Cell structure and functions
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Cells are the basic unit of structure and function in human bodies. They contain specialized structures called organelles that perform specific functions. The cell membrane controls what enters and exits the cell. Movement across the membrane occurs through diffusion, osmosis, and active/passive transport. The nucleus houses DNA and controls cell activities. Other organelles such as mitochondria, endoplasmic reticulum, Golgi apparatus, lysosomes, and ribosomes help synthesize proteins and carry out metabolic functions. Cells reproduce through mitosis and differentiate during development. Aging and death are normal cellular processes.
Cell structure and functions
- 2. CELL STRUCTURE CELLS • Determine the form and functions of the human body. • Basic living unit of all organisms. • Are complex living structures. • Are specialized to perform specific functions.
- 3. CELL STRUCTURE ORGANELLES - Specialized structures within cells. - Perform specific functions.
- 4. CELL MEMBRANE CYTOPLASM NUCLEAR ENVELOPE NUCLEOLUS NUCLEUS LYSOSOME PHAGOCYTIC VESICLE CENTROSOME CENTRIOLES PEROXISOME MICROTUBULE MICROVILICILIA SECRETORY VESICLE GOLGI APPARATUS SMOOTH ENDOPLASMIC RETICULUM ROUGH ENDOPLASMIC RETICULUM RIBOSOME MITOCHONDRION
- 5. CELL STRUCTURE CELL MEMBRANE - selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells. CYTOPLASM - The living material surrounding the nucleus. NUCLEUS - Contains genetic material of cell (DNA) and nucleoli; site of RNA synthesis and ribosomal subunit assembly. LYSOSOME - Contains enzymes that digest material taken into the cell.
- 6. CELL STRUCTURE PHAGOCYTIC VESICLE - Contains materials produced outside the cell; secreted by endocytosis. CENTRIOLES - Facilitate the movement of the chromosomes during cell division. MICROTUBULE - Supports cytoplasm; assists in cell division and forms components of cilia and flagella. MICROVILLI - Increase surface area of certain cells.
- 7. CELL STRUCTURE CILIA - Move substances over surfaces of the certain cells. SECRETORY VESICLES - Contains materials produced in the cell; formed by the Golgi apparatus; secreted by exocytosis. GOLGI APPARATUS - Modifies protein structure and packages protein in secretory vesicles. SMOOTH ENDOPLASMIC RETICULUM (SER) - Site of lipid synthesis; participates in detoxification.
- 8. CELL STRUCTURE ROUGH ENDOPLASMIC RETICULUM (ROR) - Has many ribosomes attached; site of the protein synthesis. RIBOSOME - Site of protein synthesis MITOCHONDRION - Site of aerobic respiration and the major site of ATP synthesis.
- 9. CELL FUNCTIONS 1. Cell metabolism and energy use. 2. Synthesis of molecules. 3. Communication. 4. Reproduction and inheritance.
- 10. CELL MEMBRANE - Is the outermost component of the cell. - Made up of phospholipids and proteins. EXTRACELLULAR Substances - Substances outside the cell. INTRACELLULAR Substances - Substances inside the cell. FLUID-MOSAIC MODEL
- 11. CELL MEMBRANE
- 12. MOVEMENT THROUGH THE CELL MEMBRANE DIFFUSION Movement of ions or molecules from higher concentration to lower concentration of that same solute in solution. CONCENTRATION GRADIENT - Difference in the concentration of a solute in a solvent between two points divided by the distance between the two points.
- 13. MOVEMENT THROUGH THE CELL MEMBRANE
- 14. MOVEMENT THROUGH THE CELL MEMBRANE CELL MEMBRANE CHANNELS - Consist of large protein molecules that extend one surface of cell membranes to the other. 1. Leak Channels- constantly allow ions to pass through. 2. Gated Channels- limit the movement of ions across the membrane by opening and closing.
- 15. MOVEMENT THROUGH THE CELL MEMBRANE
- 16. MOVEMENT THROUGH THE CELL MEMBRANE OSMOSIS - Is the diffusion of water across a selectively permeable membrane. - From higher water concentration to one of lower water concentration. - Occurs when the cell membrane is less permeable, selectively permeable or not permeable to solutes and a concentration gradient for water exists across the cell membrane.
- 17. MOVEMENT THROUGH THE CELL MEMBRANE OSMOTIC PRESSURE - Is the force required to prevent the movement of water across a selectively permeable membrane. HYPOTONIC- Solution usually has a lower concentration of solutes and higher concentration of water. - Solution has less tone or osmotic pressure than cell. - The cell will SWELL. - The cell can rupture a process called Lysis.
- 18. MOVEMENT THROUGH THE CELL MEMBRANE ISOTONIC- the concentrations of various solutes and water are the same on both sides of the cell membrane. - The cell will NEITHER SHINKS NOR SWELLS. HYPERTONIC- A solution usually has a higher concentration of solutes and a lower concentration of water. - Resulting in CELL SHRINKAGE or CRENATION.
