1. Cell Facts and Tissues (rev 3-10) Cells are the smallest structural and functional unit of life All cells are surrounded by a thin, outer membrane called the plasma membrane (PM). –This separates the cell from interstitial fluid which bathes the outside of the cell. On the inside of the cell is a gel-like fluid called cytoplasm. This contains specialized structures called organelles and the nucleus, a small circular body. The Plasma Membrane Forms the outer boundary of the cell –Composed of 2 layers of fat molecules called phospholipids and another kind of fat molecule called cholesterol Cell Facts & Tissues-BIO 0061

2. The plasma membrane (PM) keeps the cell whole and intact –It serves as a gateway (entrance) between the fluid inside and outside the cell –It identifies a cell as belonging to one particular person; the cell’s surface proteins act as identification tags (each person has different surface proteins) Cytoplasm: composed of a gel-like fluid called cytosol –Lies between the PM and the nucleus –Contains Organelles: structures with specialized functions which are located in the cytoplasm. Also contains a nucleus. 2

3. Cell Facts & Tissues-BIO 006 Nucleus : Controls every organelle in the cytoplasm and the cell reproduction process because it contains the genetic code—instructions for making proteins, which in turn determine cell structure and function directs all functions of the cell. Structural features : Outer surface is a double-layered nuclear membrane, also called nuclear envelope. Contains 46 chromosomes which contain DNA, the genetic code Figure 3.19a 3

4. Cell Facts & Tissues-BIO 006 Organelles Ribosomes: tiny particles found throughout the cell; responsible for making enzymes and other protein compounds –Made up of 2 tiny subunits mostly made up of a special kind of RNA— called ribosomal RNA –Ribosomes may be attached to the Endoplasmic Reticulum –Free floating ribosomes produce proteins for use by the cell 4

5. Cell Facts & Tissues-BIO 006 Endoplasmic reticulum (ER) is a system of membranes forming a network of connecting sacs and canals that wind back and forth through a cell’s cytoplasm. –manufactures proteins and chemical compounds produced by the cell. –The sacs and canals carry proteins and other substances through the cytoplasm of the cell from one area to another. Types: rough and smooth Rough ER: areas where the surface is dotted with ribosomes –Rough ER receives, from the ribosomes, and transports newly made proteins Smooth ER: Areas without ribosomes –These areas synthesize chemicals and make new cell membrane 5

6. Cell Facts & Tissues-BIO 006 Golgi Apparatus Group of flattened sacs Called the chemical processing and packaging center because it collects chemicals from the smooth ER in vesicles Mitochondria : Provide most of the power for cellular work; nicknamed the cell’s “power plant” Enzymes found in the mitochondria use oxygen to breakdown glucose to release energy 6

7. Cell Facts & Tissues-BIO 006 Lysosomes contain digestive enzymes that digest food compounds as well as other substances. –Can destroy microbes Centrioles: used in cell division Cilia: fine, hairlike extensions on the free surface of some cells; are capable of movement Flagella: is a single projection from the cell surface; is larger than cilia; “ tails” of sperm cells are the only example of flagella in humans 7

8. Cell Facts & Tissues-BIO 006 Movement of Substances through Cell Membranes Occurs through passive or active transport Energy is required only for active transport and is obtained from adenosine triphosphate or ATP –ATP is produced in the mitochondria Passive transport processes do not require added energy and result in movement “down a concentration gradient” 8

9. Solution terms –Solute is a substance that dissolves into another substance –Solvent is a substance in which other substances are dissolved Cell Facts & Tissues-BIO 0069

10. Passive Transport Transports a molecule without requiring the cell to use any energy; requires that there be a difference in concentration between 2 areas, called a concentration gradient. Movement is from area of high to area of low concentration or “down” the concentration gradient Primary passive transport processes are diffusion and osmosis 10

11. Diffusion : movement of molecules from one region to another as a result of random movement; –Molecules move from the area of higher concentration to the area of lower concentration molecules scatter themselves evenly throughout a solution Cell Facts & Tissues-BIO 00611

12. Diffusion Cell Facts & Tissues-BIO 006 (Passive transport: no energy required) Diffusion: movement from area of high concentration to low 12

13. Cell Facts & Tissues-BIO 006 Osmosis is the diffusion of water across a selectively permeable membrane (the solutes cannot cross the membrane) from the region of lower concentration to the area of higher concentration Selectively permeable means a membrane will permit some substances to pass through it but not others 13

