Chapter 12 Flashcards
He studied inheritance in pea plants. Discovered the basic principles of heredity by breeding garden peas in carefully planned experiments.
Mendel
Mendel worked with peas because:
1.) Many varieties with distinct heritable features, or characters
2.) He could control mating between plants
character variants
traits
Alternative versions of a gene. An organism inherits two alleles, one from each parent
Alleles
Determines the organisms appearance; what you see
Dominant allele
Has no noticeable effect on appearance; masked or covered up by dominant allele
Recessive allele
Genetic makeup of an individual (2 alleles)
Genotype
Where alleles are different; genotype with different alleles
Heterozygous (different)
Where alleles are same; genotype with same alleles
Homozygous (same)
physical appearance of individual; how you look
Phenotype
What is Mendel’s First Law?
Law of Segregation
The two alleles for a heritable character separate (segregate) during gamete formation and end up in different gametes.
Law of Segregation
Possible combinations of sperm and egg can be shown using this to predict the results of a genetic cross.
Punnett Square
Experiment to determine the genotype of a dominant phenotype of a dominant phenotype individual. Cross dominant phenotype individual with a homozygous recessive individual.
Testcross
What is Mendel’s Second Law?
Law of independent assortment
The results of Mendel’s dihybrid experiments (2 traits) are the basis for this. Each pair of alleles segregates independently of any other pair during gamete formation.
Law of independent assortment
True or False?
Not all inheritable characters are determined as simply as the traits Mendel studied. However, the basic principles of segregation and independent assortment apply even to more complex patterns of inheritance.
True
Occurs when phenotypes of the heterozygote and dominant homozygote are identical.
Complete Dominance
The phenotype of F1 hybrids is somewhere between the phenotypes of the two parental varieties.
AA- red
Aa-pink
aa-white
Incomplete Dominance
Where 2 alleles are both expressed. Two dominant alleles affect the phenotype in separate, distinguishable ways.
ex–>AB blood
Codominance (together/both)
1 gene has multiple genotypes. Most genes have multiple phenotypic effects, a property called this. Are responsible for the multiple symptoms of certain hereditary diseases like cystic fibrosis, sickle-cell disease
ex–> a-1 gene
ex–> cystic fibrosis
pheno: lungs, sweat glands, liver
Pleiotropy
A gene at one locus alters the phenotypic expression of a gene at a second locus. Where 1 gene alters the phenotype expression of another gene. ex–> 1 gene– Aa
1 pheno: tall
Epistasis
Many genes. Ex–> skin color in humans.
Quantitative characters are those that vary in the population along a continuum.
Quantitative variation usually indicates this, an addictive effect of two or more genes on a single phenotype.
Where many genes impact your phenotype. You can be a range of heights. Big or small. Can come up with Quantitative value. Light or dark eyes–> number of value to that or number of hairdyes
Polygenic Inheritance
Another departure from Mendelian genetics arises when he phenotype for a character depends on environment as well as genotype. Can change what DNA your body uses or expresses but does NOT change your actual DNA.
The environment
A family tree that describes the interrelationships of parents and children across generations
Pedigree
Many genetic disorders are inherited in a recessive or dominant manner?
recessive
Recessively inherited disorders show up only in individuals heterozygous or homozygous for the allele?
homozygous
Are heterozygous individuals who carry the recessive allele but are phenotypically normal
Carriers
Human disorder caused by dominant alleles. Dominant alleles that cause a lethal disease are rare and arise by mutation. Ex–> dwarfism
Dominantly Inherited Disorders
Is a form of dwarfism caused by a rare dominant allele
Achondroplasia
Where 2 alleles are expressed.
Codominance
What does not follow Mendel’s Rules?
Pleitrophy
