Chapter 11 Introduction to Genetics Flashcards
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Questions and Answers

The scientific study of heredity is called?

genetics

What is true about Gregor Mendel's peas?

When pollen fertilizes an egg cell, a seed for a new plant is formed. Pea plants normally reproduce by self-pollination.

What does it mean when pea plants are described as being true-breeding?

If the plants are allowed to self-pollinate, they would produce offspring identical to themselves.

To perform his experiments, how did Mendel prevent pea flowers from self-pollinating and control their cross-pollination?

<p>He cut away the pollen-bearing male parts of a flower and dusted that flower with pollen from another plant.</p> Signup and view all the answers

What are genes?

<p>Chemical factors that determine traits.</p> Signup and view all the answers

What are hybrids?

<p>The offspring of crosses between parents with different traits.</p> Signup and view all the answers

What are traits?

<p>Specific characteristics that vary from one individual to another.</p> Signup and view all the answers

What are alleles?

<p>The different forms of a gene.</p> Signup and view all the answers

State the principle of dominance.

<p>Some alleles are dominant and others are recessive.</p> Signup and view all the answers

An organism with a recessive allele for a particular form of a trait will always exhibit that form.

<p>False (B)</p> Signup and view all the answers

Name the traits controlled by dominant alleles in Mendel's pea plants.

<p>tall &amp; yellow</p> Signup and view all the answers

How did Mendel find out whether the recessive alleles were still present in the F1 plants?

<p>He allowed the F1 plants to produce an F2 generation by self-pollination.</p> Signup and view all the answers

About one fourth of the F2 plants from Mendel's F1 crosses showed the trait controlled by the _____________ allele.

<p>recessive</p> Signup and view all the answers

What is true about Mendel's explanation of the results from his F1 cross?

<p>Mendel assumed that a dominant allele had masked the corresponding recessive allele in the F1 generation and at some point, the allele for shortness was segregated from the allele for tallness.</p> Signup and view all the answers

What are gametes?

<p>The sex cells.</p> Signup and view all the answers

In the following F1 generation, what represents the dominant allele and which represents the recessive allele? Tt x Tt

<p>T = dominant allele, t = recessive allele</p> Signup and view all the answers

The likelihood that a particular event will occur is called?

<p>probability</p> Signup and view all the answers

What is the probability that a single coin flip will come up heads?

<p>50%</p> Signup and view all the answers

The past outcomes of coin flips greatly affect the outcomes of future coin flips.

<p>False (B)</p> Signup and view all the answers

Why can the principles of probability be used to predict the outcomes of genetic crosses?

<p>The way in which the alleles segregate is completely random, like a coin flip.</p> Signup and view all the answers

How do genetics use Punnett squares?

<p>Punnett squares can be used to predict and compare the genetic variations that will result from a cross.</p> Signup and view all the answers

What is genotype?

<p>Genetic makeup of an organism.</p> Signup and view all the answers

What is homozygous?

<p>Organism that has two identical alleles for a particular trait (TT or tt).</p> Signup and view all the answers

What is phenotype?

<p>Physical characteristic of an organism (tall).</p> Signup and view all the answers

What is heterozygous?

<p>Organisms that have two different alleles for the same trait (Tt).</p> Signup and view all the answers

Homozygous organisms are true-breeding for a particular trait.

<p>True (A)</p> Signup and view all the answers

Plants with the same phenotype always have the same genotype.

<p>False (B)</p> Signup and view all the answers

What is true about probability and segregation?

<p>The F2 ratio of tall plants to short plants produced in a cross between two hybrid tall pea plants (Tt) is 3 tall plants for every 1 short plant. Mendel observed that about 3/4 of the F2 offspring showed the dominant trait. Segregation occurs according to Mendel's model.</p> Signup and view all the answers

In Mendel's model of segregation, what was the ratio of tall plants to short plants in the F2 generation?

<p>3:1</p> Signup and view all the answers

Probabilities predict the precise outcome of an individual event.

<p>False (B)</p> Signup and view all the answers

How can you be sure of getting the expected 50:50 ratio from flipping a coin?

<p>You must flip the coin many times.</p> Signup and view all the answers

The __________ the number of offspring from genetic cross, the closer the resulting numbers will get to expected values.

