3.4 Flashcards
What did Gregor Mendel discover
the basic underlying principles of heredity through his work on garden pea plants
What did Mendel experiments include
covering each flower until it could be hand fertilized with the pollen of a chosen parent plant, then examining the traits of the offspring
What three laws did Mendel discover (of inheritance)
The law of segregation
The law of independent assortment
The law of dominance
What does the law of segregation state
two alleles are separated during meiosis so that each gamete contains only one allele for each gene, alleles are passed from one generation to the next as distinct units
exceptions include genes on sex chromosomes and mitochondrial DNA which only inherited from the mtoher
Where is mitochondrial DNA inherited from
the mother
What is only inherited from the mother
mitochondrial DNA
What is the law of independent assortment
the allele inherited for one trait does not affect which allele will be inherited fro another trait . It is caused by random orientation
exceptions are for genes who’s loci are close together on the same chromosome - linked genes)
What are linked genes
genes who’s loci are close together on the same chromsoosm
What does the law of dominance state
if an organism has two different alleles, one allele will determine the trait The allele that determines the trait is dominant; the unexpressed allele is recessive 9 there are expceptions other than dominant- recessive, co-domincance)
What is DNA
the molecule that stores genetic information and short stretches of DNA that influence a particular characteristic (genes)
What does P/F1/F2 mean
used in specific breeding test in which two parents homozygous for different forms of a trait ar emitted
P - parental generation
F1 - first generation
F2 - second filial generation
What Is a phenotype
an organisms observable charvateristics or traits including its morphology and biochemical properties
What is a genotype
the two alleles present tin an organism for a particular gene
What is an allele
a particular version of a gene
What Is a dominant allele
an allele the has the same effect on the phenotype whether one or two copies are present
What is a recessive allele e
an allele that only has an effect on the phenotype when two copies are present
What are codominant alleles
alley that jointly affect the phenotype when present together, creating an intermediate or combined phenotype
A gene has three possible alleles. How many different genotypes can be found for this gene?
6
What is true of the law of segregation?
It refers to the fact that a parent has a pair of alleles for each gene, and will pass on only one to an offspring.
How many copies of alleles are present at each gene locus in a gamete produced by a diploid organism?
one - During gamete formation, the two alleles occurring at each gene locus of a diploid organism are separated to distribute one such allele per gamete.
What was the dominant and recessive allele in Mendel’s discovery
Y = yellow allele (dominant y = green allele (recessive)
What is said about dominant alleles
they always mask the effects of the recessive alleles, when both are present, only the dominant allele affects the phenotype
What is a Punnett grid
a diagram used to determine the expected ratio of genotypes and phenotypes in the offspring of parents with known genotypes
What does it mean when something is test crossed
crossed with a homozygous recessive
