Phases of Cell Cycle

In: Science

Submitted By syahirahsuhaimi
Words 985
Pages 4
2.1 Phases of The Cell Cycle
2.1.1 Interphase Originally this phase of the cell cycle was called the "resting stage", since light microscopy could not detect any activities taking place within the cells. Today, however, it is known as a stage of considerable activity at the molecular and sub-cellular level and is usually subdivided into: * G1 - ("Gap One") - this is a period of molecular synthesis where a newly formed cell turns on a variety of genes on its DNA to make proteins, which in turn churn the metabolism of the cell, produce and breakdown carbohydrates, lipids, etc., and transform energy from food into ATP. The cell grows and enlarges. * S - ("synthesis") - during this phase the chromatin (DNA and proteins) becomes synthetically active. Using elaborate teams of enzymes, the DNA molecules of each chromosome are copied by semiconservative DNA synthesis. This phase cannot be clearly seen or distinguished under the light microscope, even with DNA stains, as the material is too diffuse. However, the making of new DNA molecules can be monitored by following the incorporation of radioactive isotopes into the newly forming DNA molecules. * G2 - ("Gap Two") - another period, of variable length, in which cells prepare for division. Many different proteins are synthesized, especially those that will act as spindle fibers (protein "ropes"). Stocks of energy are accumulated and many organelles, such as mitochondria, also grow and divide, increasing in number.• Interphase is a busy time in the life of a dividing cell. Towards the end of G2, however, things slow down and the cell gets ready for the next major phase in the cycle. |

2.1.2 Mitotic Phase Mitosis
Mitosis is a form of eukaryotic cell division that produces two daughter cells with the same genetic component as the parent cell. Chromosomes replicated during the S phase are divided in such a…...

Similar Documents

Phases of the Traditional Systems Development Life Cycle

...Phases of the traditional Systems Development Life Cycle (SLDC) for Bank ATM Software David Phillip Piña University of Phoenix Abstract This paper will attempt to explain the six different phases in a traditional systems development life cycle for developing software to run a bank’s automatic teller machine (ATM) machine. The input and output for each phase will be clearly outlined. Information from my Week 1 CIS/319 class readings will be used as a guide. Phases of the traditional Systems Development Life Cycle (SLDC) for a Bank ATM The Six Phases According to Moore, W., Nolan, E., & Gillard, “There are six different phases in a traditional systems development life cycle. The first phase is preliminary investigation, the second phase is system study, the third phase is system analysis, the fourth phase is programming and implementation, the fifth phase is support and maintenance, and the sixth phase is documentation”. (2006) According to Computer World, “Stages of the traditional system development lifecycle can be characterized and divided up in different ways, including the following: Project planning, feasibility study: Establishes a high-level view of the intended project and determines its goals. Systems analysis, requirements definition: Refines project goals into defined functions and operation of the intended application. Analyzes end-user information needs. Systems design: Describes desired features and operations in detail,......

Words: 769 - Pages: 4

Comparing Cells

...University of Phoenix Material Comparing Cell Cycles Complete the Cell Cycle charts below. Describe the events in each phase for Cell Cycle A. Compare the steps in mitosis and meiosis for Cell Cycle B. Cell Cycle A |Phase |Describe the events in each phase | |G1 (1st growth stage) |This is the portion of the cell cycle just after division, but before DNA synthesis. During this| | |time the cell grows by producing proteins and organelles. | |S (Synthesis) |DNA synthesis (or replication) occurs during this phase. At the beginning of the phase, each | | |chromosome is single. At the end, after DNA replication, each chromosome consists of two sister | | |chromatids | |G2 (2nd growth stage) |This third subphase of interphase is a period of metabolic activity and growth. During this | | |phase the cell makes final preparations for division. | |Prophase of mitosis |Prophase occupies over half of mitosis. The nuclear membrane breaks down to form a......

