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This slideshow is related to the Form 4 Biology Syllabus.
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CHAPTER 2
Cell Structure and Cell Organisation
YOU WILL LEARN…
� Draw and label an animal cell and plant cell
� Identify the cellular components of an animal cell and a plant cell
� State the functions of a cellular components in an animal cell and a plant cell
� Compare and contrast an animal cell and a plant cell
YOU WILL LEARN…
� Describe cell specialisation in multicellular organisms
� Describe cell organisation in the formation of tissues, organs and systems in multicellular organisms
� Explain the necessity to maintain optimal internal environment
Cell structure and function
� Living component of a cell is called protoplasm ---surrounded by a thin layer called the PLASMA MEMBRANE
� CYTOPLASM contains small structures called ORGANELLES.
� Organelles are cellular components and each organelle is membrane – bound in order to maintain its internal environment to perform specific function
nucleus
� Controls and coordinates all the activities and functions of the cell.
� It plays a vital role in cell division.
mitochondrion
� Energy center or powerhouse of the cell.
� Turns food into useable energy.
� It is site of ATP synthesis and respiratory enzymes.
ribosome
� Make protein, composed of RNA, sites of protein synthesis.
Endoplasmic reticulum
� Transport proteins and synthesis lipids; centrefor detoxification of drugs.
Golgi apparatus
� Processes, packages and secretes proteinsand transporting macromolecules such as proteins and carbohydrates.
lysosome
� Contains digestive enzymes for cell digestion.
� It also helps in destroying foreign substances.
vacuoles
� Storage of water and several other substances, specifically food, waste products and pigments.
� It also provides turgidity to the cell.
Density of certain organelles in specific cells
� Sperm cells
� Flight muscle cells in insects and birds
� Liver cells
� Pancreatic cells & cells of salivary glands
Cell Organisation
� Living processes of unicellular organisms
� Cell specialisation in multicellular organisms
� Cell organisation in animals
Structure
� Amoeba sp.: plasma membrane, food vacuole, contractile vacuole, pseudopodium, nucleus, ectoplasma, endoplasm.
Locomotion
� Amoeba sp.: Pseudopodium (false foot) helps it to move forward slowly and it is known as amoeboidmovement.
Feeding
� Amoeba sp.: Omnivore. Eat bacteria, plant cells, algae and other microscopic organisms
� Entrapment – extend pseudopodium.
� Engulfment – engulf tiny food (phagocytosis) with its pseudopodia.
� Digestion – food enclosed in food vacuole
� Absorption – enzyme digests the bacteria
� Engesting – expel indigestible material.
reproduction
� Amoeba sp.: two types of reproduction.
� Binary Fission – nucleus divides (favourablecondition) and then follows by division of cytoplasm. Two daughter cells are formed (mitotic division)
� Spore Formation – spores form (bad condition) and germinate into new amoeba under favourablecondition.
Osmoregulation
� Amoeba sp.: water moves into the cell by osmosis and prevention of bursting, it has a contractile vacuole.
Respiration
� Amoeba sp. and Paramecium sp. (both): exchange gases throughout the whole cell membrane
Excretion
� Amoeba sp. and Paramecium sp. (both): waste products are ammonia and carbon dioxide by diffusion.
� Solid waste in paramecium is expelled through its anal pore.
Structure
� Paramecium sp.: food vacuole, posterior contractile vacuole, cytostome, gullet, oral groove, cilia, macronucleus, micronucleus, anterior contractile vacuole.
Locomotion
� Paramecium sp.: Hair-like cilia to beat against water. It beats its cilia backwards diagonally (swim forward) and it rotates on its axis. It beats its cilia forward (swim backwards).
FEEDING
� Paramecium sp.: Eat bacteria, organic material and other microscopic organisms.
� Sweeping – movement of cilia. Food moves along the oral groove into the gullet and cytostome.
� Digestion – food vacuole circulates round the cell.
� Elimination – undigested food is eliminated at the anal pore.
REPRODUCTION
� Paramecium sp.: two types of reproduction.
� Binary Fission – micronucleus undergoes mitosis (favourable condition). Macronucleus begins to elongation and form two. Cell content divide and two daughter cells are formed.
� Conjugation (Sexual reproduction) – two same species parent paramecia exchange genetic material of their micronuclei. Each parent divides and forms four daughter cells.
Osmoregulation
� Paramecium sp.: water moves into the cell by osmosis and prevention of bursting, it has two contractile vacuoles.
Respiration
� Amoeba sp. and Paramecium sp. (both): exchange gases throughout the whole cell membrane
Excretion
� Amoeba sp. and Paramecium sp. (both): waste products are ammonia and carbon dioxide by diffusion.
� Solid waste in paramecium is expelled through its anal pore.
Cell Organisation in Multicellular Organisms
� A group of cells (similar in structure and functions) = Tissue
� Several types of different tissues which form a structural and functional unit = Organ
� Several organs (carry out major activity together) = System
� All systems work together to form an organism
Cell Organisation in animals
� 4 main types of tissues in animals are:
a.) Epithelial tissue
b.) Muscle tissue
c.) Nerve tissue
d.) Connective tissue
Epithelial tissues
� Consists of closely-packed cells to form one layer or several layers lining the outer body surface.
� Example : skin epidermis, surface of nasal cavity and the surface of mouth cavity.
� These also cover the outer and inner surfaces of organs, such as the digestive tract, trachea and lungs.
Muscle tissues
� Consist of muscle cells which are able to contract to produce motion
� The most abundant tissue in humans and most animals
� Smooth muscles : found in walls of hollow organs such as stomach, intestine, bladder, blood vessels and uterus
� Cardiac muscles : found at the walls of the heart
� Skeletal muscles : attached to bones
Connective tissues
� Made up of various cells and fibres embedded in a large amount of matrix
� Matrix may be in the form of ;
a.) liquid; such as blood plasma
b.) hard; solid such as matrix of the bone
c.) soft; solid such as chondrin of cartilage
Widely distributed and have various functions.
organs
� A group of different tissues working together to perform a specific function forms an organ.
� Example : The HEART consists of cardiac tissues which contract to pump blood ---------- epithelial tissues which lines the surface of the heart ------------nerve tissue which transmits impulses to regulate heartbeat ---------- connective tissue which strengthens valves and walls of the heart.
� Epidermis : made up of epithelial tissue; outermost layer
� Dermis : consists of connective tissue, nerve tissue, epithelial tissue and muscle tissue.
� Hypodermis : consists of muscle tissue and connective tissue.
� Sweat gland secretes sweat, sebaceous gland secretes sebum which lubricates the hair and skin (Glands : formed from modified epithelial cells)
systems
� A system consists of a group of organs working together to carry out a major living processes such as respiration, digestion, excretion, reproduction and circulation.
� There are 11 major systems in a human body.
organism
� All systems combine to form a multicellular organism
� These systems work together for the organism to survive
� Example : digestive system brings in nutrients, respiratory system brings in oxygen and eliminates carbon dioxide, circulatory system transports respiratory requirements to the cells and transports waste from the cells.