Cells Study Notes PDF

CHARACTERISTICS OF ORGANISM CHARACTERISTICS OF ORGANISM Made of CELLS Require ENERGY (food) REPRODUCE (species) Maintain HOMEOSTASIS ORGANIZED RESPOND to environment GROW and DEVELOP EXCHANGE materials with surroundings (water, wastes, gases)  LEVEL OF ORGAN...

CHARACTERISTICS OF ORGANISM CHARACTERISTICS OF ORGANISM Made of CELLS Require ENERGY (food) REPRODUCE (species) Maintain HOMEOSTASIS ORGANIZED RESPOND to environment GROW and DEVELOP EXCHANGE materials with surroundings (water, wastes, gases)  LEVEL OF ORGANIZATION Living Levels: Non-living Levels: CELL (makes up ALL ATOM (element) organisms) MOLECULE (compounds TISSUE (cells working like carbohydrates & together proteins) ORGAN (heart, brain, ORGANELLES (nucleus, ER, stomach...) Golgi...) ORGAN SYSTEMS (respiratory, circulatory...) ORGANISM  LEVEL OF ORGANIZATION Living Levels in bigger scale: POPULATION (one species in an area) COMMUNITY (several populations in an area ECOSYSTEM (forest, prairie...) BIOME (Tundra, Tropical Rain forest...) BIOSPHERE (all living and nonliving things on Earth) CELL THEORY  CELL THEORY All living things are made of cells Cells are the basic unit of structure and function in an organism (basic unit of life) Cells come from the reproduction of existing cells (cell division)  NUMBER OF CELL Although ALL living things are made of cells, organisms may be: Unicellular – composed of one cell Multicellular- composed of many cells that may organize into tissues, etc. Cells in multicellular organisms often specialize (take on different shapes & functions) NUMBER OF CELL  CELL SPECIALIZATION Cells in a multicellular organism become specialized by turning different genes on and off This is known as DIFFERENTIATION ANIMAL CELLS PLANT CELLS MUSCLE CELLS RED BLOOD CHEEK CELLS GUARD CELLS XYLEM CELLS POLLEN CELLS KINDS OF CELLS  KINDS OF CELLS Prokaryotes – The first Cells Eukaryotic Cell Cells that lack a nucleus or Contain 3 basic cell structures: membrane-bound Nucleus organelles Cell Membrane Includes bacteria Cytoplasm with organelles Simplest type of cell Single, circular chromosome KINDS OF CELLS  TWO TYPES OF EUKARYOTIC CELLS TWO TYPES OF EUKARYOTIC CELLS  ORGANELLES Very small (Microscopic) Perform various functions for a cell Found in the cytoplasm May or may not be membrane- bound ORGANELLES OF ANIMAL CELL  ORGANELLES OF ANIMAL CELLS Cell Membrane - A thin semipermeable membrane layer of protein and fats surrounding the cell. Its primary role is to protect the cell from its surrounding. Also, it controls the entry and exit of nutrients and other microscopic entities into the cell. Nuclear Membrane - It is a double-membrane structure that surrounds the nucleus. It is also referred to as the nuclear envelope. Nucleus - It is an organelle that contains several other sub-organelles such as nucleolus, nucleosomes and chromatins. It also contains DNA and other genetic materials. Mitochondrion - They are spherical or rod-shaped organelles with a double membrane. They are the powerhouse of a cell as they play an important role in releasing energy.  ORGANELLES OF ANIMAL CELLS Lysosome (Cell Vesicles) - They are round organelle surrounded by a membrane comprising of digestive enzymes which help in digestion, excretion and in the cell renewal process. Cytoplasm - A jelly-like material which contains all the cell organelles, enclosed within the cell membrane. The substance found within the cell nucleus, contained by the nuclear membrane is called the nucleoplasm. Ribosome - They are small organelles made up of RNA-rich cytoplasmic granules and they are the sites of protein synthesis. Centrosome - It is a small organelle found near to the nucleus which has a thick centre with radiating tubules. The centrosomes are where microtubules are produced.  