Cell biology

CELL BIOLOGY FOR SECONDARY SCHOOL YEAR 1

1. CELL BIOLOGY CELL THEORY CONCEPT OF THE CELL UNICELLULAR AND MULTICELLULAR ORGANISMS AKARYOTES (VIRUSES ) PROKARYOTES (BACTERIA ) DIFFERENCE BETWEEN AKARYOTES AND PROKARYOTES EUKARYOTIC CELLS (PLANT AND ANIMAL CELLS ) SPECIALISED CELLS LEVEL OF ORGANISATION FORMS OF CELLS MOVEMENT OF SUBSTANCES IN AND OUT OF CELLS

2. CELL THEORY The cell theory was proposed by two G erman scientists, Theodore Schwann and Matthias Schleiden . They proposed the following in 1839; 1. All living organisms are composed of one or more cells. 2. The cell is the basic unit of structure and organization in organisms. 3. Cells arise from pre-existing cells.

3. CONCEPT OF THE CELL Cells are the basic units from which living things are built and each cell is capable of carrying out life processes. There are two main groups of organism based on the number of cells Unicellular organisms ; these are organisms that consist of one cell only. The organism is the cell . They are also called single-celled organisms . E.g include amoeba, paramecium, euglena ,trypanosome Amoeba proteus Euglena spp. Paramecium sp.

4. MULTICELLULAR ORGANISMS These are organisms that are made up of multiple cells

5. AKARYOTES These are particles that lack nucleus, cytoplasm and cell membrane . An example is a virus. They require the body of a living organism to reproduce. They cannot live on their own . For this reason, they are regarded as particles and not organisms. Viruses are so small that they can only be seen with an electron microscope. There are several shapes of viruses . These include rod-shaped , spherical, spiral, hexagonal etc. A typical virus is made up of a protein coat and an inner core of nucleic acids. Viruses have either DNA or RNA. Viruses cause diseases in both plants and animals. Examples of viruses and the diseases they cause

6. EXAMPLES OF VIRAL DISEASES smallpox the common cold and different types of flu measles, mumps, rubella, chicken pox, and shingles hepatitis herpes and cold sores polio rabies Ebola and Hanta fever HIV, the virus that causes AIDS Severe acute respiratory syndrome (SARS) dengue fever, Zika , and Epstein-Barr

7. EXAMPLES OF VIRUSES

8. FEATURES OF VIRUSES they are smaller than bacteria can only be seen under an electron microscope there are several shapes has either DNA or RNA can only reproduce within living cells they cause diseases they lack nucleus, cytoplasm & cell membrane have a protein coat

9. Viruses as living organisms 1. they can reproduce 2. they can feed 3. they have genetic material Viruses as non-living organisms (particles) they can’t reproduce on their own They don’t grow

10. LIFE CYCLE OF VIRUSES Life Cycle of viruses the virus first attaches to the host cell the protein coat breaks and the chromosome enters the host cell the viral DNA then replicate the new viral chromosomes are surrounded by protein coats the cell wall of the host cell breaks to release the virus particles they invade other cells Mechanism of Transmission of Viruses through droplet infection through insect bites through physical contact with infected humans, objects or animals

11. PROKARYOTES These are unicellular organisms that lack membrane-bound nucleus. They are mostly bacteria and blue green algae . The bacteria cell is made up of a cell wall with a cell membrane within that surrounds the cytoplasm. Their nuclear material is found within the cytoplasm but is not bound by a membrane.

12. Features of Prokaryotes they are unicellular organisms but they mostly live in colonies they can only be seen with a microscope they occur in all environments and can tolerate the harshest of environmental conditions. Many bacteria cause diseases like diphtheria, tuberculosis, meningitis, pneumonia, cholera, Gonorrhoea , Syphilis, Tetanus, Typhoid, Anthrax They have nuclear material with no membrane They have cell wall They possess membrane that surrounds the cytoplasm They reproduce mainly by binary fission. One bacterium divides into two bacteria. Each bacteria produced is identical to the parent bacteria. Some bacteria reproduce sexually by either conjugation or genetic recombination They possess whip-like flagella used for movement Bacteria excrete carbon dioxide and water mainly by exocytosis Some bacteria can produce their own food (autotrophic bacteria) while others mostly feed on dead organic matter.

