Cellular pathways of metabolism



TAQ 1:

Criterion 3.1: Explain the way in which the genetic code in DNA controls the production of proteins.

If a DNA sequence gives rise to the following RNA fragment AUG-CGU-AAA-GCA-GAG-GGA-CAA-UAA

  1. How has this been formed from the DNA strand (150 words)

DNA is known for its double-helix structure of DNA that has its own significance. It is made up of four nucleotide base units; these are Adenine (A) Thymine (T), Cytosine (C), and Guanine (G), In RNA it is Guanine (G), Cytosine (C), Adenine (A), and Uracil (U). That is Thymine is change to Uracil because RNA does not bind to the nucleotide base Thymine. They are pair up the Adenine pairs with Thymine and Guanine pairs with Cytosine in DNA, and in RNA it is Guanine pairs with Cytosine, and Adenine pairs with Uracil. So when we know the sequence of bases on 1 strand of DNA, we also know the sequence of bases on the other strand of DNA. DNA has all the information a cell needed to synthesize protein and also to replicate itself, in other for any cell to function, it needed the storage for repository of information.

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The modern technology has provided us with a complete sequence and couple of different organisms. So we now know the sequence of the entire DNA and all the chromosomes in the organism. [24]

Strand 1:









Strand 2:









  1. How is this RNA then transformed into a protein (150 words)

RNA transformed into protein by ribosome, the mRNA code is translated into a transfer RNA (tRNA) code which will then transfer into a sequence protein. The ribosome that converts mRNA into proteins is large and complex.RNA also contains the information for making a protein is called messenger RNA (mRNA) because it carries the information, or message, from the DNA out of the nucleus into the cytoplasm. Messenger RNA (mRNA)carries the instructions for making proteins (Clancy,S.(2008)). Like DNA, proteins are polymers.Long chains assembled from prefab molecular units, which, in the case of proteins, are known as amino acids. A large molecular machine called ribosome,translates the mRNA code and assembles the proteins [7]. Messenger RNA contains the information to make just one single polypeptide chain - in other words for just one protein, or even just a part of a protein if it is made up of more than one polypeptide chain. The messenger RNA contains a sequence of bases which reads like three times, code for the amino acids used to make protein chains (Smith,A.(2008)).

TAQ 2:

Criterion 4.1 Explain the behaviour of chromosomal during meiosis in determining Mendelian inheritance mechanisms.

4.2 Interpret results of monohybrid inheritance

Part 1 – Discuss the work of the Austrian Monk Gregor Mendel. Your work should include Mendel’s rules of inheritance (200 words)

During cell division chromosomes are replicated and distributed to daughter cells during meiosis

In the nineteenth century, Mendel organise different experiments on breeding of pea plants, and this characteristics were passed from one generation to another. In the pea plants, the spherical seed (R) are dominant and dented seed (s) are recessive.

Mendel uses some selective herders in plants and animals to produce a useful hybrid. Hybrids are offspring that mature in two genetically kinds of parents. To determine the seed shape, both parents’ plants have to be heterozygous (Rr) [15]. The dominant allele (R) in homozygous (RR) or heterozygous (Rr) plants is for spherical seeds, and homozygous recessive (rr) plants have dented seeds. Mendel’s work also showed first that each parent contributes one factor of each trait shown in offspring. The second one explain how two members of each pair of factors segregation from each other during gamete formation. Four one says that males and females contribute equally to the traits in their offspring. And the last one acquired traits that are not inherited [18]. Mendel has three laws he created:

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Mendel’s first law of Dominance stated that when mating takes place between the two organisms of different traits, each offspring will display the trait of one parent.

Mendel’s second law of Segregation states that for any trait, that each parent’s pairing of genes (alleles) split and one gene passes from each parent to an offspring.

Mendel’s third law of Independence Assortment states that alleles fordifferenttraits are distributed to sex cells (& offspring) independently of one another [10].

Part 2 – In humans there is a gene that controls formation of muscles in the tongue allowing people with those muscles to roll their tongue and those without to be unable to do so. This gene is expressed as a dominant gene. Using a Punnet diagram as part of your answer discuss the children of a homozygous none tongue roller (recessive) and a heterozygous roller and what proportion of children they would have (100 words)

Heterozygous (dominant) is allele traits that form the gene that is expressed in full when two different alleles are present. While homozygous (recessive) is allele that forms the gene not expressed when two different alleles are present. Homozygous shows the genes that are same RR and rr. In Heterozygous also shows two different genes Rr. a child can have a full taster gene TT on the other hand, a child can have a taster gene and non-taster gene (not sufferer from it) but 50% chance that they will pass the condition on their children (Tt). From the Punnett diagram below shows that the proportion of a child with roller tongue and a child without roller tongue is 50/50. 50% roller tongue and 50% not roller tongue.

