1. Cellular Level of Organization

2. Cells
There are approximately 200 different types of cells that make up the basic structures of the human body.
Cell division creates new cells. A “parent” cell divides into two new “daughter” cells.
Different types of cells carry out different functions in the body.

3. Parts of a Cell Plasma membrane Cytoplasm Cytosol Organelles Nucleus
Chromosomes
Genes

4. 3 main parts of a cell
Plasma membrane – the cells flexible outer surface.
Cytoplasm – all the cellular contents between the plasma membrane and the nucleus.
Nucleus – a large organelle that houses most of the cell’s DNA. Chromosomes and genes are contained here.

5. Typical Structures

6. Plasma Membrane
A flexible, yet sturdy barrier that surrounds and contains the cytoplasm of a cell.
Fluid mosaic model.
Lipid Bilayer
Membrane proteins
Membrane Permeability – Selective

7. Plasma Membrane continued…
Gradients
Concentration
Electrochemical
Osmosis
Diffusion
Active Transport

8. Lipid Bilayer Phospholipids – 2 layers
Amphipathic – polar and nonpolar
Hydrophilic
Hydrophobic

10. Membrane Proteins
Integral Proteins – extend into or through the lipid bilayer.
Transmembrane proteins
Peripheral Proteins – attached to either the inside or outside of the membrane.

11. Functions of Membrane Proteins
Ion channel
Transporter
Receptor
Enzyme
Cell Identity Marker
Linker

13. Membrane Permeability
Selectively Permeable
Permeable to nonpolar, uncharged molecules, such as oxygen, carbon dioxide, & steroids.
Impermeable to ions and charged or polar molecules, such as glucose.
Slightly permeable to water and urea.

14. Gradients
Concentration Gradient – A difference in the concentration of a chemical from one place to another.
Electrochemical Gradient – The combination of the effects of the concentration gradient and the membrane potential.

16. Transport Across the Membrane
Passive Transport – does not require cellular energy.
Substances move down their concentration or electrochemical gradients using only their own kinetic energy.
Active Transport – requires cellular energy in the form of ATP.

17. 3 Types of Passive Transport
Diffusion through the lipid bilayer.
Diffusion through membrane channels.
Facilitated diffusion.

18. Endocytosis
Material enters the cell in vesicles.

20. Exocytosis
Material leaves the cell in vesicles.

21. Diffusion
Materials diffuse from areas of high concentration to areas of low concentration. They move down their concentration gradient.
Equilibrium – molecules are mixed uniformly throughout the solution.

23. Factors Influencing Diffusion
Steepness of the concentration gradient.
Temperature.
Mass of the diffusing substance.
Surface Area.
Diffusion distance.

24. Osmosis
The net movement of a solvent (water) across a selectively permeable membrane.
Water moves from an area of higher water concentration to an area of lower water concentration.

25. Osmotic Pressure
A solution containing solute particles that cannot cross the membrane exerts a force called osmotic pressure.
The greater the number of solute particles the greater the pressure.

27. Tonicity
A solution’s tonicity measures the solution’s ability to change the volume of cells by altering their water content.
Isotonic – cell maintains shape
Hypotonic – cell swells and bursts
Hypertonic – cell shrinks - crenation

29. Cytoplasm
2 components
Cytosol – fluid portion that surrounds organelles.
55% of total cell volume
Water with dissolved and suspended components
Ions, glucose, amino acids, fatty acids, proteins, lipids, ATP, and waste products.
Organelles – specialized structures
Specific shapes
Specific functions

30. Cytoskeleton Network of protein filaments.
Structural framework for the cell.
3 Types of filaments
Microvilli – small – increase surface area
Intermediate filaments
Microtubules – largest – in cilia and flagella – participate in cell division.

31. Centrosome Located near the nucleus
Plays a critical role in cell division

32. Cilia and Flagella Comprised of microtubules.
Cilia – short, hairlike projections that extend from the surface of the cell.
Line respiratory tract
Movement is paralyzed by nicotine
Flagella – longer than cilia
Usually move an entire cell
Sperm’s tail

34. Ribosomes Sites of protein synthesis
Free Ribosomes – located in cytosol
Attached to nuclear membrane and ER
In mitochondria

38. Endoplasmic Reticulum ER
Plasmic = cytoplasm; reticulum = network
Network of folded membranes
Transports substances throughout cell
Rough ER – ribosomes attached – synthesizes proteins
Smooth ER – synthesizes fatty acids and steroids

41. Rough ER

42. Smooth ER

43. Golgi Complex Consists of 3 – 20 golgi cisternae (membranous sacs)
Modifies, sorts, and packages proteins for distribution
Proteins leave through secretory vesicles, membrane vesicles, or transport vesicles.

44. Lysosomes Lyso = dissolving; somes = bodies
Contain powerful digestive enzymes and hydrolytic enzymes
Lysosomal enzymes can destroy their own cell – autolysis (due to pathology)

46. Lysosome

47. Mitochondria
Generate ATP – “powerhouses” of the cell

48. Mitochondrian with Matrix

49. Mitochondria

50. Nucleus Spherical or oval shaped Most prominent feature in the cell
Most structures have a single nucleus, although mature RBCs have none
Contain genes arranged in chromosomes
Genome – total genetic information for an organism

52. Nucleus

53. Nucleus

54. Cell Division
Somatic Cell Division – replaces dead or injured cells and adds new ones for growth.
Mitosis
Produces 2 identical daughter cells
Reproductive Cell Division – produces gametes – sperm and oocytes.
meiosis

55. Cell Cycle 2 major phases Interphase – the cell is not dividing
Mitotic phase – the cell is dividing

56. Interphase The cell replicates its DNA during this phase.
Produces additional organelles and cytosolic components.

57. Mitotic Phase Nuclear Division – Mitosis
Cytoplasmic Division - Cytokinesis

58. Mitosis Prophase Metaphase Anaphase Telophase
Chromatin fibers condense and shorten.
Metaphase
The microtubules align the centromeres of the chromatid pairs.
Anaphase
The centromeres split separating the two members of each chromatid pair.
Telophase
Identical chromosomes uncoil and a nuclear envelope forms around each mass.

60. Cytokinesis
Division of the parent cell’s cytoplasm and organelles into two daughter cells.

61. Cellular Diversity
The body of an average human adult is composed of nearly 100 trillion cells.
Approximately 200 different types.
The largest cell is the oocyte