biology 3 Flashcards
chromosomes
a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.
genes
a unit of heredity which is transferred from a parent to offspring and is held to determine some characteristic of the offspring.
human genome
It is made up of 23 chromosome pairs with a total of about 3 billion DNA base pairs.
bases
the lowest part or edge of something, especially the part on which it rests or is supported.
purines
a colorless crystalline compound with basic properties, forming uric acid on oxidation.
guanine
a compound that occurs in guano and fish scales, and is one of the four constituent bases of nucleic acids. A purine derivative, it is paired with cytosine in double-stranded DNA.
adenine
a compound which is one of the four constituent bases of nucleic acids. A purine derivative, it is paired with thymine in double-stranded DNA.
pyrimidines
a colorless crystalline compound with basic properties.
cytosine
a compound found in living tissue as a constituent base of nucleic acids. It is paired with guanine in double-stranded DNA.
thymine
a compound which is one of the four constituent bases of nucleic acids. A pyrimidine derivative, it is paired with adenine in double-stranded DNA.
double helix
a pair of parallel helices intertwined about a common axis, especially that in the structure of the DNA molecule.
replication
the action of copying or reproducing something.
law of independent assortment
states that the alleles of two (or more) different genes get sorted into gametes independently of one another.
linked genes
genes that are likely to be inherited together because they are physically close to one another on the same chromosome.
recombination
the rearrangement of genetic material, especially by crossing over in chromosomes or by the artificial joining of segments of DNA from different organisms.
crossing over
the exchange of genes between homologous chromosomes, resulting in a mixture of parental characteristics in offspring.
genetic engineering
the deliberate modification of the characteristics of an organism by manipulating its genetic material.
sex chromosomes
a chromosome involved with determining the sex of an organism, typically one of two kinds.
autosomes
any chromosome that is not a sex chromosome.
sex linked traits
Genes that are carried by either sex chromosome
sex limited traits
characters that are expressed physically in one sex of a species.
sex influenced traits
autosomal traits that are influenced by sex.
genome
the haploid set of chromosomes in a gamete or microorganism, or in each cell of a multicellular organism.
karyotype
the number and visual appearance of the chromosomes in the cell nuclei of an organism or species.
