Science

• Allele


  Alternative version of a specific gene
• Dominant allele


  An allele that produces the same phenotype whether its paired allele is identical or different
• Recessive allele


  An allele that produces its characteristic phenotype only when its paired allele is identical
• Phenotype


  Observable characteristics of an individual for any particular trait
• Heredity


  The passing of traits from parents to their offspring
• Variation


  Refers to individuals that possess characteristics different from the others of the same kind
• Genetics


  The study of heredity and variation
• Genetics aims to understand how traits can be passed on to the next generations and how variation arises
• Cell


  The basic structural and functional unit of all life
• Types of cells


  • Unicellular (single cell)
  • Multicellular (more than one cell)
• Unicellular organisms


  • Amoeba
  • Bacteria
  • Plankton
• Multicellular organisms


  • Humans
  • Plants
  • Animals
• Chromatic fibers


  Genetic materials of the cell in the form of long thin threads of DNA wrapped around histone proteins
• Kinetochore


  Protein complex assembled on the centromeric region of DNA
• Gene


  The basic physical functional unit of heredity, made up of DNA
• DNA (Deoxyribonucleic Acid)


  A molecule that contains the biological instructions that make each species unique
• Nuclear membrane


  A double membrane layer that separates the contents of the nucleus from the rest of the cell
• Nucleolus


  A round body located inside the nucleus of a eukaryotic cell
• Spindle fiber


  Protein structure that divides the genetic material during cell division
• Centrioles


  Paired organelles (cellular structure) found in the cytoplasm
• Plant cells


  • Rectangular, have cell walls, chloroplasts and a large vacuole
• Cell cycle


  A series of events that takes place in a cell as it grows and divides, with two main stages: Interphase and M-phase (mitosis or meiosis)
• Interphase


  Cell grows, accumulates nutrients, and replicates its genetic material; has three stages: G1 phase, S phase, G2 phase
• 1. phase (mitosis or meiosis)


  Cell division
• G1 (Growth or Gap 1) phase


  Cell is still young, undergoes rapid growth, organelles form, proteins are produced, longest phase in most cells
• S (Synthesis) phase


  DNA (main composition of chromosome) doubles; each chromosome is made of two sister chromatids attached at the centromere
• G2 (Growth) phase


  Preparation for cell division, assembly of proteins like microtubules (hollow protein fibers that cause chromosomes to move during cell division)
• Mitosis


  A type of cell division in which the nucleus of the cell divides into two nuclei with identical genetic material (diploid, 46 chromosomes)
• Cytokinesis


  Division of the cytoplasm
• Cytokinesis in plant cells vs animal cells

  In plant cells, cytokinesis starts at the middle and moves outward (plate formation); in animal cells, cytokinesis starts at the exterior and moves inward (cleavage furrow formation)
• Allele


  Alternative version of a specific gene
• Dominant allele


  An allele that produces the same phenotype whether it is paired with an identical or different allele
• Recessive allele


  Produces its characteristic phenotype only when its paired allele is identical
• Phenotype


  Observable characters of an individual for any particular trait
• Genotype


  Genetic constitution of an individual for a particular trait
• Homozygous


  2 alleles that determine the same (AA or aa)
• Heterozygous


  2 alleles that determine different (Aa)
• Punnett square is a simple method to predict the outcome of a genetic cross, proposed by British Geneticist Reginald Punnett
• Prophase


  1. Long & thread like chromatids coil & become visible

  2. Each chromosome contains two identical sister chromatids

  3. Nuclear membrane dissolves & spindle fibers are formed

  4. Nucleolus disappears
• Metaphase


  1. Chromosomes move & align themselves at the center; metaphase plate

  2. Spindle fiber connect each chromosome on its centromere to the centrioles