- 19. MOVEMENT THROUGH THE CELL MEMBRANE
- 20. MOVEMENT THROUGH THE CELL MEMBRANE
- 21. MOVEMENT THROUGH THE CELL MEMBRANE CARRIER-MEDIATED TRANSPORT MECHANISM Facilitated Diffusion Active Transport Secondary Active Transport
- 22. MOVEMENT THROUGH THE CELL MEMBRANE FACILITATED DIFFUSION - Moves substances across the cell membrane from an area oh higher concentration to an area of lower concentration. - ATP is NOT required.
- 23. MOVEMENT THROUGH THE CELL MEMBRANE SECONDARY ACTIVE TRANSPORT - Involves active transport of one substance such as Na+ that establishes concentration gradient. COTRANSPORT- diffusing substance moves in the same direction as the transported substance. COUNTERTRANSPORT- diffusing substance moves
- 24. MOVEMENT THROUGH THE CELL MEMBRANE
- 25. MOVEMENT THROUGH THE CELL MEMBRANE
- 26. MOVEMENT THROUGH THE CELL MEMBRANE
- 27. MOVEMENT THROUGH THE CELL MEMBRANE
- 28. MOVEMENT THROUGH THE CELL MEMBRANE ENDOCYTOSIS AND EXOCYTOSIS VESICLES- Membrane bound sacs. ENDOCYTOSIS- uptake of material through the cell membrane by the formation of a vesicle.
- 29. MOVEMENT THROUGH THE CELL MEMBRANE RECEPTOR- MEDIATED ENDOCYTOSIS - When specific substance binds to the receptor molecule and the substance is transported in the cell.
- 30. MOVEMENT THROUGH THE CELL MEMBRANE
- 31. MOVEMENT THROUGH THE CELL MEMBRANE PHAGOCYTOSI S - A part of the cell membrane that extends around a particle and fuses it into the cell
- 32. MOVEMENT THROUGH THE CELL MEMBRANE PINOCYTOSIS - Forms smaller vesicles and contain liquid rather than particles.
- 33. MOVEMENT THROUGH THE CELL MEMBRANE SECRETORY VESICLES - Accumulate materials for release from the cell.
- 34. MOVEMENT THROUGH THE CELL MEMBRANE EXOCYTOSIS - Allows the release of materials from the cells.
- 35. CELL ORGANELLES NUCLEUS - Large organelle that is located near the center of the cell. NUCLEAR ENVELOPE - Consist of outer and inner membranes with space between nucleus and nuclear envelope. NUCLEAR PORES - Combination of inner and outer membranes to which the materials can pass in or out of the Human cells contain 23 pairs of chromosomes. CHROMATIN - Chromosomes that are loosely coiled. NUCLEOLI - Are diffuse bodies with no surrounding membrane that are found within the nucleus. RIBOSOMAL RIBONUCLEIC ACID (rRNA) - Proteins that are joined together to form large and small ribosomal subunits.
- 36. CELL ORGANELLES
- 37. CELL ORGANELLES
- 38. CELL ORGANELLES RIBOSOMES - Organelles where proteins are produces. - Can be attached to endoplasmic reticulum. - Ribosomes that are not attached to any organelle are called free ribosomes.
- 39. CELL ORGANELLES
- 40. CELL ORGANELLES ENDOPLASMIC RETICULUM - Is a series of membranes forming sacs and tubules. SMOOTH ENDOPLASMIC RETICULUM - E.R without ribosomes. - Site for lipid synthesis and participates in detoxification of chemicals. ROUGH ENDOPLASMIC RETICULUM - E.R with ribosomes. - Large amount of Rough E.R indicates that it is synthesizing large amounts of protein for export.
- 41. CELL ORGANELLES
- 42. CELL ORGANELLES GOLGI APPARATUS - Consists of closely packed stacks of curved, membrane-bound sacs. - It modifies, packages and distributes proteins and lipids SECRETORY VESICLES - Pinch off from the golgi apparatus and move to the cell membrane. VESICLE - Is a small, membrane-bound sac that transports or stores materials within cells.
- 43. CELL ORGANELLES
- 44. CELL ORGANELLES LYSOSOMES - Are membrane- bound vesicles formed from the golgi apparatus - Contains variety of enzymes that function as intracellular digestive system. PEROXISOMES -Are small, membrane- bound vesicles containing enzymes that break down fatty acids, amino acids and hydrogen peroxide (𝐻2 𝑂2) - Hydrogen peroxide is a by- product of fatty acid and amino acid breakdown and can toxic to a cell.
- 45. CELL ORGANELLES
- 46. CELL ORGANELLES MITOCHONDRIA - Are small organelles with inner and outer membranes separated by a space. - Outer membranes have a smooth contour but the inner membranes have numerous folds called cristae. - Are the major sites of adenosine triphosphate (ATP) production within cells. - Carry out aerobic respiration, a series of chemical reactions that require 𝑂2 to break down food molecules to produce
- 47. CELL ORGANELLES
- 48. CELL ORGANELLES CYTOSKELETON - Consists of proteins that support the cell, hold organelles in place and enable the cell to change shape. - These protein structures are: Microtubules Microfilaments Intermediate filaments
- 49. CELL ORGANELLES Microtubules - Are hollow structures formed from protein subunits. FUNCTIONS: 1. Helps to support the cytoplasm of cells. 2. Assisting in cell division. 3. Forming essential components of certain organelles such as cilia and flagella.