T= roller tongue, t = not roller tongue Parents = Tt x tt









Part 3 – There is a chemical called Phenylthiocarbamate which some people can taste and others can’t due to their genetics, the ability to taste the chemical is a dominant trait. Using a Punnett diagram discuss how two heterozygous parents would have children that can taste and those that cannot and the proportions (100 words) T= taster T= taster

In a situation where two parents heterozygous (dominant) have the same genes, and heterozygous mostly dominant all. In the case where two parents have it, shows that there is 100% chance that they children are likely to have (GT). With Mendel observe shows there is 25% in TT, 50% TG and 25% GG children in all. The proportion in Punnett diagram shows 75% will be in T and 25% in G. but it stills a 50/50 chance a child can have a full taster gene and full non-taster (TT). I will use the Punnett diagram below to show how it works and the proportion of it.









Part 4 – Suppose a woman who is both a homozygous tongue-roller and non-PTC- taste marries a man who is a heterozygous tongue-roller and is a heterozygous PTC taster. If these parents have plenty of children so that they had 16 in all, how many of those would you expect in each class? (100 words)

We use dihybrid cross to define the cross between two parents, where one parent has both homozygous and heterozygous and the other parent has one. In this, I will say that because the male normally have two genes (XY) and female (X), the male (GT) will dominant the female recessive (Gt). With 16 children the proportion in ratio in general will be 9/16, 3/16, 3/16 and 1/16. This shows that inheritance of each trait is determined by the factors that passed on to the generation. But in each class it will be 3:4, 2:4, 2:4 and 1:4 chances the children with tongue-roller and PTC taster will dominant the children without tongue-roller and non PTC taster. That is because male genes always dominant.

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T = taster and t = non- taster Gene= Gg G>t T>t GGtt x GgTt

























Criteria 5.1: Describe the chemical structure of carbohydrates, proteins and lipids.

5.2: Evaluate the role of carbohydrates, proteins and lipids in nature.

TAQ 3: Complete a table similar to the one below (300 words)





Lipids did not have chemical reaction that is similar to proteins and carbohydrates. Lipid can’t be making either from protein or carbohydrate. But when one cell absorbs fat, the fat can either be stored or burn immediately [12].

Carbohydrates are compound molecules that made up of three elements of carbon, hydrogen and oxygen, with one atom of carbon and two atoms of hydrogen in every atom of oxygen. Carbohydrates are source of energy for the body like glucose and a store of energy and starch in plants.

Amino acids is the side chains, it have a great variety of chemical structures and properties.

Proteins are the central roles in a cell catalyse, the chemical reactions that are essential for the survival of the cells, that is proteins is called enzymes. It also combines effect all of the amino acid side chains in a protein that determines the three-dimensional structure and its chemical reactivity. [17]


Lipids have no single structure in general, but the common lipids are triglycerides and phospholipids. Triglycerides are fats and oils, and there have glycerol backbone bonded to three fatty acids. Phospholipids contains glycerol and fatty acids, they also have phosphoric acids and a low-molecular weight alcohol. Phospholipids have lecithins and cephalins. [21]

Carbohydrates are simple sugars known as monosaccharides like glucose are the basic carbohydrates that are joins together to make a more complex disaccharides and polysaccharides. When monosaccharides are split apart through the digestion and absorb them separately into bloodstream. Once cells will burn the chemical energy, store them or convert them into fat. [23]

The proteins also provide structure and support for cell. The protein molecule is among the important function of four levels of structure used to describe the protein. [11]

The primary structure is linear sequence of amino acids use in creating peptide chain. Secondary structure hydrogen are bonding between amino acids tertiary structure is for shape of the protein and quaternary structures Composed of two or more polypeptide chains. [19]

Roles in nature(uses ):

Lipids are used for energy storage in form of fat in humans and oil in plants. Lipid is also used as heat insulation as fat under the skin reduces the heat loss. Lipids are also used to absorb the fat vitamins likes A, E and D from your diet. Body lipids used to form and transport cholesterol. [17]

Carbohydrates are used to directly monosaccharide glucose in the body. Glucose is used as building blocks importance macromolecules like DNA, RNA and ATP. They are used to store energy and genetic information as well as playing an importance role in cell to cell interaction and communication. [23]

Proteins are used for stored foods for the cells. The brain and some major organs in our body use protein to absorb and operst properly. Proteins are also used for build cardiac muscles. Our body used protein to make haemoglobin and to also carry red blood cells oxygen to every part of the body. [17]

TAQ 4:

6.1: Explain the mechanism of enzyme action and its importance in metabolism.

