MOD 4 Flashcards
_____ are the basic units of heredity, which is the transmission of inherited traits. ____ are composed of
biochemical instructions that tell cells, the basic units of life, how to manufacture certain proteins. These
proteins control the expression of its characteristics. A ____ is the long molecule deoxyribonucleic acid (DNA)
of which that transmits information, in its sequence of four types of building blocks
Genes
______ _____ was the first to probe the underlying rules of inheritance of specific traits. Mendel described
units of inheritance that pass traits from generation to generation and called them “elementen” (which would
be later on renamed to genes by English embryologist William Bateson)
Gregor Mendel
The two copies could either be identical to
one another or nonidentical. Alternate forms of a gene are called ______
alleles
Even though the pair of alleles that governed a trait remained together throughout the life of an
individual plant, they became separated (or segregated) from one another during the formation of
gametes. This formed the basis of Mendel’s First Law:
Law of Segregation.
The segregation of the pair of alleles for one trait had no effect on the segregation of alleles for another
trait. A particular gamete could receive a paternal gene governing seed color and a maternal gene
governing seed shape. This formed the basis of Mendel’s Second Law: _________________
Law of Independent Assortment
Mendel chose
to focus on 7 clearly definable traits, each of which occurred in two alternately identifiable forms.
Seed form
Seed color
Pod form
Pod color
Flower position
Seed coat color
Stem length
■The ________ describes the organism’s alleles.
genotype
The __________ describes the outward expression of an allele combination.
phenotype
A __________________ is the most common expression of a particular allele combination in a population.
wild type phenotype
A _____ phenotype is a variant of a gene’s expression that arises when the gene undergoes a change, or mutation.
mutant
can appear in either sex because an autosome carries the gene.
If a child has the trait, at least one parent also has it.
autosomal dominant traits do not skip generations.
If no offspring inherit the trait in one generation, its transmission stops because the offspring can pass on only the recessive form of the gene.
Examples of autosomal dominant diseases include Huntington disease, neurofibromatosis, and polycystic kidney disease
AUTOSOMAL DOMINANT INHERITANCE
shows that a trait can appear in either sex.
Affected individuals have a homozygous recessive genotype, whereas in heterozygotes (carriers) the wild type allele masks expression of the mutant allele.
If a couple has a child with an autosomal recessive illness, each of their next children faces the same 25% risk of inheriting the condition.
AUTOSOMAL RECESSIVE INHERITANCE
