Biology Chapter 9 Flashcards
Explain how human experiences breeding dog and food crops can provide insights into principles of genetics.
Dogs and food have been bred for certain traits over thousands of years, so we now have an incredible variety of different kinds of dogs and food. We can see how different combinations of sperm and eggs produce different traits.
self-fertilization
When an organism can produce the necessary sperm and eggs to reproduce by itself
Cross-fertilization
When the sperm from one organism is used to fertlize the eggs of another
purebred organism
An organism which consistently passes down the same traits to offspring
Hybrids
The offspring of two different purebred varieties
P generation
Parent generation (2 different purebred organisms)
F1 Generation
Hybrid of the P generation
F2 Generation
A cross of the F1 organisms
heterozygous vs. homozygous
homozygous: organism with 2 identical alleles for a certain trait
heterozygous: organism with 2 different alleles for a certain trait.
Dominante Allele vs. Recessive Allele
Dominant Allele: Determines the organism’s appearance
Recessive Allele: Has no noticeable affect on organism’s appearance
Allele
Alternative versions of genes
Genotype vs. Phenotype
Genotype: Organism’s genetic makeup
Phenotype: Organism’s physical appearance
Phenotypic Ratio vs. Genotypic Ratio
Phenotypic Ratio: Ratio of physical appearance
Genotypic Ratio: Ratio of genetic makeup
Law of Segregation
Gametes carry only one allele for each inherited character.
The two alleles for a character segregate (separate) from each other during the production of gametes.
Define Mendel’s law of independent assortment and explain how it applies to a dihybrid cross.
Each pair of alleles segregates independently of the other pairs during gamete formation. Thus, the inheritance of one character has no effect on the inheritance of another.
Explain how a testcross can be performed to determine an organism’s genotype.
A testcross is a mating between an individual of dominant phenotype (but unknown genotype) and a homozygous recessive individual.
Rule of Multiplication
The probability of a compound event is the product of the separate probabilities of the independent events.
Explain how a pedigree is used to determine how a particular human trait is inherited.
A pedigree is a a history of a certain trait in a family
Define a carrier and explain how carriers are revealed in human pedigrees.
Organisms that carry a recessive allele but do not exhibit the trait physically
Incomplete dominance
F1 hybrids have an appearance between the phenotypes of the two parents. (A dominant red flower and a recessive white flower might have a heterozygous offspring with a pink flower)
Complete dominance
The dominant gene covers up the recessive gene (a dominant red flower and a recessive white flower have offpsring where the heterozygotes all had red flowers).
Codominance
Both genotypes express themselves at the same time (a dominant red flower and a recessive white flower would have offspring where the heterozygote had both red and white–stripes or dots or something–but not mixed to form pink)
Define and distinguish between pleiotropy and polygenic inheritance. Describe examples of each.
Pleiotropy: One gene influences several traits
Polygenic inheritance: The additive effects of two or more genes on a single phenotype.
Define the chromosome theory of inheritance and explain how linked genes are inherited differently from nonlinked genes.
genes are located at specific positions (loci) on chromosomes and the behavior of chromosomes during meiosis and fertilization accounts for inheritance patterns.
Explain how the environment influences the expression of traits.
Many human characters result from a combination of the environment and inherited genes
Explain why researchers used fruit flies and how they created linkage maps.
Researchers used fruit flies because they have very short life cycles which allows researchers to study many generations in a short time. Linkage maps were created by studying each generation and seeing which traits tended to be inherited together.
Explain how chromosomes determine the sex of a human.
Humans have a set of chromosomes called X and Y. Females inherit two X chromosomes. Males inherit an X and a Y chromosome.
escribe the general characters of the following sex-linked disorders in humans: red-green colorblindness and hemophilia.
Red-green colorblindness: malfunction of light-sensitive cells in eyes.
Hemophilia: causes excessive (dangerous) bleeding even after small cuts
Describe the relationships between the many breeds of dogs.
All dogs were descended from a common ancestor, but they were bred in areas where they became distinct.