- 51. CELL ORGANELLES Microfilaments - Are small fibrils from protein subunits that structurally support the cytoplasm. FUNCTIONS: 1. Some microfilaments are involved with cell movement.
- 53. CELL ORGANELLES Intermediate Filaments - Are fibrils formed from protein subunits that are smaller in diameter than microtubules but larger in diameter than microfilaments. FUNCTIONS: 1. Provide mechanical support to the cell.
- 56. CELL ORGANELLES CENTRIOLES CENTROSOME -Is a specialized zone of cytoplasm close to the nuecleus which microtubule formation occurs. - It contains two centrioles which are normally oriented perpendicular to each other. CENTRIOLE - Is small, cylindrical organelle composed of nine triplets; each triplet consists of three parallel microtubules joined
- 58. CELL ORGANELLES CILIA - Project from the surface of cells. - Cylindrical structures that extend from the cell. - Composed of microtubules which are enclosed by the cell membrane. - Numerous on the surface cells that line the respiratory tract. - Their movement transport mucus in which dust particles are embedded, upward and away from the FLAGELLA - Occur only one per cell. MICROVILLI - Specialized extensions of the cell membrane that are supported by microfilaments. - Abundant on the surface of cells in which absorption is an important function.
- 59. CELL ORGANELLES
- 60. CELL ACTIVITY GENE EXPRESSION - DNA contains the information that directs protein synthesis. - DNA also influences the structural and functional characteristics of the entire organism. - DNA molecule is consist of nucleotides joined together to form two nucleotide strands. - NUCLEOTIDES function as chemical “letters” that form chemical “words”. GENE - Is a sequence of nucleotides that provides a chemical set of instructions for making a specific protein.
- 61. CELL ACTIVITY GENE EXPRESSION Involves two steps: 1. Transcription - the cell makes a copy of the gene necessary to make a particular protein. 2. Translation - converting the copied information into a protein.
- 63. CELL ACTIVITY FORMATION OF mRNA by TRANSCRIPTION OF DNA
- 64. CELL ACTIVITY TRANSLATION OF mRNA TO PRODUCE A PROTEIN
- 65. CELL ACTIVITY CELL LIFE CYCLE Includes two major phases: 1. Non-dividing phase called INTERPHASE 2. CELL DIVISION
- 66. CELL ACTIVITY INTERPHASE - The DNA is replicated; two strands of DNA separate from each other and each other serves as a template for the production of a new strand of DNA - At the end of interphase, a cell has two complete sets of genetic material
- 69. CELL ACTIVITY CELL DIVISION - Is the formation of daughter cells from a single parent cell. - Growth and tissue repair are formed through MITOSIS. - Sex cells undergo MEIOSIS necessary for reproduction.
- 70. CELL ACTIVITY CELL DIVISION - Body cells contains 46 chromosomes . - Sex cells have half number of chromosomes. DIPLOID NUMBER - Pertains to 46 chromosomes. HAPLOID NUMBER -Pertains to 23 chromosomes.
- 71. CELL ACTIVITY MITOSIS - A parent cells divides to form two daughter cells with the same amount and type of DNA as the parent cells. - Is divided into four stages: Prophase, Metaphase, Anaphase, and Telophase.
- 72. CELL ACTIVITY MITOSIS STEPS EVENTS 1.Prophase Chromatic condenses to form visible chromosomes. The centrioles divided and migrate to each pole of the cells. 2.Metaphase Chromosomes align near the center of the cells. 3.Anaphase Chromatids separate. Two sets of 46 chromosomes move to the opposite cells. 4.Telophase The chromosomes in each of the daughter cells become organized to form two separate nuclei.
- 73. CELL ACTIVITY DIFFERENTIATION - Process by which cells develop with specialized structures and functions. - Some portion of DNA are active, but others are inactive. - Results from the selective activation and inactivation of segments of DNA.
- 75. CELL ACTIVITY APOPTOSIS - Programmed cell death - Normal process by which cell numbers within various tissues are adjusted and controlled. - Eliminates excess cells to maintain constant numbers of cells within the tissue. - Damaged or potential dangerous cells, virus-infected cells and potential cancer
- 76. CELL ACTIVITY CELLULAR ASPECTS OF AGING 1. Cellular clock – after a certain passage of time or a certain number of cell division, results in the death of a given cell line. 2. Death Genes – Turn late in life or sometimes prematurely, causing cells to deteriorate and die. 3. DNA damage – Resulting in cell degeneration and death.
- 77. CELL ACTIVITY CELLULAR ASPECTS OF AGING 4. Free radicals – DNA is also susceptible to direct damage, resulting in mutations. Free radicals are atoms and molecules with an unpaired electron. 5. Mitochondrial damage – May results in loss of proteins critical to mitochondrial functions.
- 78. “A cell is regarded as the true biological atom? - George Lewes