Definition
Histones: A group of especial protein molecule.
Chromatid: The 2 identical parts of a chromosome.
Centromere: The part where the chromatids join.
Homologous chromosome: The 2 members of each pair in sexual reproduction.
Diploid: A cell that contains both chromosome of a homologous pair.
Haploid: A cell that has only one chromosome of each homologous pair.
Mitosis: Is the division of the cell nucleus in which the chromosome in parent cell divide into two
identical sets.
Cell cycle: Is the sequence of events that occurs in a cell from mitosis to mitosis.
Interphase: Is a period of cell growth and development that precedes mitosis and follow
cytokinesis.
Cytokinesis: Is the division of the cytoplasm of a parent cell and its contents into 2 daughter cells.
G1 phase: Is the first period of interphase.
S phase: The DNA that makes up the chromatid replicates.
G2 phase: The cell undergoes rapid growth that prepares it for mitosis.
Prophase: Is the first phase o mitosis.
Centrioles: Dark cylindrical bodies.
Polar fibers: Extend across the cell from centrioles to centrioles.
Kinetochore: Extend across fibers extend from the centromere to a chromosome to the
centrioles.
Asters: Protein fibers that radiate from each centriole.
Metaphase: Is the 2 phase of mitosis.
Anaphase: Is the 3 phase of mitosis.
Telophase: Is the final phase of mitosis.
Cell plate: A membrane across the middle of the cell.
Meiosis: Is the process of nuclear division that reduces the number of chromosome by half.
Meiosis 1: The first division, the homologous chromosome separates separated into separate
cells.
Meiosis 2: The second division, the chromatid of each chromosome is segregate into separate
cells.
Synapsis: The pairing of homologous chromosome.
Tetrad: Is a group of 2 chromosomes.
Crossing-over: Results in the exchange of genes.
Gametes: Sexual reproductive cell.
Ootid: The egg cell
Polar bodies: Receive little or no cytoplasm and eventually disintegrate.
Asexual reproduction: Is the production of offspring from one parent, without the union of
gametes.
Sexual reproduction: Is the production of offspring through meiosis and subsequent fusion of
gametes.
Genetic recombination: Is the process by which a strand of the genetic material (usually DNA;
but can also be RNA) is broken and then joined to the end of a different DNA molecule.
Inheritance: The passing of traits by heredity.
Heredity: Is the transmission of traits from parents to their offspring.
Pure: Plants that are pure for a trait always produce offspring with that trait.
Strain: Is a term used to denote all plants pure for a specific trait.
Self-pollination: Is the reproductive process in which fertilization occurs within a single plant.
Principle of dominant and recessiveness: One factor in a pair may mask the other factor.
Dominant: It masked or dominated the other factor for this trait.
Recessive: It masked in the presence of a dominant factor for that characteristic.
Principle of segregation: The two factors for a characteristic segregate or separate during the
formation of eggs and sperm.
Principle of independent assortment: Factor for different characteristics are distributed to
reproductive cells independently.
Gene: Is the segment of DNA on a chromosome that controls a particular hereditary trait.
Allele: Is the equivalent of Mendel´s “factor”.
Genotype: The genetic makeup of an organism.
Phenotype: The external appearance of an organism.
Homozygous: When both alleles of a pair are the same.
Heterozygous: When the two alleles in the pair are not the same.
Multiple alleles: When 3 or more alleles control a trait.
Probability: Likelihood that a specific event occur.
Monohybrid crosses: A cross between individuals that involve one pair of contrasting traits.
Punnett square: An inventor created to predict the probability of the traits.
Testcross: Can determine the genotype of an individual whose phenotype is dominant.
Codominance: Is the phenomenon that occurs when two or more or more alleles the phenotype.
Dihybrid cross: Is a cross between individuals that involve two pairs of contrasting trait.
Mutation: A change in DNA.
Germ cell mutation: Occurs in sex cell.
Somatic mutation: Take place in body cell.
Deletion: Occurs when a piece of chromosome breaks off.
Inversion: Occurs when a piece breaks from a chromosome and reattaches itself to in reverse
orientation.
Translocation: A broken piece attaches to a nonhomologous chromosome.
Point mutation: The substitution, addition or removal of a single nitrogen base.
Frameshift mutation: The addition or deletion of a nitrogen base.
Mutagens: Environment factors that damage DNA.
Ames test: A procedure to identify substance.
Sex chromosome: Chromosomes that determine and individual’s sex.
Autosomes: Not include in sex determination.
Linkage group: The group of genes located on one chromosome.
Chromosome map: A diagram of alleles positions on a particular chromosome.
Map unit: Two alleles that are separated by crossing over 1 percent of the time.
Population sampling: Researchers select a small number of individuals that represent the whole
population.
Pedigree: A family record that shows how a trait is inherited over several generations.
Carrier: Someone whose is heterozygous for a trait.
Sickle-cell disease: Is a singleallele disorder that operates a codominant system.
Huntington disease: Is a single-allele trait that causes by a dominant allele.
Genetic marker: A short section of DNA that indicates the presence of an allele that codes for a
trait.
Polygenic trait: A trait that is controlled by two or more genes.
Antigen: Is a substance that causes the body to produce an antibody.
Hemophilia: Another recessive sex-linked trait that is found primary in males.
Sex-influenced traits: The presence of male or female sex hormones influences the expression of
certain human’s traits.
Monosomy: A zygote with 45 chromosomes has only one of a particular chromosome.
Trisomy: A zygote with 47 chromosomes has 3 of a particular chromosome.
Down syndrome: An extra chromosome 21 can cause this syndrome, a disorder characterized by
mental retardation by mental retardation, a fold of skin above the eyes and weak muscles.
Genetic screening: An examination of a person’s genetic makeup.
Karyotype: Is a picture of individual’s chromosome.
Genetic counseling: A type of counseling that informs them about problems that could affect
their offspring.
Amniocentesis: The physician used a needle and syringe to remove a small amount of amniotic
from the amnion.
Fetoscopy: The physician inserts a tiny camera through a small incision in the uterus.
Ultrasound: A technique in which high-frequently sound waves bounce off the fetus.
Chorion villi sampling: The physician analyzes a sample of the chorion villi.