13. FORMS OF BACTERIA There are four main forms(shapes) of bacteria; 1. Cocci ( Spherical shaped ) Cocci bacteria, singular; coccus , are spherical-shaped bacteria. When cocci bacteria divide or reproduce, they create different patterns and these are named depending on how their bacteria are arranged. Types of coccus bacteria include Coccus – single-celled spherical Diplococcus bacteria – occur in pairs Streptococcus bacteria – occur in chains Staphylococcus bacteria – occur in a grape-like cluster Sarcina – occur in a cube-like structure (8 bacteria or more) Tetrad bacteria- group of four

14. 2. Bacilli (Cylindrical /rod/ sausage-shaped ) Bacilli bacteria , singular; bacillus are cylindrical/rod-shaped bacteria. The most common rod-shaped bacteria is Bacillus anthracis , the bacteria that causes anthrax in livestock. Another example of a bacillus is the bacteria that causes typhoid fever, Bacillus typhosus .

15. 3. Vibrio ( Comma-shaped) These are groups of bacteria that possess a curved-rod/ comma shape, several species of which can cause foodborne infection. The most common vibrio bacteria is Vibrio cholerae , the bacteria that causes cholera.

16. 4. Spirilli ( Spiral shaped/twisted ) These are large , elongate, spiral shaped bacteria.

17. HOMEWORK Tabulate 10 differences between akaryotes and prokaryotes . Make a labelled diagram of a typical bacteria Make a labelled diagram of a typical virus .

18. CLASS EXERCISE 1 a. Explain the meaning of biology . (2 marks) b . State six reasons why Biology should be studied in schools (6 marks) 2 . List three ways in which Biology has been beneficial in a. The Home b. Hospitals c. Sanitation d. Agriculture. (12 marks)

19. CLASS EXERCISE 2 (10 MINS) Outline the cell theory. ( 6 marks) Explain the statement “ A cell is the basic unit of life”. (4 marks) CLASS EXERCISE 3 (10 MINS) State three living and two non-living features of viruses . (5 marks) List the main forms of bacteria. ( 4 marks) Classify the following diseases as either viral or bacteria disease; Pneumonia, cholera, E bola, influenza, poliomyelitis, hepatitis, measles, gonorrhea, dengue , meningitis, HIV/AIDS. (11 marks)

20. VIRAL DISEASES BACTERIAL DISEASES Ebola Pneumonia Influenza Cholera Poliomyelitis Gonorrhea Hepatitis Meningitis Measles Dengue HIV/AIDS

21. EUKARYOTIC CELLS By the end of the Topic, Students should be able to; State the functions of the organelles of cells Relate the structure of cell organelles to their functions iii. Differentiate between a cell wall and cell membrane iv. Make a drawing of a generalized animal cell v . Make a drawing of a generalized plant cell vi. State the differences between animal and plant cells vii. State the similarities between the plant cell and animal cell viii. identify specialized eukaryotic cells and outline their functions

22. EUKARYOTIC CELLS Eukaryotes are organisms whose cells have a nucleus enclosed within membranes. They are said to have a true nucleus. Eukaryotes include fungi, protoctists, plants and animals and have eukaryoti c cells . A typical eukaryotic cell has an outer cell membrane, a prominent true nucleus , a cytoplasm within which there are organelles .

23. CELL ORGANELLES An organelle refers to a structure bounded by a membrane found within the cytoplasm of an eukaryotic cell and performs a specific function. CELL WALL- A cell wall is a rigid structure made up of cellulose which surrounds the cell membrane of some cells . The cell wall forms a framework which protects, supports and gives shape to the cell. They are fully permeable to all substances and are non-living . They are found in bacteria, archaea, fungi, plants, and some algae.

