Biology Lecture Notes 2023-2024 PDF

Biology ‫البايولوجي المرحلة‬ First grade ‫األولى‬ Sala Jafar Nadhem ‫د سال جعفر ناظم‬ What is biology? Biology is the natural...

Biology ‫البايولوجي المرحلة‬ First grade ‫األولى‬ Sala Jafar Nadhem ‫د سال جعفر ناظم‬ What is biology? Biology is the natural science that studies life and living organisms, including their physical structure, chemical processes, molecular interactions, physiological mechanisms and evolution. Biology recognizes the cell as the basic unit of life, genes as the basic unit of heredity, and evolution as the engine that propels the creation and extinction of species. Why we study biology? Biology is important to everyday life because it allows humans to better understand their bodies, their resources and potential threats in the environment. Biology has also helped doctors learn how to keep people healthy and fight off disease. Biologists have learned that things called pathogens, which are themselves other living entities, cause diseases. By understanding how these dangerous organisms work, scientists can fight them off. Because of biology, many people have lived long lives as they have been able to avoid diseases. Importance of biology in our daily lives also lies in finding and curing hereditary abnormalities like hemophilia, Down’s syndrome, etc. Sub-division of biology The branches of biology are: 1. Cellular biology (cytology): 2. Molecular biology 3. Physiology  Biology ‫البايولوجي المرحلة‬ First grade ‫األولى‬ Sala Jafar Nadhem ‫د سال جعفر ناظم‬ 4. Genetics 8. Development biology 5. Microbiology 9. Marine biology 6. Zoology 10. Ecology 7. Botany 11. Clinical biology: It’s a field that usually involves laboratory work, such as testing, evaluating, detecting and analyzing cells, blood or body fluids. In general, clinical science is a field that evaluates and investigates medical treatments, principles and methods, using classically designed studies under controlled conditions. Cell Cell: It is the basic structural, functional, and biological unit of all known organisms. A cell is the smallest unit of life. The cell contains various structural components to allow it to maintain life which are known as organelles. All the organelles are suspended within a gelatinous matrix, the cytoplasm, which is contained within the cell membrane. All cells have an outer membrane, a control center called a nucleus that contains our DNA, and tiny powerhouses called mitochondria. One of the few cells in the human body that lacks almost all organelles are the red blood cells (RBC). Fig 1-1  Biology ‫البايولوجي المرحلة‬ First grade ‫األولى‬ Sala Jafar Nadhem ‫د سال جعفر ناظم‬ The cell types There are two types of cells: 1. Prokaryotic cell: unicellular organisms which don’t have membrane bound organelles like nucleus and mitochondria. Example: bacteria and archaea. 2. Eukaryotic cells: unicellular or multicellular organisms which have a membrane bound organelles like nucleus and others. Plants, animals, fungi, protozoa and algae are all eukaryotic. These cells are about a thousand times greater in volume than the prokaryotes  Biology ‫البايولوجي المرحلة‬ First grade ‫األولى‬ Sala Jafar Nadhem ‫د سال جعفر ناظم‬ All the body cells that comprise a single organism share the same set of genetic instructions in their nuclei the cells are not all identical. Rather, plants and animals are composed of different tissues, groups of cells that are specialized to carry out a common function. This specialization occurs because different cell types read out different parts of the DNA blueprint and therefore make different proteins. Plant cells: Special Properties of Plant Cells Among eukaryotic cells the most striking difference is between those of animals and plants Plants have evolved a sedentary lifestyle and a mode of nutrition that means they must support a leaf canopy. Their cells are enclosed Biology First grade Dr Sala Jafar Nadhem within a rigid cell wall that gives shape to the cell and structural rigidity to the organism This is in contrast to the flexible boundaries of animal cells. Plant cells frequently contain one or more vacuoles that can occupy up to 75% of the cell volume. Vacuoles are often pigmented, and the spectacular colors of petals and fruit reflect the presence of compounds such as the purple anthocyanins in the vacuole. Cells of photosynthetic plant tissues contain a special organelle, the chloroplast, that houses the light-harvesting and carbohydrate- generating systems of photosynthesis (page 271). Plant cells lack centrosomes although these are found in many algae. Animal cells: In animals there are four major tissue types: epithelium, connective tissue, nervous tissue, and muscle. Epithelia are sheets of cells that cover the surface of the body and line its internal cavities such as the lungs and intestine Connective tissues provide essential support for the other tissues of the body. They include bone, cartilage, and adipose (fat) tissue  Biology ‫البايولوجي‬ First grade ‫المرحلة األولى‬ Sala Jafar Nadhem ‫د سال جعفر ناظم‬ Nervous Tissue Nervous tissue is a highly modified epithelium that is composed of several cell types. Principal among these are the nerve cells, also called neurons, along with a variety of supporting cells that help maintain them Function of human cell: The functions of the human cell vary based on the type of cell and its location in the human body. All the organelles work together to keep the cell alive and allow it to carry out its specific function. Sometimes these organelles are highly specialized and can vary in (size, shape and number). Its functions include - Intake of nutrients and other substances, - Processing of these compounds, - Production of new substances, - Cell replication; - and energy production. - In specialized cells that need to be motile, like sperm cells, tail-like projections allow for cellular locomotion. As mentioned, there are 226 types of Body cells - some can form sheets like those in your skin or lining your mouth, while others can store or generate energy, such as fat and muscle cells.