1. Introduction to Eukaryotic cell structure Eukaryotic cell structure Function of cell organelles Function of cell structural components Differences between plant and animal cells Division of labour within a cell

2. Eukaryotic cells The eukaryotic cell structure is found in all plants, animals, fungi and protoctists The eukaryotic cell structure is found in all plants, animals, fungi and protoctists The complex structure allows for the specialisation of cells to perform certain functions The complex structure allows for the specialisation of cells to perform certain functions With the specialisation of function, cells can form tissues which can work together to form an organ With the specialisation of function, cells can form tissues which can work together to form an organ Hence eukaryotic cells can form complex multicellular organisms Hence eukaryotic cells can form complex multicellular organisms

3. The animal cell

4. A eukaryotic animal cell Mitochondria Nucleus Lysosome Rough ER Ribosomes Smooth ER Vacuole

5. The plant cell

6. A eukaryotic plant cell

7. Eukaryotic cellular organelles and structure Organelles Nucleus Nucleus Mitochondria Mitochondria Endoplasmic reticulum Endoplasmic reticulum Ribosomes Ribosomes Golgi body Golgi body Lysosomes Lysosomes Centrioles Centrioles Chloroplasts Chloroplasts Vacuole Vacuole The detailed organisation of the cell is called the cell ultrastructure The ultrastructure of a cell can only be seen using an electron microscope

8. Nuclear envelope Nuclear pore Nucleolus Chromatin Mitochondrion Rough ER

9. Nucleus The nucleus controls the cells activities The nucleus controls the cells activities It contains chromatin which are coils of DNA bound to protein. During cell division the chromatin condenses to form the chromosomes. It contains chromatin which are coils of DNA bound to protein. During cell division the chromatin condenses to form the chromosomes. The nucleus is surrounded by a nuclear envelope (double membrane) continuous with Rough ER. Pores allow transport of mRNA and nucleotides from the nucleus to the cytoplasm. The nucleus is surrounded by a nuclear envelope (double membrane) continuous with Rough ER. Pores allow transport of mRNA and nucleotides from the nucleus to the cytoplasm. The cytoplasm like material in the nucleus is called nucleoplasm The cytoplasm like material in the nucleus is called nucleoplasm A region called the nucleolus synthesises ribosomes. A region called the nucleolus synthesises ribosomes.

10. DNA and histone proteins form chromatin. During cell division chromatin condenses to form visible chromosomes (prophase)

11. The Mitochondria

13. Mitochondria (pleural) mitochondrion (single) are sites isolated from the rest of the cytoplasm where enzyme- catalysed reactions of respiration take place. Their main function is to synthesis ATP (adenosine tri-phosphate) Their main function is to synthesis ATP (adenosine tri-phosphate) The organelle has a double unit membrane – the inner one being highly folded to increase surface area called the cristae. The organelle has a double unit membrane – the inner one being highly folded to increase surface area called the cristae. The inner and outer membrane are separated by a narrow fluid filled inter membrane space The inner and outer membrane are separated by a narrow fluid filled inter membrane space The interior of the mitochondria contains a fluid called the matrix The interior of the mitochondria contains a fluid called the matrix Some of the reactions of aerobic respiration takes place in the matrix while others on the inner membrane Some of the reactions of aerobic respiration takes place in the matrix while others on the inner membrane Mitochondria have their own DNA (the genes code for respiratory enzymes) Mitochondria have their own DNA (the genes code for respiratory enzymes)

14. Smooth Endoplasmic Reticulum Nucleus Nuclear envelope Rough endoplasmic reticulum Transitional elements Golgi body Rough and smooth Endoplasmic Reticulum

15. Rough ER

16. Rough and smooth Endoplasmic Reticulum There is a system of flattened membranes which form sacs in the cytoplasm of all eukaryotic cells called Endoplasmic Reticulum. There is a system of flattened membranes which form sacs in the cytoplasm of all eukaryotic cells called Endoplasmic Reticulum. It is continuous with the nuclear membrane and can link to the Golgi body It is continuous with the nuclear membrane and can link to the Golgi body It ’ s function is to transport substances throughout the cell It ’ s function is to transport substances throughout the cell The fluid filled spaces between the membranes are called cisternae The fluid filled spaces between the membranes are called cisternae ER encrusted with ribosomes is called Rough ER, whilst that devoid of ribosomes is smooth ER. ER encrusted with ribosomes is called Rough ER, whilst that devoid of ribosomes is smooth ER. Smooth ER is concerned with lipid metabolism and the manufacture of steroids. Smooth ER is concerned with lipid metabolism and the manufacture of steroids. Rough ER transports proteins made by the ribosomes Rough ER transports proteins made by the ribosomes

