Cells

The 3 Basic Parts of all Cells Plasma Membrane Controls what enters & exits the cell Cytoplasm Entire contents of cell between P.M. and nucleus Where most metabolic activity occurs Nucleus or Nuclear Area Contains DNA, the genetic material

Phospholipids form a two-layer sheet Called a phospholipid bilayer, with the heads facing outward and the tails facing inward Water Hydrophilic heads Hydrophobic tails Figure 5.11B

Classes of Cells Two basic types of cells: Prokaryotic cells Eukaryotic cells

Prokaryotic cells are structurally simpler than eukar yotic cells Nucleoid region Nucleus Eukaryotic cell Organelles Colorized TEM 15,000  Figure 4.3A

Prokaryotic Cell Pili Cell wall Plasma membrane Nuclear area Ribosomes Figure 4.3B Pili Cell wall Plasma membrane Nuclear area Ribosomes Flagella

Eukaryotic cells Animal Cell Fig 4.4A

1. The nucleus is the cellular control center Containing the cell’s DNA, which directs cellular activities Nucleus Chromatin Two membranes of nuclear envelope Nucleolus Pore Rough endoplasmic reticulum Figure 4.5 Ribosomes

2. Smooth endoplasmic reticulum, or smooth ER Synthesizes lipids Processes toxins and drugs in liver cells Stores and releases calcium ions in muscle cells Smooth ER Rough ER Nuclear envelope Ribosomes Smooth ER Rough ER TEM 45,000 Figure 4.7

3. Rough endoplasmic reticulum or Rough ER Ribosomes on the surface Produce proteins that are secreted, inserted into membranes, or transported in vesicles to other organelles Transport vesicle buds off Secretory (glyco-) protein inside trans- port vesicle 4 Polypeptide Ribosome 1 3 Sugar chain Figure 4.8 Rough ER Glycoprotein 2

4. The Golgi apparatus finishes, sorts, and ships cell products Stacks of membranous sacs receive and modify ER products then ship them to other organelles or the cell surface Figure 4.9 Golgi apparatus “Receiving” side of Golgi apparatus Golgi apparatus Transport vesicle from ER TEM 130,000 New vesicle forming Transport vesicle from the Golgi “Shipping” side of Golgi apparatus

5. Vesicles: Membrane-bound “balloons” that transport and store substances in cells

6. Lysosomes are sacs of enzymes function in digestion within a cell Lysosomes in white blood cells destroy bacteria that have been ingested recycle damaged organelles

Fig 4.13 The various organelles of the endo-membrane system are inter-connected structurally and functionally

7. Mitochondria harvest chemical energy from food Mitochondria carry out cellular respiration which uses the chemical energy in food to make ATP for cellular work Mitochondrion Outer membrane Intermembrane space Figure 4.14 Inner membrane TEM 44,880 Cristae Matrix

8. Cytoskeleton & related structures - a network of protein fibers help organize its structure and activities Fig 4.17 Tubulin subunit Actin subunit Fibrous subunits 25 nm 7 nm 10 nm Microfilament Intermediate filament Microtubule

Microfilaments of actin Intermediate filaments Enable cells to change shape and move Intermediate filaments Reinforce the cell and anchor certain organelles Microtubules give the cell rigidity And provide anchors for organelles and act as tracks for organelle movement

Cilia and flagella move when microtubules bend Eukaryotic cilia and flagella are locomotor appendages that protrude from cer tain cells LM 600 Colorized SEM 4,100 Figure 4.18

Tight junctions Anchoring junctions Gap junctions can bind cells together into leakproof sheets Anchoring junctions link animal cells into strong tissues Gap junctions allow substances to flow from cell to cell Tight junctions Figure 4.18B Anchoring junction Gap junctions Extracellular matrix Space between cells Plasma membranes of adjacent cells

Please do the activities at the following 2 sites: http://learn.genetics.utah.edu/content/begin/cells/insideacell/ http://learn.genetics.utah.edu/content/begin/cells/scale/

Plant Cell –Fig. 4.6b

Plant cells also have: Vacuole stores water, solutes, waste Important for growth and rigidity Chloroplasts Site of photosynthesis: conversion of light to ATP which drives formation of sugars Cell wall Protects, supports **Plant cells do not have lysosomes

Vacuoles function in the general maintenance of the cell lysosomal and storage functions Chloroplast Central vacuole Nucleus Colorized TEM 8,700 Figure 4.12

Chloroplasts convert solar energy to chemical energy found in plants and some protists convert solar energy to chemical energy in sugars TEM 9,750 Chloroplast Stroma Intermembrane space Inner and outer membranes Granum Figure 4.15

have rigid cell walls made of cellulose Plant cells have rigid cell walls made of cellulose Are connected by plasmodesmata - connecting channels Plasma membrane Cytoplasm Plasmodesmata Vacuole Layers of one plant cell wall Walls of two adjacent plant cells Figure 4.22