Words: 594 - Pages: 3

The Life Cycle Assessment of Cell Phones

...The Life Cycle Assessment of Cell Phones The mobile phone has become an essential product all around the world. A small handheld device with the ability call, send messages, and access the internet from almost anywhere in the world has become a necessity for many citizens of developed countries. Due to rapid technological advances, cellular phones become obsolete in a very short period of time. The average lifespan of a cell phone is only 18months in the US (LCA of Cell Phones). With over 233 million active cell phones in use in the US alone and 4 billion worldwide, it’s mindboggling to consider how many phones that have been created and discarded over the past few decades. 1. What environmental impacts are the most significant? The energy usage costs accounts for over 30% of the total life cycle energy (LCA of Cell Phones). Depending on how the electricity is created (coal, natural gas, oil, etc.) lots of greenhouse gases and other pollutants are released into the air. 2.      What lifestage(s) contribute the most to these impacts? Energy usage occurs in the Product Consumption stage. The daily recharging of the battery is a huge energy obligation. 3. What are the strengths, flaws, and limitations of the analysis? The analysis has a great amount of cell phone data within the US and gives great examples of LCA goals from companies like AT&T and Nokia. However there is almost no information about the LCA from the global perspective. Also there is no......

Words: 468 - Pages: 2

Cell Cycle

...the cell cycle, including the steps of Interphase. G1 phase - growth and synthesis. Gap phase 1 begins at the completion of mitosis and cytokinesis and lasts until the beginning of S phase. This phase is generally the longest of the four cell cycle phases and is quite variable in length. During this phase, the cell chooses either to replicate its deoxyribonucleic acid (DNA) or to exit the cell cycle and enter a quiescent state (the G0 phase). S phase Replication of the chromosomes is restricted to one specific portion of interphase, called S phase (DNA synthesis phase), which typically lasts about 6 h. In mammalian cells, the start of S phase—the actual initiation of DNA synthesis—takes place several hours after the cell has committed to carrying out DNA synthesis. During S phase, each chromosome replicates exactly once to form a pair of physically linked sister chromatids. In animal cells, a pair of centrioles is also duplicated during S phase. G2 phase - Preparation for division The portion of interphase that follows S phase is called gap phase 2. Some cells can exit the cell cycle from G2 phase, just as they can from G1 phase. M phase M phase includes the overlapping processes of mitosis and cytokinesis. Mitosis is divided into five stages: prophase, prometaphase, metaphase, anaphase, and telophase. Cytokinesis usually begins during anaphase and ends at a point after the completion of mitosis. At the end of cytokinesis, the parent cell......

Words: 1135 - Pages: 5


...Structures in All Eukaryotic Cells We're going to start with eukaryotic cells even though they tend to be more complex than prokaryotic. But, there is a method to our madness: you are a eukaryote and have eukaryotic cells, so we thought you might relate better. And, eukaryotic comes before prokaryotic alphabetically. Come up with whatever reasons you want for it, but eukaryotes are up first. Tough cookies. Eukaryotic Cell Structure and Function A cell is defined as eukaryotic if it has a membrane-bound nucleus. Any organism composed of eukaryotic cells is also considered a eukaryotic organism. Case in point: You. Biologists do not know of any single organism on Earth that is composed of both eukaryotic and prokaryotic cells. However, many different types of prokaryotic cells, usually bacteria, can live inside larger eukaryotic organisms. Creepy, but true. We humans, for example, have trillions of bacteria living in our colons, not to mention in our mouths and stomachs and small intestines and…you get the picture. Despite the fact that we have gobs of prokaryotic cells living inside and on us, humans are still categorically eukaryotic organisms. Deal with it. This means that all human cells, including those found in the brain, the heart, the muscles, and so on, are also eukaryotic. Here is what one of these little guys looks like: OK, we are slightly impressed. That is a lot of stuff jam-packed into something we can't see too well with the naked eye. All......

