chapter 8 Flashcards
what is the origin of replication and what direction does replication occur?
replication of the circular prokaryotic chromosome begins at the origin of replication and continues in both directions at once. The cell begins elongate. FtsZ proteins migrate toward the midpoint of the cell. The duplicated chromosomes separate and continue to move away from each other toward opposite ends of the cell. FtsZ proteins for my ring around the periphery of the midpoint between the chromosomes. The FTSZ ring directs the formation of a septum that divides the cell. Plasma membrane and cell wall materials accumulate. After the septum is complete, the cell pinches and two, forming two daughter cells FTSZ is disbursed throughout the cytoplasm of the new cells.The two daughter cells are genetically identical to the mother cell.
interphase
G1: cell growth
S: DNA replication
T2: cell growth and mitochondrial replication
G1: cell is physically increasing in size and recovering from previous cell division.
S: two copies of your DNA.
G2: brief recovery from replication, Develops more mitochondria through binary fission so that they can produce more ATP for reproduction
centrioles divide
what are somatic cells and give an example? What are germ cells an example? How does each divide?
somatic cells don’t participate in sexual reproduction for example nerve cells. They are genetically identical.
Germ– Line cells do participate in sexual reproductionfor example testes and ova. they are genetically diverse.
proPhase
nuclear envelope at disintegrating, nucleolus disintegrating, centrioles migrating to opposite poles, spindle fibers start to form, chromosomes are visible
metaphase
chromosomes line up at the equatorial plane, spindle fibers elongate and attached to the centromeres which is the center of a chromosome
anaphase
spindle fibers shorten pulling the sister chromatids apart like tug o war, Nonattached spindle fibers along the cell, centromere starts to replicate itself, centrioles act like anchors
telophase
nucleoli start to reform, nuclear envelopes start to reform, chromosomes unwind, chromosomes shrink down to fit into nucleus, Organelles start to reappear, cleavage furrow starts at form
cytokinesis a.k.a. to break the cell
cell pinched off into two genetically identical daughter cells
chromosomes
prior to subdivision, each of the homologous chromosomes replicates, forming two identical copies called the sister chromatids; the sister chromatids are joined together by a structure called the centromere; Humans have 23 pairs of homologous chromosomes, when each chromosome in the pair is replicated, this makes for a total of 92 chromatids
karyotype
an arrangement of chromosomes; chromosomes can be compared based on size, shape, and centromere location
apoptosis
during fetal development, many cells are programmed to die. This results in the formation of fingers and toes from paddle like hands and feet.
checkpoints for cell division
The cell cycle is controlled by checkpoints to ensure the previous phase is fully completed before advancing to the next phase; feedback from the cell determines whether the cycle switches to the next stage;three principal checkpoints control the cycle in eukaryotes: G1, G2, and M checkpoints
G1 checkpoint, G2 check point, and M checkpoint
G1: makes the decision about whether the cell should divide and enter S, some cells never pass this point and are said to be in G0
G2: leads to mitosis
M: occurs during metaphase and triggers the exit process of the M phase and entry to the G1 phase
what is cancer?
cancer is a growth disorder of cells; begins when apparently normal cells grow uncontrollably and spread to other body parts; the result is a growing cluster of cells called a tumor
what is cancer?
benign tumor’s are surrounded by healthy layer of cells also known as encapsulated and do not spread to other areas; malignant tumors are not encapsulated and are invasive; Sells for a malignant tumor sleep and spread to different areas of the body to form new tumors, these cells are called metastases