ORGANELLES OF ANIMAL CELLS Endoplasmic Reticulum (ER) - This cellular organelle is composed of a thin, winding network of membranous sacs originating from the nucleus. Vacuole - A membrane-bound organelle present inside a cell involved in maintaining shape and storing water, food, wastes, etc. Golgi Apparatus - A flat, smooth layered, sac-like organelle which is located near the nucleus and involved in manufacturing, storing, packing and transporting the particles throughout the cell. Centrosome - is a cellular structure involved in the process of cell division. Proteins called microtubules assemble into a spindle between the two centrosomes and help separate the replicated chromosomes into the daughter cells. ORGANELLES OF PLANT CELL  ORGANELLES OF PLANT CELLS Cell Wall It is a rigid layer which is composed of cellulose, glycoproteins, lignin, pectin, and hemicellulose. It is located outside the cell membrane. It comprises proteins, polysaccharides, and cellulose. The primary function of the cell wall is to protect and provide structural support to the cell. The plant cell wall is also involved in protecting the cell against mechanical stress and to provide form and structure to the cell. It also filters the molecules passing in and out of the cell. The formation of the cell wall is guided by microtubules. It consists of three layers, namely, primary, secondary and the middle lamella. The primary cell wall is formed by cellulose laid down by enzymes.  ORGANELLES OF PLANT CELLS CELL WALL NOTE: Cell wall for other organism has different components peptidoglycan in bacteria and chitin in Fungi  ORGANELLES OF PLANT CELLS Cell membrane It is the semi-permeable membrane that is present within the cell wall. It is composed of a thin layer of protein and fat. The cell membrane plays an important role in regulating the entry and exit of specific substances within the cell. For instance, cell membrane keeps toxins from entering inside, while nutrients and essential minerals are transported across.  ORGANELLES OF PLANT CELLS Nucleus The nucleus is a membrane-bound structure that is present only in eukaryotic cells. The vital function of a nucleus is to store DNA or hereditary information required for cell division, metabolism, and growth. Nucleolus: It manufactures cell’s protein-producing structures and ribosomes. Nucleopore: Nuclear membrane is perforated with holes called nucleopore that allows proteins and nucleic acids to pass through.  ORGANELLES OF PLANT CELLS Plastids They are membrane-bound organelles that have their own DNA. They are necessary to store starch, to carry out the process of photosynthesis. It is also used in the synthesis of many molecules which form the building blocks of the cell. Some of the vital types of plastids and their functions are stated below: Leucoplasts - They are found in non-photosynthetic tissues of plants. They are used for the storage of protein, lipid, and starch. Chloroplast - It is an elongated organelle enclosed by phospholipid membrane. The chloroplast is shaped like a disc and the stroma is the fluid within the chloroplast that comprises a circular DNA. Each chloroplast contains a green coloured pigment called chlorophyll required for the process of photosynthesis. The chlorophyll absorbs light energy from the sun and uses it to transform carbon dioxide and water into glucose. ORGANELLES OF PLANT CELLS Chromoplasts They are heterogeneous, coloured plastid which is responsible for pigment synthesis and for storage in photosynthetic eukaryotic organisms. Chromoplasts have red, orange and yellow coloured pigments which provide colour to all ripe fruits and flowers.  ORGANELLES OF PLANT CELLS Central Vacuole It occupies around 30% of the cell’s volume in a mature plant cell. Tonoplast is a membrane that surrounds central vacuole. The vital function of central vacuole apart from storage is to sustain turgid pressure against the cell wall. The central vacuole consists of cell sap. It is a mixture of salts, enzymes, and other substances. Golgi Apparatus They are found in all eukaryotic cells which are involved in distributing synthesized macromolecules to various parts of the cell.  ORGANELLES OF PLANT CELLS Ribosomes - They are the smallest membrane-bound organelles which comprise RNA and protein. They are the sites for protein synthesis, hence, also referred to as the protein factories of the cell. Mitochondria - They are the double-membraned organelles found in the cytoplasm of all eukaryotic cells. They provide energy by breaking down carbohydrate and sugar molecules, hence they are also referred to as the “Powerhouse of the cell.” Lysosome - are called as suicidal bags as they hold digestive enzymes in an enclosed membrane. They perform the function of cellular waste disposal by digesting worn-out organelles, food particles and foreign bodies in the cell. CELL MEMBRANE  CELL MEMBRANE Composed of double layer of phospholipids (phospholipids bilayers) and proteins Surrounds outside of ALL cells Controls what enters or leaves the cell NEXT TOPIC: CELL DIVISION