DNA, inheritance, and genetics
•Describe the relationships between DNA, genes, chromosomes, and the nucleus
I. The molecule that carries all an organism’s genetic information is called _DNA________
II. DNA is separated into individual _______chromosomes__________, and they are located in the cell’s ____nucleus_____________
III. A ____gene____________ is a small part of the DNA of a chromosome that contains the information that is needed for building a single trait or protein
•Mention the basic differences between a genotype and phenotype
I. The composition of alleles of an organism is its ______genotype_____________
II. The combination of traits that an organism chooses to express are its ________phenotype___________
•What is the difference between homozygous and heterozygous
I. An organism that is associated with being homozygous because of a particular trait has two __similar_________________ alleles for the trait
II. An organism that is heterozygous for one single trait has two ____different_______________ alleles for the trait
•Predict the genotype and phenotype of the first and second generations of a cross between two true-breeding parents
I. A true-breeding plant is one that when crossed with its offspring will always produce the same trait. Because of this inheritance pattern, we can deduce that a true-breeding plant is heterozygous / homozygous (homozygous)
II. The eggs and sperm produced by a true-breeding plant will all contain the same / different (the same) alleles for the trait of interest.
III. Two plants are true-breeding for two contrasting traits: one plant comes from a line of plants that only produce wrinkly seeds and the other comes from a line of plants that only produce smooth seeds. The two true-breeding plants are crossed, and all the first-generation offspring all have the smooth seed phenotype.
a. If the allele for smooth seeds is S and the allele for wrinkly seeds is s, what were the genotypes of the two true-breeding parent plants?
i. Smooth seed parent: __dominant__________
ii. Wrinkly seed parent: ___recessive_________
b. Based on the phenotypes of all the offspring in the first generation, which allele, S or s, is dominant? ____S________
c. What is the genotype of all the first-generation offspring? ______Ss______
d. Next, two smooth-seeded plants from the first-generation offspring are crossed. Using the Punnet square below, predict the genotypes and phenotypes of the second-generation offspring produced from this cross:
|
|
|
Pollen: |
|
|
|
|
S |
|
|
Ovules: |
S |
SS |
Ss |
|
s |
Ss |
ss |
|
Inheritance & Genetics: Practice Test Cross
Name: ________________________________
In peas, the allele for tall plants, T is dominant over the allele for short plants, t. A farmer growing pea plants for seed would like to obtain parental plant stock that is homozygous (TT) for the tall plant allele (he prefers tall plants).
1. The farmer obtains a tall pea plant. What are the two possible genotypes for this plant?
TT or Tt
2. To figure out which of the above genotypes the tall plant is carrying, the farmer carries out a test cross between the tall plant and a pea plant with the short phenotype. What is the genotype of the short plant?
tt
3. A test cross is useful, because the phenotypes of the first-generation offspring from the test cross can be compared to the expected phenotypes of offspring arising from crosses between a short plant (genotype known – see #2) and either of the possible genotypes for the tall plant (see #1). Use the two squared below to predict the phenotypic ratios of the first-generation offspring for both the possible tall plant genotypes:
|
|
|
Tall Plant Gametes: |
|
|
|
|
T |
|
|
Short Plant Gametes: |
t |
Tt |
Tt |
|
t |
Tt |
Tt |
|
|
|
|
Tall Plant Gametes: |
|
|
|
|
T |
t |
|
Short Plant Gametes: |
t |
Tt |
tt |
|
t |
Tt |
tt |
|
Tall: ___4__ / Short: ___0____Tall: __2_ / Short: __2__
4. If the farmer performed the test cross and all the first-generation offspring were tall, which of the two possible genotypes from question #1 did the tall parent plant have?
TT or Tt
Academic levels
Skills
Paper formats
Urgency types
Assignment types
Prices that are easy on your wallet
Our experts are ready to do an excellent job starting at $14.99 per page
We at GrabMyEssay.com
work according to the General Data Protection Regulation (GDPR), which means you have the control over your personal data. All payment transactions go through a secure online payment system, thus your Billing information is not stored, saved or available to the Company in any way. Additionally, we guarantee confidentiality and anonymity all throughout your cooperation with our Company.