Cell Metabolism

Define metabolism, anabolism, and catabolism in full details

The cell is a complex organisms in which many chemical reaction take place so as to maintain normal cellular function. Cell metabolism can be defined as the process through which cells manufacture ATP which provides energy to the cells. Cells have evolved to form highly efficient metabolic mechanisms which differ depending on the cell. Aerobic respiration is responsible for cellular energy needs in animals while photosynthesis is the energy source for plants. The biochemical processes taking place in a cell are influenced by enzymes. Enzymes are catalysts made of proteins and they speed up the reactions in the cells (Porth, Carol & Carol, 2011).

Anabolism and catabolism comprise the two sets of chemical reactions that make up metabolism. During Anabolism, the cells of living organisms synthesize complex molecules from simple molecules through the use of energy. The main aim of anabolic reactions is building up tissues and body organs. Anabolic processes are responsible for increase in bone and muscle mass in animal. The end product for this reaction is includes proteins, lipids and nucleic acids. All cells require anabolic process and catabolic processes. The anabolic processes consume energy that is released by the catabolic processes in the cell (Solomon, BERG & Martin, 2008).

Cell catabolism is where large molecules are broken down into smaller molecules with the release of energy. Some of the molecules broken down include polysaccharides which are broken down into monosaccharides and proteins into amino acids. The broken down molecules are used to form other bigger molecules or broken down to produce energy and waste products (Watson & Berry, 2003).

2. define endothermic and exothermic in full details

Chemical reactions occur with the release or absorption of energy to form the end products. The same case applies to cellular reactions occurring in the body or plant. Energy can be in the form of heat, sound or sound. The form of energy used by the cellular processes is heat energy from the ATP molecules. Monosaccharides in the cell absorb energy from the surrounding in form of ATP to form larger molecules called polysaccharides. Polysaccharides are larger molecules and are more complicated compared to monosaccharide chains. The amount of heat needed for endothermic reactions needs to be maintained at an optimum to ensure that the reaction speed is maintained. Low temperatures may make the enzymes inactive or destroy them, low temperature also make the rate of the reaction slow. High temperatures may denature the enzymes or destroy them. This may affect the nature of reaction for endothermic reactions.

Exothermic reactions are reactions that release energy in to the surrounding. In the cells, cell catabolism is an example of an exothermic reaction in which energy is released in to the surrounding cells. Polysaccharides are broken down with the release of energy in to the surrounding. The temperatures surrounding should also be optimal to ensure that the reaction takes place. High temperatures will affect the speed of reaction by affecting the enzymes (Hartl, Daniel & Maryellen, 2012).

3. why do biochemists often prefer to use the term “exergonic” and” energonic” instead of exothermic and endothermic

The term exergonic is used instead of exothermic and to refer to the chemical process taking place in the cell due to the meanings. The term endothermic evaluates the release of energy from a chemical reaction while exergonic refers to the release of energy in the form of work. The biochemist view the chemical processes taking place in the cell as work done in breaking up big molecules into small molecules. This work is thermodynamics terms involve the flow of energy in the system and the surrounding during a chemical process. The term exergonic refers to positive energy flow from the system to the surrounding in the downhill process. All the exergonic reactions in the cell take place spontaneously with the energy released being used to convert the small molecules into big molecules (Calladine, 2008).

The term endergonic is preferred instead of endothermic to refer to reactions that absorb energy because the endergonic reactions evaluate the absorbed energy in form of work. Work is done in using the energy in the surrounding in the system to enable the cell to convert small molecules into big molecules. Endergonic reactions in the cell are anabolic where energy is absorbed during formation of big molecules. Energy stored in the big molecules is released during the breakdown of the molecule into smaller particles. The main difference between the two sets of terms is the definition of energy and its quantification in the form of work (Hartl & Daniel, 2011).

4. Explain why less ATP is synthesized per molecule of FADH2, than per molecule of NADH.

Oxidative phosphorylation which takes place in the mitochondrial cristae comprise of an electron transport chain in the inner membrane of the molecule due establishment of a chemiosmotic gradient. NADH and FADH2 are electron donors and will donate their extra electrons to the electron transport chain. The electrons will reduce the oxygen in the cell to water in the last step of electron transportation. The reason why NADH yields more molecules of ATP compared to FADH2 lies on the number of electrons donated by the electron donors. Energy is required to produce ATP molecules from the electron donors; the ease of losing an electron from the electron donor to the transport chain also determines the amount of ATP formed. The H+ gradient for electron transportation for the two electron donors are situated in different locations of the mitochondrion. In the overall evaluation of the two proton donors, FADH2 has two protons pumped in the electron chain while NADH has three protons pumped during the electron transport process. Due to the difference in the number of protons pumped, the amount of energy generated from the NADH is more than the energy generated from FADH2. It is evident from the process that the more the protons donated to the transport chain the more the ATP molecules released from the electron donors (Schomburg & Lessel, 1996).

5. Describe the primary, secondary and tertiary structure of DNA.

DNA structure can be evaluated using primary, secondary or tertiary dimensions. The primary structure evaluates the chemical bonds and the atomic composition. The structure which is represented by GATC letters of the alphabet is the sequence of nucleotides in the deoxyribonucleic chain. The sequence represents the order of amino acids in the protein. The primary structure starts with amino-terminal and ends with the carboxyl-terminal. The secondary structure evaluates the three dimensional form of the nucleic acid making up the DNA strand. The atoms making up the molecule are evaluated in a three dimensional space. The secondary structure is defined by the hydrogen bonds in the atom. The secondary structure is a double helix which is supper coiled, twisted around histones. The tertiary structure is complicated and like the secondary structure, it is three dimensional. The nucleic acid has various functions including molecular recognition and catalysis. The tertiary structure is recurrent and it’s a motif used as a molecular building block. The tertiary structure can be predicted from the primary structure. This mode of prediction is known as structural prediction. Many proteins form complexes with DNA in the replication process and transcribing it into RNA. The proteins are also used in regulation of the transcription process. The proteins bind in a specific sequence to the DNA thus the primary sequence can be evaluated as the determinant of functionality (Sinden, 1994).

6. Define transcription and translation in full detail. Please cite all reference and in text

Transcription can be defined as the process where DNA is re-written into the messenger RNA. The process is very complicated it entails the conversion of genetic information stored in the DNA to RNA to facilitate the formation of specific proteins in the cells. The process takes place is the RNA polymerase in eukaryotic organism. The mRNA is made up of expressed and non-expressed regions called exons and introns. The genetic information is transferred to the ribosome and used to make the required protein from the amino acids. Translation can be defined simply as translating information from the nucleotide language to the amino acids in the formation of the proteins needed in the normal functioning of the human body (Engel, 2009).

Translation refers to the process where the mRNA transported to the cytoplasm is translated ensure that the right order of amino acids produces the right proteins. The translation process requires many enzymes. Ribosomal RNA combine with proteins to form the ribosome, the ribosome can accept one tRNA and mRNA at a time. These three types of RNA are used in the formation of proteins from the information stored in the DNA. The translation process takes place in three steps; the initiation is the first step where mRNA penetrates the cytoplasm. The second step is elongation where the amino acids are added to the chain. The last step is where the formation of the protein comes to the end. At this stage the ribosome falls apart (Garrett & Grisham, 2010).

Bibliography

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