Chapter 11: Introduction to Genetics

Independent assortment

________ helps explain the many genetic variations we see in all living things.

new combinations of alleles

Crossing- over produces ________ on each chromatid.

Environmental conditions

________ can change gene expression and influence genetically controlled traits.

Biological characteristics

________ are inherited through units called genes, which are passed from parents to offspring.

Telophase

________ I and Cytokinesis: Nuclear membranes form and the cell separates into two cells.

F1

When doing genetic crosses, we call each original pair of plants the P, or parental, generation, and their offspring are called the ________ generation.

Interphase

________: Cells undergo a round of DNA replication, forming duplicate chromosomes.

Punnett squares

Use probability to predict combinations of alleles in a genetic cross

Mitosis

________ can be a form of asexual reproduction.

Anaphase I

________: The fibers pull the homologous chromosomes to opposite ends of the cell.

Meiosis

________ makes two identical diploid cells.

Diploid

________ is the term used to refer to a cell that contains two sets of homologous chromosomes.

TT

The tall (________) plants are homozygous because they have two identical alleles (________) for a gene; the short plants are also homozygous because they have two identical alleles (________) for a gene.

physical traits

Mendel noticed that all of the tall pea plants had the same phenotype, or ________, but they did not, however, have the same genotype, or genetic makeup.

Alleles

________ for different genes usually segregate independently of each other.

Metaphase I

________: Spindle fibers attach to the chromosomes.

Mendel

________ used garden pea plants in his studies partly because peas are small, easy to grow, can make hundreds of offspring, and have many traits that are easy to see.

zygote undergoes

The ________ cell division by mitosis and grows into an organism.

self pollination

A plant grown from a seed made by ________ has just one parent because both reproductive cells came from the same plant.

Prophase II

________: Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original cell.

Homologous

The term used to refer to chromosomes in which one set comes from the male parent and one set comes from the female parent

gene

A(n) ________ with more than two alleles is said to have multiple alleles.

recessive allele

An organism with a(n) ________ for a form of a trait will show that form only when the dominant allele for the trait is not there.

Mitosis

________ does not change the number of chromosomes.

Meiosis

________ cuts the chromosome number in half.

Chromosomes

________ are made of many genes linked together; gene maps show how far apart these genes are from each other.

Independent assortment

One of Mendel's principles that states that genes for different traits can segregate independently during the formation of gametes

Meiosis

The process in which the number of chromosomes per cell is cut in half through the separation of homologous chromosomes in a diploid cell

Meiosis

________ makes four genetically different haploid cells.

Meiosis

________ is a step in sexual reproduction.

Meiosis

________ involves two rounds of cell division, called ________ I and ________ II.

For example, when flipping a coin, there are only two possible outcomes

the coin can land either heads up or tails up

Although three different combinations of the alleles t and T are possible

Tt, TT, and tt, only two different forms of the plant are possible

Interphase

Cells undergo a round of DNA replication, forming duplicate chromosomes

Prophase I

Each chromosome pairs with its corresponding homologous chromosome to form a tetrad, which has four chromosomes

Metaphase I

Spindle fibers attach to the chromosomes

Anaphase I

The fibers pull the homologous chromosomes to opposite ends of the cell

Telophase I and Cytokinesis

Nuclear membranes form and the cell separates into two cells

Prophase II

Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original cell

Metaphase II

The chromosomes line up in a similar way to the metaphase stage of mitosis

Anaphase II

The sister chromatids separate and move toward opposite ends of the cell

Telophase II and Cytokinesis

Meiosis II results in four haploid daughter cells

Genetics

The scientific study of heredity

Fertilization

The process in sexual reproduction in which male and female reproductive cells join to form a new cell

Trait

A specific characteristic of an individual

Gene

A factor that is passed from parent to offspring

Allele

One of a number of different forms of a gene

Principle of dominance

States that some alleles are dominant and others are recessive

Segregation

The separation of alleles

Gametes

Sex cells

Probability

The likelihood that a particular event will occur

Homozygous

Having two identical alleles for a particular gene

Heterozygous

Having two different alleles for a particular gene

Phenotype

The physical characteristics of an organism

Geneotype

The genetic makeup of an organism

Codominance

A situation in which the phenotypes produced by both alleles are completely expressed

Incomplete dominance

A situation in which one allele is not completely dominant over another allele

Multiple alleles

A gene that has more than two alleles

Polygenic trait

A trait controlled by two or more genes

Diploid

The term used to refer to a cell that contains two sets of homologous chromosomes

Haploid

The term used to refer to a cell that contains only a single set of genes

Crossing-over

The process in which homologous chromosomes exchange portions of their chromatids during meiosis

Zygote

A fertilized egg