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Unit 2 Bold Textbook and LMR Vocabulary Terms

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Genetics
Scientific study of heredity; transmission of traits from parents to offspring.
Trait
A specific characteristic.
Gene
Section of DNA that determines a trait.
Allele
Alternative forms of a gene.
Dominant
An allele that expresses its phenotypic effect even when heterozygous with a recessive allele.
Recessive
An allele whose phenotypic effect is not expressed in a heterozygote. It is only expressed when homozygous.
Fertilization
Process of sexual reproduction in which male and female reproductive cells join to form a new cell.
Gamete
Sex cell involved in sexual reproduction.
Zygote
Fertilized egg formed during the fusion of gametes during sexual reproduction.
Pollination
Fertlization in plants.
True breeding
The term used describe organisms that produce offspring identical to themselves if allowed to self-pollinate (homozygous).
Hybrid
Offspring formed of crosses between parents with different traits.
Segregation
Separation of alleles during gamete formation.
Principle of Dominance
Some alleles are dominant, some are recessive (in Mendalian genetics).
Principle of Segregation
In most sexually reproducing organisms, each adult has two copies of a gene--one from each parent. These genes are segregated from each other when gametes are formed.
Principle of Independent Assortment
Genes for different traits can segregate independently during formation of gametes.
Probability
Likelihood that a particular event will occur; used to predict outcomes of genetic crosses.
Punnett Square
Diagram showing the gene combinations that might result from a genetic cross.
Homozygous
Term used to describe an organism that has two identical alleles for a particular trait.
Heterozygous
Term used to describe an organism that has two different alleles for a particular trait.
Genotype
Genetic make up of an organism.
Phenotype
Physical characteristics of an organism; determined by genotype.
Dihybrid Cross
Hybridization using two traits with two alleles each.
Monohybrid Cross
Hybridization using a single trait with two alleles.
P1 Generation
Parent generation.
F1 Generation
First filial generation; offspring of the cross of a P1 generation. (children)
F2 Generation
Second filial generation; offspring of the cross of a F1 generation. (grandchildren)
Incomplete Dominance
Situation in which one allele is not completely dominant over the other.
Codominance
Situation in which both alleles of a gene contribute to the phenotype of an organism.
Multiple Alleles
Three or more alleles of the same gene.
Polygenic Traits
Trait controlled by two or more genes.
Sex-linked Gene
Gene located on the X or Y chromosome
Sex-linked Trait
A trait that is carried on the X chromosome and has no allele on the Y chromosome
Male
XY
Female
XX
Male Gamete
Sperm cell
Female Gamete
Egg cell
Gregor Mendel
Father of genetics; scientist who followed the scientific method when designing genetic experiments.
Hypothesis
Possible explanation for a set of observations or answer to a question; accepted or rejected, can not be proven; must be testable
Manipulated (Independent) Variable
Factor in an experiment that a scientist purposely changes to cause an effect; on x-axis
Responding (Dependent) Variable
Factor in an experiment a scientist wants to observe; on y-axis
Constant (Control) Variables
All factors in an experiment that are kept the same and have a fixed value
Control Group
The group that will not be affected by the experimental variable; is used as a standard of comparison in an experiment
Experimental Group
The group that receives experimental treatments