Chemistry, Cellular Structure, and Function

1. Chemistry, Cellular Structure, and Function Surgical A&P for Surgical Technologists Frey and Price

2. Objectives • Describe the basic concepts of chemistry • Compare and contrast the structures and functions of the cell • Evaluate the importance of cell movement and responsiveness • Compare and contrast the elements of cell reproduction • Compare and contrast glycolysis and the Krebs cycle

3. Why do we have to study chemistry? • Surgical technologists deal with tissue and organs on a daily basis. • The foundation for tissues is cells. • We have to understand cells so that we understand sterility (the destruction of certain cells) • Surgical technologists come into contact with cancerous cells on a near daily basis • Refer to case study 1 p. 17

4. Matter • Anything that takes up space and has mass • Weight and mass are different. • Weight represents the gravitational pull on an object • Objects in space still have mass even though they are weightless

5. Matter, cont’d • All matter is made of atoms • Different matter is made of different types of atoms • Matter constantly changes, physical states can change, but it will retain fundamental characteristics • Water in solid form is ice, liquid is water, and gas is steam

6. Energy • Energy causes change in matter • Light, electricity, sound, heat, and mechanical energy • Mechanical energy makes objects move or change course • Objects can store energy as “potential energy” • Kinetic energy is the energy of motion • Total mechanic energy is the sum of potential and kinetic energy

7. Atoms • Made of subatomic particles • Protons are positively charged • Electrons are negatively charged • Neutrons are neutral

8. Atoms, cont’d • Atomic mass is the mass of the protons and neutrons that make up the nucleus • Atomic number is the number of protons in the nucleus • An isotope is two elements that have the same number of electrons, but different number of neutrons. The difference in the number of neutrons changes the atomic mass, but the atomic number is still the same. • Electrons orbit around the nucleus like the planets orbit the sun • Valence electrons are in the outermost orbit

9. Electrons • Each energy level can only hold a certain number of electrons • 1st level has the capacity for only 2 electrons • 2nd-4th level can hold up to 8 electrons • The valence (outermost) electrons determine how atoms behave • Ionization is the gain or loss of an electron • Positive ions LOST an electron (remember, electrons have a negative charge • Negative ions GAINED an electron

10. Elements • Elements are made of only one type of atom • Oxygen is made only of oxygen atoms • Hydrogen is made only of hydrogen atoms • COHN- 96% of living things are made from Carbon, Oxygen, Hydrogen and Nitrogen

11. Compounds • Can be broken down into smaller substances • Represented by formulas • For example: water is a compound made of two hydrogen atoms and one oxygen. The formula is H2O

12. Molecules • Atoms joined by chemical bonds • Molecular weight is the sum of the atomic weights

13. Inorganic vs. Organic • Inorganic compounds do not contain carbon • Salts, CO2, water, acids and bases • Organic compounds contain carbon-hydrogen bonds • Proteins, fats and carbohydrates

14. Ions and Electrolytes • A charged atom (one that has given up or taken an electron) is called an ion • A compound that dissociates (breaks apart) in water and forms positive and negative ions is an electrolyte • Salt in water is an electrolyte because the salt breaks apart and forms sodium and chlorine ions

15. Acids and Bases • Acids are substances that increase the number of H+ ions in a solution • Bases decrease the number of H+ ions in a solution

16. pH Scale • The scale ranges from 0-14 • 7 is neutral • 0-6.9 is an acid; the closer to 0, the stronger the acid • 7.1-14 is a base; the closer to 14, the stronger the base • Blood must remain in very strict limits; 7.35-7.45

17. Cells • The smallest living unit of the human body • Cancer is a cell that malfunctions and reproduces itself

18. Cell Theory • 1. All known living things are made of cells • 2. The cell is the structural and functional unit of all living things • 3. All cells come from preexisting cells by division (no spontaneous generation) • 4. Cells contain hereditary info, which is passed from cell to cell

19. Cell Theory, cont’d • 5. All cells are basically the same in chemical composition. (Same types of organelles) • 6. All energy flow of life occurs within cells.

20. Cell Strucutre • Animal cells posses specific structures • Cells may vary by shape, location, and function

21. Cell Size and Shape • Cells are not always perfect spheres. The shape can be controlled by substances outside the cell, or the contents of the cell. • Some cells will maintain their shape, others will vary • The mass of organs is due to the number of cells, not the volume of the cells

22. Cell Composition • All cells contain: • Carbohydrates • Proteins • Lipids (fats) • Nucleic acids

23. Carbohydrates • Aka sugars • Carbon, hydrogen and oxygen form long chains to make carbohydrates • Monosaccharide-single sugar • Disaccharide- double sugar • Polysaccharide- many sugars

24. Proteins • Made of amino acids attached to one another by peptide bonds • 20 types of amino acids

25. Lipids • The fats • Fats are solid at room temperature, oils are liquid at room temperature

26. Nucleic Acids • RNA- ribonucleic acid • DNA- deoxyribonucleic acid • RNA and DNA are made of nucleotides • Each nucleotide has a nitrogenous base, a sugar and a phosphate • The nitrogenous bases are: • Adenine-thymine • Cytosine-guanine • Uracil replaces thymine in RNA

27. Cytoplasm • The material that lies within the boundaries of the cell • Contains no genetic material • Contains the organelles

28. Cell (Cytoplasmic) Membrane • Surrounds the cell and separates the inside of the cell from the outside • Allows cells to interact with their surroundings if needed • Phospholipids and proteins compose the membrane • The phosphate end of the phospholipids love water, the 3 fatty acid tails repel water

30. Functions of Cell Membrane • Keeps cytoplasm in • Osmosis is a process where water equilibrates on both sides of the cell membrane. The cell membrane is selective about what comes in and out. Nutrients in, waste out.

