Lecture 1 Human Biology

The Diversity of life Biology is the science of living things- The Science of Life The living worlds teems with a breath-taking variety of creatures. Creatures can be categorized into six groups, or kingdoms.

1- Cellular Organization Properties of Life The living world is very diverse, but all living things share five more basic properties 1- Cellular Organization All living things are composed of ONE or MORE CELLS. Cell: is a tiny compartment with a thin covering called Membrane. Some cells have very simple content. For example: Bacteria Other organisms have many cells. For example: animals, plants, fungi Human body cell Bacterial cell

All living organisms use energy to grow. 2-Metabolism The complex of physical and chemical processes occurring within a living cell or organism that are necessary for the maintenance of life. All living organisms use energy to grow. Metabolism in a bacterial cell

3- Homeostasis Homeostasis can be defined as the stable condition of an organism and of its internal environment. Your body acts to maintain an internal temperature (37C). However hot or cold the weather might be.

4- Growth and Reproduction All living things grow and reproduce sexually or asexually. Bacteria increase in size and simply split in two cells. More complex organisms grow by increasing the number of cells and reproduce sexually. Bacterial cell division Human reproduction

5- Heredity All organisms have a genetic systems that is based on the replication and duplication of along molecules called DNA (deoxyribonucleic acid). The transmission of characteristics from parent to offspring is a process called heredity. Bacterial cell Animal cell

The Organisation of Life The biological levels of organization of living things arranged from the simplest to most complex. It can be classified into three levels: 1- Cellular level Molecules: atoms are joined together into complex clusters called Molecules Organelles: complex biological molecules are assembled into tiny compartments within the cell called Organelles. Cells: organelles and other elements are assembled in the membrane bound units called cells

At the organismal level, cells are organized into three levels 2-Organizmal level At the organismal level, cells are organized into three levels Tissues: A tissue is an ensemble of similar cells and their extracellular matrix from the same origin that together carry out a specific function. Organs: Tissue are grouped into organs which are a body structures composed of several different tissues grouped together in a structural and functional units. Organs systems: organ are grouped into organ systems. Human digestive system

3- Populational level Population: it is a group of organisms of the same species living in the same place. Species: all the population of a particular kind of organisms together form a species , its members similar in appearance and able to interbreed. Community: at a higher level of biological organization, a community consists of all the populations of different species living together in one place. Ecosystem: at the highest tier of biological organization, a biological community, and the soil and water within which it lives together constitute an ecological system or ecosystem.

The Chemistry of Life All organism are chemical machines. Any substance in the universe that has the mass and occupies space is defined as matter. Matter is composed of extremely small particles called atoms. Molecules: is a group of atom held together by chemical bonds. E.x. glucose Macromolecules: A macromolecule is a very large molecule, such as carbohydrate, commonly created by polymerization of smaller subunits (monomers).

Macromolecules  the four major macromolecules essential forms of life are proteins, nucleic acids, carbohydrates, and lipid 1- proteins Proteins are macromolecules that carry many functions in the cell. The are produced by linking together of amino acid with covalent bond called Peptide bond. The sequence of amino acids is the primary structure of the protein. The chain of amino acids then folds into its final shape, exhibiting different level of complexity, from secondary to tertiary to quaternary structure.

DNA (Deoxyribonucleic acid) 2- Nucleic acids DNA (Deoxyribonucleic acid) DNA is the molecule that carries the genetic information in all cellular forms of life and some viruses. It belongs to a class of molecules called the nucleic acids, which are polynucleotides - that is, long chains of nucleotides. Each nucleotide consists of three components: a nitrogenous base: a five-carbon sugar molecule (deoxyribose in the case of DNA) a phosphate molecule

Primary Structure of DNA

Secondary Structure of DNA Secondary structure is the set of interactions between bases, i.e., which parts of strands are bound to each other. In DNA double helix, the two strands of DNA are held together by hydrogen bonds. The nucleotides on one strand base pairs with the nucleotide on the other strand.

Ribonucleic acid (RNA) RNA is typically single stranded and is made of ribonucleotides that are linked by phosphodiester bonds. A ribonucleotide in the RNA chain contains ribose (the pentose sugar), one of the four nitrogenous bases, and a phosphate group.

3- Carbohydrates Polymers called carbohydrates make up the structural frame work and play critical role in energy storage. A carbohydrate with one unit of sugar is called a simple sugar or a monosaccharide.  A disaccharide: is the sugar formed when two monosaccharides (simple sugars) are joined by glycosidic linkage. Polysaccharides are polymeric carbohydrate molecules composed of long chains of monosaccharide 

4- Lipids Fats and other biological molecules that are not soluble in water but soluble in organic solvents called lipids. Fat molecules are composed of fatty acid and glycerol. Fatty acid is along chain of carbon and hydrogen atoms (called a hydrocarbon) The three carbons of glycerol form the backbone to which three fatty acids are attached. The membrane of cells made of a modified fat called a Phospholipid