3.4 Flashcards
what are differences in phenotype caused by?
genotype and the environment
characteristics that are controlled almost completely by the organisms genotype show and are controlled by what?
controlled by genes at a single locus and show discontinuous variation
characteristics that are affected by both the genotype and the environment are controlled by and show what?
they are controlled by genes at many loci and show continuous variation
what are the two types of inheritance?
monohybrid and polygenic
what is monohybrid inheritance?
when each locus is responsible for a different heritable feature
what is polygenic inheritance?
when a number of genes are involved in the inheritance of a characteristic
where is melanin made?
melanocytes
what activates the production of melanin?
melanocyte-stimulating hormone (MSH)
what is on the surface of the melanocyte cells?
receptors for MSH
what do the melanocytes do?
place melanin in to melanosomes
people with darker skin have more what?
receptors
when making melanin, what enzyme do animals use?
tyrosinase
what are environmental factors that can affect gene expression?
chemicals, diet, physical activity, lifestyle choices and stress
what can cause cancer?
when the rate of cell multiplication is faster than the rate of cell death or mutations when cells divide
what does abnormal methylation cause?
activation or deactivation of genes that are involved in the control of the cell cycle
