Summary Unit 5 Biology AS (9700)

What are the two types of cell division?

Respuesta: Mitosis is the division into two daughter cells that are genetically identical to each other and to the parent cell.-------------------------------------------------------- Meiosis is the division into four unique daughter cells with half the chromosomes of the parent cell

What are the names of the three main stages in the cell cycle?

Respuesta: Interphase, Mitosis and Cytokinesis

Describe the interphase:

Respuesta: Interphase consists of all the processes that occur when a cell isn’t dividing. During this phase, the cell increases in mass and size and carries out its normal cellular functions (synthesising proteins and replicating its DNA ready for mitosis)

What are the three phases of interphase?

Respuesta: G1: during G1, the new cell grows and carries out its normal life functions, such as protein synthesis and respiration. --------------------------------------------------S: during the S phase, the cell’s DNA is replicated so that each chromosome is double-stranded. Energy is also saved up in the form of ATP, ready for the process of cell division--------------------------------------------------------------------- G2: this G2 phase is another gap, or growth phase. It is followed by a control checkpoint, , when the cell checks the DNA synthesised and repairs any errors before mitosis. Other preparations for cell division are made, like producing tubulin, to make microtubules for the mitotic spindle.------------------------------ Interphase: G1 + S + G2

What is mitosis?

Respuesta: It is the process of nuclear division, which places one strand of each chromosome in each daughter nucleus. Each is now identical to the parent nucleus (as it was before DNA replication)--------------------------------------------- During mitosis, the cell’s DNA is copied into each of the two daughter cells. In multicellular organisms, mitosis provides new cells for growth and tissue repair. In eukaryotes, it can also be a form of asexual reproduction, such as in yeast

What are the different phases in mitosis?

Respuesta: Prophase (early): Mitosis begins. The chromatin condenses and becomes inactive. Centrioles migrate in pairs to opposite poles and the nuclear envelope and nucleolus break up-------------------------------------------------------- Prophase (late): The chromosomes are now tightly coiled and visible as separate bodies under the microscope. The mitotic spindle begins to form at the centrioles-------------------------------------------------------------------------------- Metaphase: The mitotic spindle grows further and attaches to the centromere of each chromosome. The fibres then arrange the chromosomes to line up along the cell equator.--------------------------------------------------------------------- Anaphase: The centromere of each chromosome breaks. Sister chromatids separate into daughter chromosomes.------------------------------------------------- Telophase: New nuclear membranes and nuclei form. The chromosomes start to unwind back into chromatin and are no longer visible under the microscope----------------------------------------------------------------------------------- Cytokinesis: Finally, the cytoplasm is divided between the two daughter cells to finish the cycle. Each new cell enters interphase and resumes its normal functions