Cell Cycle Flashcards
What is a cell cycle?
A regulated sequence of events that occur between one cell division
Which type of cell retain the ability to show a cell cycle?
Eukaryotic cells that retain the ability to divide
What phases are in interphase?
G1, S and G2
What is the G1 phase?
Make RNA, enzymes and other proteins required for growth - protein synthesis. During this phase, a signal is received telling it to divide. The organelles also duplicate
What is the S phase?
The synthesis of DNA, where DNA in the nucleus is replicated by semi-conservative replication resulting in each chromosome consisting of two identical sister chromatids. A relatively short phase
What is the G2 phase?
The cell continues to grow in preparation for mitosis e.g. micro tubes produced to form mitotic spindles. Final checks + making missed organelles as well as new DNA is checked for any errors
What’s the purpose of centrioles?
Allow for effective mitosis when pulling spindle fibres
What is the purpose of spindle fibres?
They pull the chromosomes to opposite poles of a cell
What is nuclear division?
Following interphase mitosis via 4 stages separate sister chromatids among two emerging daughter cells which results in two genetically identical daughter cells with the same number of chromosomes as the parent
Importance of mitosis: Growth
•Growth of multicellular organisms -> Unicellular zygotes enabled to grow into multicellular organisms, may occur across the whole body or meristem
Importance of mitosis:Replacement and repair
•Cell replacement and tissue repair -> Damaged tissues, constantly dying cells both need to be replaced via mitosis. Humans = Skin and gut lining, Animals = Body parts like fins and tails
Importance of mitosis: Asexual reproduction
New individual of a species by a single parent which the offspring is genetically indentical to the parent.
•Unicellular = Amoeba use mitosis to repopulate
•Multicellular = Plants use mitosis to grow from parent plant then detach for repopulation
What is prophase?
•The chromosomes condense and become visible (when stained), consists of two identical sister chromatids (DNA replicated) joined by centromeres
•Two centrioles move to opposite poles in the cell
•Spindle fibres that are attached to the chromosomes begin to emerge from the centrioles
•Nuclear envelope breaks down into small vesicles so all DNA is free
What is metaphase?
•Chromosomes like up and meet at the equator attached to spindle fibres by their centromeres
What is anaphase?
•Spindle fibres contract and centromere splits which pulls the sister chromatids apart to opposite poles into a u-shape
What is telophase?
•Chromosomes arrive at the opposite poles and begin to uncool and become thinner
•Spindle fibres break down
•Nuclear envelope begins to reform around each set
What is cytokinesis?
•Cytoplasm splits and divides forming two genetically identical daughter cells
•This stage is not mitosis but happens as a result
