Ch.7 Terms Flashcards
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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
The complete set of nucleic acid sequences for humans, encoded as DNA within the 23 chromosome pairs in cell nuclei
Bases/Nucleotides
A compound consisting of a nucleoside linked to a phosphate group. Nucleotides form the basic structural unit of nucleic acids such as DNA.
Purines
A colorless crystalline compound with basic properties, forming uric acid on oxidation.
Guanine
A purine nucleobase with a chemical formula of C5H5N5O. also is one of the four main nucleobases found in the nucleic acids
Adenine
One of the four constituent bases of nucleic acids. A purine derivative, it is paired with thymine in double-stranded DNA.
Pyrimidines
A substituted derivative of pyrimidine, especially the bases thymine and cytosine present in DNA.
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 process of duplicating or producing an exact copy of a polynucleotide strand such as DNA.
Law of Independent Assortment
The principle, originated by Gregory Mendel, stating that when two or more characteristics are inherited, individual hereditary factors assort independently during gamete production, giving different traits an equal opportunity of occurring together.
Linked genes
Genes that are likely to be inherited together because they are physically close to one another on the same chromosome. During meiosis, chromosomes are recombined, resulting in gene swaps between homologous chromosomes.
Recombination
A process by which pieces of DNA are broken and recombined to produce new combinations of alleles. This recombination process creates genetic diversity at the level of genes that reflects differences in the DNA sequences of different organisms.
Crossing over
The exchange of genetic material between non-sister chromatids of homologous chromosomes during meiosis, which results in new allelic combinations in the daughter cells.
Genetic engineering
The direct manipulation of an organism’s genes using biotechnology.
Sex Chromosomes
A type of chromosome that participates in sex determination. Humans and most other mammals have two sex chromosomes, the X and the Y. Females have two X chromosomes in their cells, while males have both X and a Y chromosomes in their cells.
Autosomes
Any chromosome not considered as a sex chromosome, or is not involved in sex determination. It occurs in pairs in somatic cells and singly in sex cells (gametes) Supplement.
Sex-linked traits
A particularly important category of genetic linkage has to do with the X and Y sex chromosomes. These not only carry the genes that determine male and female traits but also those for some other characteristics as well. Genes that are carried by either sex chromosome are said to be sex linked.
Sex-limited traits
Those characters that are expressed physically in one sex of a species. These traits are controlled by sex limited genes or autosomal genes that are expressed only in one sex.
Sex-influenced traits
Autosomal traits that are influenced by sex. If a male has one recessive allele, he will show that trait, but it will take two recessive for the female to show that same trait. One such gene is baldness. A lot of sex-limtied traits can determine parental carriers by using a pedigree.
Genome
A genome is the genetic material of an organism. It consists of DNA. The genome includes both the genes and the noncoding DNA, as well as mitochondrial DNA and chloroplast DNA.
Karyotype
The number and appearance of chromosomes in the nucleus of an eukaryotic cell. The term is also used for the complete set of chromosomes in a species or in an individual organism and for a test that detects this complement or measures the number.
Nondisjunction
The failure of one or more pairs of homologous chromosomes or sister chromatids to separate normally during nuclear division, usually resulting in an abnormal distribution of chromosomes in the daughter nuclei.
Monosomy
The condition of having a diploid chromosome complement in which one (usually the X) chromosome lacks its homologous partner.
Trisonomy
When a diploid organism has three copies of one of its chromosomes instead of two. Trisomy is an example of aneuploidy, or an organism having an abnormal number of chromosomes.
Polyploidy
The state of a cell or organism having more than two paired (homologous) sets of chromosomes. Most species whose cells have nuclei (eukaryotes) are diploid, meaning they have two sets of chromosomes—one set inherited from each parent.
