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What is Binary Fission?
how prokaryotic cells reproduce. One cell splits into two, chromosomes uncoil & replicate and other organelles, cell grows larger than divides in two.
What are the stages of Interphase and what happens?
G1- growth, S- DNA synthesis, G2- prep for mitosis
Steps of Prophase
Chromatins condense, visible pairs of chromatids, centrioles move to opposite ends, spindles emerge, nucleus not visible
Steps of Metaphase
chromosomes move to the centre & line up, centromeres of each chromosomes attach to spindle fibres
Steps of Anaphase
spindles contract, pulling chromatids apart
Steps of Telophase
chromosomes de-condense so chromosomes are less visible, nuclear envelope reforms, spindles disassemble.
Purpose of checkpoints & where are they?
to ensure mutations are repaired before the cell continues through the cell cycle and divides. End of G1, end of G2 and start of mitosis
What is Apoptosis?
programmed cell death, very uniform, highly coordinated
What is Necrosis?
when a cell dies due to damage to its plasma membrane
Process of Apoptosis
signal come from within cell or from other cell, enzymes shred DNA, nucleus dismantles, membrane forms blebs, apoptotic bodies form containing contents of the dead cells, clears by macrophages and phagocytes
What is Proto-oncogene?
genes that promote cancer, code for proteins that stimulate cell division, prevent cell differentiation, regulate apoptosis. Any changes can promote uncontrolled cell growth & cancer
What is Tumor Suppressing genes?
normal genes that slow cell division, repair DNA and tells cells when to undergo apoptosis
What is a mutagen?
agents that can induce or increase the frequency of mutation in DNA
What is Genetic Predisposition to Cancer?
mutations in proto-oncogenes and tumor supressor gemes result in genetic predisposition to cancer
Examples of chemical mutagens
tobacco and alcohol
Examples of Physical mutagens
UV light, x-rays, nuclear radiation
What is a Biological Mutagens
viruses that can cause mutations in DNA or impair cell cycle regulation and eventually result in cancer
