Chapter 11 Meiosis and Sexual Reproduction Section 1 Reproduction

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Chapter 11 Meiosis and Sexual Reproduction
Section 1 Reproduction
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Chapter 11 Section 1Reproduction

• Key Vocabulary Terms

Adapted from Holt Biology 2008
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Meiosis

• A special process of cell division that results
  in haploid sex cells
• The total number of chromosomes decreases to half
  the original number

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Gamete

• A reproductive cell a haploid reproductive cell
  that unites with another reproductive cell to
  form a zygote

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Zygote

• The cell that results from the
• fusion of gametes (a fertilized egg)

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Diploid

• Describes a cell, nucleus, or organism that
  contains two sets of chromosomes

diploid cell
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Haploid

• Describes a cell, nucleus, or organism that has
  only one set of unpaired chromosomes

haploid cell
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Homologous Chromosomes

• Chromosomes that have the same order of genes,
  the same structure, and that pair during meiosis

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Chapter 11 Section 1Reproduction

• Supplementary Words

Adapted from Holt Biology 2008
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Reproduction

• The process of producing offspring

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Asexual Reproduction

• A single parent passes a complete copy of its
  genetic information to each of its offspring.
• An individual formed by asexual reproduction is
  genetically identical to its parent.

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Sexual Reproduction

• Two parents give genetic material to produce
  offspring that are genetically different from
  their parents. Each parent produces a
  reproductive cell, called a gamete. A gamete from
  one parent fuses with a gamete from the other
  parent. The resulting cell, called a zygote, has
  a combination of genetic material from both
  parents

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Binary Fission

• This process results in the reproduction of a
  living prokaryotic cell by division into two
  parts which each have the potential to grow to
  the size of the original cell.

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Fragmentation

• A kind of reproduction in which the body breaks
  into several pieces. Some or all of these
  fragments regrow missing parts and develop into
  complete adults.

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Budding

• New individuals split off from existing ones

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Parthenogenisis

• A process in which a female makes a viable egg
  that grows into an adult without being fertilized
  by a male.

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Fertilization

• A process in sexual reproduction that involves
  the union of male (sperm) and female (ovum)
  gametes (each with a single, haploid set of
  chromosomes) to produce a diploid zygote

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Germ Cells

• Cells that are specialized for sexual reproduction

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Somatic Cells

• Other body cells that do not participate in
  sexual reproduction.

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Gene

• A segment of DNA that is located in a chromosome
  and that codes for a specific hereditary trait

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Chromosomes

• In a eukaryotic cell, one of the structures in
  the nucleus that are made up of DNA and protein
  in a prokaryotic cell, the main ring of DNA

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Autosomes

• Chromosomes with genes that do not determine the
  sex of an individual.

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Sex Chromosomes

• Chromosomes that have genes that determine the
  sex of an individual. In humans and many other
  organisms, the two sex chromosomes are referred
  to as the X and Y chromosomes. The genes that
  cause a zygote to develop into a male are located
  on the Y chromosome. Human males have one X
  chromosome and one Y chromosome (XY), and human
  females have two X chromosomes (XX).

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Chromosome Number

• Genes are located on chromosomes. Each
  chromosome has thousands of genes that play an
  important role in determining how an organism
  develops and functions. Each species has a
  characteristic number of chromosomes.

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Crossing-over

• The exchange of genetic material between
  homologous chromosomes during meiosis

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Independent Assortment

• The random distribution of pairs of genes on
  different chromosomes to the gametes

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Life cycle

• All of the events in the growth and development
  of an organism until the organism reaches sexual
  maturity

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Sperm

• The male gamete (sex cell)

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Ovum

• The female gamete A mature egg cell

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Chapter 11Section 1 Reproduction

• Notes

Adapted from Holt Biology 2008
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Reproduction

• Asexual Reproduction - A single parent produces
  genetically identical offspring

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Asexual Reproduction

• Prokaryotes Reproduce by splitting - binary
  fission

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Asexual Reproduction

• Unicellular Eukaryotes
• Reproduce by mitosis and cytokinesis

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Asexual Reproduction

• Multicellular Eukaryotes
• Reproduce by
• Fragmentation sea stars
• Budding yeast, hydra
• Cuttings - plants
• Parthenogenesis water fleas, some bees

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Advantages of Asexual Reproduction

• Many offspring are produced in a short mount of
  time.
• Little energy is required for Gamete production
• Finding a mate

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Sexual Reproduction

• Two parents produce genetically different
  offspring

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Sexual Reproduction Background

• Types of cells
• Germ cells cells that produce gametes
• Somatic cells other body cells that do not
  participate in sexual reproduction

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Advantages of Sexual Reproduction

• Genetically diverse populations
• Variety increases the likelihood that some
  individuals will survive if the environment
  changes.

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Chromosome Number

• Each chromosome has thousands of genes.

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Chromosome Number

• Each species has a certain number of chromosomes.
• Mosquitoes 6
• Chimpanzees 48
• Humans 46
• Potato 48

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Human Chromosome Number

• Each somatic cell has two sets of 23 chromosomes.
• Each gamete has one set of 23 chromosomes.
• When fertilization occurs, the zygote will have
  two sets of 23 chromosomes one from each
  gamete.

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46
23


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Haploid and Diploid Cells

• Gametes are haploid
• Symbol n
• Somatic cells are diploid
• Symbol 2n
• For humans, n 23 2n 46

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Homologous Chromosomes

• Paired chromosomes found in diploid cells.

Chromosome
Chromosome
Centromere
Centromere
Genes
Genes
Chromatids
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Autosomes and Sex Chromosomes

• Autosomes Chromosomes with genes that do not
  determine sex

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Autosomes and Sex Chromosomes

• Sex chromosomes
• Chromosomes with genes that determine sex, X and
  Y in humans
• Boys have an X and a Y
• Girls have two Xs

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autosomes 1-22
sex chromosomes 23