17. Ribosomes

18. Ribosomes

19. Ribosomes These are the sites of protein synthesis within cells and are composed of ribosomal RNA and protein. These are the sites of protein synthesis within cells and are composed of ribosomal RNA and protein. Ribosomes are synthesised in a region of the nucleus called the nucleolus. Ribosomes are synthesised in a region of the nucleus called the nucleolus. They can be attached to the ER or free-floating in eukaryotic cells but only free-floating in prokaryotic cells. They can be attached to the ER or free-floating in eukaryotic cells but only free-floating in prokaryotic cells. Attached ribosomes make proteins used outside the cell. Attached ribosomes make proteins used outside the cell. Free-floating ribosomes make protein for use inside the cell. Free-floating ribosomes make protein for use inside the cell.

20. Golgi Body

22. Action of Lysosomes

23. Lysosomes

24. Lysosomes Larger vesicles surrounded by a single unit membrane - formed from the Golgi body. Larger vesicles surrounded by a single unit membrane - formed from the Golgi body. They contain hydrolytic enzymes (proteases and lipases) to digest the contents of food vacuoles with which they fuse. (Phagocytosis) They contain hydrolytic enzymes (proteases and lipases) to digest the contents of food vacuoles with which they fuse. (Phagocytosis) They can also fuse with and digest worn out cellular organelles. The entire cell can be destroyed on occasions when the lysosomes break down (suicide bags). They can also fuse with and digest worn out cellular organelles. The entire cell can be destroyed on occasions when the lysosomes break down (suicide bags).

26. Centrioles Centrioles are found in all animal cells, protoctists but not in higher plants. Centrioles are found in all animal cells, protoctists but not in higher plants. They are found outside the nucleus in a region of the cytoplasm called the centrosome. They are found outside the nucleus in a region of the cytoplasm called the centrosome. These have a 9 + 2 microtubular arrangement when viewed in cross-section. These have a 9 + 2 microtubular arrangement when viewed in cross-section. They consist of two hollow cylinders positioned at right angles to each other. They consist of two hollow cylinders positioned at right angles to each other. They are the regions from which the spindle fibres emerge during cell division. Centrioles migrate to opposite ends of the nucleus and molecules of tubulin (a dimer protein with a large molecular weight) polymerise to form the spindle. They are the regions from which the spindle fibres emerge during cell division. Centrioles migrate to opposite ends of the nucleus and molecules of tubulin (a dimer protein with a large molecular weight) polymerise to form the spindle.

28. Chloroplast (Plants only)

29. Sites isolated from the rest of the cytoplasm in eukaryotic plant cells where reactions of photosynthesis occur. Sites isolated from the rest of the cytoplasm in eukaryotic plant cells where reactions of photosynthesis occur. They consist of a double membrane with a fluid filled stroma. They consist of a double membrane with a fluid filled stroma. The stroma contains ribosomes, lipid, circular DNA and starch The stroma contains ribosomes, lipid, circular DNA and starch The thylakoids (stack of pennies) form the granum and house the photosynthetic pigments The thylakoids (stack of pennies) form the granum and house the photosynthetic pigments The thylakoids are adapted to form a large surface area to trap light The thylakoids are adapted to form a large surface area to trap light Main function is to manufacture reduced nicotinamide adenine dinucleotide phosphate (NADP.H 2 ) and ATP in the light dependent reactions, to use in the light independent reactions to fix CO 2 into a storage carbohydrate (Starch). Main function is to manufacture reduced nicotinamide adenine dinucleotide phosphate (NADP.H 2 ) and ATP in the light dependent reactions, to use in the light independent reactions to fix CO 2 into a storage carbohydrate (Starch).

30. Permanent Vacuole

31. These include numerous small vesicles found in animal cells (food vacuoles) and a large central cavity surrounded by a single membrane called the tonoplast, in plant cells. These include numerous small vesicles found in animal cells (food vacuoles) and a large central cavity surrounded by a single membrane called the tonoplast, in plant cells. In animal cells vacuoles are a temporary store of food and secretions In animal cells vacuoles are a temporary store of food and secretions In plants the permanent vacuole is a store of amino acids, carbohydrates and lipids (mainly oils). They also store tannins and other substances that comprise cell sap. In plants the permanent vacuole is a store of amino acids, carbohydrates and lipids (mainly oils). They also store tannins and other substances that comprise cell sap. The cell sap provides an osmotic system which plants can alter to move water in and out The cell sap provides an osmotic system which plants can alter to move water in and out

32. Structural components of the cell These are the structural elements of the cell required for protection, shape, boundary layers and movement Cellulose cell wall Cellulose cell wall Cytoskeleton Cytoskeleton Flagella and cilia Flagella and cilia Plasma membrane Plasma membrane Cytoplasm Cytoplasm

33. Cellulose cell wall The cell wall consists of cellulose microfibrils embedded in a polysaccharide matrix. The cell wall consists of cellulose microfibrils embedded in a polysaccharide matrix. The cell wall provides strength and support and also permits the movement of water from cell to cell via the plasmodesmata. The cell wall provides strength and support and also permits the movement of water from cell to cell via the plasmodesmata.

