Biology Test 3 Flashcards
What is inheritance?
Process by which the characteristics/traits of individuals are passed to their offspring
What is a gene?
Unit of heredity; encodes the characteristics that determines a phenotype
What is an allele?
Alternate versions of the same gene at the same locus (in homologous pairs), genes form
What is a locus?
The location of a particular gene on a chromosome
What is a phenotype?
Physical traits (ex: yellow seeds)
What is a genotype?
Genetic makeup of an organism, determine phenotype = genetic makeup (ex: Yy)
What is a dominant trait?
Allele that dominates over others in determining phenotype (capital letters)
What is a recessive trait?
Allele whose phenotypic expression is “hidden” when a dominant allele is present (lowercase letters)
What does it mean to be homozygous?
Both homologous chromosomes carry the same allele at a given gene locus (genotype: YY or yy)
What does it mean to be heterozygous?
Two homologous chromosomes carry different alleles at a given locus (Yy)
What is a hybrid?
Offspring from a cross-breeding
What is a monohybrid cross?
Evaluate the inheritance pattern of 1 trait
What is a dihybrid trait?
Evaluate the inheritance pattern of 2 traits
What is the P generation (P1)?
Parental generation
What is the F1 generation?
First generation offspring
What is the F2 generation?
Second generation offspring (offspring of F1 generation)
What is the Law of Segregation?
Two alleles separate to each other during meiosis randomly
Facts about linkage
The closer two genes are on a chromosome, the lower the probability that a crossover will occur between them. Linked genes are found on same chromosomes. The frequency of recombination of two linked genes that are far apart from each other is greater than those closer ones. Crossing over can break the linkage.
Genetic linkage
Genes on the same chromosome tend to be inherited together
How does crossing over affect linkage?
Crossing over in prophase I of meiosis breaks the linkage, and creates new allele combinations
What is genetic mapping?
Placement of a gene into a position in a linkage group
What is a map unit?
Distance between genes (one map unit = 1% recombination)
What is map distance?
Between genes on the same chromosome are measured in map units
What is a linkage group?
All genes on a particular chromosome; tend to be inherited together
What is incomplete dominance?
Combined phenotypes
What is complete dominance?
Occurs when phenotypes of the heterozygote and dominant homozygote are identical
What is codominance?
Two dominant alleles affect the phenotype in separate, distinguishable ways
What is pleiotropy?
Alleles at a single locus that may have effects on two or more traits (ex: albinism)
What are polygenic traits?
Traits affected by interaction of two or more genes (ex: human skin color)
What is the norm of reaction?
The phenotypic range of a genotype influenced by the environment
What are autosomes?
Non-sex chromosomes
What are sex-linked genes?
Genes carried on one sex chromosome (ex: eye color gene in fruit flies)
What is a carrier?
Someone with a normal phenotype, but a heterozygous genotype
What is pedigree?
A family tree that describes the interrelationships of parents and children across generations
What is aneuploidy?
Missing one copy or have an extra copy of a single chromosome (trisomy: 3 copies, monosomy: one copy)
Wild type
Normal phenotype
Mutant type
Anything other than a wild type
Autosomal
The gene is located on one of the numbered, or non-sex, chromosomes
