Topic 25: Mitosis Flashcards
Describe the process of Mitosis in the human life cycle?
Mitosis is a process of cell division. It involves one division to make two identical daughter cells with same number of chromosomes as the parent cells.
Define ploidy, diploid, and haploid.
Ploidy: Is the number of sets of chromosomes in the cell.
Diploid: 2n (two sets of chromosomes) mainly in somatic cells
Haploid: n (one set of chromosomes) mainly in gametes
What are the products of mitosis?
Two identical daughter cells with same number of chromosomes.
Describe the steps of Interphase.
Growth Phases
G1 Phase: The cell begins to gather all the building blocks required for the replication of DNA, such as energy and proteins.
S Phase: DNA is now replicated into sister chromatids and are attached by the centromere but don’t have the X shape. The centrosome is also duplicated.
G2 Phase: Cell replenishes its energy and synthesis of proteins needed for the mitotic phase are synthesized. Some cell organelles are also duplicated and the cytoskeleton is completely dismantled to sort the DNA and help us make two new cells.
Describe the steps that occur in each phase of mitosis. Draw a cell in mitosis with 2n=8.
Steps of Mitosis:
Prophase: The nucleus falls apart and DNA is condensed into chromsomes. And the mitotic spindles begin to move to opposite sides.
Prometaphase: Mitotic spindles begin to attach to the kinetochores of the chromsosomes and basically fight for each side of the chromosome.
Metaphase: In metaphase all mitotic spindles are attahced to the kinetochores placing the daughter chromatids in a straight line. Some spindles are attached to kinetochores and some are not.
Anaphase: In Anaphase onece all mitotic spindles are attached to all the chrosmosomes the centromer is sliced and the spindle move opposite directions seperating to sister chromatids into daughter chromosmes.
Telophase: In Telophase the spindles deattach from the kinetochore and a nucleus is fromed surroundng the DNA chromosomes for each side of the cell. The only thing left to do is the dividing the one cell into two cells.
Describe cytokinesis and understand how it differs in plants and animals.
Cytokinesis is described as the the division of the cytoplasmic components of a cell into two daughter cells.
In animals cytokinesis happens around the end of anaphase where a ring is formed by actin filaments from inside the plasma membrane. The actin filaments pull the equator inward creating a cleavage furrow. As the actin ring contracts we eventually have two daughter cells.
In plants for cytokinesis to occur a new cell wall needs to be built. During interphase the Golgi accumulates proteins, enzymes, and glucose molecules. The vesicles during telopase accumalate and fuse from the center towards the cel wall. The more the vesicles the more the cell wall enlrges until it touches the parent cell wall.
