Q1.The cell cycle is the series of events which occur in a cell leading to its division and replication.
In animal cell, the cell cycle can be divided in following three periods:
- interphase
- mitotic (M) phase
- cytokinesis
Interphase and mitotic are two difference periods on the cell cycle, each period has their difference importance.
First of all, interphase included three stages: G1 stage, S stage and G2 stage.Cells in the G1 stage will undergo the primary growth. Such as making more cytoplasm and organelles which makes the cells mature for use the next stage of chromosome replication. In this phase the cell is carries on its normal metabolic activities. Then, DNA copied performed in S stage. In the final stage of interphase is G2 stage which produced an organelles and proteins that need to be use in cell division.
For the mitotic (M) phase, there are four stages as following:
- Prophase
- Metaphase
- Anaphase
- Telophase
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.
In the Metaphase, chromosomes around equatorial plane of spindle with centromeres of chromosome attached to fibrils of spindle.
Then, in the Anaphase, centromeres divides and the each chromatid moves apart.
Finally, daughter chromosomes approaching poles and loss individuality. Nucleolus reappears and nuclear membrane reconstituted.
(picture source: http://cyberbridge.mcb.harvard.edu/mitosis_3.html)
There are some specific checkpoint which is the regulation mechanism of the cell cycle. When certain conditions are met, the cell cycle will continue, so the cell ...
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...finally inversions is change the nucleotide sequence.
Mutation that results in an increase in the amount of genetic materials is extremely important in promoting evolutionary novelty. Mutation and competition in the original or new environment present powerful forces in the creation and survival of new, better genotypes in a haploid organism. In diploid organisms, recombination of these new genes already present, when subjected to selection by environment, also permits the evolution of new types.
And there also made hybrid vigour. In any population there are some bad recessive genes. Inbreeding results in a high proportion of the offspring being homozygous for these genes. Outbreeding result in many offspring being heterozygous. Therefore bad genes are masked by their normal dominant alleles. Offspring are tougher, more fertile and have a greater chance of survival.
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.
The next step includes the two nuclei of the dikaryon fusing through karyogomy (Ross 146). The resulting diploid zygotic nucleus then undergoes meiosis, and four haploid nuclei are formed in the basidium (Webster 280). The haploid nuclei move into projections on the basidium, which turn into spores. The spores are attached to the sterigmata until they are released (Ross 146). The cycle then starts over again.
Do you know how you are able to run long distances or lift heavy things? One of the reasons is cellular respiration. Cellular respiration is how your body breaks down the food you’ve eaten into adenosine triphosphate also known as ATP. ATP is the bodies energy its in every cell in the human body. We don’t always need cellular respiration so it is sometimes anaerobic. For example, when we are sleeping or just watching television. When you are doing activities that are intense like lifting weights or running, your cellular respiration becomes aerobic which means you are also using more ATP. Cellular respiration is important in modern science because if we did not know about it, we wouldn’t know how we are able to make ATP when we are doing simple task like that are aerobic or anaerobic.
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.
The cell cycle is the process by which cells progress and divide. In normal cells, the cell cycle is controlled by a complex series of signaling pathways by which a cell grows, replicates it’s DNA and divides, these are called proto-oncogenes. A proto-oncogene is a normal gene that could become an oncogene due to mutations. This process has mechanisms to ensure that errors are corrected, if they are not, the cells commit suicide (apoptosis). This process is tightly regulated by the genes within a cell’s nucleus. In cancer, as a result of genetic mutations, this process malfunctions, resulting in uncontrolled cell proliferation. Mutations in proto-oncogene or in a tumour suppressor gene allow a cancerous cell to grow and divide without the normal control imposed by the cell cycle. A change in the DNA sequence of the proto-oncogene gives rise to an oncogene, which
Meiosis, also called reduction division, is a distinct type of cell division that is essential for sexual reproduction to occur. It is one in which two successive divisions of diploid cell occur thereby producing four genetically different haploid daughter cells, also called gametes, each with half the number of chromosomes and thus, half the total amount of genetic material as compared to the amount before meiosis began. Interphase precedes meiosis and thus, paves the way for meiosis to eventuate as the cell’s DNA replicates in the S phase yielding corresponding, identical chromosomes. Interphase sparks the marvelous process of meiosis that allows variation to transpire within the organisms it occurs, hence, giving rise to millions of organisms with unique aspects unlike any other on Earth. Because meiosis is a form of sexual reproduction itself, it is the means through which gametes are produced, each with a reduced number of chromosomes, so that when two gametes fuse during fertilization, not only do they form a diploid zygote with 46 chromosomes, but also have manifested differing features due to the rearrangement (crossing-over) of chromosomes.