Words: 1363 - Pages: 6

Nitrogen Cycle

...SC4730 Environmental Science Analysis 2 Nitrogen cycle Nitrogen exists in nature in many different forms, from molecular nitrogen in gaseous to the complex organic compounds in the body of plants, animals and humans. In an organism, Nitrogen exists in the form of organic compounds such as proteins, amino acids. When the microorganisms die, the amount of nitrogen exists in soil. Under the action of the group saprophytic microorganisms, proteins are degraded to amino acids. The amino acid to be a group of other microorganisms into NH3 or NH4+ called ammonium group of bacteria. This process called mineralization of organic matter such as through organic nitrogen is converted into nitrogen mineralization types. NH4 + form will be converted into the form of NO3- by nitrifying bacteria. (Wikipedia, Nitrogen cycle) Of the nitrate compounds are converted into nitrogen molecules, this process is called nitrification reaction was carried out by reaction of nitrate bacteria. N2 gas will be fixed in bacterial cells and plant cells are then transformed into organic forms of nitrogen by microorganisms group of fixed nitrogen. (Wikipedia, Nitrogen cycle) Thus nitrogen cycle is closed in most phases of the cycle metabolism and involvement of different groups of microorganisms. If the activities of a group are stopped the whole metabolism of the cycle will be seriously affected. The process of ammonium The organic forms of nitrogen converted to NH3 or NH4 +. a / The chemical urea......

Words: 810 - Pages: 4

Cell An introduction to the microscope and magnification MAGNIFICATION AND RESOLUTION Because cells are too small to be seen with the naked eye, the light microscope was developed to produce enlarged and more detailed images of cells. The magnification of an image is how much bigger it appears under the microscope than it is in real life, and is worked out using the following formula: magnification = image size ÷ actual size unit metre decimetre centimetre millimetre micrometre nanometre picometre symbol m dm cm mm μm nm pm metres 1 0.1 0.01 0.001 0.000 001 0.000 000 001 0.000 000 000 01 However, magnification on its own does not increase the level of detail seen, it just increases the size. The term resolution refers to the ability to see two distinct points separately. For example, if the resolution of a light microscope is 200nm (0.2μm), this means it can see any two different points as separate objects if they are 200nm apart or more; but if they are any closer than this amount, they appear as one object. THE LIGHT MICROSCOPE Light microscopes use a number of lenses to produce an image that can be viewed directly at the eyepiece. Light passes from a bulb under the stage, through a condenser lens and then through the specimen. This beam of light is passed through an objective lens and then the eyepiece lens. The light microscope usually has a number of objective lenses which can be rotated into......

Words: 8313 - Pages: 34

Cell Cycle Short Essay

...Cell Cycle A cell spends the most time in the stage of interphase. The first stage of interphase is known as G1 phase. G1 is where most of the cell growth occurs. After the G1 phase, the cell goes through the G1 checkpoint and if the cell is well developed, it will proceed to the S phase. During S phase, the DNA of the cell is synthesized, or copied. The cell then enters G2 phase in which the cell prepares for cell division. The cell goes through a G2 checkpoint. If the cell doesn’t have any problems in relation to the cell’s growth and development, then the cell is ready for mitosis. There are two parts to cell division, mitosis followed by cytokinesis. Mitosis is the process in which the nucleus of the cell splits into two. The four stages of mitosis are prophase, metaphase, anaphase, and telophase. During prophase, the cell’s nuclear envelope disappears and the chromatin tightly coils to become visible chromosomes. Each chromosome contains two sister chromosomes that are held together at the centromere. The cell then enters metaphase where the spindle fibers located at the centrioles attach to the centromeres. The sister chromatids are then pulled to the middle of the cell and lined up in the center. The third checkpoint occurs here to make sure that the chromosomes are aligned, if so then it proceeds to anaphase. During anaphase the centromeres split and the sister chromatids are pulled to opposite poles of the cell. The cell then enters telophase in which the......