<p>larger</p> Signup and view all the answers

The ratios of an F1 generation are more likely to match Mendelian predicted ratios if the F1 generation contains hundreds or thousands of individuals.

<p>True (A)</p> Signup and view all the answers

What is probability?

<p>Likelihood that a particular event will occur.</p> Signup and view all the answers

What is a Punnett square?

<p>Diagram showing the gene combinations that might result from a genetic cross.</p> Signup and view all the answers

What is the term used to refer to an organism that has two identical alleles for a particular trait?

<p>homozygous</p> Signup and view all the answers

What is the term used to refer to an organism that has two different alleles for the same trait?

<p>heterozygous</p> Signup and view all the answers

What is the term for the physical characteristics of an organism?

<p>phenotype</p> Signup and view all the answers

What is the genetic makeup of an organism called?

<p>genotype</p> Signup and view all the answers

What is independent assortment?

<p>Independent segregation of genes during the formation of gametes.</p> Signup and view all the answers

What is incomplete dominance?

<p>Situation in which one allele is not completely dominant over another.</p> Signup and view all the answers

What is codominance?

<p>Situation in which both alleles of a gene contribute to the phenotype of the organism.</p> Signup and view all the answers

What are multiple alleles?

<p>Three or more alleles of the same gene.</p> Signup and view all the answers

What is a polygenic trait?

<p>Trait controlled by two or more genes.</p> Signup and view all the answers

What does homologous refer to?

<p>Term used to refer to chromosomes that each have a corresponding chromosome from the opposite-sex parent.</p> Signup and view all the answers

What does diploid refer to?

<p>Term used to refer to a cell that contains both sets of homologous chromosomes.</p> Signup and view all the answers

What does haploid refer to?

<p>Term used to refer to a cell that contains only a single set of chromosomes and therefore only a single set of genes.</p> Signup and view all the answers

What is meiosis?

<p>Process by which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell.</p> Signup and view all the answers

What is a tetrad?

<p>Structure containing 4 chromatids that forms during meiosis.</p> Signup and view all the answers

What is crossing-over?

<p>Process in which homologous chromosomes exchange portions of their chromatids during meiosis.</p> Signup and view all the answers

What is true about meiosis?

<p>During meiosis I, homologous chromosomes separate. During anaphase II, the paired chromatids separate.</p> Signup and view all the answers

What are eggs?

<p>Haploid gametes produced in females.</p> Signup and view all the answers

What are sperm?

<p>Haploid gametes produced in males.</p> Signup and view all the answers

What are polar bodies?

<p>Cells produced in females that do not participate in reproduction.</p> Signup and view all the answers

What is true about mitosis and meiosis?

<p>Mitosis begins with a diploid cell. Meiosis begins with a diploid cell.</p> Signup and view all the answers

What is the conclusion Morgan made about genes and chromosomes?

<p>Each chromosome is a group of linked genes. Chromosomes assort independently, not individual genes.</p> Signup and view all the answers

Why didn't Mendel observe gene linkage?

<p>Six of the seven genes he studied are on different chromosomes. The two genes on the same chromosome are so far apart that they also assort independently.</p> Signup and view all the answers

Explain why two genes found on the same chromosome are not always linked forever.

<p>Crossing-over during meiosis sometimes separates genes that had been on the same chromosome onto homologous chromosomes.</p> Signup and view all the answers

What do new combinations of alleles produced by crossover events help to generate?

<p>Genetic diversity.</p> Signup and view all the answers

Genes that are closer together are more likely to be separated by a crossover event in meiosis.

<p>False (B)</p> Signup and view all the answers

What is a gene map?

<p>It shows the relative locations of each gene on a chromosome.</p> Signup and view all the answers

Flashcards

Genetics

The scientific study of heredity.

Gregor Mendel

He laid the foundation for genetic principles using pea plants.

Self-pollination

A process where pea plants fertilize their own egg cells.

True-breeding plants

Plants that produce identical offspring when self-pollinated.

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Experimental cross

Mendel's method of mixing pollen to prevent self-pollination.

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Genes

Chemical factors that determine traits, with forms called alleles.

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Alleles

Different forms of a gene that can exist for a trait.

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Dominant allele

An allele that masks the presence of a recessive allele.

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Recessive allele

An allele that is masked by a dominant allele.

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F1 generation

Result from the first cross of different traits.

