---
title: "Law of Segregation | Biological Anthropology"
description: "Law of segregation is Mendel’s rule that allele pairs separate during gamete formation, shaping inheritance patterns studied in Biological Anthropology."
canonical: "https://fiveable.me/biological-anthropology/key-terms/law-of-segregation"
type: "key-term"
subject: "Biological Anthropology"
unit: "Unit 2"
---

# Law of Segregation | Biological Anthropology

## Definition

The law of segregation says that the two alleles for a gene separate during gamete formation, so each gamete gets one allele. In Biological Anthropology, it explains how traits are inherited across families and populations.

## What It Is

The law of segregation is the Mendelian rule that the two alleles for a gene separate when gametes are made, so each egg or sperm carries only one allele for that gene. In Biological Anthropology, this is the basic mechanism behind simple inheritance patterns you see in family traits and genetic cross problems.

Think of an individual as carrying two versions of a gene, one from each parent. If those versions are different, meiosis does not keep them together in the same gamete. Instead, homologous chromosomes separate during meiosis I, and the alleles on those chromosomes end up in different cells. That means a parent does not pass both alleles for a trait to one child through the same gamete, only one allele at a time.

This is why a heterozygous person, such as someone with one dominant allele and one recessive allele, can make gametes that carry either version. If the dominant allele is present, it may affect the phenotype, but the recessive allele is still there and can be passed on. That hidden inheritance is what makes traits seem to skip generations in pedigrees, even though the allele has not disappeared.

The law of segregation is about allele separation, not trait blending. A child does not get a mixed allele from each parent. Instead, the offspring gets one allele from the mother’s gamete and one from the father’s gamete, and those two alleles combine to form the genotype. The genotype then influences the phenotype, depending on whether the allele is dominant, recessive, or part of a more complex pattern.

In Mendelian genetics problems, you often use the law of segregation to predict offspring ratios. A Punnett square works because each gamete is assumed to carry one allele for the trait. For example, if two carriers have a child, the possible allele combinations can be mapped out to estimate genotypic ratio and phenotype outcomes. That same logic shows up in Biological Anthropology when you compare inheritance of observable traits, discuss variation in human families, or connect modern genetics to evolutionary patterns.

## Why It Matters

The law of segregation gives you the basic logic behind how inherited variation moves through families and populations in Biological Anthropology. Without it, you cannot make sense of dominant and recessive traits, carrier status, or why a trait can appear in one generation and not the next.

It also connects genetics to the study of human variation. Biological anthropologists look at how traits are inherited, how genetic variation is maintained, and how family patterns fit into larger evolutionary questions. Segregation is the first step in those explanations because it tells you how alleles leave one generation and enter the next.

This concept is also a foundation for reading pedigree charts, interpreting genotype possibilities, and solving simple inheritance problems. If you know how alleles separate in gametes, you can trace probable offspring outcomes instead of guessing from appearance alone. That matters when a phenotype hides the underlying genotype, which happens a lot with dominant and recessive traits.

It also sets up more advanced genetics. Once you understand segregation, it becomes easier to see how independent assortment, linkage, and non-Mendelian patterns add extra layers. Segregation is the baseline rule, and the rest of the course often asks you to notice when a trait follows that rule and when it does not.

## Connections

### alleles

Alleles are the different versions of a gene, and the law of segregation explains how those versions get divided into gametes. If you are tracking inheritance, you have to know which allele each parent can pass on. Segregation is the process, while alleles are the actual gene variants being separated and inherited.

### gametes

Gametes are the sperm and egg cells that carry genetic information to the next generation. The law of segregation describes what happens to allele pairs when gametes form. Each gamete ends up with one allele for each gene, which is why offspring inherit one copy from each parent rather than a full pair from one parent.

### Mendelian inheritance

Mendelian inheritance is the broader pattern of heredity that includes segregation and other classic Mendel rules. The law of segregation is one of its core ideas, especially for single-gene traits with dominant and recessive alleles. When a trait follows Mendelian inheritance, Punnett squares and expected ratios usually make sense.

### [law of independent assortment](/biological-anthropology/key-terms/law-of-independent-assortment)

The law of independent assortment is related, but it deals with different genes, not the two alleles for one gene. Segregation says the alleles of one gene separate into different gametes. Independent assortment says the way one gene’s alleles separate does not usually affect another gene’s alleles, if the genes are on different chromosomes.

## On the AP Exam

A quiz question or problem set item will usually ask you to identify what happens to alleles during meiosis, predict offspring outcomes, or explain why a recessive trait can show up after skipping a generation. You might also get a pedigree or cross and need to trace which allele each parent can pass on.

The move you make is simple: separate the allele pair into gametes, then combine one allele from each parent to find the possible genotypes. If the problem gives you a dominant and recessive trait, use the law of segregation to justify why a heterozygous parent can produce more than one kind of gamete. In essay or discussion answers, connect that separation to variation in family traits and inheritance patterns.

## law of segregation vs law of independent assortment

These two Mendelian laws are easy to mix up. The law of segregation is about the two alleles for one gene splitting apart during gamete formation. The law of independent assortment is about different genes being distributed into gametes independently of one another, usually when they are on separate chromosomes.

## Key Takeaways

- The law of segregation says that the two alleles for a gene separate when gametes form, so each gamete carries only one allele.
- In Biological Anthropology, this is the basic rule behind simple inheritance patterns, carrier status, and many family-trait examples.
- The separation happens during meiosis, when homologous chromosomes are divided into different cells.
- A recessive allele can be passed on even if it is not visible in the phenotype, which is why traits can skip generations.
- Punnett squares work because they use segregation to predict which allele combinations offspring can inherit.

## FAQs

### What is the law of segregation in Biological Anthropology?

It is the rule that paired alleles separate during gamete formation, so each sperm or egg gets one allele for each gene. In Biological Anthropology, that rule is used to explain inheritance patterns, family traits, and basic Mendelian crosses.

### When does the law of segregation happen?

It happens during meiosis, when homologous chromosomes separate into different cells. That physical separation is why a parent’s two alleles do not stay together in the same gamete.

### How is the law of segregation different from independent assortment?

Segregation is about the two alleles of one gene splitting apart. Independent assortment is about different genes being distributed independently into gametes. They are related Mendelian ideas, but they describe different parts of inheritance.

### Why can a trait skip a generation because of segregation?

A recessive allele can be inherited without showing in the phenotype if a dominant allele masks it. Segregation lets that hidden allele move through gametes, so it can reappear when two recessive alleles meet in a child.

## Related Study Guides

- [2.2 Mendelian genetics and inheritance](/biological-anthropology/unit-2/mendelian-genetics-inheritance/study-guide/MqiLaR7dPgQsodz5)

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