Words: 326 - Pages: 2

Cell Division

...|2.3 Cell Continuity |Objectives | |2.3 Cell continuity + Mitosis |Explain the terms: cell continuity & chromosomes. | | |Define the terms: haploid & diploid number. | | |Describe the cell activities in the state of non-division: Interphase and | | |Division (mitosis). | | |Define the term: mitosis. | | |Define cancer and state causes. | | |State the primary function of mitosis for single-celled vs multi-cell. Organisms.| | |Define the term: meiosis. ......

Words: 2917 - Pages: 12


...Cells Assessment- Second Sitting 2015-6 Watch the short video at: (see footnote ), then answer the following question 1. Type your answers into the boxes 1) a) What substance are the “yellow, little knobby things” called “Keys” on the virus made of? ------------------------------------------------- These are made of proteins 1.2 b) The narrator says the “keys” fit into locks”. Do eukaryotes and prokaryotes have similar “locks” and where are they found? ------------------------------------------------- 1.2 c) Specifically what type of substance are these “locks” in eukaryotes made of? ------------------------------------------------- Cell membrane. 1.2 d) “If the lock fits, the cell welcomes the virus in.” Name the transport process by which the cell takes the virus in. ------------------------------------------------- Endocytosis. 2.1 e) Name the structure in the host cell that is described as the “welcoming committee, that pulls the virus deeper into the cell” ------------------------------------------------- The cytoplasm. 1.1 f) Name the......

Words: 606 - Pages: 3

Phases and Events of the Cell Cycle

...DISCUSSION 2.1 Phases And Events Of The Cell Cycle 2.1.1 Phases And Subphases Generally, there are two phases in cell cycle. Those are interphase and mitotic phase. Figure 1.0: The cell cycle Interphase consist of G1, S, and G2. The name of G actually represent as “gap” while S represent as “synthesis”. So, the name for G1 is also known as “first gap”, S is “synthesis”, and G2 is “second gap”. There is a reason why it is called “gap”. It is because, when the cells were observed long time ago, it appeared as inactive which in inactive period, it create a gap between S phase and mitotic phase. However, as the world hurtles down the path of fast scientific development, we now know that there is a growth and metabolic activity inside cells. The mitotic phase is divided into two, mitosis and cytokinesis. Mitosis consist of prophase, prometaphase, metaphase, telophase, and anaphase. 2.1.2 Duration Of Cell Cycle Approximately, G1 takes about 5 – 6 hours, S takes about 10 – 12 hours, and G2 takes about 4 – 6 hours. Mitotic phase takes less than 1 hour. Overall, a normal human cells take about 24 hours to complete a cell cycle. 2.1.3 Events In The Cell Cycle In each subphases, several events occurred in well ordered. Starting from G1, the growth of cells occurred in this phase by producing proteins and cytoplasmic organelles. Until at the end of G1, the enzymes required for DNA synthesis become more active. The process continue with S phase, in this entire phase, the......

Words: 625 - Pages: 3

Cell Bio

...However, for Cell Biology we will touch upon those concepts that complement the cellular aspects of transcription. In particular, we will look at the genetic code, called the CODON, frameshift mutations, the structure of theTRANSCRIPTIONAL UNIT, and the phases of transcription. I will point out those aspects of transcription that I feel are important to this course. The study guide will also help you to focus on those parts of transcription that the examination will cover. CHAPTER 19 1. What important event (related to DNA) occurs in G1 before the cell enters the S phase? 2. What important event (related to DNA) occurs in G2 before the cell enters mitosis? 3. Why are G1 and G2 called gap phases? What happens during S phase? 4. Can mitosis occur without cytokinesis? (hint, Drosophila) 5. During which phase of mitosis do sister chromatids separate? 6. How do the experiments of Meselson and Stahl verify the semiconservative model of DNA replication? 7. What is the name of the locus (location) from which DNA replication begins? Does DNA replication occur uni- or bi-directionally? 8. Name the two major components of the primosome. 9. What are the functions of DNA polymerase III, the primosome, primase, DNA polymerase I, and DNA ligase? 10. What structure along the lagging strand allows the replisome to replicate both strands in the same direction? 11. How does cell cycle relate to cell type? 12. What is MPF? What two molecules make up MPF? Which one cycles in......

