cell division Flashcards
is a process by which the cell divides and produces new ones, the daughter cells. This is a basic process in all living things which is important for the maintenance of the genome, reproduction, growth and replacement of worn out cells.
cell division
4 stages of mitosis
prophase
metaphase
anaphase
telophase
At first, chromosomes are observed as long, thin and coiled filaments, called chromatids. Then eventually they become short and thick with two identical strands held by the centromere.
The nuclear membrane disintegrates and the nucleolus disappears.
Centrioles in the centrosomes move toward the opposite poles forming the asters that become the spindle fibers.
prophase
Centromeres of the chromosomes are attached to the spindle fibers and aligned at the equator of the cell.
metaphase
Separation of the chromosomes moving to the opposite poles.
anaphase
Cleavage furrow is formed to divide the cytoplasm and produce the two daughter cells.
Nuclear membrane and nucleolus reappear.
Chromosomes are again long and threadlike.
Telophase
IS A SERIES OF EVENTS THAT TAKES PLACE IN A CELL AS IT GROWS AND DIVIDES. A CELL SPENDS MOST OF ITS TIME IN WHAT IS CALLED INTERPHASE, AND DURING THIS TIME IT GROWS, REPLICATES ITS CHROMOSOMES, AND PREPARES FOR CELL DIVISION. THE CELL THEN LEAVES INTERPHASE, UNDERGOES MITOSIS, AND COMPLETES ITS DIVISION.
cell cycle
IS WHEN THE CELL GROWS, AND THE ORGANELLES DOUBLE PRIOR TO THE ACTUAL SPLITTING OF THE NUCLEUS.
93% OF A CELL’S LIFE IS SPENT IN INTERPHASE.
INTERPHASE HAS THREE PARTS
UGROWTH 1 (G1)
USYNTHESIS (S)
UGROWTH 2 (G2)
INTERPHASE : G1, S, G2
G1 IS WHEN ORGANELLES DOUBLE.
REMEMBER EACH NEW CELL NEEDS A COMPLETE SET OF ORGANELLES.
S WHEN DNA IS REPLICATED.
EACH CELL NEEDS A COMPLETE AND IDENTICAL SET OF DNA
G2 PROTEINS NEEDED FOR MITOSIS ARE PRODUCED.
G1, S, G2
THE PROCESS BY WHICH THE CELL NUCLEUS DIVIDES INTO TWO IDENTICAL CELL NUCLEI.
IN SOME HUMAN CELLS INTERPHASES LASTS 15.3 HOURS, WHILE MITOSIS LASTS ONLY .7 HOURS.
OCCURS IN A SERIES OF STEPS
PROPHASE
METAPHASE
ANAPHASE
TELOPHASE
CYTOKINESIS
mitosis
MUST DUPLICATE AND SEPARATE DURING MITOSIS
STRUCTURES OF THE TIGHTLY PACKAGED DNA
DNA IS TANGLED UP INTO A SUBSTANCE OF CHROMATIN
THE CHROMATIN IS PACKAGED ON THE CHROMOSOME
Chromosomes
CHROMOSOMES NOW CALLED CHROMATIDS BECAUSE THEY DOUBLED TO FORM SHORT THICK RODS WHICH PAIR UP AND LINE UP IN THE CENTER OF THE NUCLEUS.
A CENTROMERE CONNECTS THE TWO HALVES OF THE DOUBLED CHROMATIDS.
SPINDLE FIBERS BEGIN TO FORM.
SPINDLE FIBER – A FIBROUS STRUCTURE FROM THE CYTOPLASM WHICH FORMS TO THE CENTRIOLE.
CENTRIOLES MOVE TO OPPOSITE SIDES OF THE CELL.
THE NUCLEAR MEMBRANE BREAKS DOWN.
prophase
CENTROMERES OF THE CHROMATID PAIRS LINE UP IN THE MIDDLE OF THE CELL.
METAPHASE PLATE- LOCATION WHERE THE CENTROMERES LINE UP IN THE CENTER OF THE CELL.
BY THE END OF METAPHASE EACH CHROMATID HAS ATTACHED TO SPINDLE FIBERS.
metaphase
THE SPINDLE FIBERS PULL THE CHROMATIDS APART.
THIS SEPARATES EACH ONE FROM ITS DUPLICATE. THESE MOVE TO OPPOSITE SIDES OF THE CELL.
NOW THERE ARE TWO IDENTICAL SETS OF CHROMOSOMES.
Anaphase
WHEN THE CHROMOSOMES REACH OPPOSITE SIDES OF THE CELL THE SPINDLE FIBERS BREAK UP.
THE NUCLEAR MEMBRANE BEGINS TO REFORM.
A FURROW BEGINS TO DEVELOP BETWEEN THE TWO SETS OF CHROMOSOMES.
Telophase