14. Cell Facts & Tissues-BIO 00614

15. Cell Facts & Tissues-BIO 006 Active transport Movement of substances is “up the concentration gradient”— movement from an area of lower to higher concentration Requires energy from ATP Ion pumps –An ion pump is a protein structure in the cell membrane Is called a “carrier” –Ion pumps use energy from ATP to move substances across cell membranes against their concentration gradients –Examples: sodium-potassium pump, calcium pump –Some ion pumps work with other carriers so that glucose or amino acids are transported along with ions 15

16. Cell Facts & Tissues-BIO 006 Na+-K+ Pump 3 sodium ions are pumped out of the cell and 2 potassium ions are pumped in during a pumping cycle of the carrier molecule. ATP is broken down and used for energy to pump the ions 16

17. Why are passive and active transport important in the human body? –Hint: how do substances move across the plasma membrane? Cell Facts & Tissues-BIO 00617

18. Cell Facts & Tissues-BIO 006 Body Tissues Tissue: group of similar cells that perform a common function 4 main kinds of tissues –Epithelial –Connective –Muscle –Nervous Tissues differ from each other in their –Size and shape of cells –Amount and kind of material between the cells –Special functions they perform 18

19. Cell Facts & Tissues-BIO 006 Epithelial Tissue covers the body and lines body cavities –Cells packed closely together Can be categorized according to shape: –Squamous (flat) –Cuboidal (cube) –Columnar (tall) Can be categorized according to arrangement-layers of cells: –Simple –Stratified 19

20. Cell Facts & Tissues-BIO 006 EPITHELIAL TISSUE Absorbs –substances can easily pass through it for example absorption of oxygen into the blood Secretes –cells function in clusters and form glands which make and release substances to help the body work i.e. saliva, digestive juices, and hormones –cells forms the urine-producing tubules of the kidneys Protects tissues –when there are several layers of closely packed cells, microorganisms can’t get through them –cilia move mucus and protect against entry of foreign particles into the lung 20

21. Cell Facts & Tissues-BIO 006 Most abundant tissue in body  Most widely distributed tissue in body  Multiple types, appearances, and functions - Connects tissues to each other - Forms a supportive framework for the body and the organs - Transports substances throughout the body (blood is a type of connective tissue) - Defends us against microorganisms  Relatively few cells in an intercellular matrix Connective tissue 21

22. Cell Facts & Tissues-BIO 006 Types of Connective Tissue Blood— fluid “tissue”; –function is transportation and protection –cells are suspended in a fluid matrix called plasma. (Considered a connective tissue because all blood cells derive from earlier stem cells located within bone.) 22

23. Areolar: glue that holds organs together Most widely distributed type of connective tissue Cell Facts & Tissues-BIO 00623

24. Cell Facts & Tissues-BIO 006 Adipose (fat) specialized to store lipids Oil filled cells 24

25. Cell Facts & Tissues-BIO 006 Dense Fibrous Has bundles of collagen fibers arranged in parallel rows Provides strength and flexibility; does not stretch example is tendons and ligaments 25

26. Cell Facts & Tissues-BIO 006 Bone functions in support and protection Stores the mineral calcium 26

27. Cell Facts & Tissues-BIO 006 Cartilage bone will be formed from this type tissue Matrix is the consistency of firm plastic or a gel 27

28. Cell Facts & Tissues-BIO 006 Muscle tissue :  movement “specialist”;  can contract 28

29. Cell Facts & Tissues-BIO 006 Skeletal Muscle also called striated or voluntary; attaches to bones; Has striations is multinucleated has long cells 29

30. Cell Facts & Tissues-BIO 006 Cardiac Muscle also called striated or involuntary forms the walls of the heart has intercalated disks; fibers branch 30

31. Cell Facts & Tissues-BIO 006 Smooth also called nonstriated, visceral, or involuntary found in blood vessel walls and hollow organs push food and fluids through body 31

32. Cell Facts & Tissues-BIO 006 Nervous tissue provides rapid communication between body structures and control of body functions  Consists of 2 types of cells:  Neurons—conducting cells  Neuroglia—supportive and connecting cells  Neurons  Cell components o Cell body o Axon (one or more) carries nerve impulses away from cell body o Dendrites carry nerve impulses toward the cell body 32