Words: 810 - Pages: 4

Cell Reproduction

...WHAT IS CELL REPRODUCTION AND WHY IT HAPPENS According to our text book, Essentials of Biology, we begin life as a single cell but over the period of several months, we become a collection of trillions of cells. This process continues as we grow up and as we reach a fully mature adult age, old cells are replaced with new ones. Many cells divide at least once during their short life span and some divide many times before they die. This is known as cell division (parent cells and daughter cells) which are given the names of binary fission, meiosis and mitosis. New red blood cells, skin cells and digestive track cells are also generated. Reproduction is also how organisms are able to reproduce through meiosis which involves the replication of DNA and the splitting of molecules. Mitosis involves the cell division which produces two of the same identical cells from one single cell and happens as a result of a process that cells go through to form to nuclei with each of the nuclei containing the same number of chromosomes. Many eukaryotic organisms use this process for reproduction. Cells go though many cycles but all of the cycles happen in a specific event, some of which I partially mentioned above. The first in the Interphase cycle which is time it takes for a cell to perform its normal functions, depending on where it is in the human body. The next stage is the M state which includes both the division of the nucleus and the division of the cytoplasm—this is......

Words: 619 - Pages: 3


...Stem cells: What they are and what they do Researchers believe stem cells offer great promise for new medical treatments. Learn about stem cell types, current and possible uses, ethical issues and the state of research. By Mayo Clinic staff You've heard about stem cells in the news, and perhaps you've wondered if they might help you or a loved one with a serious disease. You may wonder what stem cells are, how they're being used to treat disease and injury, and why they're the subject of such vigorous debate. Here are some answers to frequently asked questions about stem cells. Why is there such an interest in stem cells? Researchers hope stem cell studies can help to: * Increase understanding of how diseases occur. By watching stem cells mature into cells that eventually become bones, heart muscle, nerve cells, and other organs and tissue, researchers and doctors may better understand how a variety of diseases and conditions develop. * Generate healthy cells to replace diseased cells (regenerative medicine). Researchers hope they can train stem cells into becoming specific cells so that those specialized cells can be used to regenerate and repair diseased or damaged tissues in people. People who might benefit from stem cell therapies include those with spinal cord injuries, type 1 diabetes, Parkinson's disease, Alzheimer's disease, heart disease, stroke, rheumatoid arthritis, osteoarthritis and multiple sclerosis. Stem cells could also be grown to become......

Words: 19974 - Pages: 80

Cell Reproduction

...Cell Reproduction The term cell reproduction refers to the process of a cell splitting to form two similar cells; this is known as cell division. Eukaryotic cells reproduce by mitosis or meiosis; and prokaryotic cells use binary fission as a means of cell reproduction. (Simon,Reece,Dickey.(2010)) Mitosis is defined as a process of asexual reproduction in which the parent cell divides in two producing a replica, with an equal number of chromosomes in a haploid cell. The product of mitosis is two diploid daughter cells. The process of mitosis creates everything accept sex cells; and occurs in all organisms. The steps of mitosis are Interphase, Prophase, Metaphase, Anaphase, Telophase and Cytokinesis. In the prophase step of mitosis the chromosomes duplicate into two sister chromatids. In metaphase the chromosomes align in the center of the cell, the spindle microtubes attach to the two sister chromatids are pulled toward the opposite poles of the cell. In anaphase the two sister chromatids separate and are considered full daughter chromosome; the mirotubes push toward opposite poles cause the cell to elongate. In telophase the chromosomes are at the far point of the opposite poles of the cell; the nucleus separates into two separate but identical daughter nuclei. In the final stage cytokinesis the cytoplasm divides forming two separate but genetically identical daughter cells. (Simon,Reece,Dickey.(2010)) Meiosis is a process of sexual reproduction which creates sex......

Words: 780 - Pages: 4