Eukaryote cellular division goes through mitosis and in the sex cells reproduce through meiosis. Mitosis and Meiosis are very complicated compared to prokaryote division because prokaryotes go through binary fission. Mitosis and Meiosis are complex because they go through multiple phases such as; prophase, metaphase, anaphase, and telophase. While binary fission is less complex because the process consists of DNA replication and then the duplicated strand moves to the opposite side pulling the sides away from each other causing the plasma membrane to pinch and separate.
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.
Sometime after anaphase onset, the chromosomes have moved close to the spindle pole regions, and the spindle middle begins to clear. In this middle region of the spindle, a thin line of vesicles begins to grow. The vesicle aggregation event is a harbinger to the assembly of a new cell wall that will be positioned midway along the length of the original cell. It will form the boundary between the newly separating daughter cells. This basket shaped structure forms in late anaphase or early telophase and breaksdown about the time that the vesicles begin to grow.
The differences between the two phases of meiosis are that in meiosis I, while the cell undergoes the phases, prophase I, metaphase I, anaphase I, and telophase I, it causes the cell to divide into two with each of the cells having a double stranded chromosome. But in meiosis II, it is just the division of the the cells from meiosis I. The ending result being that four haploid daughter
From my reading I learned that cellular respiration is a multi-step metabolic reaction type process that takes place in each living organism 's cell rather it be plant or animal. It’s my understanding that there are two types of cellular respiration, one called aerobic cellular respiration which required oxygen and anaerobic cellular respiration that does not require oxygen. In the anaerobic cellular respiration process, unlike the aerobic process oxygen is not required nor is it the last electron acceptor there by producing fewer ATP molecules and releasing byproducts of alcohol or lactic acid. The anaerobic cellular respiration process starts out exactly the same as anaerobic respiration, but stops part way through due to oxygen not being
Breeding between individuals are closely related , and called inbreeding , may be the result of one side to the qualities recessive harmful more to show themselves , because the genome of mates pair are more similar : the qualities recessive can only happen in the offspring if it is present in the genome of both parents , and more genetically similar parents , recessive traits appear often in their offspring . Thus, the more closely related pair and breeding and harmful genes may be more symmetric offspring , resulting in individuals who are not very valid . For alleles that give an advantage in the heterozygous state and / or homozygous dominant , and the fitness of the state symmetric - recessive may be zero ( mean offspring sterile or non- viable ) .
Efficient communication between cells is crucial in governing cellular activities. Cytokines are a key element of the cell signaling process and mediate communication among cells. Cytokines are a type of small proteins released by cells that have an effect on the behavior of other cells. There are several different types of cytokines including interleukins, interferons, and tumour necrosis factor. Many different types of cells can produce cytokines, such as immune cells like macrophages, mast cells, and B lymphoctyes. Cytokines are especially important in the immune system because they help coordinate that balance between the cell-based immune response and the humoral immune response.
During this phase the DNA aka “deoxyribose nucleic acid” clone then forms chromatin. Chromatin is the mass of genetic material that forms into chromosomes. Interphase is divided into smaller parts: G1 Phase, S phase and G2 Phase. Throughout all the phases, the cells continuously develop by producing mitochondria, endoplasmic reticulum, and proteins. The actual division occurs during the S phase bur the G phases are mainly for the purpose of growing. Starting with the G1 phase the cell grows in preparation for certain intracellular components and DNA replication. This phase makes sure the cell is prepared for the process of DNA replication. It reviews the size and environment to ensure that is it ready to go, and cannot leave the G1 until it is complete. But what happens to a cell when it is not complete and cannot exit out of the phase? It will pause and transfer to phase G0. There’s no certain time to be in this phase but it will remain until it reaches the fitting size and is in a supportive surroundings for DNA replication. It will exit either G1 or G0 and there is no other way besides these. Then the cell will advance to the next phase which is the S phase. Synthesis, or more known as S phase is the section of the cell cycle when the DNA is wrapped into chromosomes then duplicated. This is a very important part of the cycle because it grants each of them that is created, to have the exact same genetic