Biology Chapter 8

• Surface area

  The total area of the surface of a three-dimensional object
• Individual chromosomes are visible under a light microscope only during cell division; otherwise, they are thin, loosely packed chromatin fibers
• Prokaryotes reproduce

  By binary fission: the cell replicates its single chromosome, the copies move apart, the plasma membrane pinches inward, and more cell wall is made, eventually dividing the parent cell into two daughter cells
• Cell cycle


  An ordered sequence of events from the time a cell is formed until its division
• Cytokinesis

  Animal cells constrict to form a cleavage furrow, while in plants, a membranous cell plate forms and splits the cell in two
• Radiation and chemotherapy interfere with cell division and are effective cancer treatments
• Cells divide because it is necessary for growth, repair, and reproduction
• Volume

  The amount of space occupied by a three-dimensional object
• Eukaryotic cell cycle and mitosis

  The large, complex chromosomes duplicate with each cell division. Before division, chromosomes duplicate, producing sister chromatids containing identical DNA joined together along their lengths by proteins, most closely at a region called the centromere
• If a firm increases advertising, their demand curve shifts right, leading to an increase in equilibrium price and quantity
• Important terms

  • Somatic cells, Gametes, Haploid, Diploid, Homologous chromosomes
• Mitosis


  Distributes duplicated chromosomes into two daughter nuclei. Mitotic spindle moves chromosomes to the middle of the cell, sister chromatids separate and move to opposite poles forming two new nuclei
• Meiosis and Crossing Over

  Chromosomes are matched in homologous pairs, somatic cells contain a specific number of chromosomes, and gametes have a single set of chromosomes
• Sexual life cycles involve the alternation of haploid and diploid stages
• Homologous chromosomes

  Chromosomes of a pair carrying genes for the same characteristics at the same place, or locus
• Chromosome breakage can lead to rearrangements such as deletions, duplications, inversions, and translocations that can produce genetic disorders or cancer
• Genetic recombination from crossing over during prophase I of meiosis increases variation
• Cells with two sets of homologous chromosomes are diploid
• Gametes have a single set of chromosomes
• Human cells have 46 chromosomes, consisting of 23 pairs of homologous chromosomes
• Meiosis produces four genetically unique haploid gametes
• Volume

  The amount of space occupied by a three-dimensional object
• Cytokinesis

  Differs for plant and animal cells; in animals, cell constricts forming a cleavage furrow, in plants, a membranous cell plate forms and splits the cell in two
• Normal cell division is essential in all forms of life
• Prokaryotes reproduce

  Asexually by binary fission: the cell replicates its single chromosome, copies move apart, plasma membrane pinches inward, more cell wall is made, dividing the parent cell into two daughter cells
• Mitosis


  Distributes duplicated chromosomes into two daughter nuclei; after coiling up, a mitotic spindle made of microtubules moves chromosomes to the middle of the cell, sister chromatids separate and move to opposite poles, two new nuclei form
• Gametes have a single set of chromosomes
• Each species contains a specific number of chromosomes; for example, human cells have 46, consisting of 23 pairs of homologous chromosomes
• Mitosis produces two genetically identical diploid somatic daughter cells
• A karyotype is a photographic inventory of an individual’s chromosomes
• Chromosome breakage can lead to rearrangements deletions, duplications, inversions, and translocations—that can produce genetic disorders or cancer
• Cells with two sets of homologous chromosomes are diploid
• Sexual life cycles involve the alternation of haploid and diploid stages
• Homologous chromosomes

  Chromosomes of a homologous pair carry genes for the same characteristics at the same place, or locus
• Nondisjunction can produce polyploid organisms, organisms with extra sets of chromosomes
• Binary Fission


  Asexual reproduction in single-celled organisms where the cell divides into two identical daughter cells
• Sexual Reproduction


  Formation of offspring through the combination of genetic material from two parent cells, leading to genetic diversity
• Cell Cycle/Phases

  Series of events that a cell undergoes, including growth and division; phases include interphase, mitosis, and cytokinesis
• Chromatin


  DNA and proteins in a cell's nucleus that form a complex structure, visible as thread-like during interphase
• Chromosome

  Thread-like structure composed of DNA and proteins, carrying genetic information