Chapters 11-12 Flashcards
Differentiate between the “blending” hypothesis and the “particulate” hypothesis of genetic inheritance. Which did Mendel support?
Blending-Taking two things and making it into one while the particulate hypothesis of genetic inheritance states that parents pass discrete heritable genes to their offspring.
Mendel supported the particular hypothesis.
Mendel used the term “character” to describe a heritable feature that varies among a population. What term do we now use? What about the term “trait” that Mendel used?
characters=genes
-trait= allele
Name three advantages of using pea plants for genetic study.
- Many different varieties (color/shape/ length) either or characteristic
- He could control the mating (which plant mated with another)
- Produces many offsprings
What is “true-breeding”?
Plants that produce an offspring of the same variety when they self-pollinate/reproduce. Same phenotype (homozygous)
What is hybridization?
Mating two different true breeding organisms/varieties
Name 4 of the 6 characters that Mendel studied in his pea plants.
1.plant size. 2. flower color. 3. seed color 4. seed shape
Differentiate between the P, F1 and F2 generations.
p= parent F1= offspring of the parent F2= offspring of the F1 generation (offspring) -second generation
What did Mendel obtain for F1 offspring when he crossed a true breeding purple and a true breeding white flowered pea plant?
All purple flowers
What did Mendel cross to obtain his F2 generation?
Two of the purple flower offsprings from generation 1 (self or cross pollination)
What ratio of purple to white flowers did Mendel obtain in his F2 offspring?
3:1
Differentiate between a “gene” and an “allele”.
gene- = an particular trait (blue eyes) Allele- a form of a gene (hair color)
How many alleles are inherited for each gene? Why?
2, one from each parent
What is the difference between a dominant and a recessive trait? What do we use in genetics to represent dominant and recessive alleles?
- Dominant trait is a trait that is expressed while a recessive trait is a trait that will only show up if the whole gene is recessive.
- Recessive= two lowercase letters Dominant= 2 capital letters or one capital letter and a lowercase letter
Differentiate between homozygous and heterozygous and give an example.
homozygous= 2 of the same letter(AA or aa) heterozygous- 1 lowercase and one capital letter (Aa)
What is the law of segregation?
When two alleles for a heritable character separate during gamete formation. End up in different gametes
Differentiate between genotype and phenotype.
Genotype- genetic makeup phenotype-physical appearance
If you are uncertain of an individual’s dominant genotype, what can you do to figure it out?
You do a testcross between the individual and a homozygous recessive individual of the same type.
Differentiate between a monohybrid and a dihybrid cross.
Monohybrid- individuals heterozygous for one character
dihybrid= individuals heterozygous for two characters
What did Mendel observe in the offspring of his YyRr x YyRr cross? What were the phenotypic ratios? Make sure you understand how to perform a dihybrid (or two-factor) cross.
Phenotypic ratio 9:3:3:1
What gametes would result from the genotype YyRr?
YR, yr, yR, yr
What is the law of independent assortment?
Each pair of alleles segregates independently from any other pair during gamete formation
How did the dihybrid cross prove independent assortment?
The alleles for the color of the seed did not affect the shape of the seed
Mendel stated that each pair of alleles is what assorts independently. We now know this isn’t entirely true. What would be a correct statement?
Each chromosome segregates independently from any other chromosome
Why can probability be used in genetics?
To determine how likely two independent events will happen together
A homozygous recessive for seed shape and color (rryy) is crossed with one that is heterozygous for seed shape and color (RrYy). What is the probability the offspring will be RrYy? (Use the rule of multiplication instead of the Punnett square).
¼
Differentiate between complete dominance, incomplete dominance and codominance. Give an example of each.
Complete dominance- phenotypes of the heterozygous and dominant homozygous are identical and dominant (Rr and RR will both be round)
Incomplete dominance= the phenotype of f1 is between its parents (ex: parents red and white -offspring=pink)
codminance= two dominant alleles affect the phenotype in separate and distinguished ways (ex; parent 1= stripes parent 2=dots- offspring-strips and dots)