science chapter 13

traits

Characteristics inherited from parents.

genes

small sections of DNA that control traits of an organism.

hereditary

The passing of traits from parents to offspring.

DNA

Molecules carry the chemical code that tells cells what to do. DNA is shaped like a twisted spiral ladder, a double helix. It is made up of four basic molecules called bases.

Francis Crick and James Watson

Scientists who discovered the DNA molecule.

chromosomes

contain dna

Gregor Mendel

“Father of Genetics“ experimented with pea plants to study how traits were passed on between generations

purebred

plants that show the same trait for many generations when pollinated naturally

hybrid

plants produced by mixing purebred plants with different forms of the same trait

dominant traits

a characteristic that is shown in the hybrid generation

recessive trait

a hidden characteristic in the hybrid generation and appears only when no dominant factor is inherited

“P”

“parent plants“ in Mendels experiments

phenotype

the physical appearance of an organism

genotype

the genetic arrangement of an organism

codominance

both genes are expressed instead of one being dominant and the other recessive

incomplete dominance

occurs when genes seem to blend together for a trait in one generation

punnet square

a chart that shows the genetic possibilities of a certain trait in the offspring of a specific pair of parents

pedigree

a chart that traces a trait through generations of family members

sickle cell anemia

genetic disease that causes a person’s red blood cells to become hard and curved

cystic fibrosis

genetic disease that affects a person’s lungs and digestive system due to thick mucus

down syndrome

a genetic occurrence that is sometimes caused by an extra chromosome

genetic engineering

involves changing a gene or moving some of one organism’s genes into another organism