Question
in mendel's monohybrid crosses, what is homozygous?
give formula
p(f0)
f1
f2
give formula
p(f0)
f1
f2
Answers
GPT-4o mini
In Mendel's monohybrid crosses, the term "homozygous" refers to an organism that has two identical alleles for a specific gene. For example, an organism can be homozygous dominant (AA) or homozygous recessive (aa).
### Monohybrid Cross Overview:
1. **Parental Generation (P)**: The initial parents in the cross. They can be homozygous for different alleles, such as one being AA (homozygous dominant) and the other aa (homozygous recessive).
2. **First Filial Generation (F1)**: The offspring from the parental generation. In a typical monohybrid cross, all F1 offspring will be heterozygous (Aa) if one parent is homozygous dominant and the other is homozygous recessive.
3. **Second Filial Generation (F2)**: The offspring produced by crossing two F1 individuals (Aa x Aa). In this generation, you can observe the typical phenotypic ratio of 3:1 (dominant:recessive) in the offspring.
### Genetic Cross Notation:
- **P (Parent Generation)**: AA x aa
- **F1 Generation**: All offspring will be Aa (heterozygous).
- **F2 Generation**: The cross of F1 generation (Aa x Aa) produces:
- AA (homozygous dominant)
- Aa (heterozygous)
- aa (homozygous recessive)
### Punnett Square for F2 Generation:
```
A A
__________
a | Aa | Aa |
a | Aa | Aa |
```
In the F2 generation:
- 1 AA (homozygous dominant)
- 2 Aa (heterozygous)
- 1 aa (homozygous recessive)
### Phenotypic Ratio in F2 Generation:
- 3 dominant phenotype (AA and Aa) : 1 recessive phenotype (aa)
### Summary:
- **Homozygous**: Organisms with two identical alleles (AA or aa).
- **F0**: Parental generation (e.g., AA x aa)
- **F1**: First generation offspring (e.g., 100% Aa)
- **F2**: Second generation offspring (from F1 cross, e.g., 1 AA : 2 Aa : 1 aa)
### Formula:
For a typical monohybrid cross, the genotype frequencies in F2 can be summed up as:
- P = \( p^2 + 2pq + q^2 \)
Where:
- \( p \) = frequency of dominant allele
- \( q \) = frequency of recessive allele
- \( p + q = 1 \)
In our case, for P = AA (p=1) and aa (q=1), frequencies in F1 and F2 can be represented in ratios or percentages.
### Monohybrid Cross Overview:
1. **Parental Generation (P)**: The initial parents in the cross. They can be homozygous for different alleles, such as one being AA (homozygous dominant) and the other aa (homozygous recessive).
2. **First Filial Generation (F1)**: The offspring from the parental generation. In a typical monohybrid cross, all F1 offspring will be heterozygous (Aa) if one parent is homozygous dominant and the other is homozygous recessive.
3. **Second Filial Generation (F2)**: The offspring produced by crossing two F1 individuals (Aa x Aa). In this generation, you can observe the typical phenotypic ratio of 3:1 (dominant:recessive) in the offspring.
### Genetic Cross Notation:
- **P (Parent Generation)**: AA x aa
- **F1 Generation**: All offspring will be Aa (heterozygous).
- **F2 Generation**: The cross of F1 generation (Aa x Aa) produces:
- AA (homozygous dominant)
- Aa (heterozygous)
- aa (homozygous recessive)
### Punnett Square for F2 Generation:
```
A A
__________
a | Aa | Aa |
a | Aa | Aa |
```
In the F2 generation:
- 1 AA (homozygous dominant)
- 2 Aa (heterozygous)
- 1 aa (homozygous recessive)
### Phenotypic Ratio in F2 Generation:
- 3 dominant phenotype (AA and Aa) : 1 recessive phenotype (aa)
### Summary:
- **Homozygous**: Organisms with two identical alleles (AA or aa).
- **F0**: Parental generation (e.g., AA x aa)
- **F1**: First generation offspring (e.g., 100% Aa)
- **F2**: Second generation offspring (from F1 cross, e.g., 1 AA : 2 Aa : 1 aa)
### Formula:
For a typical monohybrid cross, the genotype frequencies in F2 can be summed up as:
- P = \( p^2 + 2pq + q^2 \)
Where:
- \( p \) = frequency of dominant allele
- \( q \) = frequency of recessive allele
- \( p + q = 1 \)
In our case, for P = AA (p=1) and aa (q=1), frequencies in F1 and F2 can be represented in ratios or percentages.