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
What happens during anaphase ?
- sister chromatids are pulled apart to opposite poles of the cell
What happens during telophase ?
- nucleolus and nuclear membrane reappear ,chromosome begin to uncoil and relax back into chromatin
What happens during cytokinesis?
-cytokinesis occurs as the plasma membrane pinches in along the equator
- 2 identical daughter cells are formed
What happens in plants because they have a cell all and cannot pitch off their plasma membrane?
- a structure known as the cell plate forms across the cells equator
What happens after mitosis ?
- each new daughter cells is an identical copy of the parent cell . Both cells enter interphase to carry out the assigned function until they are ready to divide
Where do cells spend the most time ?
Interphase
What are cells life span like ?
Some cells have a short life span and can divide ( ex: skin cells )
While others must last your entire life and cannot divide (ex :heart cells )
What is G0 phase ?
It is the cell’s resting phase where it doesn’t divide. Cells can go back into the cell cycle if needed
What happens when the genes that control cell division become damaged ? And some cells do not respond to the signals that regulate growth ?
Result : uncontrolled cell growth . Aka cancer
