CELL DIVISION
Cell division involves 2 phases:
1- MITOSIS
The process by which nuclear material is divided
2 identical daughter cells result
2- CYTOKINESIS
the process by which the cytoplasm and its contents (organelles) separate into equal parts.
cytokinesis begins before mitosis is complete
cytokinesis differs in plant and animal cells
ANIMAL CELLS
the cell membrane pinches near the middle of the cell, dividing the cytoplasm into equal parts(2 new cells)
PLANT CELLS
a cell plate develops across the centre of the cell, creating a new cell wall between the 2 new cells
Cells alternate between stages (phases) of dividing and not dividing.
This sequence is called the cell cycle.
The 2 major phases of the CELL CYCLE are:
1- DIVISION PHASE
During this phase the cell undergoes mitosis (nuclear division)
There are 4 phases of mitosis:
Prophase
Metaphase
Anaphase
Telophase
2- INTERPHASE
During this phase, the cell takes in nutrients and builds proteins that are used by the cell for energy
Chromosomes duplicate (DNA replication)
This is the period of growth and repair for the cell (in preparation for the division phase)
THE CELL CYCLE
CELL CYCLE: the continuous process of mitosis, cell division, and interphase.
HOW CELL GETS READY FOR MITOSIS
Nucleus makes a copy of its chromatin(replication)
Chromatin coils into double stranded chromosomes joined in the middle by a centromere
2 sets of DNA are bundled together
nucleus is ready for mitosis to begin.
Animal cell division: cell membrane pinches near the middle of the cell, dividing the cytoplasm into 2 new cells
Plant cell division: a cell plate develops across the centre of the cell, forming a new cell wall between the 2 cells
Original cell, parent cell
New cells, daughter cells
# of chromosomes in the nucleus of each cell is identical to eachother and to the number in the original cell
Why must nuclear membrane break down in mitosis?
So that the contents of the cell can divide.
The NUCLEUS controls the process of mitosis.
REGENERATION: repair of injured cells or the making of lost body parts
Normal Cell Replacement:
cells die when they receive instruction to do so
when they are no longer needed
The building of the grocery store is like the cell membrane, because it gives it structure and keeps everything inside safe. The security guard of the front door in the grocery store is like the cell membrane, because it says what can come in and out of the cell. The boss of the store is like the nucleus, because they tell the employes what to do and what needs to be done. The floors of the grocery store is like the cytoplasm, because it hold everything in it place, where it need to be. The illes in the store is
These cells form a shape such that each individual cell always remains in contact with 3 other cells at all times. The cells are held together by regions known as intercalated disks. These overlapping, finger-like extensions of the cell membrane contain gap junctions and desmosomes. Gap junctions are protein-lined tunnels which allow currents to travel from cell to cell to ensure the cells contract in unison. Desmosomes are known to hold the heart cells together during a contraction.
10.4) In animal cells cytokinesis involves the formation of a cleavage furrow which pinches the cell in two. While in plants cells cytokinesis involves the division of cytoplasm by late telophase, so the daughter cells appear shortly after the end of mitosis.
Animal metabolism consists of the utilization of nutrients absorbed from the digestive tract and their catabolism as fuel for energy or their conversion into substances of the body. Metabolism is a continuous process because the molecules and even most cells of the body have brief lifetimes and are constantly replaced, while tissue as a whole maintains its characteristic structure. This constant rebuilding process without a net change in the amount of a cell constituent is known as dynamic equilibrium (Grolier1996). In the combustion of food, oxygen is used and carbon dioxide is given off. The rate of oxygen consumption indicates the energy expenditure of an organism, or its metabolic rate (Grolier1996).
divide to make new blood cells. Once blood cells mature, they leave the bone marrow and enter
Each cell contains the same genetic code as the parent cell, it is able to do this because it has copied it’s own chromosomes prior to cell death. division. The. Meiosis consists of two divisions whilst mitosis is followed. in one division; both these processes involve the stages of interphase, prophase, metaphase, anaphase, and telophase.
During interphase, cell growth, DNA replication, separation of centrioles and protein synthesis takes place. This phase is acknowledged to being the most extensive period of the cell cycle thus signifying the stage in which the cell devotes th...
In the Prophase, chromosome as double threads joined at centromere and then shorten and thicken. Then nucleolus and nuclear membrane disappears. Fibrils of astral rays extend across forming mitotic spindle. After that centriole divides into two.
Cell division is extremely important; cells must divide in order to maintain an efficient volume to surface area ratio, allow organisms to grow and develop, and repair any damaged tissue. Cells are able to do all this through two processes: meiosis and mitosis. Without these processes, humans would not be able to do many of the basic functions we are so accustomed to, including growing, healing even the smallest cuts, and even reproducing! However, meiosis and mitosis, although both procedures for cell division, are very different.
Our metabolism, “the totality of an organism’s chemical reactions”, manages energy usage and production of cells. We use energy constantly and our metabolism breaks down food through complex chemical reactions into energy our cells
A chromosome is made up of two identical structures called chromatids. The process of nuclear division is called interphase; each DNA molecule in a nucleus makes an identical copy of itself. Each copy is contained in the chromatid and a characteristic narrow region called the centromere holds the two chromatids together. The centromere can be found anywhere along a chromosome but the position is the characteristic for a particular chromosome. Each Chromatid contains one DNA molecule. DNA is the molecule of inheritance and is made up of a series of genes. The fact that the two DNA molecules in the sister chromatids, and hence their genes, are identical is the key to precise nuclear division.
The process of cell division plays a very important role in the everyday life of human beings as well as all living organisms. If we did not have cell division, all living organisms would cease to reproduce and eventually perish because of it. Within cell division, there are some key roles that are known as nuclear division and cytokinesis. There are two types within nuclear division. Those two types being mitosis and meiosis. Mitosis and meiosis play a very important role in the everyday life as well. Mitosis is the asexual reproduction in which two cells divide in two in order to make duplicate cells. The cells have an equal number of chromosomes which will result in diploid cells. Mitosis is genetically identical and occurs in all living
Sepkowitz, Kent. "The Inner Life of Cells." Newsweek 17 Sept. 2012: 8. Educators Reference Complete. Web. 12 Nov. 2013.
The first period, the germinal period, is classified as the first two weeks after conception, that is identified by how fast cells divide and differentiate. During this phase a zygote duplicates. After that differentiation begins, this is where early cells take on their own characteristics and move to their predetermined locations. Once that is complete a cell mass will then become either a placenta or a nucleus, together they will become the embryo. The second period is called the embryonic period. This. Is this stage of development that occurs during the third to the eighth week after conception. During this phase, the basic structural forms of the baby's body appear. At the beginning of this period a line (the primitive streak) appears turning into the neural tube, and eventually turning into the central nervous system. in the fourth week eyes, ears, nose, mouth, and minuscule blood vessels (becoming the heart) begin to appear. Between the fifth week and the end of the embryonic period arms, legs, hands, feet, fingers, and toes appear. The final stage, the