Table of Contents
How are dominant alleles expressed?
A dominant allele is denoted by a capital letter (A versus a). Since each parent provides one allele, the possible combinations are: AA, Aa, and aa. Offspring whose genotype is either AA or Aa will have the dominant trait expressed phenotypically, while aa individuals express the recessive trait.
How are alleles expressed through transcription and translation?
Together, transcription and translation are known as gene expression. During the process of transcription, the information stored in a gene’s DNA is passed to a similar molecule called RNA (ribonucleic acid) in the cell nucleus. A type of RNA called transfer RNA (tRNA) assembles the protein, one amino acid at a time.
Which gene is expressed in a heterozygous allele?
Some alleles are dominant or recessive. When an organism is heterozygous at a specific locus and carries one dominant and one recessive allele, the organism will express the dominant phenotype.
What type of allele will be expressed if both dominant and recessive alleles are present for a given trait in basic Mendelian law of dominance inheritance patterns?
Codominance If the alleles are different, the dominant allele usually will be expressed, while the effect of the other allele, called recessive, is masked. In codominance, however, neither allele is recessive and the phenotypes of both alleles are expressed.
How genes are transcribed and translated into proteins?
During transcription, the enzyme RNA polymerase (green) uses DNA as a template to produce a pre-mRNA transcript (pink). The pre-mRNA is processed to form a mature mRNA molecule that can be translated to build the protein molecule (polypeptide) encoded by the original gene.
How are proteins related to gene expression?
Genes encode proteins and proteins dictate cell function. Therefore, the thousands of genes expressed in a particular cell determine what that cell can do.
When both alleles are expressed in the heterozygous state?
Closely related to incomplete dominance is codominance, in which both alleles are simultaneously expressed in the heterozygote.
How do dominant and recessive alleles interact in a heterozygote?
Dominant alleles are expressed exclusively in a heterozygote, while recessive traits are expressed only if the organism is homozygous for the recessive allele. A single allele may be dominant over one allele, but recessive to another.
Are heterozygous alleles dominant or recessive?
An organism with one dominant allele and one recessive allele is said to have a heterozygous genotype. In our example, this genotype is written Bb. Finally, the genotype of an organism with two recessive alleles is called homozygous recessive.