BIO 222 Chapter 3: Basic Principles of Heredity

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

Which principle states that alleles separate independently of other loci during meiosis?

Principle of recombination

Principle of segregation

Principle of independent assortment (correct)

Principle of dominance

What does the term 'dihybrid cross' refer to?

Crossing two individuals with two traits (correct)

Crossing individuals with different genotypes for one trait

Crossing individuals of the same genotype

Crossing two homozygous individuals

In a chi-square goodness-of-fit test, a probability of 0.72 indicates what?

The results obtained are incorrect

There is a significant difference between observed and expected numbers

The test is inconclusive

The difference between observed and expected numbers could be due to chance (correct)

Which phase of meiosis is primarily concerned with the principles of segregation?

Anaphase I Signup and view all the answers

What is likely true about the expected ratios of progeny in a genetic cross?

They may deviate from the observed ratios by chance Signup and view all the answers

What is the outcome of applying a branch diagram in genetics?

It visually represents the distribution of allele combinations in dihybrid crosses Signup and view all the answers

Which of the following statements is true about alleles during meiosis?

Alleles separate and are distributed randomly into gametes Signup and view all the answers

What does a high chi-square value indicate in a goodness-of-fit test?

Observed numbers significantly differ from expected numbers Signup and view all the answers

Which factor was not a key contributor to Mendel's success in his study of heredity?

His study of plant chromosomes Signup and view all the answers

What term describes an individual organism with two different alleles at a locus?

Heterozygote Signup and view all the answers

Which term refers to the specific location on a chromosome where an allele resides?

Locus Signup and view all the answers

Which statement accurately distinguishes genotype from phenotype?

Genotype is the set of alleles, while phenotype is the observable characteristics. Signup and view all the answers

What is an allele?

An alternative form of a gene Signup and view all the answers

Which of these terms is synonymous with an observable characteristic of an organism?

Phenotype Signup and view all the answers

In genetic terminology, what does homozygote mean?

An individual with two of the same alleles at a locus Signup and view all the answers

Which factor did Mendel not utilize in his genetic experiments?

Studying complex characteristics of animals Signup and view all the answers

What is the correct binomial expansion for $n = 3$?

$a^3 + 3a^2b + 3ab^2 + b^3$ Signup and view all the answers

Which of the following ratios represents the expected genotypic ratio for a monohybrid cross between Aa and Aa?

1:2:1 Signup and view all the answers

In a dihybrid cross examining two traits, what is the principle that states gametes located on different chromosomes will sort independently?

Principle of Independent Assortment Signup and view all the answers

What phenotypic ratio would you expect from a cross between Aa and aa?

1:1 Signup and view all the answers

Which of the following is NOT a part of the binomial expansion for $p + q$?

$qp$ Signup and view all the answers

How are the principles of segregation and independent assortment similar?

Both involve the formation of gametes. Signup and view all the answers

What is the expected progeny ratio for a cross between AA and aa?

All Aa Signup and view all the answers

What is the correct expansion for the binomial expression $(p + q)^4$?

$p^4 + 4p^3q + 6p^2q^2 + 4pq^3 + q^4$ Signup and view all the answers

What does a monohybrid cross examine?

Cross between two parents that differ in a single characteristic Signup and view all the answers

What is the principle of segregation?

Alleles separate when forming gametes, with one allele going to each gamete Signup and view all the answers

Which statement about dominant and recessive alleles is true?

Only the trait indicated by the dominant allele is observed Signup and view all the answers

During which phase of meiosis do alleles segregate into gametes?

Anaphase I Signup and view all the answers

What is true regarding two alleles in an individual organism?

They segregate, with one allele in each gamete Signup and view all the answers

What does the concept of independent assortment state?

Different characteristics are inherited independently of each other Signup and view all the answers

What happens to alleles during gamete formation?

They separate into different gametes with equal probability Signup and view all the answers

According to Mendel’s theory, which statement about gametes is correct?

Gametes are haploid and carry only one allele Signup and view all the answers

How did Mendel determine that each of his pea plants carried two alleles for a characteristic?

