Cell Cycle Flashcards
What are the 4 reasons why cells divide?
- Efficiency : as cell grows bigger demand for transport across membrane is too great
- DNA overload: as cell grows bigger, DNA can’t send out instructions fast enough to instruct organelles on work to do
- Growth
4: Cells divide to replace word out or damaged cells
What is cell division called in prokaryotes ?
Binary Fission
What happens in Binary Fission?
DNA is copied then cell divides
What is cell division called in Eukaryotes ?
Mitosis
What happens in mitosis?
cell grows and copies its DNA before it can divide
What is the cell cycle?
The series of events that cell go through as they grow and divide
What are the two phases of the cell cycle?
Interphase and “m” phase
What does the “m” phase include?
mitosis-division of the nuclei
cytokinesis-division of the cytoplasm
What are the steps in Interphase?
-G1(Growth /Gap 1)-cell grows in size, makes new organelles and performs assigned function; DNA is relaxed in chromatin and is not visible
-S phase (synthesis) :duplicates DNA to prepare for mitosis
-G2(growth/Gap 2) -cell prepares for mitosis
chromatin
DNA “scrunched up” in the nucleus and is not visible / DNA is relaxed; DNA appears as chromatin during interphase
Chromosome
cell structure that carries the genetic material/ visible DNA during mitosis
Sister chromatids
identical halves of the duplicated parent chromosome
centromere
cell structure that joins the 2 sisters chromatids of chromosome
What happens during prophase?
1) DNA organizes
- chromatin condense into visible chromosomes
-chromosomes are paired with their identical copies and are called sister chromatids
- sister chromatids are held together as a pair by centromere
2) ;nuclear membrane and nucleolus disappear
3) spindle fibers form between the pairs of centrioles, which have moved to opposite ends of the cell
What happens during metaphase ?
- chromosomes line up on the middle of the cell
- each chromatid is attached to a separate spindle fiber by its centromere