Cell Structure Biochemistry Lectures 1 PDF

Biochemistry BIO Chemistry Cell structure ‫ندي‬/‫د‬ Lectures 1 Prepared By 01289689034 Dr : Ahmed Hesho 01289689034 Biochemistry Cell All organis...

Biochemistry BIO Chemistry Cell structure ‫ندي‬/‫د‬ Lectures 1 Prepared By 01289689034 Dr : Ahmed Hesho 01289689034 Biochemistry Cell All organisms are built from cells. All animal tissues including human are also organized from collections of cells. Thus cell is the fundamental unit of life. If cell dies, tissue dies and it cannot function. Prokaryotic cells Eukaryotic Nuclear envelop & Lack (absent) the absence of a nucleus Present conventional nucleus but contains genetic material where genetic material is separated from the cytoplasm Size Smaller & simpler Larger Genome Less complex More complex Cytoplasmic Absent Present Organelles (except ribosomes) Cytoskletone Absent Present Examples Bacteria are the most numerous All members of the plant and animal prokaryotes and considered as kingdoms, including the fungi, which single-celled organisms (unicellular) exist in both: multicellular forms (molds) & unicellular forms (yeasts and protozoans, which are exclusively unicellular). Similarities between Prokaryotic and Eukaryotic Cells:  They have a surrounding cell membrane, which envelopes the cell.  They contain DNA as genetic material.  They have ribosomes, accomplish similar functions, and are very diverse. Dr : Ahmed Hesho 01289689034 Biochemistry Level of Organization Explanation Example Atoms are defined as the smallest unit of an element Carbon, Hydrogen, Oxygen that still maintains the property of that element. Atomic Level Atoms combine to form molecules which can have entirely different properties than the atoms they Water, DNA, Carbohydrates contain. Molecular Level Cellular Level Cells are the smallest unit of life. Cells are enclosed Muscle cell, Skin cell, by a membrane or cell wall and in multicellular Neuron organisms often perform specific functions. Tissues are groups of cells with similar functions (Epithelial, Connective, Muscular, and Nervous cells ‫نفس النوع من ال‬ tissues). Tissue Level Organs are two or more types of tissues that work Heart, Liver, Stomach together to complete a specific task. Organ Level respiratory, urinary, An organ system is group of organs that carries out nervous, cardiovascular, more generalized set of functions. digestive, reproductive, endocrine, muscular Organ System Level An organism has several organ systems that function Human together. Organismal Level Dr : Ahmed Hesho 01289689034 Biochemistry Eukaryotic cells contain many membrane-bound organelles (cellular departments defined by their own membranes) that carryout specific cellular processes. Chief organelles and their functions are as follows: Dr : Ahmed Hesho 01289689034 Biochemistry Overview &  Nucleus contains more than 95 percent of the cell’s DNA Description:  It is the control center of the eukaryotic cell.  The outer nuclear membrane continuous with other cytomembranes.  The nucleus is in the center of most cells.  The nucleus is the largest membrane-bound organelle.  Some cells contain multiple nuclei, such as skeletal muscle and neutrophils (a type of WBCs).  In some eukaryotic cells like erythrocyte (mature red blood cells), nucleus is absent. Function of the  The nucleus is responsible for the storage and transitions of genetic information. nucleus:  DNA is similar in every cell of the body, but depending on the specific cell type, some genes may be turned on or turned off. That's why a liver cell is different from a muscle cell, and a muscle cell is different from a fat cell, and so on.  DNA replication, RNA transcription of DNA.  Transcription is the first step in the expression of genetic information and is the major metabolic activity of the nucleus. Dr : Ahmed Hesho 01289689034 Biochemistry Dr : Ahmed Hesho 01289689034