24. CELL MEMBRANE The cell membrane (also known as the plasma membrane or cytoplasmic membrane or cell surface membrane is a biological membrane that separates the interior of all cells from the outside environment. The cell membrane is flexible and partially permeable / semi-permeable. The cell membrane controls the movement of materials in and out of the cell. It is composed of phospholipids, globular proteins and 2 layers of lipids(fats)

25. DIFFERENCES BETWEEN CELL MEMBRANE AND CELL WALL CELL MEMBRANE CELL WALL 1. Its flexible Its rigid 2. semi-permeable Fully permeable 3. Made up of phospholipids and proteins Made up of cellulose 4. Its thin Its thick 5. Present in both plant and animal cell Present in plant cells only 6. Cell membrane is metabolically active and living Cell wall is non-living and metabolically inactive 7. Cell membrane encloses the cytoplasm Cell wall encloses the cell membrane and inner components

26. CYTOPLASM The cytoplasm consists of a watery ground substances within which several organelles and cell inclusions are found. The ground substance is 90% water with some salts, sugars, fats, proteins and enzymes in it. The cytoplasm moves , thus moving the cell organelles. This type of movement is called cytoplasmic streaming .

27. NUCLEUS The nucleus is the main control centre of the cell. It comprises an outer nuclear membrane/ nuclear envelope within which there are pores for the movement of materials in and out of the nucleus. Within the nucleus is a spherical body called nucleolus. This is the site of ribosome production. Nuclear envelope/membrane Nuclear pore Nucleoplasm Chromatin Nucleolus

28. MITOCHONDRIA Mitochondria are minute spherical or sausage-shaped organelles. Each mitochondrion is bounded by two membranes and separated by a fluid-filled space. The inner of the two membranes is folded into cristae (singular: crista). There are enzymes on the cristae that are involved in the release energy during respiration. The number and location of mitochondria in the cell depends on the energy requirements of the cell. Therefore cells that require a lot of energy contain many mitochondria . The sperm cell for example has a high concentration of mitochondria close to its tail because energy is required in movement of the sperm cell towards the egg cell.

29. MITOCHONDRIA

30. ENDOPLASMIC RETICULUM This is a network of channels that run through the cytoplasm and are bound by membrane. The endoplasmic reticulum is continuous with the nuclear membrane. There are two types of endoplasmic reticulum; smooth endoplasmic reticulum and rough endoplasmic reticulum. The rough endoplasmic reticulum appears rough due to the presence of ribosomes while smooth endoplasmic reticulum lacks ribosomes.

31. ROUGH ENDOPLASMIC RETICULUM

32. SMOOTH ENDOPLASMIC RETICULUM

33. ENDOPLASMIC RETICULUM

34. ENDOPLASMIC RETICULUM The rough endoplasmic reticulum is the pathway for the transport of protein from the ribosomes. The smooth endoplasmic reticulum is the pathway for the transport of other materials in the cell. The endoplasmic reticulum also provides surfaces for chemical reactions within the cell.

35. RIBOSOMES Ribosomes are minute organelles found in large numbers in the cytoplasm of all prokaryotic and eukaryotic cells . Some occur freely in the cytoplasm while others are bound to the endoplasmic reticulum. They comprise mainly RNA (ribosomal RNA) and protein and are the sites of protein synthesis (protein formation) . A ribosome comprises two subunits; the large subunit and small subunit.

