Chapter 10: Patterns Of Inheritance Flashcards
Why is Mendel the father of genetics?
His experiment with the pea plants help jump start the study of genetics.
Who was the father of genetics?
Gregor Mendel
Define allele
Alternative forms
Define homologous chromosomes
Look alike and have the same sequence of genes in the same positions.
Define gene.
Is a portion of DNA whose sequence of nucleotides encodes a protein.
What is the relationship between allele pairs and homologous pairs of chromosomes?
The two homologous may or may not carry the same alleles. Since each homologous comes from a different parent, each person inherits two alleles for each gene in the human genome.
Compare autosomes and sex chromosomes
Autosomes are chromosomes that are the same for both sexes.
Sex chromosomes determines whether a person is a male or female.
A person with X and X are female and a male are X and Y.
Compare haploid and diploid.
Haploid has one set of chromosomes.
Diploid contains two sets of chromosomes, with one set inherited from each parent.
What is the P generation?
The parental generation.
What is the F1 generation?
Offspring of P generation.
What is the F2 generation.
Offspring of F1 generation.
Define chromosome.
A continuous molecule of DNA plus associated proteins.
Define gene?
A sequence of DNA that encodes a protein.
Define locus.
The physical location of a gene on a chromosome.
Define allele
One of the alternative forms of a specific gene.
Define dominant allele
An allele that is expressed if present in the genotype.
Define recessive allele.
An allele whose expression is masked by a dominant allele.
Compare homozygous and heterozygous?
Homozygous-possessing identical alleles of one gene.
Heterozygous-possessing different alleles of one gene.
Compare genotype and phenotype.
Genotype expresses the genetic makeup of an individual.
Phenotype are observable characteristics.
Why are peas a good organismic for genetic studies?
Pea plants are easy to grow, develop quickly, and produce many offspring.
Why don’t humans make a good choice?
It takes to long to observe.
How did Mendel uncover the some alleles are dominant and some are recessive?
Dominant alleles appear to mask recessive alleles.
How do the alleles end up in different gametes?
Punnett square uses the genotypes of parents to reveal which allele combinations the offspring may inherit.
Define monohybrid cross.
A mating between two individuals that are both heterozygous for the same gene.
Define test cross.
Is a mating between an individual of unknown genotype and a homozygous recessive individual.
Explain the law of segregation?
The law of segregation states that two alleles of each gene are packaged into separate gametes.
How does meiosis explain the law of segregation?
During meiosis, homologous pairs of chromosomes segregate from one another and are packaged into separate gametes. At fertilization, gametes combine at random to form the next generation
Define dihybrid cross.
Is a mating between individuals that are each heterozygous for two genes.
Explain the law of independent assortment.
Law of independent assortment states that during gamete formation, the segregation of the alleles for one gene does not influence the alleles for another gene.
Why do alleles on different chromosomes move independently of each other?
?
How is the product rule related to genetics laws
The product states that the chance that two independent events will both occur equals the product of the individual chances that each event will occur.
Define linkage.
Collection of genes that tended to be inherited together.
Define crossing over.
An exchange of genetic material between homologous chromosomes during prophase 1.
Explain why some dihybrid cross combinations do not seem to follow the law of independent assortment.
When genes are not linked on the same chromosomes, they assort independently. The gametes then represent all possible allele combinations, and the cross yields the expected phenotypic ratio.
Compare incomplete dominance and codominance.
Incomplete dominance is when the heterozygous has a third phenotype that is intermediate between those of the two homozygotes.
Codominance is two different alleles are expressed together in the phenotype.
What is an example of an incomplete dominance.
A red flowered snapdragon of genotype r1 r1 crossed with a white flowered r2 r2 plant gives rise to an r1 r2 plant with pink flowers.
What is an example of codominance.
A person’s ABO blood type is determined by the I gene, which has three possible alleles: Ia, Ib, and I.
Define pleiotropic.
One gene has multiple effects on the phenotype.
Define Epistasis.
Occurs when one gene product affects the expression of another gene.
What is an example of Epistasis.
Male pattern baldness a genetic condition is associated with gradual hair loss, which hides the effects of the allele for a widow’s peak hairline.
What is an example of pleiotropic.
A single connective tissue protein abnormality causes Marfan syndrome.
Define sex linked.
The alleles controlling them are on the X or Y chromosomes.
Compare the inheritance patterns of sex linked recessive disorders in males and females.
X linked recessive disorder affect more males than females. Thomas hunt was the first to unravel the unusual inheritance patterns associated with genes on the X chromosome.
Why do x linked recessive traits more common in males and females
A female therefore exhibits an x linked recessive disorder only if she inherits the recessive alleles from both parents. A male in contrast express every allele on his single X chromosome whether dominant or recessive.
Define Pedigree.
Charts depicting family relationships and phenotype are useful for determining the mode of inheritance.
How does the environment affect phenotype?
The temperature of the environment can affect the phenotype. An example in humans is the fetal alcohol syndrome.
Define polygenic?
The phenotype reflects the activities of more than one gene.
Identify several traits which are affected by polygenic inheritance.
Baldness, eye color, height.
