Terminology Flashcards
Tetrads
a group of four synapsed chromatids that become visibly evident in prophase.
Crossing over
the exchange of DNA between paired homologous chromosomes (one from each parent) that occurs during the development of egg and sperm cells (meiosis)
Independent Assortment
how different genes independently separate from one another when reproductive cells develop
Nondisjunction
the failure of the chromosomes to separate, which produces daughter cells with abnormal
numbers of chromosomes
Haploid Chromosome Number
a cell that contains a single set of chromosomes
Diploid Chromosome Number
A cell containing two copies of each chromosome
Twisted Double Helix
a term used to describe the physical structure of DNA
James Watson and Frances Crick
both had ideas that the double-stranded molecule could both produce exact copies of itself and carry genetic instructions.
Sugar-phosphate backbone
forms the structural framework of nucleic acids, including DNA and RNA
Nucleotides that comprise DNA
the basic building block of nucleic acids (RNA and DNA) - adenine (A), thymine (T), guanine (G), and cytosine (C)
Nucleotide base-pairing in DNA
Two nitrogen-containing bases (or nucleotides) that pair together to form the structure of DNA
Genotype
The letter combo that shows which alleles are present in an organism.
Phenotype
The appearance of an expressed trait.
Dominant
the relationship between two versions of a gene (effectively over-rule the other), for example
the allele for brown eyes is dominant
Recessive
the relationship between an observed trait and the two inherited versions of a gene related to
that trait
Allele
One of two or more DNA sequences occurring at a particular gene locus
Homozygous
A genotype showing 2 identical alleles, AA or aa.
Heterozygous
A genotype showing 2 different alleles, Aa
Punnett Square
a table in which all of the possible outcomes for a genetic cross between two individuals with
known genotypes are given
Pure-bred
an organism that always passes down certain phenotypic traits to its offspring of many
generations
Hybrid
An individual formed by mating between unlike forms, usually genetically
differentiated populations or species
Heredity
specific mechanisms by which characteristics or traits are passed from one generation to the
next via genes
Probability
provides information about the likelihood that something will happen
Gametes in plants
Female gametes are called ova and male gametes are called pollen grains. (plants) These are
the reproductive cells
Gametes in animals
Female gametes are egg cells and male gametes are called sperm cells. (animals) These are
the reproductive cells.
Meiosis
A special form of cell division in which each daughter cell receives half the amount of DNA as
the parent cell. Meiosis occurs during formation of egg and sperm cells in mammals.
Mitosis
The process where a single parent cell divides to make two daughter cells. Each daughter cell
receives a complete set of chromosomes from the parent cell. (both plants and animals)
Budding
an asexual reproduction method in which a new organism develops from a bud of an existing
organism
Tubers
specialized storage stem of certain seed plants
Runners
a slender stem that grows horizontally along the ground, giving rise to roots and aerial (vertical)
branches at specialized points called nodes
Plantlets
A small or young plant.
Cuttings
portion of a stem, root, or leaf cut from the parent plant for the production of a new
independent plant by it forming shoots and roots under favorable environmental conditions
Fragmentation
When an organism breaks down into several fragments or pieces.
Regeneration
the natural process of replacing or restoring damaged or missing cells, tissues, organs, and
even entire body parts to full function in plants and animals
Binary Fission
a process by which a single cell splits into
two cells to multiply
Internal fertilization
sperm fertilizing the egg within the female
External fertilization
the release of both sperm and eggs into an external environment