He noted that the traits encoded by both alleles appeared in the F2 progeny. Signup and view all the answers

What is the probability of obtaining an offspring with winkled seeds when an F1 plant is backcrossed with a parent having round seeds?

1/4 Signup and view all the answers

Which rule is used to calculate the probability of a specific genetic outcome in a cross?

Multiplication rule Signup and view all the answers

If the probability of blood-type A is 1/8 and the probability of blood-type O is 1/2, what is the correct calculation for the probability of being either blood-type A or O?

5/8 Signup and view all the answers

Which of the following best describes the binomial expansion in a genetic context?

Expressed as (p + q)n, with n being the total possible outcomes. Signup and view all the answers

In which scenario would the multiplication rule of probability apply?

Determining the occurrence of two independent traits in offspring. Signup and view all the answers

Which concept is crucial for understanding the outcomes of Mendelian crosses?

Principle of Segregation Signup and view all the answers

How do backcrosses contribute to understanding dominant traits?

They help predict the ratio of dominant to recessive traits in progeny. Signup and view all the answers

Study Notes

Basic Principles of Heredity

Gregor Mendel's success in genetics stemmed from a proper experimental design and mathematical analysis of results, focusing on easily discernible characteristics.
Mendel's study of pea plants (Pisum sativum) revealed traits like seed color (yellow/green), seed shape (round/wrinkled), pod color (yellow/green), pod shape (inflated/constricted), flower position (axial/terminal), and stem length (short/tall).

Mendelian Experiments and Success

Mendel's controlled experiments involved hybridizing pea plants through cross-pollination.
He tracked traits through generations, observing consistent patterns. Analysis of these patterns mathematically led to conclusions about inheritance.
His detailed approach contributed to the principles of inheritance.

Genetic Terminology

Gene: An inherited factor (within DNA) influencing a characteristic.
Allele: One of multiple forms of a gene at a specific locus.
Locus: The specific location of a gene on a chromosome.
Genotype: The genetic makeup (allele combination) of an organism.
Heterozygote: An organism with two different alleles at a locus.
Homozygote: An organism with two identical alleles at a locus.
Phenotype: The observable characteristic or trait resulting from the genotype.
Characteristic/Character: An attribute or feature of an organism.

Monohybrid Crosses

A monohybrid cross investigates a single trait, revealing the concept of dominance (one allele masks another) and segregation (alleles separate during gamete formation, each gamete receiving only one allele).
Mendel's experiments illustrated these principles using pea plant traits, leading to significant conclusions and observations.
The Punnett square is a tool for predicting the genetic outcomes of crosses.

Principle of Segregation

Each diploid organism has two alleles for a trait. This is due to the fact that each gamete, during meiosis, receives only one copy.
The alleles separate during gamete formation.
During fertilization, each offspring inherits one allele from each parent.
When determining the genetic outcome of a cross, the alleles should be treated as separate entities.

Principle of Independent Assortment

Alleles on different pairs of chromosomes sort independently during meiosis.
This means that the inheritance of one trait doesn't influence the inheritance of another trait.
Mendel's experiments demonstrated independent assortment using pea plant traits, leading to the observation of distinct ratios in offspring traits.

Probability in Genetics

Probability is the likelihood of a specific event occurring.
The multiplication rule calculates probabilities of independent events.
The addition rule calculates probabilities of mutually exclusive events.
These methods (multiplication and addition rule) are helpful for predicting outcomes of genetic crosses.

Chi-square Goodness-of-Fit Test

This test is used to assess the difference between predicted and observed results in genetic experiments.
It evaluates the probability that observed deviations are due to random chance.

Dihybrid Crosses

These experiments examine inheritance patterns of two traits simultaneously.
They confirm the principle of independent assortment, where alleles of different traits sort independently during meiosis and are passed on to the offspring.
The use of branch diagrams can be used to illustrate the possible results of a dihybrid cross
The dihybrid testcross is a tool for verifying inheritance patterns.

Testcross

A testcross involves crossing an individual of unknown genotype with a homozygous recessive individual (for the trait in question).
Analysing the offspring phenotypes reveals the unknown genotype.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.