How do enzymes work and what is the role they play in the processes of metabolism? (300 words)

The major mechanism by which the enzymes catalyse in chemical reactions begins with the binding of the substrate to the active site on the enzyme. In general enzyme has an area with a particular shape that is referred as the active site of the enzyme; in there is where the reaction carries out. [20] In work when a molecule of the right chemical for the enzyme comes along and fits exactly into the shape, and where enzyme and substrates were combine, to formed it is called enzyme-substrate complex. One substrate and one enzyme is called binary complex. The substrates attracted the active site with the use of hydrophobic force and electrostatic is called noncovalent bonds and it happens because it has physical attractions and not chemical bonds.[25] Energy activation is the amount of energy need to bring the entire molecules in one mole of a substance and that gives temperature of the transition state. After the reaction take place, the products of the reaction then leave the active site which leaving it ready for another molecule of the chemical. When the product was released from the enzyme, the surface will regenerate the enzyme for another reaction cycle. [14]

Enzymes are known as biological catalysts; they lower the energy barrier and then speed up the reaction without it being used up in that reaction. Enzymes are chemical in peoples saliva, it help break down the food so that it can be digested. Without enzymes, we can’t be able to digest most of our foods. Some enzymes help in break down large nutrient molecules like fats, proteins and carbohydrates and into smaller molecules. [19] Enzymes shows the broken down of molecules in smaller pieces, it travels through the intestinal wall into the bloodstream. The enzymes also promote the formation of large, complex molecules from the small, simple ones to produce cellular constituents. Enzymes are also responsible for numerous other functions, which include the storage and release of energy, the course of reproduction, the processes of respiration, and vision. They are indispensable to life. [20]

TAQ 5:

7.1: Explain the importance of glucose and oxygen in energy production within the cell.

7.2: Outline the key biochemical pathways involve in cellular respiration.

There are two major pathways involved in the production of energy within the cell. What are they and how do they link to each other? (300 words)

GLYCOLYSIS: It is a multistep metabolic pathway is found in the cytoplasm of cells in general the living organisms and anaerobic. There are six enzymes used that operate in the metabolic pathway. The first and three steps of pathway used ATP to energize the molecules. During this process, two molecule of ATP will expended. Also somewhere in the process, the six-carbon glucose molecule changed into intermediary compounds where there will be divided into two-three of carbon compounds. Latter stages of glycolysis have four ATP molecules that is synthesized using energy during the chemical reactions.

Why the four ATP molecules are synthesized, the two ATP molecules are inserted in the net gain of two ATP molecules in glycolysis during the process. Latter will undergo a conversion and will later form pyruvic acid.

The electrons that transferred the coenzymes NAD form NADH were dehydrogenase enzymes that remove electrons from the intermediates. ATP and NADH is molecule cell used for energy. But glycolysis does not use oxygen, the process is called anaerobic. Kerbs cycle uses two molecules of pyruvic acid to formed glycolysis and with high-energy molecules of NADH and FADH with some ATP and carbon dioxide. The kerbs cycle is a chain of enzyme-catalysed chemical reactions, which is the most important in aerobic respiration. Kerbs cycle is known as citric acid cycle it is part of a metabolic pathway involved in chemical that conversion of carbohydrates, fats and proteins into carbon dioxide and water to generate a form of usable energy. [22] Whenever oxygen is present, mitochondria will have to undergo aerobic respiration that leads to Krebs cycle. When citric acid cycle was inside the mitochondrial, will complete the breakdown of pyruvic acid and that will lead into releasing of carbon dioxide, ATP and electrons. There are 8 steps process in citric acid cycle that involves the 8 different enzymes. In all the process the whole cycle, like acetyle-CoA will change to citrate, isocitrate, α-ketoglutarate, succinyl-CoA, succinate, fumarate, malate, and oxaloacetate (Hinkle, P. C (1978)).


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