Macromolecular Compsition of the Liver Cell

Topics: Protein, DNA, RNA Pages: 10 (3513 words) Published: March 14, 2012
Macromolecular Composition of the Liver Cell
Formal Report
The aim of the experiment was to test for the presence of DNA, RNA, protein and glycogen in the cytoplasm and the nucleus of bovine liver cells. From the findings of the results the distribution of these macromolecules can be shown within the liver cell. This was carried out by undertaking qualitative experiments, where the observation of a colour change was noted and a quantitative experiment, where numerical data was recorded from the measurements of light absorbance. Introduction

The liver is the largest gland in the human body, it is a vital organ which is essential for human survival. The liver cells serve for over 500 functions within the body, their main functions are to process and store various nutrients from food, the release energy, to clean the blood of toxins and to make proteins. ( Glycogen

Glycogen is sugar composed of multiple units of glucose linked together by α-1.4. glycosidic bond. These large units are called polymers, they also contain branched links every 8 – 10 units by a α-1.6. glycosidic bond (fig 1). These polymers form granules ranging in size from 10 – 40 nm (fig 2).

Fig 1. A section of glycogen showing fig 2. Structure of a glycogen granule the α-1.4. and α-1.6. Glycosidic Bonds

Glucose is consumed in the diet and is required by the bodily tissues and the brain as a source of energy. The smooth endoplasmic reticulum (ER) in the liver and muscle cells synthesise glucose into glycogen and store this as an energy reserve in the cytoplasm. When this energy is required by the body, the smooth ER can quickly convert it back into glucose and release it into the bloodstream. The liver cells act as a buffer by keeping the blood sugar levels at a constant rate of approximately 0.1% at all times. The muscle cells differ from the liver cells as they do not release their reserves of glycogen into the blood stream, they keep it purely for their own use. (Berg et al.. 2002) Protein

A protein is a polypeptide chain which consists of amino acid molecules joined together with peptide bonds. Protein is an essential ingredient of living organisms and plays a fundamental role in nearly all cellular processes. Each cell consists of thousands of different proteins, each protein has its own structure and function which is important for its specific attributes. Proteins serve many functions within the body, fig 3 shows a table explaining the overview of some common functions:- Protein Type| Protein Function|

Enzymes (most common type)| Proteins that speed up a chemical reaction whilst not being changed themselves| Defence proteins | Proteins that fight off viruses and bacteria| Transport proteins| Proteins that transport molecules across a cell or to different locations in the body| Storage proteins| Proteins that store amino acids, nutrients or other proteins for later use by the cell| Structural proteins| Proteins that provide support to the cell, cell-cell connections, tissue connections and skin appendages| Hormonal proteins| Proteins that produce hormones in homeostasis | fig 3. Table of common protein functions

Proteins are constructed in the cell from only 20 different amino acids. The order in which the amino acids occur will determine the primary structure of the protein, the polypeptide chain will progress through further modifications within the cell by spiralling and folding due to the interactions and chemical bonds between the different amino acid molecules and hydrogen bonding. Some amino acids are necessary to be consumed within the diet as the body cannot make these. Once the body has consumed these within the diet it will go about breaking them down into their individual amino acid building blocks and reassembling them into the protein...
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