science revision Flashcards
Genetics
the study of genes, heredity, and genetic variation in living organisms.
DNA
a molecule that carries the genetic instructions used in the growth, development, functioning, and reproduction of all living things.
Chromosome
a long, thread-like structure composed of DNA and protein found in the nucleus of most living cells.
Gene
a sequence of DNA or RNA that encodes the synthesis of a functional molecule such as a protein or RNA molecule.
Haploid
a cell or organism containing a single set of chromosomes.
Diploid
a cell or organism containing two sets of chromosomes.
Gamete
a specialized cell that combines with another to form a zygote, which develops into a new individual.
Somatic
relating to the body, especially as distinct from the mind.
Helix
a three-dimensional shape like that of a wire spiral or a DNA molecule.
Complementary base pairs
specific pairs of nucleotides that form the rungs of the DNA ladder: adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C).
Heredity
the passing of traits from parents to offspring.
Karyotype
the number and appearance of chromosomes in the nucleus of a eukaryotic cell.
Autosomes
any chromosome that is not a sex chromosome.
Genome
all of an organism’s genetic material, including chromosomes and cytoplasmic DNA.
Nucleotide
the basic building blocks of DNA and RNA, consisting of a sugar, a phosphate group, and a nitrogenous base.
Interphase
the period of the cell cycle between mitotic divisions when the cell grows, copies its DNA, and prepares for cell division.
Replication -
the process of copying DNA to form new DNA molecules.
Meiosis
a type of cell division that results in four daughter cells each with half the number of chromosomes as the parent cell.
Mitosis
a type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus.
Chromatids
one of the two identical halves of a replicated chromosome.
Allele
one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.
Homozygous
having two identical alleles for a particular gene.
Heterozygous
having two different alleles for a particular gene.
Phenotype
the observable physical or biochemical characteristics of an organism, as determined by both genetic makeup and environmental influences.