bio 120 genetics lab test

Monohybrid Cross

Cross between 2 individuals that differ in respect to one characteristic (ex. Plant height)

Dihybrid Cross

Mating between 2 individuals that differ in respect to 2 characteristics

What Would Happen w/out the Reduction of Division of Meiosis?

Sexual reproduction would cause chromosome numbers to increase with each passing generation

Gene

Unit of hereditary information that contributes to the inherited characteristics or traits of an organism, composed of a specific organized sequence of DNA

Allele

Alternative form of a gene (e.g. Either dominant or recessive)

Dominant

Allele that expressed in both the heterozygous and homozygous condition

Recessive

Allele that is not expressed phenotypically in the heterozygous condition

Genotype

Genetic makeup of an organism (ex. Aa or AaBB)

Phenotype

Organisms physical appearance, or visible traits as a result of the expressed genes

Frequency

Proportion of 1 type of individual (genotype or phenotype) to the total population

Ratio

Proportion of one thing to another, in genetics both genotypic and phenotypic ratios are often used

Punnett Square

Diagram commonly used for predicting the outcome of simple genetic crosses

Mendel’s First Law

Alleles of one gene segregate from one another during the formation of gametes

Mendel’s Second Law

Alleles of different genes assort independently of one another during gamete formation

Test Cross

Mating between an individual of unknown genotype for a particular characteristic and an individual that is homozygous recessive for that characteristic

Gene Linkage

Genes that are located close together on the same chromosome and are inherited together (less 50 map units apart)

P1, P2, F1, F2

• Parent 1, Parent 2 (original parents)

• 1st Filial Generation (The offspring of P1, P2)

• 2nd Filial Generation (Offspring between 2 F2 individuals, or F1 self fertilization)

Heterozygous

An organism that has 2 different alleles for the same gene (e.g., Aa or Bb)

Homozygous

Individual with 2 identical alleles for the same gene (e.g., AA or aa)

Sex Chromosomes

Distinctive pair of chromosomes that are different in males and females; determines whether an individual is male or female

Autosomes

Any chromosome that is not a sex chromosome

Tuner Syndrome

Chromosomal disorder where females either have a missing X chromosome or part of one X chromosome is deleted

Down Syndrome

Condition associated with physical disorders caused by an extra chromosome in ones genetic makeup

Klinfelter’s Syndrome

Human males have an extra X chromosome (XXY)

Sex-Linked Gene

Gene found on a sex chromosome; typically refers to genes found on the X but not the Y chromosome in humans

Pedigree Chart

Diagram that shows the occurrence and appearance or phenotypes of a particular gene or organism and its ancestors from one generation to the next

Carrier

Individual who has the recessive allele for a condition or disease but does not express any symptoms of the condition or disease

Red-Green Colour Blindness

Sex-linked human disorders involving several genes on the X chromosome; affects mostly males but also homozygous females

Polygenetic Inheritance

Phenotypic traits that involve contributions from the alleles of several or many genes at multiple locations on the chromosomes; typically with an additive effect

Recombinant Gametes

In a test cross, gametes that are result of crossing over/recombination between parental gametes

Parental Gametes

In a test cross, gametes that come from the parents of the heterozygous organism

Map Units Indicate…

Relative distance and order, not precise locations of genes

How does the Male Determine the Sex of the Child?

The egg only has an X chromosome, and the sperm can either have an X or Y, which determines the sex of the child