Why Actin Is A Protein Of Any Cell

Cytoplasmic streaming is the organised flow of the cytoplasm and its constituents within a living cell (Shimmen et al., 2004). Organelles and important molecules move through the cytosol along the structure of the cytoskeleton (actin filaments and microtubules) with the aid of myosin I, an actin-binding motor protein that plays a part in various cell functions including cell motility and endocytosis (Flavell et al., 2008). Actin microfilaments (F-actin) are the thinnest filaments of the cytoskeleton,

A muscle is made of fibers. They are long cylinders that are larger than many specialized cells in the human body, about 1-40 microns long and 10-100 microns in diameter. Muscle fibers are made of myofibrils, or filaments. The filaments are arranged in a hexagonal shape. There are both thick and thin filaments. The z-disk or z-line runs down the long axis of the muscle fiber. The z-disk is a structure made up of myofibrils and is called a sarcomere. Running along the z-disk is the t-tubule which is a membrane system called the sarcoplasmic reticulum. This stores and releases the calcium ions that cause muscle contractions. While a muscle is contracting, the myosin

A protein has multiple existing structures, these are the primary, secondary, tertiary and quaternary structures which occur progressively. A protein is essentially a sequence of amino acids which are bonded adjacently, and interact with one another in various ways depending on the R group that the amino acid contains. There are 20 different amino acids which are able to be arranged in any given order, thus giving rise to a potential 2.433x1018 (4.s.f) different combinations, and therefore interactions between the various amino acids.

Proteins are complex structures made up of chains of amino acids. Each protein has a different function such as enzymes to catalyze reactions or protein hormones to trigger certain functions of a cell. First let’s start with the most basic component of a protein: an amino acid. An amino acid is made up of a central carbon atom attached to a hydrogen atom, a carboxyl group, an amino group, and an R group which varies

They are made up of amino acids (consists of amino group, carboxyl group, hydrogen atom, and R group). Polypeptide bonds form between amino acids to form polypeptide chains. Amino acid sequence is primary protein structure. The secondary structure is the bonding pattern of the amino acids (e.g. helix, sheet, etc.). The tertiary structure consists of the domain, where the sheets or helixes fold on each other and become stable. The quaternary structure consists of several polypeptide chains that form advanced proteins such as human leukocyte

The basic building blocks of proteins are amino acids, the biuret reaction tests for protein. A solution of sodium hydroxide is added to a sample then a few drops of copper sulphate solution, if positive – the solution will turn mauve. There are 20 different amino acids and they can be joined in any order. Therefore there can be many different functions. A protein consists of one or more polypeptide chains (a polypeptide chain being multiple amino acids joined together via condensation, producing a peptide bond). Different proteins have different shapes as the shapes are determined by the sequence of amino acids.

These proteins differ depending on their function in the cell, but often prevent misfolding of nascent protein, and assist in refolding of the misfolded proteins. Protein folding is dependent on the amino acid sequence within the polypeptide chain that is synthesized from the DNA strand in the ribosome.2 Upon release from the ribosome, the polypeptide chain undergoes a series of conformational changes based on the amino acid sequence to produce a functional protein structure. The assembled native protein is directed to the ER via vesicle

Proteins are polymeric chains that are built from monomers called amino acids. All structural and functional properties of proteins derive from the chemical properties of the polypeptide chain. There are four levels of protein structural organization: primary, secondary, tertiary, and quaternary. Primary structure is defined as the linear sequence of amino acids in a polypeptide chain. The secondary structure refers to certain regular geometric figures of the chain. Tertiary structure results from long-range contacts within the chain. The quaternary structure is the organization of protein subunits, or two or more independent polypeptide chains.

actin “slid” past each other and neither filament changed in length. In 1957 Allan Huxley

They have four levels of conformations (primary, secondary, tertiary and quaternary structures). The primary structure of enzymes is a linear sequence of amino acids. The secondary structure of enzymes is a regular and recurring of amino acids in a peptide chain as a result of the hydrogen bond. The tertiary enzyme conformation is a complete 3-D shape of a peptide, which occurs because of weak electrostatic forces. The quaternary enzyme structure is a spatial correlation between various subunits or polypeptides.

Actin is an important component of cell migration and muscle contraction. But it is not the answer we are looking for. Actin is a globular protein that combines into chains, two of which twist about each other forming microfilaments in the muscle and other kinds of the cell. Actin filaments can form structural networks when certain proteins link along the sides of each filament and allow a new filament to form. The structural role is actually to bear tension. (Campbell, pg. 115). The other choice that goes with choice A is microtubules. This seems to be part of the answer after carefully evaluating its definition and functions. However, I wont reveal my explanation yet as to why this is part of the answer. So for consider choice A to be

Microfilament: Microfilaments are narrow protein fibers within the cytoskeleton. They are made up of two twisted proteins called actin; this is why they are also known as actin filaments. Their function is to give the cell its shape and also aid in cellular movement.

Microfilaments are the thinnest/finest of all the filaments and are about 3-6 nm in diameter. Microfilaments are composed of contractile globular protein known as actin. They are also responsible for movement as it is associated with myosin which is a protein responsible for muscle contraction. Intermediate filaments are mid-sized proteins as the name suggests usually measuring 8-12nm in diameter. These filaments are constructed from a number of different subunit proteins namely desmins, keratins, laminins and vimentin. Intermediate filaments play a structural role by providing strength to cells and tissues instead of cell motility. Tubulin proteins have a cylindrical shape, comprising alpha and beta subunits polymerized into microtubules.

Immunohistochemical analysis for smooth muscle actin (SMA) was done and the intensity of staining and staining location were considered.

Bettelheim, Brown, Campbell and Farrell assert that polypeptide chains do not extend in straight lines but rather they fold in various ways and give rise to a large number of three-dimensional structures (594). This folding or conformation of amino acids in the localized regions of the polypeptide chains defines the secondary structure of proteins. The main force responsible for the secondary structure is the non-covalent