Ch.12 Cell Mitosis Flashcards
explain how the cell division function in reproduction, growth, and repair
- mitosis causes growth and repair by providing more identical cells to replace old, damaged, or missing cells for repair or to produce more tissues for growth
- it also helps with reproduction by creating haploid cells to form zygotes for reproduction
describe the structural organization of a prokaryotic and a eukaryotic genome
prokaryotic genomes are found in a single strand of DNA in a circular shape. Eukaryotic are packed into chromosomes in a double helix shape
describe the major events of cell division that enable the genome of one cell to be passed on to two daughter cells
in cell division, the S phase ensures that all 46 chromosomes are duplicated for the cell to give to each daughter cell. G2 phase checks them for error, and then mitosis happens in which the cell divides to give each daughter cell the same genome
describe how chromosome number changes throughout the human life cycle
n = haploid number = 23 for humans
Fertilization: sperm (n) + egg (n) zygote (2n)
Mitosis: zygote (2n) body cells (2n) + germ cells (2n)
Meiosis: germ cells (2n) sperm (n) + egg (n)
list the phases of the cell cycle and describe the sequence of events that occurs during each phase
in the G1 Phase, all cellular contents of the cell, excluding the chromosomes are duplicated. The cell grows, ensures it has enough nutrients, and space. Then in the S phase, the chromosomes are all duplicated. After S phase, is the G2 phase, where the cell double checks for error and ensure the chromosomes were duplicated properly. After it gets it’s Ok signal, Mitosis occurs, and then cytokinesis
list the phases of mitosis and describe the events characteristic of each phase
in Mitosis, the DNA is replicated during the S phase of Mitosis. in prophase, the chromatin condense to form chromosomes, and the nuclear envelope disappears. Then in Metaphase, the chromosomes line up into the middle of the cell, and spindle fibers attach to them. In anaphase, the chromosomes are pulled apart giving each new daughter cell a copy of the original genome. Then telophase, new nuclear envelope forms, chromosomes unfold back into chromatin, nucleoli reappear, cell continue to elongate
compare cytokinesis in animals and in plants
in cytokinesis in animals, the cell splits into two with a cleavage furrow. in plants, a cell plate forms in between the splitting cells
describe the changes in the mitotic spindle during each stage of mitosis
prophase=chromatin coils condense into chromosomes.
mitotic spindles form.
metaphase=chromosomes become align at equator of the spindles
anaphase daughter chromosomes move to opposite ends and poles separate
telophase vesicles of nuclear envelope fuse around set of chromosomes. 2 new nuclei
chromosomes uncoils-chromosomes
spindles disassemble
describe mechanisms for how motor proteins associated with the kinetochore microtubules bring about the poleward movement of chromosome
motor proteins appear to “walk” a chromosome along the kinetochore microtubules as these shorten by depolymerizing at their kinetochore end. Motor protein at the spindle poles also appear to “reel in” the chromosomes, with the microtubules depolymerizing at the poles. The extension of the spindle poles away from each other as an animal elongates is probably due to the overlapping nonkinetochore microtubules walking past each other, also using motor proteins
explain how nonkinetochore microtubules lengthen the cell during anaphase
by pulling the centrosomes (and the set of chromosomes to which they are attached) apart to opposite ends of the cell. The force that causes the centrosomes to move towards the ends of the cell
describe the roles of checkpoints, cyclin, Cdk, and MPF in the cell cycle control system
the checkpoints in the cell cycle, ensure that there are no errors or mistakes in each part of the cycle. Cyclin is a regulatory protein that a Cyclin dependent kinase much be attached to. The maturation promoting factors give the go ahead signals at the checkpoints after the cell has been checked
describe the process of binary fission in bacteria
the bacterial chromosome, a single circular DNA molecule, begins to replicate at the origin of replication and one of these duplicated origins moves to the opposite pole of the cell. Replication is completed as the cell doubles in size, and the plasma membrane grows inward to divide the two identical daughter cells
describe the internal and external factors that influence the cell cycle control system
an internal factor that influences the cell cycle control system is for instance in the M phase; the cell cannot split the chromosomes until they are all aligned at the metaphase plate. An external factor could be the fibroblasts which give a signal for the cell to go past the G1 checkpoint
explain how the abnormal cell division of cancerous cells escapes normal cell cycle controls
they ignore checkpoints and signals and keep dividing without any regulation. Because of this an overabundance of cells is created and tumors may appear
distinguish between benign, malignant, and metastatic tumors
- benign: don’t invade and spread
- malignant: spread cancer cells throughout
blood or lymphatic system - metastatic: cancer has spread from where it
started to another part of the body
