ch 7 review Flashcards
(28 cards)
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
he genome of Homo sapiens. It is made up of 23 chromosome pairs with a total of about 3 billion DNA base pairs. There are 24 distinct human chromosomes: 22 autosomal chromosomes, plus the sex-determining X and Y chromosomes. Chromosomes 1-22 are numbered roughly in order of decreasing size.
basis or 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 substituted derivative of purine, especially the bases adenine and guanine present in DNA
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.
prismidines
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 action of copying or reproducing something.
law of independent assortment
the principle, originated by Gregor 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
Linked genes are 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
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
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
are 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. … Despite having the same genotype, both the sexes show different traits or phenotypes for these genes.
sex-influenced traits
are 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
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.