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F2 generation

Second generation from the cross of F1 plants; exhibits a 3:1 trait ratio.

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Gametes

Sex cells that carry alleles for traits.

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Independent assortment

Genes for different traits segregate independently during gamete formation.

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Multiple alleles

More than two forms of a gene for one trait.

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Polygenic traits

Traits controlled by multiple genes, leading to a range of phenotypes.

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Meiosis

Reduction division that halves chromosome numbers in gametes.

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Homologous chromosomes

Paired chromosomes that are similar in shape and size, aligning during meiosis.

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Crossing-over

Exchange of genetic material between homologous chromosomes during meiosis.

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Diploid cell

A cell that contains two complete sets of chromosomes.

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Haploid cell

A cell that contains one complete set of chromosomes, produced by meiosis.

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Gene map

A diagram showing the relative positions of genes on chromosomes.

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Gene linkage

The tendency of genes located close together on a chromosome to be inherited together.

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Genetic diversity

Variation in a population's genes, often enhanced by crossing-over.

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Mitosis vs. Meiosis

Mitosis produces identical cells; meiosis produces diverse haploid cells.

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Probability in genetics

Used to predict genetic outcomes in crosses, similar to coin flips.

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Environmental influence on traits

External factors that can affect the expression of traits alongside genetics.

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Mendelian genetics

Principles established by Mendel that apply to many organisms.

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Genetic makeup

The genotype of an organism representing its alleles.

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Physical appearance

The phenotype of an organism representing how traits look.

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Homozygous

Having two identical alleles for a trait.

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Heterozygous

Having two different alleles for a trait.

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Study Notes

Genetics Overview

  • Genetics is the scientific study of heredity.
  • Gregor Mendel's experiments using pea plants laid the foundation for genetic principles.
  • When pollen fertilizes an egg cell, a seed for a new plant is formed; pea plants naturally reproduce through self-pollination.

Mendelian Principles

  • True-breeding pea plants produce offspring identical to themselves when self-pollinated.
  • Mendel prevented self-pollination by removing male parts of flowers and introducing pollen from other plants.
  • Genes are chemical factors that determine traits, with different forms called alleles.
  • Dominant alleles mask the presence of recessive alleles.

Experimental Findings

  • F1 generation resulted from crosses between different traits, while F2 generation exhibited a 3:1 ratio for dominant to recessive traits.
  • Gametes are sex cells that carry alleles for traits.
  • Probability principles can predict genetic cross outcomes, similar to coin flips.

Genetic Terminology

  • Genotype: An organism's genetic makeup (e.g., TT, tt, Tt).
  • Phenotype: An organism's physical appearance (e.g., tall, round peas).
  • Homozygous: Organisms with two identical alleles for a trait.
  • Heterozygous: Organisms with two different alleles for a trait.

Genetic Ratios and Principles

  • The principle of independent assortment states that genes for different traits segregate independently during gamete formation.
  • Multiple alleles can exist for a single gene, influencing traits like blood type and coat color in rabbits.
  • Polygenic traits are controlled by multiple genes, leading to a range of phenotypes.

Meiosis and Chromosomal Concepts

  • Meiosis is a reduction division, halving chromosome numbers in gametes.
  • Homologous chromosomes pair during prophase I, forming tetrads and allowing crossing-over.
  • A diploid cell produces four haploid cells at the end of meiosis.

Genetic Mapping and Linkage

  • A gene map shows the relative positions of genes on chromosomes.
  • Thomas Hunt Morgan demonstrated gene linkage, showing that genes inherited together are located on the same chromosome.
  • Crossing-over can separate linked genes, creating genetic diversity.

Comparative Genetics

  • Mitosis results in two identical diploid cells; meiosis results in four genetically diverse haploid cells.
  • Mendel did not observe gene linkage because most genes he studied were located on different chromosomes or assort independently.

Summary of Key Concepts

  • Probability is fundamental in predicting genetic outcomes.
  • Environmental factors also influence traits alongside genetic inheritance.
  • Mendelian genetics applies broadly across many organisms, reaffirming basic genetic principles.

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Description

Explore key concepts in genetics with these flashcards focused on Chapter 11. Test your knowledge with questions about heredity, Gregor Mendel's experiments, and true-breeding pea plants. Perfect for students looking to reinforce their understanding of genetic principles.

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