Cell Cycle Flashcards
Describes what happens in interphase first stage.
G1 (Growth): Cellular contents excluding the chromosomes are duplicated. This includes stores so that the ATP content is increased (ATP provides the energy needed for cell divsion) The organelles are replicated so it has spare ones.
Describe the second stage of interphase
S (Synthesis): The cell’s DNA is unraveled and replicated, to double the gene content and produce a copy of each chromosome.
Describe the third stage of interphase
G2 (Growth): The cell ‘double checks’ the duplicated chromosomes for error, making any needed repairs. Cell kept growing and proteins needed for cell division are made.
What is mitosis
Mitosis is a form of cell division that occurs during the cell cycle. In mitosis a parent cell divides to produce two genetically identical daughter cells ( they contain an exact copy of the DNA of the parent cell) Mitosis is needed for the growth of multicellular organisms and for repairing damaged tissue.
Name the four stages of mitosis
- Prophase
- Metaphase
- Anaphase
- Telophase
Describes what happens in prophase
The chromosome condense getting shorter and fatter. Tiny bundles of proteins called centrioles start moving to opposite ends of the cell, forming a network of protein fibers across it called the spindle. The nuclear envelope breaks down and the chromosomes lie free in the cytoplasm.
Describe what happens in metaphase
The chromosomes (each with two chromatids) line up along the middle of the cell and become attached to the spindle by their centromere.
Describe what happens in anaphase
The centromeres divide, separating each pair of sister chormatids. The spindle contract, pulling chromatids to opposite poles of the spindle, centromere first. This, makes the chromatids appear v-shaped.
Describe what happens in telophase
The chromatids reach the opposite poles on the spindle. They uncoil and become long and thin again. They’re now called chromosomes again. A nuclear envelope forms around each group of chromosome, so there are now two nuclei. Division of the cytoplasm (cytokinesis) finishes telophase. There are now two daughter cells that are genetically identical to the original cell and to each other. Mitosis is finished and each cell starts the interphase part of the cell cycle to get ready for the next mitosis round.
Define a stem cell
Undifferentiated and can go through the cell cycle
Define Differentiation
Stem cell turned into differentiated cell (can no longer no through cell cycle) with gene expression that creates right protein
Describe bacterial (prokaryotic) binary fission
Asexual reproduction
Replication of lose, circular loop of DNA
Cell membrane forms creating 2 cells
Cell wall divides cells
Outline how you would prepare a slide showing the stages of mitosis in plant cells.
Use a sharp scalpel to remove the last 1mm of a actively growing root tip e.g. garlic - cells at tip will be actively going through the cell cycle / dividing / mitosis observable
Place tip in some 5M hydrochloric acid for 10 minutes - breaks down the plant tissue so easier to separate cells for viewing.
Rinse the root tip in water
Crush the root tip on your slide - “one cell thick” (don’t slide) so individual cells will be visible.
Add the stain - darkens the chromosomal DNA so phases of mitosis are easier to distinguish.
Lower the cover slip with a mounted needle to remove air bubbles
Cell preparation to be “1 cell thick” - light can come through and individual cells can be counted / seen clearly.
How could you calculate the mitotic index for eukaryotic cells going through the cell cycle?
Mitotic index= cells in mitosis/ total number of cells
Genetically, how may tumours and cancer develop
Tumors (cancer) develops when cells lose control over the cell cycle and divide in an uncontrollable manner.
Results in a mass of rapidly dividing, abnormal cells.
Cancers result from mutations of key genes that control the cell cycle.
