Chapter 14-15 Test Vocab Flashcards
This is a heritable feature that varies among individuals. (Ex: that which determines eye color, hair color, height, etc.)
Character
These are variants of a character. (Ex: brown, blue, green, etc.)
Traits
Which term describes an individual that only passes on the same trait that it has itself for a given character?
True-Breeding, Purebred
This is the result of crossing two different trait-carrying, true-breeding individuals.
Hybridization
Describe these terms in order: P, F1, F2.
True-breeding parents; their hybrid offspring; F1’s offspring
These are alternative forms of the same gene that account for variations in the physical appearance of individuals.
Alleles
Which allele has a noticeable effect on an organism’s appearance: dominant or recessive?
Dominant
What happens when you breed an organism of unknown genotype with a homozygous recessive individual?
Testcross
Why are testcrosses done?
To determine unknown genotypes in individual organisms.
How are unknown genotypes determined by testcrosses?
By the ratio of phenotypes in the offspring.
What is the difference between genotype and phenotype?
Genotype refers to the actual genes themselves; phenotype refers to the physical appearance of an organism.
When is the multiplication rule used? The addition rule?
F1 monohybrid cross; heterozygous F2 organism
What is an organism that is heterozygous for one particular character being followed in a cross?
Monohybrid
What term describes an organism that is heterozygous for two characters being followed in a cross?
Dihybrid
What Mendelian law states that the two alleles for a heritable character separate from each other during gamete formation and end up in different gametes?
Law of Segregation
Which Mendelian law states that each pair of alleles separate independently of alleles for other characters during gamete formation?
Law of Independent Assortment
When do Mendelian genetics apply to inheritance?
When one locus (one gene) determines the phenotype, when there are only two kinds of alleles possible, and when one allele is dominant and the other is recessive.
What is it called when one allele is dominant and the other is recessive?
Complete Dominance
What is incomplete dominance?
When neither of two alleles for a given gene are dominant.
What is the result of incomplete dominance?
Heterozygous individuals showing a blended phenotype (ex: black + white –> gray).
What is codominance?
When two alleles for a given gene are both dominant.
What is the result of codominance?
Both alleles are observable, or expressed, in an individual’s phenotype (ex: pink and red flower).
What is meant by multiple alleles?
Many genes have more than two allele possibilities, but individuals still receive only two (one from each parent).
(Ex: human blood type)
What is meant by pleiotropy?
Some genes affect more than one phenotype characteristic.
What are polygenic traits?
Polygenic traits are the result of two or more genes collectively affecting a single phenotype.
Describe an example of polygenic traits.
Epistasis - a gene at one locus affects the expression of a gene at another locus.
What else can have an influence on phenotype?
Environment
What are pedigrees and what do they show us?
A pedigree shows a family tree and the members of the family who are affected by a genetic trait.
What did Mendel call genes?
Hereditary Factors
This law states that Mendelian genes have specific loci (positions) on chromosomes and that chromosomes undergo segregation and independent assortment.
Chromosome Theory of Inheritance
Where is the physical evidence for the laws of segregation and independent assortment found?
Segregation: Anaphase I (and sometimes II)
Independent Assortment: Metaphase I
What conclusions can be drawn from Morgan’s experiment with fruit flies?
Chromosomes are the location of Mendel’s genes.
This term describes phenotypes that are common in populations of organisms in nature.
Wild Type
These are traits alternative to wild type.
Mutant Phenotypes
What are X-linked genes? What is an example of when this can be seen?
Genes that are located on the X chromosome. This can be seen when all male members of an F2 generation display a trait resulting from a recessive gene.
What are the four systems (and types of organisms) in which genes can be X-linked?
X-Y (humans), X-0 (grasshoppers), Z-W (chicken), haplo-diploid (beetle)
What are sex-linked genes?
Genes that are located on either the X or Y chromosome.
What needs to happen in order for a recessive X-linked trait to be expressed?
- Female must be homozygous.
2. Male must be hemizygous.
These are X chromosomes that are randomly inactivated during embryonic development and condensed.
Barr Body
What are individuals with nonparental phenotypes (new combinations of traits)?
Recombinant
What is responsible for the breaking of the physical connection between genes on the same chromosome?
Crossing Over
This is an ordered list of the genetic loci along a particular chromosome.
Genetic Map
What is a linkage map?
A genetic map of a chromosome based on recombination frequencies.
What is the general rule regarding linkage maps and recombination frequencies?
The farther apart two genes are, the higher the probability that a crossover will occur between them and therefore the higher the recombination frequency.
These indicate the positions of genes with respect to chromosomal features.
Cytogenetic Maps
What happens during meiotic nondisjunction?
Pairs of homologous chromosomes do not separate normally. As a result, one gamete receives two of the same type of chromosome, and another receives no copy.
This results from the fertilization of gametes in which nondisjunction occurred.
Aneuploidy
Which type of zygote has only one copy of a particular chromosome?
Monosomic Zygote
Which type of zygote has three copies of a particular chromosome?
Trisomic Zygote
This is a condition in which an organism has more than two complete sets of chromosomes.
Polyploidy
This removes a chromosomal segment.
Deletion
This repeats a chromosomal segment.
Duplication
This reverses orientation of a segment within a chromosome.
Inversion
This moves a segment from one chromosome to another.
Translocation
