2.2 All Cells Arise From Other Cells Flashcards
(29 cards)
What is the cell cycle?
Cycle of division with intermediate growth periods.
Interphase
Stage of the cell cycle where the cell synthesizes proteins for replication, DNA replicates, and organelles divide.
Mitosis
Nuclear division that occurs during the cell cycle.
Cytokinesis
Cytoplasmic division that follows mitosis or meiosis.
Explain why the cells cycle does not occur in some cells.
After differentiation, some types of cells in multicellular organisms, such as neurons, lose the ability to divide.
Difference between Cell Cycle and Mitosis
Cell cycle includes growth periods between divisions; mitosis is only 10% of the cycle and refers only to nuclear division.
G1 Phase
Phase in interphase where the cell synthesizes proteins for replication and doubles in size.
S Phase
Phase in interphase where DNA replicates, resulting in chromosomes consisting of 2 sister chromatids joined at a centromere.
G2 Phase
Phase in interphase where organelles divide.
Purpose of Mitosis
Produces 2 genetically identical daughter cells for growth, cell replacement/tissue repair, and asexual reproduction.
Stages of Mitosis
- Prophase
- Metaphase
- Anaphase
- Telophase
Prophase
Chromosomes condense and become visible, centrioles move to opposite poles, and the nuclear envelope breaks down.
Metaphase
Sister chromatids line up at the cell equator, attached to the mitotic spindle by their centromeres.
Anaphase
Spindle fibers contract, centromeres divide, sister chromatids separate into distinct chromosomes, and are pulled to opposite poles.
Telophase
Chromosomes decondense, new nuclear envelopes form around each set of chromosomes, resulting in 2 new nuclei.
Explain the procedure for a root tip squash experiment.
- Prepare a temporary mount of root tissue.
- Focus the optical microscope on the slide. Count the total number of cells in the field of view and the number of cells in a stage of mitosis.
- Calculate mitotic index.
How to prepare a temporary mount of root tissue.
Place root in hydrochloric acid, stain with dye, macerate tissue, and press down coverslip to obtain a single layer of cells.
Name 2 dyes that bind to chromosomes.
- Toluidine blue (blue)
- Acetic orcein (purple-red)
Mitotic Index Calculation
Only the root tip is used because meristematic cells are actively undergoing mitosis.
What are Tumour Suppressor Genes?
Genes that code for proteins to trigger apoptosis or slow the cell cycle.
Whar are Proto-Oncogenes?
Genes that code for proteins to stimulate the cell cycle to progress from one stage to the next.
How can mutations to tumour suppressor genes & proto-oncogenes cause cancer?
Tumour suppressor: no production of a protein needed to slow the cell cycle.
Proto-oncogenes: form permanently activated oncogenes.
Disruption to the cell cycle → uncontrolled cell division → tumour
How cancer treatments control rate of cell division
Disrupt the cell cycle by preventing DNA replication or disrupting spindle formation.
Prokaryotic Cell Replication
Binary fission where DNA loop replicates, cell elongates, and then splits into 2 identical progeny cells.
