SUBMITTED TO:

ANISA NAYEEMA ANWAR
LECTURER,
DEPT. OF ANTHROPOLOGY
SUST.




























GROUP – A
COURSE NO -231
ELEMENTS OF PHYSICAL ANTHROPOLOGY
SUST.








CONTENTS:




    SUBJECT                                    PAGE NO.

INTRODUCTION         .....................................................................         01
CELL                             ......................................................................       01
TYPE OF CELL            .....................................................................        01
CELL STRUCTURE    ......................................................................       2-4
CELL DIVISION         .......................................................................       5-6
CROMOSOME            ......................................................................       7-8
GENE                            .......................................................................      8-9
CONCLUSION             ......................................................................       09
REFERENCE                ......................................................................       10





















INTRODUCTION:
                      
The basic evolutionary process applies to all forms of life – to plants as well as to animals; however, our invest is mainly human-kind. And all cells and genetics will be discussed for the most Part from the point of view of human beings. Never the less, we should keep in mind that the cell is basic to all forms of life, and that cellular characteristics (such as genes, chromosomes, and DNA) are found in the cells of all complex organisms, but the DNA massages differ. Certain messages produce tomatoes, other roses, and still other human beings. We should remember that the process of heredity is essentiality similar in all species. Heredity, as we deal with it hear, refers simply to the passage of genetic information from the cells of one generation to those of another.

CELL:
       
Cell is the building block of all living body. Ideas about cell structure have changed considerably since 1662, the year that Robert Hook discovered cell. He visualized them as,”Hollow of rooms”. As early as the 17th century microscopic studies of specimen of living things showed, they were divided into many similar units. The concept of cell, was first put forward convincingly in 1839, by the German microscopic, Matthias schleiden and Theodor Schwann. They proposed that all plants and animals are contracted from small fundamental units called cells and that all cells arise from other cells.
 
        Cell is the smallest unite of life. Begin at a single cell the zygote or fertilized egg-and that all of the genetic material inherited from our parents is contained within this cell. It is really difficult to say the number of cell in body.

    The number is far too high for most of us to appreciate. Bonner (1962), estimated conservatively over a trillion, Dodzhansky (1970), about to trillion, and Tevitan and Montagu (1971) about 10 quadrillion.

TYPE OF CELL:


TYPE OF CELL    TYPICAL SHAPE     LOCATION       
Epithelial    Cuboidal, brick shape    Skin      
Muscular    Spindale    Muscle      
Nervous    Cell body with long fibers    Sensory and motor neuron      
Connective tissue    Spheroidal    Cartilage ,bone, tendon      
Blood     Disc – shaped     Blood cells      
Ova    Spherical    Ovaries      
Sperm    Flagellated    Testes   
     
TABLE: - Examples of different types of human cells. Desoription of their shapes and their location in the individual, (giese, 1962)

CELL STRUCTURE:

The cell consists of a cytoplasm, bounded by the plasma membrane, within which there is the nucleus, surrounded by the nuclear membrane. In the cytoplasm, are a number of micro organs called organelles? These serve specific functions within the cell. The basic contents of the cell are as follows:

CYTOPLASMIC MEMBRANE: As observed with the electron microscope, the width of this membrane is about, 75 angstroms (pecken, 1960). The plasma membrane encloses the cellular contents and selective passage of certain elements into and out of the cell.
ENDOPLASMIC RETICULUM: This is a network, comprised of membrane bound tubules, with osmotic properties, and is continuous with the Golgi apparatus and the other layer of the nuclear membrane. It may control entry or exit of elements into the nucleus.
RIBOSOME: Ribosomes are granules, abort 15nm across. And composed of protein and RNA. Ribosomes are found as attached to the granular endoplasmic reticulum. Or lie in the cytoplasm as well. It may be solitary, relatively inactive monosome, or jorm groups attached to mRNA.


























MITOCHONDRIA:  The mitochondria, is known as the power house of the cell. They appear either as granules of as rods. They can move, change shape & size, divide and fuse.
Size: Most range from 00.5 to 2 n microns
Structure: Each mitochondrion is bounded by a smooth outer membrane, within which there is an inner membrane. The inner membrane is thrown into a series of internal folds, forming incomplete waves called, cristae. The inner space bounded by the inner membrane is filled with a granular material, called matrix. Contents of the matrix are:-calcium salts
organic crystal
Glycogen
 Some ribosome
DNA & RNA
Functions: production of energy is the primary function of the mitochondria, they supply energy for protein synthesis and in so doing, make contact with the ribosomes on the endoplasmic reticulum.

