Final answer:
The phenotype of an organism is influenced by its genotype, environmental conditions, and their interaction. A cell's DNA remains constant throughout an organism's body, but its phenotype can vary due to differential gene expression. Humans have roughly 37.2 trillion cells of about 200 different types.
Step-by-step explanation:
An Organism's Phenotype
An organism's phenotype is dependent on three main factors: the organism's genetic makeup (genotype), the environmental conditions it experiences, and the interactions between these two factors. An allele is a variant form of a gene, and the type of allele that only affects the phenotype in the homozygous condition is called a recessive allele.
Cellular Uniformity and Diversity
What is identical in every cell of the same organism is its DNA. Although every cell contains the same genetic material, different cells can have varying phenotypes due to differences in gene expression in response to environmental conditions. Differences in gene expression also explain how the same cells can look and function differently—bone cells differ from fat cells although they have the same DNA.
Cell Numbers and Types within Humans
The average adult human has approximately 37.2 trillion cells, encompassing around 200 different cell types. These diverse cell types form through a process called differentiation, where cells become specialized for specific functions within the body.
Genotype and Phenotype Examples
Discussing the relationship between genotype and phenotype, if two individuals have a certain phenotype, it does not necessarily imply they have the same genotype. This is because different genotypes can lead to the same phenotype. For instance, a tall, green plant that is homozygous for each trait would have a genotype of TTGG and a phenotype of tall and green.