cell structure and cell organisation (edit)

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.