31. Transportation through the membrane • Some substances are too big or polar, and cannot cross the membrane. To allow the entry of certain substances, there are 4 transport systems • Passive diffusion • Facilitated diffusion • Group translocation • Active transport

32. Transport Processes • Passive diffusion- no energy is required • Facilitated diffusion- no energy is required, a molecule binds to a specific protein in the cell membrane. It is selective. • Group Translocation- most requires energy. The target molecule is chemically changed as it enters the cell. • Active transport- pumps are used to move substances up the concentration gradient. Energy in the form of ATP is required.

33. Nucleus • Largest structure within a cell. • Eukaryotic cells are animal cells. They possess a true nucleus surrounded by a nuclear membrane. • Prokaryotic cells are any cells not found in animals. They do not have a true nucleus. • Nucleus houses DNA • See functions on pg 25

34. Nuclear Membrane • Endoplasmic reticulum is continuous with the membrane. • Nuclear envelope is similar to the cell membrane, but it surrounds the nucleus • The envelope has small holes that will allow a few substances to move into and out of the nucleus

35. Nucleolus • Contains ribosomes, RNA, DNA, and proteins • rRNA is transcribed and processes and assembled into ribosomes • Ribosomes leave through the nucleus and they aid in protein synthesis

36. Chromatin and Chromosomes • Chromatin contains the genetic code and is stored in chromosomes • Two types of chromatin • Heterochromatin is condensed chromatin • Euchromatin is most abundant in active, transcribing cells. The DNA must uncoil before the code can be read.

37. Organelles • Lysosomes • Vacuoles • mitochondria • ER • Golgi apparatus • Ribosomes • Centrioles • Cilia • Flagella

38. Organelles • Lysosomes digest waste materials and food • Vacuoles are areas of the cell membrane that fold inward and trap substances on the outside of the cell. It will pinch off and bring the molecule inside. (Think Pac-Man) • Endoplasmic reticulum (ER) transports substances. Rough ER is covered in ribosomes. Smooth ER is not.

39. Organelles, cont’d • Mitochondria convert food into ATP. They are the major source of energy for the cell. Mitochondria have their own DNA. All mitochondria are derived from the mother. This is a very useful tool in forensics or identification. • The Golgi apparatus modifies and refines proteins and packages them in vesicles.

40. Organelles, cont’d • Ribosomes are the protein factories and can be free in the cytoplasm or attached to ER. The main function is to serve as mRNA translation. • Centrioles are rod-shaped and play a role in cell division • Cilia are shorter than flagella and function to move fluid or materials past an immobile cell. Millions of cilia line the respiratory tract to keep substances from entering the lungs.

41. Organelles, cont’d • Flagella are whip-like and propel a cell. The only flagellated cell in the human is sperm.

42. Cell Movement • Some cells must be able to move throughout the body. • Cancer cells are very capable of movement. • Understanding how cancer cells move may lead to the advancement in fighting cancer.

43. Nucleic Acids • There are 46 chromosomes inside the nucleus and 1000’s of genes are contained on each chromosome. • The nucleic acids (RNA and DNA) contain our hereditary info. • DNA is the cookbook, RNA translates the cookbook

44. Base Pairing • Adenine pairs with Thymine • Forms two hydrogen bonds • Cytosine pairs with Guanine • Forms three hydrogen bonds

45. DNA and RNA • DNA is a double helix structure • RNA is single stranded • DNA will “unzip” and a copy of one side will be made. This copy is called messenger RNA or mRNA. • Each 3 bases are called a triplet, and that is the specific code for one amino acid

46. DNA and RNA • Transfer RNA or tRNA lives in the cytoplasm. The tRNA picks up the appropriate amino acid • When all of the amino acids have been assembled and all of the peptide bonds have been formed, it is now a protein.

47. DNA Replication • Before cells divide, the DNA must make a copy of itself. • The DNA will ‘unzip’ and one side serves as a template to make a complementary strand. • After complete division, each cell will have one old side and one new side.

48. Mitosis • 5 Stages • Prophase • Metaphase • Anaphase • Telophase • Interphase

49. Prophase • Chromosome condense and distribute between the two cells • Centromere forms between two identical chromosomes • Microtubules from each side of the cell attach at the centromere.

50. Metaphase • The chromosomes will line up in the middle of the cell • The microtubules will eventually pull the chromosomes apart.