1 Basic Structure of a Cell

2 Introduction to Cells Cells are the basic units of organisms Cells can only be observed under microscope Basic types of cells: Animal CellPlant Cell Bacterial Cell

3 Number of Cells Organisms may be: Unicellular – composed of one cell Multicellular- composed of many cells that may organize

4 Discovery of Cells By Robert Hooke in Did not take place until a microscope was invented. Looked at cork cells. Only saw cell walls. Named them after the rooms or “cells” of a monastery.

5 Led to the Cell Theory All living things are made of cells. A cell is the basic unit of structure and function in a living thing. Cells only come from other cells.

6 Old Theory Spontaneous generation: living things can come from nonliving materials. Ex – rats from grain stored in dark room - maggots from rotting meat

7 Modern Compound Microscope Instrument for observing small objects Magnify images up to 2000X their size

Cells Vary Cells vary in shape and size All cells are small 8

3-9 Cells are Small Size is limited by the ratio between outer surface area and volume As a cell gets bigger, its volume increases faster than its surface area. Surface area must be large to supply nutrients and oxygen to all of its volume

10  Prokaryotes are bacterial cells. They lack a nucleus or membrane- bound structures called organelles  Eukaryotes include most other (plants, fungi, protists, & animals)  They have a nucleus and membrane-bound organelles Cells May be Prokaryotic or Eukaryotic

11 Prokaryotes Nucleoid region contains the DNA Cell membrane & cell wall Contain ribosomes in their cytoplasm that make proteins Ribosomes are tiny structure that are NOT covered with membranes

12 Eukaryotic Cell Contain 3 basic cell structures: Nucleus Cell Membrane Cytoplasm with organelles

13 Two Main Types of Eukaryotic Cells Plant Cell Animal Cell

14 Organelles Cell structures that are very small Can only be observed under a microscope Have specific functions Found throughout cytoplasm Most are surrounded by a membrane

15 Organelles Found in Cells include: Endoplasmic reticulum (ER)– canals for movement. Two types: rough & smooth Golgi Bodies – wrap & export proteins Nucleolus – makes ribosomes Lysosomes – digest & get rid of wastes Ribosomes – makes proteins

16 Golgi Bodies Stacks of flattened sacsStacks of flattened sacs Have a shipping side & a receiving sideHave a shipping side & a receiving side Receive & modify proteins made by ERReceive & modify proteins made by ER Transport vesicles with modified proteins pinch off the endsTransport vesicles with modified proteins pinch off the ends Transport vesicle

17 Lysosomes Contain digestive enzymesContain digestive enzymes Break down food and worn out cell parts for cellsBreak down food and worn out cell parts for cells Programmed for cell death (lyse & release enzymes to break down & recycle cell parts)Programmed for cell death (lyse & release enzymes to break down & recycle cell parts)

18 Nucleolus Cell may have 1 to 3 nucleoli Cell may have 1 to 3 nucleoli Inside nucleusInside nucleus Cannot be seen when cell dividesCannot be seen when cell divides Makes ribosomes that make proteinsMakes ribosomes that make proteins

19 Smooth & Rough Endoplasmic Reticulum Smooth ER lacks ribosomes & makes hormones that are used in the cell Rough ER has ribosomes on its surface & makes proteins to EXPORT

20 Rod shape organelle Site of Cellular respirationMitochondria Mitochondrion ( powerhouse )

21 Active cells like muscles have more mitochondria than other cells Burn sugars to produce energy ATP In Animal Cells: Mitochondria

22 Lies immediately against the cell wall in plant cells Made of protein and phospholipids Selectively permeable Cell membrane Surrounding the Cell

23 Controls the movement of materials into and out of the cell Selectively permeable Cell membrane Cell or Plasma Membrane

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26 Jelly-like substance enclosed by cell membrane Provides a medium for chemical reactions to take place Cytoplasm Cytoplasm of a Cell

27 Contains organelles to carry out specific jobs Cytoplasm More on Cytoplasm

28 Controls the normal activities of the cell Bounded by a nuclear membrane Contains chromosomes (DNA) Control Organelle Nucleus

29 Each cell has fixed number of chromosomes that carry genes Genes control cell characteristics Nucleus More on the Nucleus

30 Contains the green pigment chlorophyll Traps sunlight to make sugars (food) Process called photosynthesis Special Plant Cell Organelles Chloroplast

31 Large empty spaces present between cellulose fibers Cell wall Plant Cell

32 Plant Cell Made of cellulose Strong and rigid Cell wall

33 Protects and supports the enclosed substances (cytoplasm) Prevents entry of excess water into the cell Give shape to the cell Cell wall Plant Cell

34 Plants have a large central vacuole Contains: Water, sugars, proteins, minerals, wastes, & pigments Plant Cell Organelles Central Vacuole

35 Different kinds of plant cells Onion Epidermal Cells Root Hair Cell root hair Guard Cells

36 mitochondrion nucleus glycogen granule cell membrane cytoplasm Animal cell No cell wall, large central vacuole, or chloroplast vacuole

37 Organelle Unique to Animal Cells Near the nucleus Paired structures Help cell divide

38 Different kinds of animal cells white blood cell red blood cell cheek cells sperm nerve cell muscle cell Amoeba Paramecium

39 Similarities between plant cells and animal cells Both have a cell membrane surrounding the cytoplasm Both have a nucleus Both contain mitochondria and other organelles

40 Differences between plant cells and animal cells Animal cellsPlant cells Relatively smaller in size Irregular shape No cell wall Relatively larger in size Regular shape Cell wall present

41 Animal cellsPlant cells Vacuole small or absent Nucleus at the center Large central vacuole Nucleus near cell wall Differences between Plant Cells and Animal Cells

42 Different parts of a microscope

43 Eyepiece Fine adjustment Arm Stage Condenser control knob Base Body tube Coarse adjustment Iris diaphragm Revolving nosepiece Objective Clip Condenser Mirror

44 The cell is the Basic Unit of Life Unicellular organisms are made of one cell only The cells of multicellular organisms are specialized to perform different functions –e.g. mesophyll cells for photosynthesis and root hair cells for water absorption