36. CHLOROPLASTS They are large egg-shaped organelles with double membranes found in the cytoplasm of plant cells. They are also present in other organisms like green algae(spirogyra) and euglena. Chloroplasts contain the green pigment chlorophyll . Chlorophyll helps in the trapping of sunlight for photosynthesis. Organisms that possess chloroplast and can manufacture their food through photosynthesis are called Autotrophs and their mode of feeding is termed as autotrophic nutrition . A chloroplast has the following parts ;

37. Stroma : it is the medium in which the grana(singular; granum) and is the site of the dark stage of photosynthesis Grana: It is the site of light stage of photosynthesis and contains chlorophyll

38. GOLGI BODY (GOLGI APPARATUS) It refers to a stack of flattened , membrane bound sacs with numerous vesicles at the edges. They are present in eukaryotic cells only. The main functions of the G olgi bodies are To produce cell membranes To package carbohydrates, proteins and other substances by forming vesicles around them.

39. DICTYOSOMES These are the Golgi bodies of plant cells. They play an important role in the formation of a new cell wall after cell division in plant cells. LYSOSOMES Lysosomes are organelles that contain digestive enzymes. They digest excess or worn out organelles, food particles, and engulfed viruses or bacteria.

40. VACUOLE Vacuoles are organelles that appear as sacs filled with fluid. They are present in all cells but differ in size. Animal cells possess small vacuoles while plant cells possess larger vacuoles. Vacuoles are the "storage system" of the cell. They store nutrients , waste, enzymes, and water. There are three types of vacuoles ; central vacuole - helps maintain plants' shape and structure by storing water . contractile vacuole - pumps water out of protozoan cells to maintain a suitable concentration (osmoregulation). food vacuole - storage for molecules that is a food source for the cell.

41. Other organelles in cells include centrioles and peroxisomes.

42. PLANT CELL Plant cells have an outer cell wall enclosing the cell membrane with the organelles within the cytoplasm.

43. DIFFERENCES BETWEEN PLANT AND ANIMAL CELL PLANT CELL ANIMAL CELL 1. Possess cell wall Lack cell wall 2. have fixed shape Lack a fixed shape 3. Possess chloroplast Lack chloroplast 4. Lack centrioles Possess centrioles 5. Store food as starch Store food as glycogen 6. Possess large vacuoles Possess small vacuoles 7. Vacuoles are permanent Vacuoles are temporary

44. SIMILARITIES BETWEEN PLANT AND ANIMAL CELLS They both possess Nucleus Cytoplasm Cell membrane Mitochondrion Ribosomes Endoplasmic reticulum Lysosomes

45. SPECIALISED EUKARYOTIC CELLS A specialized cell refers to a cell that is modified/ adapted to perform a specific function. Examples of specialized cells include ; Sperm cell- The sperm cell is specialized in the following ways a. The tail helps the sperm to move to the egg. b. Lots of energy is sorted in the middle section of the sperm cell. c. The head contains enzymes that enables the cell to penetrate into the egg cell

46. MUSCLE CELLS Muscle cells have protein fibres with lots of mitochondria to provide the energy needed for contraction to produce movement .

47. Red blood cells Red blood cells - Red blood cells carry oxygen around the body. They are specialized by having ; Lack a nucleus to allow them to contain more haemoglobin . 2. Have a biconcave shape to increase their surface area to increase the amount of oxygen absorbed quickly

48. WHITE BLOOD CELLS White blood cells (WBCs), also called leukocytes or leucocytes, are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders . White blood cells originate in the bone marrow but circulate throughout the bloodstream. There are five major types of white blood cells: 1. neutrophils 2. lymphocytes 3. eosinophils 4. monocytes 5. basophils

49. NERVE CELL/NEURON They are long and thin so messages can be carried all over the body. They are specialized to carry electrical signals. They have connections at each end that allows easy transmission of impulses. There are three types of neurons; motor neurons, sensory neurons and interneurons.

50. Palisade cells They are arranged cylindrically to allow sunlight to reach them easily. They also contain numerous chloroplasts which makes them efficient at producing food by photosynthesis.

