Growth and Division of Cells Flashcards
an orderly series of events where cells divide
Cell Cycle
Cell Cycle 2 DIVISIONS
1) Interphase
2) Mitosis
Process of division that produces two daughter cells with identical chromosomal content of parent cell.
Mitosis
- A period in which chromosomes are NOT visible with light microscope
- Living cells are NOT dividing
Interphase
3 INTERVALS of INTERPHASE
1) G1 –(growth or gap one)
2) S- synthesis
3) G2- (growth or gap two)
lengthy period after the nucleus divides; RNA are ribosomes are produced & cell increase in size
G1 –(growth or gap one)
DNA replication takes place
S- synthesis
mitochondria & other organelles divide; microtubules are produced; coiling & condensation of chromosomes begin
G2- (growth or gap two)
Where one cell divides into two daughter cells
Mitosis
Mitosis’ location is found in roots and stem tips called?
MERISTEM
normally comes with mitosis; division of the remainder of the cell
CYTOKINESIS
The daughter cells have the _____ number of chromosomes
as the parent cell
EXACT
The first and longest stage of mitosis.
Prophase
Main feature:
1) 2 chromosomes become shorter & Thicker; 2 strands are apparent (CHROMATIDS)
2) Nuclear envelop dissociates; nucleolus DISINTEGRATES
Prophase
band formed from microtubules & microfilaments inside the plasma membrane
PRE-PROPHASE
hold each pair of chromatids together (short, thick & rod like)
CENTROMERES
a dense region composed of protein complex found on the outer surface of each centromere
KINETOCHORE
help distinguish certain chromosomes
from others in a nucleus; knob like appearance
SATELLITE
develop extend in arcs between 2 invisible poles located towards the end of the cell
SPINDLE FIBERS
(keg shaped structure) found on fungi and algae and animal cells located outside the nucleus with radiating ASTERS (star like rays)
CENTRIOLES
MAIN FEATURE: Alignment of the chromosomes in the circle midway between the 2 poles around the spindle and in the same plane as the PREPROPHASE BAND
Metaphase
in metaphase, __________ become aligned; centromeres are in the center of the cell
Chromosomes
an invisible circular plate (similar to earths equator)
EQUATOR
- Shortest phase
- Sister chromatids of each chromosome separate & move to opposite poles which are now the DAUGHTER CHROMOSOMES
- movement may be due to Shortening of spindle fibers
Anaphase
5 MAIN FEATURES:
- Each group of daughter chromosomes are surrounded by a reformed nuclear envelop
- Daughter chromosomes become longer & thinner
- Nucleoli reappear
- Spindle 2fibers disintegrate
- Cell plates are formed
Telophase
- The division of the cytoplasm to form two new cells, overlaps with the final stages of mitosis
- cell plate forms down the middle of the cell, splitting it into two daughter cells separated by a new wall
Cytokinesis
the form of cell division in which a cell divides into four “daughter cells” each of which has half of the number of chromosomes of the original cell
Meiosis
In MEIOSIS, the cells return to having the normal number of chromosomes after fertilization of the ova by the sperm, and it is called?
diploid
occurs prior to the formation of sperm (in males) and ova (in females)
Meiosis
STAGES OF MEIOSIS
- Prophase I
- Metaphase I
- Anaphase I
- Telophase I and Cytokinesis
5.Prophase II
6.Metaphase II
7.Anaphase II
8.Telophase II and Cytokinesis
the chromosomes condense, and the
nuclear envelope breaks down; crossing- over
occurs
Prophase I
pairs of homologous chromosomes
move to the equator of the cell
Metaphase I
homologous chromosomes move to
opposite poles of the cell
Anaphase I
- Chromosomes gather at the poles of the cells.
- The cytoplasm divides
Telophase I and Cytokinesis
A new spindle forms around the
chromosomes.
Prophase II
chromosomes line up at the equator
Metaphase II
- centromeres divides
- chromatids move to opposite poles of the cell
Anaphase II
- A nuclear envelope forms around each set of chromosomes.
- The cytoplasm divides.
Telophase II and Cytokinesis
