Term | Definition |
Trait | Characteristic an organism may pass on to its offspring through its genes. Examples: eye color and height |
allele | Different forms of a gene. For example, the gene that controls stem height in peas has one allele for tall stems and one allele for short stems. |
gene | Factor that controls a trait. |
genotype | An organism's genetic make-up or its allele combinations |
phenotype | An organism's physical appearance. |
homozygous | A organism that has two identical alleles for a trait. |
heterozygous | An organism that has two different alleles for a trait. Also can be called a "hybrid" organism. |
hybrid | An organism that has two different alleles for a trait. Also can be called a "heterozygous" organism. |
punnett square | A chart that shows all the possible combinations of alleles that can result from a genetic cross. |
probability | A number that describes how likely it is that an event will occur. It can be expressed as a percentage or a fraction. |
dominant allele | The alleles that always appears in the organism when the allele is present. |
recessive allele | An allele that shows up in an organism only if a dominant allele is not present. |
codominant | Situation in which alleles are neither dominant or recessive, such that both alleles are represented in the offspring. |
Whose discoveries formed the foundation of genetics? | Gregor Mendel, a 19th century priest. Studied the traits of pea plants. He discovered genes and alleles. Before this, people thought that the traits of an organism were simply a blend of their parents' characteristics. |
genetics | the scientific study of heredity |
heredity | the passing of physical characteristics from parents to offspring |
fertilization | joining of an egg and sperm |
purebred organism | the offspring of many generations that have the same trait -- purebred short pea plants always come from short parent plants |
technique that Mendel used to study genetics of pea plants | cross pollinization -- he removed pollen from a flower on one plan and brushed it onto the flower of a second plant. |
genetic disorder | an abnormal condition that a person inherits through genes or chromosomes. |
What can cause genetic disorders? | Mutations in the DNA of genes or changes in the overall structure or number of chromosomes |
pedigree | a chart or "family tree" that tracks which embers of a family have a particular trait. |
karyotype | a picture of all the chromosomes in a cell |
what do genetic counselors do? | they help couples understand their chances of having a child with a particular genetic disorder. They use karyotypes, pedigree charts, and punnett squares. |
selective breeding | the process of selecting organisms with desired traits to be parents of the next generation -- e.g., seeds from the healthiest plants |
inbreeding | crossing 2 individuals that have similar characteristics. e.g., plump, fast growing turkeys |
hybridization | crossing 2 genetically different individuals -- bred to have the best traits from both parents. e.g. corn that produces many kernels and corn that is resistant to disease. |
clone | an organism that has exactly the same genes as the organism from which it was produced. |
genetic engineering | genes from one organism are transferred into the DNA of another organism. Sometimes bacteria are used to do this because they reproduce quickly |
gene therapy | involves inserting copies of a gene directly into a person's cells, to try to correct genetic disorders in humans |
genome | all the DNA in one cell of an organism |
Goal of the Human Genome Project | to identify the DNA sequence of every gene in the human genome |
sperm | the male sex cell or gamete |
a yeast cell reproduces by... | asexual reproduction -- budding |
| cell division that creates sex cells |
bacterium reproduce by | cell fission |
starfish | organism that can undergo regeneration of severed parts |
egg | female sex cell or gamete |
meiosis | cell division to replace damaged skin cells |
What process would be used to produce corn that is taller and produces more ears than average? | selective breeding |
When an amoeba, a one-celled organism divides, this is an example of __________________ reproduction | asexual |
You are a multi-cellular organism. Where did all of your cells originate? | 1 fertilized egg |
vegetative propagation | the ability of plants to reproduce without sexual reproduction, by producing new plants from existing vegetative structures. |
budding | a form of asexual reproduction of yeast in which a new cell grows out of the body of a parent. |
binary fission | a form of asexual reproduction in which one cell divides to form two identical cells |
regeneration | a form of asexual reproduction where an animal amputates its limb and that limb grows into a full animal that is genetically identical to the parent |
runners | horizontal stems |