LYSOSMOME: Lysosome is membrane bound spheroidal or ellipsoidal bodies, 0.08 – 0. Micron in diameter. The enzymes present in lysosomes, include lipase and acid phosphates. After death off the cell it begins to self destruct by autolysis.

GOLGI APPARATUS: The Golgi apparatus are membranous structures that store and may form secretary products. It may also be involved in lysosome formation and it has been hypothesized, that it comprises part of the intra cellular water transfer system.

CENTRIOLES: These are small, about 00.2 microns in diameter, cylindrical structures, located near the nucleus. Centrosomes are involved in cell division and originated from a common body celled Centro some.

NUCLEUS: The nucleus is an essential component of nearly all cells and takes a deep stain.














Shape: Usually spherical of ellipsoidal
Size:   4-10 n microns in diameter.
Position: central in most cells, basal in mucoid cells and peripheral in skeletal muscle fibres.

Component part of nucleus:      - Nuclear membrane
 -  Nucleolus.
                                                             -  Nucleoplasm.
                                                             -  Chromosome

Functions of the nucleus:
It is essential, for biosynthetic events that, characterise cell type and functions.
Takes direct part in cell division.
It is the vault of the genetic massage, expressing the past history and future prospects of the cell.

The nucleus contains the primary nucleic acids, in addition to the proteins, that make up the chromatic network. During cell division, the threads in the network form into the chromosomes, which are located inside the nucleus.























CELL DIVISION:

Multiplication of cells, to sustain the continuity of cell itself, is called, cell division, the cell can produce additional cells, in three probable ways:
           
Amitosis or direct division.
Mitosis or indirect division.
Meiosis or reduction division.


MITOSIS: The nature of most cells to divide. Since division of the two kinds of cells differs, let us first take the less complex somatic cell division, called mitosis.














In mitosis, cell division passes through five basic phases: Interphases, prophase, metaphase, anaphase and telophase. Present Purpose, we need not describe division in complex detail, for those whose interests lie in that direction figure 3.7 separates mitosis into its basic phases, and even greater detail may be found in any college introductory any biology or genetics textbook. A cell with 46 chromosomes must divide into two daughter cells, each containing the exact number of chromosomes as the mother cell. Very briefly, this is accomplished in the following manner:

At the beginning of the division process, each of the 46 chromosomes duplicates itself and actually consists of two longitudinal components called chromatids. There are now 46 2-stranded chromosomes, or 92 chromatics.
The chromosomes position themselves along the equator of the nucleus
The centromeres split and draw the chromatids to opposite poles.
The cell divides, and when division is complete there are two daughter cells, each with 46 chromatids,

MEIOSIS: We have seen how daughter cell with the same number of chromosomes and genetic material as the mother cell. Sexual reproduction, however, is quite another matter, requiring a specialized division process called meiosis. 
        Meiosis is a special type of cell division, that yields haploid daughter cells from diploid parent cell that occur only in sex cells. In the Interphase, DNA is replicated tetraploid in amount, the chromosomes being diploid in number. It takes place in two phases:-Meiosis I & Meiosis II.
Meiosis I: DNA is reduced to diploid amount, in each new cell. Although the chromosome number is haploid. The stages this part of the meiotic process is:                 - Prophase I
            - Metaphase I
            - Anaphase I















Meiosis II: DNA is further reduced to haploid number, while chromosome number remaining the same. Stages of this process are:-
       - Prophase II
       - Metaphase II
       - Anaphase II












CHROMOSOME:

The term chromosome itself was introduced by, waldeyer, in 1988. The chromosome is a sticky, longitudinal thread, It condidts of a very fine filament, which wind spirally around each other. Each member of the pair is called the chromatid, the chromatids bear genes. The chromated pair lies in a matrix, which has a delicate sheath of pellicle. The chromosome strands become identifiable only, during cell multiplication.

   















CHROMOSOME NUMBER: The diploid chromosome number in humans, has been accurately known for only a short time, and consists of 22 pairs of autosomes and two sex chromosomes. By convention, the human chromosome complement has been divided into seven groups, according to; (1) their relateve lengths and (2) the position of the centromere in the chromosomes of approximately the same size. The location of the sex chromosomes, of approximately the same size. The location of the sex chromosomes, however, is not arranged quite the same way. In the case of the male body, consisting [XY], for instance, the instance, the [X] is attached at the beginning of the first series of the autosomes, whereas the [Y] chromosome belongs to ghee end of the last series. The same format works for the female body as well.
    The chromosome numbers in a few species of the primate order are shown here:


TAXONOMIC NAMES    VERNACULAR NAME    CHROMOSOME NUMBER      
Ateles paniscus    Black spider monkey    34      
Homo sapiens    Man, women    46      
Pongo pigmaeus    Orang-utan    48      
Lemur variegatus    Ruffed lemur    46      
Tarsirs bancanus    Horsfield’s tarsier    80   

Table: Natural chromosome number in few primate species.