34. Plasmodesmata There are gaps in the cell wall that allow neighbouring cells to link together There is a continuation of cytoplasm from cell to cell and the endoplasmic reticulum can also be linked cytoplasm endoplasmic reticulum

35. Cytoskeleton

36. Cytoskeleton The cytoskeleton is an internal network of protein fibres which helps to keep the cell shape. There are three types: The cytoskeleton is an internal network of protein fibres which helps to keep the cell shape. There are three types: The actin filaments are able to move against each other and can cause the cell to move (WBC) or move organelles around The actin filaments are able to move against each other and can cause the cell to move (WBC) or move organelles around Intermediate filaments help provide structure Intermediate filaments help provide structure Microtubules are cylinders made from a protein called tubulin. Microtubule motors on the tubulin use ATP for movement Microtubules are cylinders made from a protein called tubulin. Microtubule motors on the tubulin use ATP for movement Move chromosomes during mitosis Move chromosomes during mitosis Move vesicles from ER to golgi body Move vesicles from ER to golgi body

37. Flagella and cilia Both have the same structure but cilia are shorter and tend to occur in greater numbers (flagella 1-2) Both have the same structure but cilia are shorter and tend to occur in greater numbers (flagella 1-2) Flagella also tend to move the entire cell (sperm) cilia tend to ‘ sweep ’ substances and mucus Flagella also tend to move the entire cell (sperm) cilia tend to ‘ sweep ’ substances and mucus Each consists of a cylinder with a 9 + 2 arrangement of microtubules which use ATP as a source of energy Each consists of a cylinder with a 9 + 2 arrangement of microtubules which use ATP as a source of energy

38. Cell membrane Function of the plasma membranes: Function of the plasma membranes: Occur around the cell and determine what enters and leaves the cell Occur around the cell and determine what enters and leaves the cell Occur around organelles isolating enzymes within the organelle Occur around organelles isolating enzymes within the organelle Within organelles providing a large surface area for the attachment of enzymes Within organelles providing a large surface area for the attachment of enzymes Provide a transport system within the cell. e.g vesicles Provide a transport system within the cell. e.g vesicles The structure of the plasma cell membrane will be studied in section 1.3

39. Cytoplasm The cytoplasm outside the organelles is called the cytosol The cytoplasm outside the organelles is called the cytosol The cytosol is a complex mixture of cytoskeleton filaments, dissolved molecules, and water that fills much of the volume of a cell. The cytosol is a complex mixture of cytoskeleton filaments, dissolved molecules, and water that fills much of the volume of a cell. cytoskeleton The cytosol is the site of glycolysis (respiration) The cytosol is the site of glycolysis (respiration)

40. ANIMAL CELL PLANT CELL Courtesy of Dr. Julian Thorpe – EM & FACS Lab, Biological Sciences University Of Sussex

41. Plant and animal cells are eukaryotic cells Both types of cell possess characteristic organelles; Nucleus Rough endoplasmic reticulum Smooth endoplasmic reticulum Mitochondria Golgi apparatus Microtubules Differences between mature plant and animal cells include: PLANT CELLS Cellulose cell wall Large vacuoles that store cell sap Chloroplasts in photosynthetic cells ANIMAL CELLS Microvilli Centrioles

42. Division of labour The relationship between organelles The relationship between organelles The DNA in the nucleus contains the code to produce the protein. A gene on the DNA will be copied The DNA in the nucleus contains the code to produce the protein. A gene on the DNA will be copied The code will be ‘ transcibed ’ by mRNA The code will be ‘ transcibed ’ by mRNA The mRNA attaches to the ribosome (free or on RER) The mRNA attaches to the ribosome (free or on RER) The protein will be made using tRNA The protein will be made using tRNA The assembled protein inside the RER will be pinched off into a vesicle and transported to the golgi body The assembled protein inside the RER will be pinched off into a vesicle and transported to the golgi body The golgi will package the protein and maybe modify The golgi will package the protein and maybe modify Another vesicle will be pinched off the golgi and moved to cell surface for exocytosis Another vesicle will be pinched off the golgi and moved to cell surface for exocytosis

43. Division of labour How organelles work together