W6 Flashcards
What are the main purposes of cell division?
- Growth
- Cell Replacement
- Repair(heal)
- Reproduction
What is binary fission?
Binary fission is the form of cell division used by bacteria
What are three key characteristics that allow bacteria cells to reproduce via binary fission?
- The circular bacterial DNA is attached by proteins to the inner membranes
- DNA replication begins at a specific location and proceeds bidirectionally around the circle
- The newly synthesised DNA is also attached to the inner membrane
Why are the three characteristic important to binary fission?
As replication proceeds, the cell elongates symmetrically around the midpoint, separating the DNA attachment sites
Cell division begins with the synthesis of new membrane at the midpoint
What are the steps of the cell cycle?
- M-phase
- Interphase (time between two M-phases) Contains G-phase 1, S-phase and G-phase 2, G0-phase
What occurs during the M-Phase?
- Mitosis and cytokinesis
- Parent cell divides into two daughter cells
What occurs in the G1-phase?
- Size and protein content of the cell increases
- Regulator proteins are made and activated
What occurs in the S-phase?
-Where the entire DNA content of the nucleus in replicated
What occurs in the G2-phase?
-The cell prepares for mitosis and cytokinesis
What occurs in the G0 phase?
- No activate preparation for cell division
- In cell types do not actively dividing
What are sister chromatids?
The two ends of DNA chromosomes that occur after S phase from DNA replication they are held together by centromeres
What are the 5 stages of Mitosis?
- Prophase
- Prometaphase
- Metaphase
- Anaphase
- Telophase
- Cytokinesis
What occurs during Prophase?
The chromosomes condense. Centrosomes radiate microtubules and migrate to opposite pole. The nuclear envelope breaks down
What occurs during Metaphase?
Chromosomes align in the middle of the cell
What occurs during Anaphase?
Sister chromatids separate and travel to opposite poles
What occurs during Telophase?
Nuclear envelope reforms and chromosomes condense
What occurs during Cytokinesis? (animal)
The contractile ring forms against the inner face of the cell membrane at the equator of the cell. The ring contracts pinching the cytoplasm dividing the one cell into two
What occurs during Cytokinesis?(plant)
A new cell wall is formed called the cell plate, once it is big enough, it fuses with the original cell wall. separating the newly formed cells
What cells do Meiosis occur?
Germline cells
What are the stages of Meiosis?
Meiosis 1
- Prophase 1
- Metaphase 1
- Anaphase 1
- Telophase 1
What occurs in Prophase 1?
- Chromosomes condense and thicken
- Homologous chromosomes move closer together
- Cross over occurs
- DNA recombination occurs(Exchange genetic information)
- Nuclear membrane brakes down and centrosomes radiate and migrate to opposite poles
- Spindle fibres attach to kitecal protein complex
What occurs in Metaphase 1?
-Paired chromosomes are pulled to the middle of the cell by the spindle fibres
What occurs in Anaphase 1?
Homologous chromosomes are pulled away from each other by spindle fibres
What occurs in Telophase 1?
The nuclear envelope reforms around the two groups of chromosomes
