Final answer:
The two major types of SMC proteins are condensins, involved in chromosome condensation, and cohesins, ensuring proper sister chromatid separation during cell division.
Step-by-step explanation:
The two major types of SMC (Structural Maintenance of Chromosomes) proteins are the condensins and the cohesins. Condensins help organize and condense chromosomes into highly compact structures during mitosis and meiosis, ensuring proper segregation of chromosomes during cell division. Cohesins are crucial for the correct separation of sister chromatids during cell division by holding them together after DNA replication until the time comes for them to be pulled apart in anaphase. Both types of SMC proteins are essential for maintaining chromosomal stability and integrity throughout the cell cycle.