Science (summative)

• Represent dominant and recessive alleles

  Using letters
• Genotype


  The genetic composition of an organism
• Phenotype


  The observable characteristic or appearance from the genotype of an organism
• Mitosis


  • Differentiates from meiosis
• Allele


  A specific version of a gene and is responsible for the variations that a given trait can be expressed
• Genetic laws


  • Law of Dominance
  • Law of Segregation
  • Law of Independent Assortment
• Dominant allele


  Carries the dominant trait and is written in capital letters
• Recessive allele


  Carries the recessive trait and is written in small letters
• Homozygous dominant genotype


  Consists of two identical dominant alleles represented by two capital letters
• Homozygous recessive genotype


  Consists of two identical recessive alleles represented by two small letters
• Heterozygous genotype


  Consists of two different alleles: dominant and recessive alleles written in capital and small letters
• Punnett Square


  A table used to predict the result of a cross involving one pair of alleles (Monohybrid cross)
• Monohybrid cross


  A cross between two organisms involving one trait
• Genotypic ratio


  Shows the number of times a genotype (represented by letters) appears in the outcome of a given cross
• Phenotypic ratio


  Predicts the number of times a certain trait/characteristic appears in a cross
• Widow's peak (a V-shape or heart shape) at the hairline is a dominantly inherited trait
• Let (V) represent the dominant allele, and (v) represent the recessive allele
• CELL DIVISION Mitosis and Meiosis
• Cell division


  The process by which a single cell divides into two or more daughter cells, each with the potential to grow, develop, and carry out specific functions
• Mitosis


  The process by which a single cell divides into two identical daughter cells
• Meiosis


  The process by which a single cell divides into four genetically diverse daughter cells
• Cell cycle


  The two major phases are Interphase (G1, S, and G2) and M Phase (Cell division)
• Chromosome


  A structure found in the nucleus of cells that carries genetic information in the form of DNA
• Cell


  The basic unit of life and the smallest functional and structural unit of living organisms
• Spindle fibers


  Microtubules that separate the chromosomes into two daughter cells
• Centrioles


  Cylindrical organelles found in eukaryotic cells that are involved in the organization of cell division
• Centrosome


  A small organelle found in eukaryotic cells, which functions as a microtubule-organizing center
• Characteristics of Mitosis


  • Produces two genetically identical daughter cells
  • The major purpose is for growth and to replace worn-out cells
  • Occurs only in somatic cells
  • No reduction in the number of chromosomes
• Stages of Mitosis


  1. Prophase

  2. Metaphase

  3. Anaphase

  4. Telophase

  5. Cytokinesis
• In mitosis, 2 identical daughter cells are formed from one parent cell after telophase
• Meiosis


  A form of cell division that produces haploid sex cells or gametes (with a single copy of each chromosome) from diploid cells (with two copies of each chromosome)
• Characteristics of Meiosis


  • Two-step cell division process in sexual reproduction
  • Results in cells with one-half the chromosome number of the original parent
  • One diploid cell (2N) results in 4 haploid cells (N)
• Stages of Meiosis I


  1. Prophase I

  2. Metaphase I

  3. Anaphase I

  4. Telophase I
• Stages of Meiosis II


  1. Prophase II

  2. Metaphase II

  3. Anaphase II

  4. Telophase II
• In meiosis, 4 daughter cells are formed by one parent cell, each receiving half the number of chromosomes from its parent cell. Every daughter cell is genetically distinct from each other due to crossing-over
• Gametogenesis


  The production of gametes from haploid precursor cells
• During fertilization, gametes such as eggs and sperm unite, forming a diploid zygote
• Sperm cells


  Produced in the testes through meiosis, with the nucleus in the head and mitochondria in the middle section to provide energy for the tail to move
• Egg cells


  Produced in the ovary through meiosis, with only the large cell retained as it has all the necessary nutrients and functions, while the small cells are disintegrated