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Chapter7 Looking at cells.

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Presentation on theme: "Chapter7 Looking at cells."— Presentation transcript:

1 Chapter7 Looking at cells

2 Where does cork come from?
The bark of an oak tree that grows in Spain and Portugal The bark is dead All that is left are the cell walls enclosing air

3 Microscopes reveal cell structure
Robert Hooke , an English scientist, invented the microscope in the 1600’s to view cork He named the “little boxes” he saw, “cells”

4 Anton van Leeuwenhoek 10 years after Hooke’s findings
Used a microscope to view pond water He named the single-celled organisms he discovered “animalcules”

5 The Cell Theory All living things are made of cells
Cells are the basic units of structure and function in organisms All cells arise from existing cells

6 Measuring the size of cell structures
Measurements are in metric units International System of Measurements (SI) Based on powers of 10 Micrometers are one-millionth of a meter ( the size of a bacterial cell)

7 Cells must be small Small is good! Big is bad!
Lower surface area to volume ratio = inability to move substances across the membrane in large enough numbers Higher surface area to volume ratio = greater ability to exchange substances Small is good! Big is bad!

8 Common features of all cells
Cell membrane Cytoplasm Cytoskeleton Ribosomes Genetic material

9 Prokaryotes do not contain internal compartments
No nucleus Smaller Ex: bacteria

10 Characteristics of bacteria
Prokaryotes All have a cell wall surrounding the cell membrane Some have flagella for movement DNA is circular instead of linear Some have a capsule for clinging

11 Eukaryotic cells are organized
Have a nucleus Have other membrane enclosed organelles Some have flagella or cilia for movement

12 Eukaryotes Larger More complex Many are highly specialized
Plants, animals, fungi, and many protists

13 Cell Organization Two divisions: Nucleus- eukaryotes only
Cytoplasm- fluid portion of the cell outside the nucleus Eukaryotes and prokaryotes

14 Organelles Specialized structures “Little organs”

15 Nucleus Controls cell functions
Surrounded by a double membrane with nuclear pores Contains DNA wound around proteins Wind up into chromosomes before division takes place

16 Nucleus Nucleolus- where ribosomes are made
Nuclear pores- allow materials in and out

17 Vacuoles Large, saclike, membrane-enclosed structures that store materials such as water, salts, proteins, and carbohydrates

18 Vacuoles Plants- large central vacuole, helps keep leaves and flowers rigid Found in some unicellular organisms and animals Contractile vacuole in paramecium

19 Vesicles In almost all eukaryotic cells Used for storage and movement

20 Lysosomes Small organelle filled with enzymes
Digest old organelles, cellular “junk,” lipids, proteins, and carbohydrates Type of vesicle, found in animal and some plant cells

21 Ribosomes Made of RNA and protein Produce proteins
Found in the cytoplasm (free) and rough ER (attached)

22 Endoplasmic Reticulum (ER)
A system of internal membranes that moves proteins and other substances through the cell Rough ER- has ribosomes on the surface that create exported proteins Smooth ER- no ribosomes, makes lipids for the cell membrane Detoxifies drugs

23 Golgi Apparatus Stack of flattened sacs
Modifies, sorts, and packages proteins made from the rough ER Sent into or out of the cell

24 Sources of Energy Mitochondria- animal and plant cells
Chloroplasts- plant cells

25 Chloroplasts Converts sunlight into food energy in a process called photosynthesis Double membrane Contains a green pigment called chlorophyll

26 Mitochondria In eukaryotic cells Power plant of the cells
Converts food energy into smaller units the cell can more easily use Double membrane

27 Mitochondria Inherited only from your mother
A way to trace the maternal lines of animals

28 Endosymbiotic Theory Chloroplasts and mitochondria have their own DNA and double membranes Theory states: These may have been independent organisms at one time Create their own energy May have been beneficial once absorbed and found to be beneficial

29 Unique features of plant cells
Cell wall -surrounds the cell membrane, supports and protects the cell Chloroplasts- green structures that absorb sunlight and produce glucose Central vacuole- stores water and other substances, when full makes a cell rigid

30 Cytoskeleton Network of protein filaments
Gives cells their shape and internal organization Helps to transport materials inside the cell Protein filaments Microtubules Microfilaments

31 Microfilaments Threadlike structures made of protein called actin
Make up a tough flexible framework that helps support the cell Help cells move Amoebas- assemble and disassemble to help them move

32 Microtubules Hollow structures Made of protein tubulin
Maintains cell shape Centrioles Makes spindle during mitosis to separate chromosomes

33 Microtubules Make up cilia and flagella Arranged in a 9+2 pattern
Used for swimming Arranged in a 9+2 pattern Small bridges between aid in movement

34 Cell Boundries Cell wall Cell membrane

35 Cell Wall Prokaryotes, plants, algae, fungi Outside the cell membrane
Animal cells do not Outside the cell membrane Strong supporting layer Porous- allows water, carbon dioxide and oxygen to pass through

36 Cell Membrane Protects and supports cell
Regulates what enters and leaves Phospholipid bilayer- to layers of lipids


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