Cell Division Flashcards
Chapter 4, Pt 1
What is the cell cycle?
The sequence of events by which a cell duplicates its genome, synthesizes the other constituents of the cell and divides into two daughter cells.
What is cell division?
Cell division is the process by which a single cell divides into two or more daughter cells.
What is Interphase?
The phase between two successive M phases
Consist of
-G0 phase
-G1 phase
-S phase
-G2 phase
What is the G1(Gap 1) phase?
The phase where the cell is metabolically active but does not replicate it DNA
What is the S (Synthesis) Phase
The period in which DNA synthesis/replication takes place.
What is the G2 (Gap 2) Phase
The phase in which proteins are synthesized in prep for mitosis.
What is the G0 (Quiescent) Phase
The phase in which cells that do not divide further exit G1phase to enter an inactive state.
M (Mitosis) Phase
The phase in which actual cell division occurs
-Starts with karyokinesis and ends with cytokinesis
Split into Prophase, Metaphase, Anaphase, and Telophase (PMAT).
What occurs during prophase?
The phase in which chromatin in the nucleus condenses into chromosomes, centrioles move towards opposite ends of the cell, and nuclear membrane come apart.
What is a homologous chromosome?
Homologous chromosomes are chromosome pairs that have the same genes but may carry different versions (alleles) of those genes.
What is metaphase?
The phase in spindle fibers attach to kinetochores and chromosomes are moved to the metaphase plate
What is the metaphase plate?
The plane of alignment the chromosomes.
What is a centromere?
The structure that holds sister chromatids together.
What is a kinetochore?
They are disc-shaped structures at the surface of centromeres that function in the attachment of spindle fibers.
What is Anaphase?
The phase in which centromeres split, and chromatids separate, moving to opposite poles.
What is Telophase?
The phase in which chromosomes decondense into chromatin, nuclear envelope reforms, and membrane-bound organelles reform
What is Cytokinesis?
The phase in which the cell itself is divide into two daughter cells
How does Cytokinesis occur in Animal Cells?
Cytokinesis occurs by the appearance of a furrow in the plasma membrane, the furrow deepens and ultimately joins in the center dividing the cytoplasm into two
How does Cytokinesis occur in Plant Cell?
Cytokinesis occurs by the formation of a wall in the center of the cell and grows outward to meet the existing lateral walls
What is a Cell-Plate?
A simple precursor that represents the middle lamella between the wall of two adjacent cells.
What is the Significance of Mitosis?
-Results in the production of diploid daughter cells
-Responsible for the growth of multicellular organisms
-Restores the nucleo-cytoplasmic ratio
-Important in cell repair
What happens when karyokineses is not followed by cytokinesis?
In some organisms this leads to the formation of syncytium
(e.g. liquid endosperm in coconut)
What is Meiosis?
A specialized kind of cell division that results in the production of haploid daughter cells
What are the special characteristics of Meiosis
-Involves two sequential cycles of nuclear division (Meiosis I & II)
-Involves the pairing of homologous chromosomes and recombination between them
-Four haploid cells are formed at the end of meiosis II