51. Leaf epidermal cell These cells fit together perfectly and produce a waxy substance called cuticle that helps to reduce water loss from the leaf. Guard Cell Guard cells  are  cells  surrounding each stoma. They help to regulate the rate of transpiration by opening and closing the stomata . They are located beneath the leaf to decrease the rate of Water loss

52. LEVEL OF ORGANISATION IN LIVING THINGS Multicellular organisms are made up of many cells. These cells do not function alone but they are grouped in similar types to form tissue , which are further grouped to form organs. Groups of organs form the organ system and the organ systems collectively form the organism. There are five levels of organisation in multicellular organisms. These are;

53. Cell Cardial muscle tissue Heart (organ) Circulatory system Human body (organism) Plant cell Plant tissues Plant leaf(organ) Shoot system of the plant Plant(organism)

54. 1. Cells are the basic building blocks of all organisms. Although cells are made of smaller parts, none of those parts could survive on their own. Cells are the simplest level of organization. 2. Tissue- Many cells working together form tissue. A tissue is a group of cells which are similar in shape and size and perform similar functions . The cells in a tissue are specialized to cooperate with each other to accomplish one common goal. Examples of tissues in plants and animals include; muscle tissue, blood, bone, connective tissue, epithelial tissue, xylem, phloem, palisade tissue etc

55. 3. Organ- When there are layers of tissue working together, they form an organ. All animals and plants contain organs. These organs include kidneys , lungs, liver, heart, brain, leaf, stem, flower, branch etc 4. Organ system - When organs work together, they form organ systems. Organ systems keep the body regulated and in a stable state. These systems often work together and rarely work in isolation. The human body has 11 organ systems which include respiratory system, immune system, circulatory system, reproductive system , nervous system, endocrine system, integumentary system, excretory system, digestive system, muscular system, skeletal system

56. Organ system Organs Tissue Cells present Muscular system Muscles Muscle tissue Muscle cells Nervous system Brain, nerves and spinal cord Nerve tissue Nerve cells/neuron Circulatory system Heart, veins, arteries, capillaries Blood , epithelial tissue, cardiac tissue Red blood cells, white blood cells, epithelial cells Shoot system Leaf, branch,stem Xylem, Phloem, Strengthening tissue, Photosynthetic tissue Parenchyma cells, mesophyll cells, palisade cells, chlorenchyma , sclerenchyma, collenchyma Root system Roots Xylem, phloem, Strengthening tissue Collenchyma, sclerenchyma, root tip cells Reproductive system Testes, ovaries, uterus, Muscular tissue, vascular tissue, epithelial tissue Sperm cells, egg cells, muscle cells

57. MOVEMENT OF SUBSTANCES INTO AND OUT OF CELLS In order for cells to function and survive, they need to take in substances from the outside and eliminate waste. There is therefore the need for transport of substances in and out of cells. Examples of substances that are transported in and out of cells include; Food nutrients Ions Salts Waste products Oxygen Carbon dioxide Amino acid Water Hormones Enzymes other useful substances

58. WHY SUBSTANCES MOVE IN AND OUT OF CELLS Food nutrients are needed by cell for energy production and growth Amino acids and minerals are needed by the cell to construct cell components Ions must be moved in and out of cells to allow for nerve impulses to be sent Waste substances must be eliminated from the cells Oxygen must be taken into the cell and carbon dioxide must be taken away from the cell Hormones and enzymes must be transported from the manufacturing cell to different parts of the body The products of photosynthesis have to be taken away from manufacturing cells

59. WAYS OF TRANSPORT IN AND OUT OF CELLS Substances that move in and out cells are mainly in solution. These substances are mainly moving through the cell membrane and cell walls in plants. Cell membranes and cell walls allow water, carbon dioxide, oxygen and nutrients to pass through them. The main ways in which substances are transported within cells are; DIFFUSION OSMOSIS ACTIVE TRANSPORT EXOCYTOSIS ENDOCYTOSIS

60. DIFFUSION It is the movement of molecules(solid, gases, ions) move from an area of high concentration to an area of low concentration until the molecules are evenly distributed. There are several factors that will affect the rate of diffusion and these include ; Concentration gradient /Difference in concentration Temperature Diffusion distance Size of molecules Stirring

61. CONCENTRATION GRADIENT Concentration gradient refers to the difference in concentration between two regions . The steeper(greater) the concentration gradient, the higher the rate of diffusion.

