. What is the dominant and rexessive phenotype.
c. What letters will you use.
Solving Dihybrid Crosses: Step 2
Step 2: Determine the gametes each parent could give by using FOIL. AaBb
F: First set - Aa
O: Outerset - Ab. (4 possible combos)
I: Inner set - aB
L: Last set - ab
Solving Dihybrid Crosses: Step 3
Line up the possible gametes on a 4x4 punnett square. (Must account for every unique geneotype)
Short cut for dihybrid crosses.
If 2 of the 4 gametes (combos) are repeated you don’t have to do both.
In the early 1900’s, a researcher named Thomas Morgan discovered.
Sex chromosomes are either X or Y
For the 23rd pair of chromosomes, females have _ _ and males have _ _.
Female: XX
Male: XY
During 1._____, females will only produce 2.________…
- Oogenesis 2. Eggs with an x chromosome
During _______, males produce _______…
- Spermatogenesis 2. Sperm with either an X or Y chromosome.
The fathers sperm…. of the baby
Determines the gender.
Comparing X and Y chromisomes
The Y chromosome is 1/3 the size of the X chromosome. Therefore the X chromosomes can carry more genes than the Y chromosomes.
The presence of a gene on a sex chromosome (X or Y)
Sex linkage- sex linked traits are [physical traits] that whose genes are on the X and Y chromosome.
Examples of sex linked traits
Colorblindness, Hemophilia, Muscular dystrophy.
SLT: Female
A feamale has two X chromossomes can AA, Aa, aa.
Geneotype: X^A X^A, X^a X^a, X^A X^a
SLT: Male
Only one X chromosome. So whichever gene he gets (dominant or recessive) will determine his phenotype.
Chromosome Y
Males cannot be carriers because Y can’t carry any genes.
Pedigree
A genetic representation of a family tree that diagrams the inheritance of a trait or disease through several generations.