Science: Topic 7 Study Guide-7th Grade

heredity

The passing of traits from parent to offspring

dominant allele

An allele whose trait always shows up in the organism when the allele is present.

recessive allele

An allele that is hidden whenever the dominant allele is present

probability

A number that describes how likely it is that a particular event will occur

genotype

An organism's genetic makeup, or allele combinations.

Phenotype

An organism's physical appearance, or visible traits.

Chromosome

threadlike structure within the nucleus containing the DNA that is passed from one generation of cells to the next

cell cycle

series of events in which a cell grows, prepares for division, and divides to form two daughter cells

pedigree

A tool that geneticists use to map out the inheritance of traits.

meiosis

The process that occurs in the formation of sex cells (sperm and egg) by which the number of chromosomes is reduced by half.

chromatids

The structure formed when a chromosome divides during meiosis.

mitosis

The second stage of the cell cycle during which the cell's nucleus divides into two new nuclei and one set of DNA is distributed into each daughter cell.

DNA

deoxyribonucleic acid, the material that contains the information that determines inherited characteristics

protein synthesis

The process by which amino acids link together to form proteins.

messenger RNA

type of RNA that carries copies of instructions for the assembly of amino acids into proteins from DNA to ribosomes in the cytoplasm.

transfer RNA

Type of RNA in the cytoplasm that carries an amino acid to the ribosome during protein synthesis.

variation

any difference between individuals of the same species

sex chromosomes

The pair of chromosomes carrying genes that determine whether a person is biologically male or female

autosomal chromosomes

The 22 pairs of chromosomes that are not sex chromosomes

mutation

any change in the DNA of a gene or chromosome

sex-linked genes

A gene carried on a sex chromosome

artificial selection

The process by which humans breed only those organisms with desired traits to produce the next generation; selective breeding.

genetic engineering

the transfer of a gene from the DNA of one organism into another organism, in order to produce an organism with desired traits

gene therapy

The process of replacing an absent or faulty gene with a normal working gene to treat a disease or medical disorder.

clone

An organism that is genetically identical to the organism from which it was produced

genome

A complete set of genetic information that an organism carries in its DNA