Life on Earth: At a Glance

Life on Earth
Audesirk & Audesirk
Prentice-Hall, Inc.

Genetic Variability, Genetic Exchange, and the Evolution of Sexual Reproduction: Mutations in DNA are the ultimate source of genetic variability.
The effects of a mutation depend on the nature of the mutation, the organism in which it occurs, and the environment in which the organism lives.
Genetic exchange may combine useful mutations.
Eukaryotic organisms use a specialized cell division process called meiosis to combine genetic material from two separate parents in a single offspring.
"Permanent" diploidy protects against some of the harmful effects of mutations.

Meiosis and Sexual Reproduction
Meiosis separates homologous chromosomes in a diploid cell to produce haploid daughter cells containing one copy of each type of chromosome.

The Mechanisms of Meiosis
Meiosis I
Meiosis II

Mitosis, Meiosis, and Eukaryotic Life Cycles
In haploid life cycles, the majority of the cycle consists of haploid cells.
In diploid life cycles, the majority of the cycle consists of diploid cells.
In alternation-of-generations life cycles, there are both diploid and haploid multicellular stages.

The Roles of Meiosis and Sexual Reproduction in Producing Genetic Variability; The effects of a mutation depend on the nature of the mutation, the organism in which it occurs, and the environment in which the organism lives.
Genetic exchange may combine useful mutations.
Eukaryotic organisms use a specialized cell division process called meiosis to combine genetic material from two separate parents in a single offspring.
"Permanent" diploidy protects against some of the harmful effects of mutations.

Meiosis and Sexual Reproduction
Meiosis separates homologous chromosomes in a diploid cell to produce haploid daughter cells containing one copy of each type of chromosome.

The Mechanisms of Meiosis
Meiosis I
Meiosis II

Mitosis, Meiosis, and Eukaryotic Life Cycles
In haploid life cycles, the majority of the cycle consists of haploid cells.
In diploid life cycles, the majority of the cycle consists of diploid cells.
In alternation-of-generations life cycles, there are both diploid and haploid multicellular stages.

The Roles of Meiosis and Sexual Reproduction in Producing Genetic Variability; Genetic exchange may combine useful mutations.
Eukaryotic organisms use a specialized cell division process called meiosis to combine genetic material from two separate parents in a single offspring.
"Permanent" diploidy protects against some of the harmful effects of mutations.

Meiosis and Sexual Reproduction
Meiosis separates homologous chromosomes in a diploid cell to produce haploid daughter cells containing one copy of each type of chromosome.

The Mechanisms of Meiosis
Meiosis I
Meiosis II

Mitosis, Meiosis, and Eukaryotic Life Cycles
In haploid life cycles, the majority of the cycle consists of haploid cells.
In diploid life cycles, the majority of the cycle consists of diploid cells.
In alternation-of-generations life cycles, there are both diploid and haploid multicellular stages.

The Roles of Meiosis and Sexual Reproduction in Producing Genetic Variability; Eukaryotic organisms use a specialized cell division process called meiosis to combine genetic material from two separate parents in a single offspring.
"Permanent" diploidy protects against some of the harmful effects of mutations.

Meiosis and Sexual Reproduction
Meiosis separates homologous chromosomes in a diploid cell to produce haploid daughter cells containing one copy of each type of chromosome.

The Mechanisms of Meiosis
Meiosis I
Meiosis II

Mitosis, Meiosis, and Eukaryotic Life Cycles
In haploid life cycles, the majority of the cycle consists of haploid cells.
In diploid life cycles, the majority of the cycle consists of diploid cells.
In alternation-of-generations life cycles, there are both diploid and haploid multicellular stages.

The Roles of Meiosis and Sexual Reproduction in Producing Genetic Variability; "Permanent" diploidy protects against some of the harmful effects of mutations.

Meiosis and Sexual Reproduction
Meiosis separates homologous chromosomes in a diploid cell to produce haploid daughter cells containing one copy of each type of chromosome.

The Mechanisms of Meiosis
Meiosis I
Meiosis II

Mitosis, Meiosis, and Eukaryotic Life Cycles
In haploid life cycles, the majority of the cycle consists of haploid cells.
In diploid life cycles, the majority of the cycle consists of diploid cells.
In alternation-of-generations life cycles, there are both diploid and haploid multicellular stages.

The Roles of Meiosis and Sexual Reproduction in Producing Genetic Variability
Meiosis and Sexual Reproduction: Meiosis separates homologous chromosomes in a diploid cell to produce haploid daughter cells containing one copy of each type of chromosome.

The Mechanisms of Meiosis
Meiosis I
Meiosis II

Mitosis, Meiosis, and Eukaryotic Life Cycles
In haploid life cycles, the majority of the cycle consists of haploid cells.
In diploid life cycles, the majority of the cycle consists of diploid cells.
In alternation-of-generations life cycles, there are both diploid and haploid multicellular stages.

The Roles of Meiosis and Sexual Reproduction in Producing Genetic Variability
The Mechanisms of Meiosis: Meiosis I
Meiosis II

Mitosis, Meiosis, and Eukaryotic Life Cycles
In haploid life cycles, the majority of the cycle consists of haploid cells.
In diploid life cycles, the majority of the cycle consists of diploid cells.
In alternation-of-generations life cycles, there are both diploid and haploid multicellular stages.

The Roles of Meiosis and Sexual Reproduction in Producing Genetic Variability; Meiosis II

Mitosis, Meiosis, and Eukaryotic Life Cycles
In haploid life cycles, the majority of the cycle consists of haploid cells.
In diploid life cycles, the majority of the cycle consists of diploid cells.
In alternation-of-generations life cycles, there are both diploid and haploid multicellular stages.

The Roles of Meiosis and Sexual Reproduction in Producing Genetic Variability
Mitosis, Meiosis, and Eukaryotic Life Cycles: In haploid life cycles, the majority of the cycle consists of haploid cells.
In diploid life cycles, the majority of the cycle consists of diploid cells.
In alternation-of-generations life cycles, there are both diploid and haploid multicellular stages.

The Roles of Meiosis and Sexual Reproduction in Producing Genetic Variability; In diploid life cycles, the majority of the cycle consists of diploid cells.
In alternation-of-generations life cycles, there are both diploid and haploid multicellular stages.

The Roles of Meiosis and Sexual Reproduction in Producing Genetic Variability; In alternation-of-generations life cycles, there are both diploid and haploid multicellular stages.

The Roles of Meiosis and Sexual Reproduction in Producing Genetic Variability
The Roles of Meiosis and Sexual Reproduction in Producing Genetic Variability

Designed in cooperation with Andrew Stull and Steven Brunasso.

Last Update - July 25, 1997