CELL STRUCTURE AND CELL ORGANISATION

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Silvester Edwards
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1 CELL STRUCTURE AND CELL ORGANISATION CHAPTER 2

2 Cellular components of animal & plant cells

3 Plant Cells Cell wall Plasma membrane Animals Cells Vacuole Chloroplast

4 Vacuole Lysosome Nucleolus Mitochondrion Ribosomes Centriole Cytoplasm Vesicles Smooth Endoplasmic Reticulum Nucleus Plasma membrane Rough Endoplasmic Reticulum Golgi Apparatus

5 Cellular components Organelles Non-organelles Vacuoles Nucleus Ribosomes Endoplasmic reticulum Golgi apparatus Lysosomes Centrioles (animal cell only) Chloroplast (plant cell only) Plasma membrane Cytoplasm Cell wall (plant cells only)

6 Functions

7 Nucleolus Nucleus Controls all the cell activities Has many pores (nuclear pores) in the nuclear membrane for materials to enter & exit the nucleus Nucleolus is involved in the synthesis of ribosome & ribonucleic acid (RNA) Separates the genetic material from cytoplasm

8 Ribosomes Are either attached to the ER or occur freely in the cytoplasm Are small protein factories for protein synthesize

9 Rough Endoplasmic Reticulum Synthesizes & transports proteins made by ribosomes Present in large amounts in cell that makes protein E.g. in gut cells that manufacture digestive enzymes

10 Golgi Appratus Receives proteins from Rough ER, modifies & combines the proteins with carbohydrates to form glyco-protein Transport & stores lipids

11 Smooth Endoplasmi c Reticulum Does not have ribosomes Synthesizes & transport lipids Present in large amounts in cells that make lipids & steroids E.g. cell of liver & testes

12 Mitochondrion Forms the cell s powerhouse Produce adenosine triphosphate (ATP), which is the energy source for the cell

13 Cytoplasm Supports & protects the cell organelles provides a medium for all cellular metabolic reactions medium to produce energy, to manufacture materials & to store minerals

14 Lysosome Break down macromolecules such as proteins, lipids, nucleic acids, polysaccharides as well as worn-out organelles Transport undigested material to the cell membrane for removal

15 Centriole Are found only in animals cells Involved in cell division (mitosis & meiosis)

16 Plasma membrane The outer covering of the cell separates the cell from its environment and allows materials to enter and leave the cell

17 Comparing & contrasting the structure of animal and plant cells

18 Animal cells Plant cell Similarities Both animal and plant cells have plasma membrane, cytoplasm, nucleus, endoplasmic reticulum, Golgi apparatus, ribosomes and mitochondria Differences Not fixed SHAPE Fixed Absent CELL WALL Present Absent CHLOROPLAST Present If present, are small & scattered throughout the cell VACUOLE Has one or a few large vacuole(s) filled with cell sap Present LYSOSOME Normally absent Present CENTRIOLE Absent Carbohydrates are stored in the form of glycogen granules FOOD STRORAGE Carbohydrates are stored in the form of starch grains

19 The Density of Certain Organelles in Relation to Functions of Specific Cells

20 What are organelles? little organs Are tiny structures inside a cell that perform specific functions for the cell 20

21 What are organelles? 3 main functions of organelles: a. Carry out their specialized functions: E.g. Mitochondria; FUNCTION? b. Acts as containers to separate parts of the cell from other parts E.g. lysosomes c. Sites for chemical reaction E.g. Chloroplast

22 Relationship between the Density & Functions of certain Organelles Density of an organelles : total number of that particular organelles within a cell depends on the function of the cell to make sure that the cell can perform its specialized functions well

23 Relationship between the Density & Functions of certain Organelles E.g. Cell that specialize in producing enzyme generally have more ER & ribosomes to & mitochondria to for its activities

24 The density of mitochondria in active cells Depends on: a) The activity level of an organism The more active an organism is, the higher its average density of mitochondria b) The specific function of a particular cell Cell of active tissues & organs have higher mitochondria densities

25 The density of mitochondria in active cells Active cells that have high mitochondria densities: Sperm cells flight muscle cells meristemic cells liver cells kidney cells

26 The density of Chloroplast in the Palisade Mesophyll Cells of Leaves Palisade mesophyll of a leaf is : the main photosynthesis tissue Packed with chloroplast to trap sunlight needed to synthesize sugar during photosynthesis Are arranged in a vertical position to optimise sunlight trapping

27 Type of cells Function Density of certain organelles Sperm cells Flight muscle cells insects and birds To swim towards either one of the Fallopian tubes to fertilise the ovum Contraction and relaxation of muscles provide movement & locomotion Mitochondria are sites of cellular respiration in which energy in the form of ATP is generated through oxidation of food substances such as glucose Mitochondria Cells in the meristem Palisade mesophyll cells Goblet cells in the respiratory tract Divided actively to produce new cells for growth Carry out photosynthesis Secrete mucus Mitochondria Chloroplast contain chlorophyll which trap light energy for photosynthesis Golgi apparatus Liver cells Detoxification of drugs Smooth endoplasmic reticulum Pancreatic cells, cells of salivary glands, stomach cells, cells of intestine Produce enzyme Rough endoplasmic reticulum and golgi apparatus

Basic Structure of a Cell

Basic Structure of a Cell 1 Introduction to Cells Cells are the basic units of organisms Cells can only be observed under microscope Basic types of cells: Animal Cell Plant Cell Bacterial Cell 2 Number