biology

• DNA


  Molecule of life
• Trillions of cells
• Human chromosomes


  • 46 chromosomes
  • 23 nearly-identical pairs
• Male


  XY
• Female


  XX
• 2 meters of DNA
• 3 billion DNA subunits (bases: A, T, C, G)
• 30,000 genes for proteins
• Phases of cell cycle

  • Interphase
  • Mitotic
• Cell division


  • Results in genetically identical daughter cells
  • Cells duplicate genetic material
• Functions of cell division

  • Reproduction
  • Growth and development
  • Tissue Renewal
• DNA


  • Carries genetic code that determines characteristics of living organism
  • Genome (genetic information)
  • Packaged into chromosomes
• Eukaryotic cell


  • About 1,000 times more DNA than prokaryotic
  • DNA organized into several linear chromosomes, whose organization is much more complex than the single DNA molecule in a prokaryotic cell
• Chromosomes


  • Cell's nucleus has chromosomes
  • Long threads of DNA, made up of genes
  • Eukaryotic cells store genetic information in chromosomes
  • Genome (genetic information)
  • Packaged into chromosomes
• Chromosome structure


  • Composed of a complex of DNA and protein called chromatin that condenses during cell division
  • DNA exists as a single, long, double-stranded fiber extending chromosome's entire length
  • Each unduplicated chromosome contains one DNA molecule, which may be several inches long
• Karyotype


  • Ordered, visual representation of the chromosomes in a cell
  • Chromosomes are photographed when highly condensed, then the individual chromosomes are arranged by decreasing size
• Non-homologous chromosomes


  Look different and control different traits
• Sex chromosomes


  • Distinct from each other in their characteristics
  • Represented as X and Y
• Diploid cell


  Has two sets of each of its chromosomes
• Homologous chromosomes


  • Look the same
  • Control the same traits
  • May code for different forms of each trait
  • Independent origin - each one was inherited from a different parent
• Chromosome duplication


  • In preparation for cell division, DNA is replicated and the chromosomes condense
  • Each duplicated chromosome has two sister chromatids, which separate during cell division
  • Each condensed chromosome consists of 2 identical chromatids joined by a centromere
  • Each duplicated chromosome contains 2 identical DNA molecules (unless a mutation occurred), one in each chromatid
• Centromere


  • Constricted region of the chromosome containing a specific DNA sequence, to which is bound 2 discs of protein called kinetochores
  • Kinetochores serve as points of attachment for microtubules that move the chromosomes during cell division
• Diploid


  Cell that has two copies of each chromosome (human body cells)
• Haploid


  Cell that has a single copy of each chromosome (human sex cells)
• Homologous chromosomes


  Made up of sister chromatids joined at the centromere
• Genes


  • Section of DNA that codes for a specific protein
  • Unit of heredity and may be copied and passed on to the next generation
• Extra chromosomes


  • XXX - Trisomy 21 or Down Syndrome
  • XXY - Female physical traits but biologically male
• Underdeveloped/Lacking chromosomes


  Sterile/Infertile
• Interphase stages


  • G1 - primary growth
  • S - genome replication
  • G2 - secondary growth
• Mitosis


  • Some haploids and diploids divide by mitosis
  • Each new cell receives a copy of every chromosomes that was in the original
  • Produces 2 new cells that are genetically identical to the mother cell
  • Only consists of one parent cell
• Mitosis stages


  • Prophase
  • Metaphase
  • Anaphase
  • Telophase
• Mitotic spindle


  • Consisting of centrosomes, spindle microtubules, and asters, directs chromosome movement during mitosis
  • Centrosomes replicate, migrate, and initiate spindle microtubule assembly
  • Some spindle microtubules attach to kinetochores, guiding chromosome alignment at the metaphase plate
  • In anaphase, sister chromatids separate and move toward opposite cell ends along kinetochore microtubules
• Types of reproduction


  • Mitosis - Asexual
  • Meiosis - Sexual
• Types of cells


  • Somatic - Body cells
  • Gametes - Sex cells
• Number of cell divisions

  • Mitosis - 1
  • Meiosis - 2
• Number of daughter cells

  • Mitosis - 2
  • Meiosis - 4
• Characteristics of daughter cells

  • Mitosis - Genetically Identical
  • Meiosis - Genetically Different
• Meiosis stages


  • Prophase I
  • Metaphase I
  • Anaphase I
  • Telophase I & Cytokinesis
  • Prophase II
  • Metaphase II
  • Anaphase II
  • Telophase II & Cytokinesis
• Macromolecules


  • Four groups of molecules that make up the building blocks of life
  • Formed by polymerization, in which large polymers are built by joining small subunits called monomers together
• Carbohydrates


  • Organisms' main source of immediate energy
  • Structural purposes
  • Made up of C, H, and O
  • Polysaccharides are polymers made up of monosaccharides, or simple sugars