Mendel's Laws 1 Flashcards
What is the difference between “phenotype” and “genotype”? How are they related?
Phenotype:
observable traits.
example: color, shape, or size.
Genotype: genetic constitution of an organism
*the genes inherited from the parents regarding a particular character. *
Phenotype is derived from genotype, but it can also be influenced by the environment.
What is the difference between “a mutant” and “a mutation”? How are they related?
Mutant: cell or organism with one or more mutation.
Mutation: process or the result of such changes.
Mutations can cause changes in the genotype and phenotype of a mutant.
What does “Dominant” mean? And “Recessive”?
terms used to describe the relationship between two alleles of a gene.
dominant allele:
allele that determines the visible trait
recessive allele:
cannot be detected when paired with a dominant allele
only show its effect when paired with another recessive allele.
What does “Homozygous” mean? And “Heterozygous”?
terms used to describe the genotype of an organism.
Homozygous: two identical alleles for a gene, such as YY or yy.
Heterozygous: two different alleles for a gene, such as Yy.
Explain P, F1, F2 and F3 generations.
P: parental generation, which are the true-breeding strains that are crossed to produce the hybrids.
F1: first filial generation, hybrids that result from the cross between the P.
F2: second filial generation, the offspring from the self-fertilization of F1.
F3: third filial generation, offspring from self-fertilization of F2.
What is an allele?
variant form of a gene.
For each trait (gene), there are two copies of a specific factor/unit of inheritance (allele), one from the father and one from the mother.
The combination of alleles determines the genotype and the phenotype of an organism.
Enunciate the Principle of segregation and make an example.
two alleles of each gene segregate from each other during gamete formation.
one allele from each parent unite at random at fertilization and determine the trait.
For example:
plant has the genotype Yy for seed color, it produce two types of gametes, Y and y. If crossed with another plant with the same genotype, alleles in the offspring are YY, Yy, yY, and yy.
The resulting phenotypes are yellow (YY, Yy, yY) and green (yy) seeds, with a ratio of 3:1.
How can you draw a Punnet square for a cross involving 1 gene/2 alleles?
write the genotypes of the parents,
list the possible gametes from each parent,
draw a square and put all the possible gametes on the sides
fill the squares with the possible zygotes.
How do alleles segregate during gamete formation? How do they reunite?
during meiosis, the chromosomes are separated into two haploid cells, each with one allele of each gene.
Then, each haploid cell divides again to produce four haploid gametes, each with one allele of each gene.
Alleles reunite during fertilization, two gametes fuse to form a diploid zygote
What is a test-cross? How is it performed?
method to determine if a dominant phenotype is due to homozygosity or heterozygosity.
performed by crossing an individual with dominant phenotype to an individual with recessive phenotype.
The individual with the recessive phenotype is homozygote recessive.
If the offspring shows only dominant phenotype, original individual homozygote dominant.
If the offspring shows both the dominant and the recessive phenotypes, then it was heterozygote.
What makes pea a good model organism?
Easy to fertilize
Fast growing
Produces a large number of individuals
Has obvious and discrete traits that are constant from parents to offspring
relatively simple genome, with seven pairs of chromosomes and about 25,000 genes.
What are the characteristics of good genetic research models and why?
short generation time,
large number of offspring,
easy to manipulate and maintain,
well-characterized genome,
availability of genetic tools and resources,
relevance to human biology and diseases,
ethical acceptability.