FUNCTIONS: Sex of any given animal is determined by two sex chromosomes, which are different from the autosomes in size, shape & functions. They are usually expressed as [X] and [Y] chromosomes. In most insects and mammals, if there be double dose of [XX] present in the zygote, introduced by the gametes, the zygote develops to be female, and if there be one [X] and one [Y] , it develops into the male. Sex is therefore fixed at the time of the fertilization, and long before the birth of the child.
    The chromosomes bear genes that are said to be respondible for all the somatec and internal characters. Colour characters, which are carried down through generation. By means of inheritance.

    CHROMOSOME MUTATION: A chromosome mutation is a heritable change in the structure or number of chromosomes. Although, cell division is a remarkably accurate process. Chromosomes in the parent cell. For a variety of reasons, things sometimes go wrong. Chromosome mutations may occur both artificially and spontaneously. An individual with a chromosome mutation, will posses either an abnormal number of chromosomes of a structural alteration in one of more chromosomes in the cell. This in turn, means that the individual may suffer from serious mental or physical or both defects.




GENE:

Although not all biologists agree on the definition, we have defined the gene as that section of DNA-a sequence of cordons on the DNA temple- responsible for the ultimate synthesis of a specific polypeptide chain of amino acids. To put it another way a gene is that portion of a DNA molecule that specifies the manufacture (synthesis) of a protein of part of a protein (hemoglobin, say) that will produce or assist in the production of one or more physical traits. A gene, then, is not a discrete unit operating in the nucleus or the cell; it is a part of a large DNA molecule.

GENE & DNA: Gene, the hypothetical unit of inheritance, can be defined as a segment of DNA, which has a specific or definite locus, measurement and function. DNA is the chemical vehicle of the actual genetic information. The hereditary material contained in the chromosome, is only a small fraction of their masses. Assuming the weight of DNA required specifying the hereditary make up of four billion people, is less than 3/100 grams. The duplication of DNA, in the cell is accomplished prior to mitosis. As the basic chemical of both gene & chromosome, DNA is the nucleic acid that plays the direct role in heredity.




COMPOSITION OF DNA:  DNA, RNA and proteins are polymeric molecules. They are made of smaller sub units. In DNA & RNA, these sub units are nucleotides, each of which consists of three components. These include:            


1.  A    5-carbon sugar molecule.
                    2.  Phosphoric acid.
                3.  The nucleotide base:
                    a) Adenine, A.
                    b) Guanine, G.
                    c) Thymine, T.
                    d) Cytosine, C.

DNA STRUCTURE: On the basis of results of X-ray crystallography on DNA, James walson and Francis crick in 1953, propoded their famors model, that shows DNA as composed of two sporally wound chains, in which Adenines in all strand, are always linked y double hydrogen bonds, to Thymines and accordingly Guanines to cytosine by triple hydrogen bonds. The four nucleotide basws, adenines, Thymines, Guanines & cytosine, are provided with constant supply of ATP, the organic currency of energy.
The DNA molecule begins duplication by uncoiling itself. The paired strands start to separate at the end by breaking the relatively weak hydrogen bonds between base pairs. There are at least three possible ways, to envisage the mechanism of replication of DNA. They are:
Semi-conservative replication: This would result in two molecules of DNA, each composed of one old and one new strand.
Conservative replication: This makes the DNA molecules. To serve as templates for the synthesis of new DNA, without separation of the pairs of strands.
Dispersive replication: Here the parent DNA breaks up into fragments, each of which is replicated separately. Identical replication of the original DNA molecule is ensured by the specific hydrogen bonds, assigned to each of these nucleotides. Adenine pairs only with Thymine and Guanine with cytosine. Thus, the same molecular structure, as in the original DNA, is reinstated & passed on to all cell division products, in the individual.
               

CONCLUSION:

    Our assignment was on cell. Through this study we tried to reveal the interactions between physical Anthropology and Cell. We discussed about Cell, type of Cell, structure of Cell, Cell division, chromosomes & gene. The field of cell is really broad and highly specialized. This work only provided the basic information about cell. Physical Anthropologist attempts to explain human body & structure. Genetics & cell is the way physical Anthropologists, Study and tried to foresee our ultimate destination.






 REFERENCE:


1. AN INTRODUCTION TO PHYSICAL ANTHROPOLOGY

                   - ROBART GERMIN & J. NELSON.


2. ASSIGNMENT ON GENETICS


            - MS. ANISA NAYEEMA ANWAR (1995)