62. TEMPERATURE Increasing the temperature increases the diffusion rate by adding energy to each particle. Similarly , lowering the temperature will lower the diffusion rate by lowering the energy of each particle.

63. SIZE OF MOLECULES The smaller the size of the molecules , the higher the rate of diffusion. DIFFUSION DISTANCE Particles moving through smaller distances result in faster diffusion rates and larger distances result in slower diffusion rates. For example, a gas diffuses through a thin wall much faster than it would diffuse through a thick wall.

64. DIFFUSION IN A LIQUID

65. DIFFUSION IN AIR

66. EXAMPLES OF DIFFUSION IN LIVING THINGS The uptake of nutrients from the soil by the roots in plants The distribution of nutrients to all the parts of the plant Diffusion of Carbon dioxide into the leaf of the plants during photosynthesis Release of oxygen out of the stomata of the leaf in plants Oxygen diffuses into the cell in animals Glucose diffuses into animal cells by diffusion

67. 7. Carbon dioxide diffuses out of cells in animals 8. Oxygen diffuses into the bloodstream by diffusion in animals 9. Carbon dioxide diffuses out of the bloodstream into the lungs by diffusion in animals 10. Selective reabsorption of nutrients in the kidney of animals 11. The movement of materials in and out of unicellular organisms is by diffusion

68. OSMOSIS Osmosis refers to the movement of water molecules from a region of higher water concentration(dilute solution) to a region of lower water concentration (more concentrated solution) through a semi-permeable membrane. Osmosis therefore takes place only in living things because it can only occur through a living cell membrane , that is semi-permeable. NB: A dilute solution is a solution with a high water concentration. A concentrated solution is a solution with very low water concentration

69. EXAMPLES OF OSMOSIS IN LIVING THINGS The uptake of water from the soil by the roots The movement of water through the stem to the leaves T he evaporation of water from leaves through the stomata The movement of water into the cytoplasm in unicellular organisms such as paramecium and Amoeba . Re-absorption of water in the kidney of mammals

70. SIMILARITIES BETWEEN OSMOSIS AND DIFFUSION 1. Both osmosis and diffusion equalize the concentration of two solutions. 2. Both diffusion and osmosis are passive transport processes, which means they do not require any input of extra energy to occur. 3. In both diffusion and osmosis, particles move from an area of higher concentration to a lower concentrated region.

71. DIFFERENCES BETWEEN OSMOSIS AND DIFFUSION DIFFUSION OSMOSIS 1. Does not require a semi-permeable membrane Requires a semi-permeable membrane 2. Involves movement of solids, gases and ions Involves movement of liquids (water) 3. Occurs in living and non-living organisms Occurs in only living organisms 4. Free movement of solute particles Movement of solute particles are restricted 5. Diffusion is fast 6. Increase in temperature increases the rate of diffusion Osmosis is slow Increases in temperature does not have an effect on osmosis

72. Higher concentrated region – high solute, less water Lower concentrated region – low solute , high water (dilute solution)

73. SOLUTIONS There are three types of solutions that cells can be associated with; Isotonic solution Hypotonic solution Hypertonic solution

74. ISOTONIC SOLUTION When a cell is found in a solution that has the same concentration as the cell, the solution is said to be an isotonic solution. An isotonic solution therefore is a solution whose concentration is the same as the cell. There is no net movement of water between the cell and the solution . The fluid that surrounds most body cells is isotonic.

75. If an animal cell is placed in a isotonic solution, water will move in and out of the cell at the same rate and the cell will remain intact. Water moves in and out of the cell membrane at equal rates.

76. HYPOTONIC SOLUTION A hypotonic solution refers to a solution whose concentration is lower than the cell around it. Such a solution has a higher water concentration than the cell and there is movement of water into the cell. This results in an increase in pressure inside the cell called turgor pressure in plants and osmotic pressure in animals. When a plant cell is placed in a hypotonic solution, water moves into the cell continuously and fills the vacuole. The vacuole pushes against the cell membrane and the cell wall until the cell becomes turgid . The plant cell would not burst because of the thickness of the cell wall

77. Turgor pressure is the force within the plant cell that pushes the cell membrane against the cell wall when the plant cell is placed in a hypotonic solution. Turgidity is the state of a cell being turgid or swollen .

78. Importance of turgidity in Plant cells Gives the plant cell shape and makes the plant stand upright Turgidity in guard cells ensures the opening of the stomata It helps in the movement of nutrient solutions from cell to cell

79. When an animal cell is placed in a hypotonic solution, water enters the animal cell continuously till the cell bursts. This happens because the cell membrane is thin and cannot withstand the osmotic pressure . The bursting of t he cell is called cytolysis . T he bursting of the Red blood cell is called hemolysis. Water moves into the cell

80. HYPERTONIC SOLUTION A hypertonic solution refers to a solution whose concentration is greater (has more solute) than the cell which is found in it. Such a solution has a low water concentration and will take up water from the cell. When a plant cell is placed in a hypertonic solution, the cell loses water continuously from the vacuole till the cell contents pull away from the cell wall. The shrinking away of the cell contents from the cell wall as a result of excessive loss of water by the plant cell when placed in a hypertonic solution is known as plasmolysis . The plant cell will lose its definite shape and if it occurs for long , will result in wilting.

81. Hypotonic solution Hypertonic solution

82. When an animal cell(red blood cell for example) is placed in a hypertonic solution, the cell loses water to the solution continuously till it shrinks and Shrivels completely. The cell is said to h ave undergone crenation.

83. Identify the solution in which the red blood cell is placed in each of the following

84. FACILITATED DIFFUSION Facilitated Diffusion is the movement of larger molecules like glucose through the cell membrane . These larger molecules must be “helped ” in order to be carried through the cell membrane. Proteins form protein channels in the cell membrane for large molecules to pass through.

85. ACTIVE TRANSPORT This refers to the movement of solute molecules from a region of lower concentration to a region of higher concentration against concentration gradient using energy (ATP). Active transport uses transport/carrier proteins (protein pumps) that are embedded in the plasma membrane.

86. EXAMPLES OF ACTIVE TRANSPORT Absorption of sugars and amino acids into the blood stream from the small intestine in humans Absorption of some mineral salts from the soil by roots in plants

87. ENDOCYTOSIS Is the process by which large molecules such as proteins are transported into cells by forming vesicles.. There are two main types of endocytosis depending on the material being taken into the cell 1. Phagocytosis – refers to the intake of large solid molecules. Can be called Cell eating”. White blood cells(macrophages) engulf bacteria by this mechanism 2. Pinocytosis – refers to the intake of small droplets of liquid. Can be called ” Cell Drinking”

88. EXOCYTOSIS Exocytosis is a form of bulk transport in which a cell transports molecules out of the cell by secreting vesicles around them and requires the use of energy. The secretion of hormones and enzymes and their release is by exocytosis.

89. EXERCISE 1. List three features of organisms belonging to kingdom protoctista 2. List 4 major phyla under kingdom protoctista

90. HOMEWORK MAKE A DRAWING OF AN AMOEBA AND LABEL THE PARTS FULLY

91. HOMEWORK MAKE A DRAWING OF A PARAMECIUM AND LABEL THE PARTS FULLY

92. MAKE A DRAWING OF AN EUGLENA AND LABEL THE PARTS FULLY

93. Active Transport against the concentration gradient