1. Introducing Cells Cell Theory Microscopy Cell organelles Cell organelle function

2. The Cell To understand life in a useful and meaningful way, you have to understand the cell.

3. Seeing the big picture Chemistry (atoms and molecules) CellsTissueOrganOrganismBiosphere

4. The Cell Theory Although different living things may be as unlike as a violet and an octopus, they are all built in essentially the same way. The most basic similarity is that all living things are composed of one or more cells. This is known as the Cell Theory. Prokayrotic bacteria Eukaryotic (true nucleus) animal animal plant plant fungus fungus Cells are the building blocks of life. blocks of life.

5. The Cell Theory The Cell Theory can be summarized as: A.All living organisms are made up of one or more cells B.The cell is the basic unit of life C.All cells come from the division of pre-existing cells our knowledge of cells is built on work done with microscopes cells come in many shapes and sizes, although most are microscopic: most cells are small, about 0.001 cm in length (1/100 of a mm, or 10  m).

6. Some cells are large. e.g. some giant algal cells may be several centimeters long. A chicken's egg is a single cell. 40,000 red blood cells would fill the letter "O" on a page of type. You produce about 2.5 million new red blood cells every second! Each square cm of your skin contains about 150,000 skin cells. Human beings are composed of about 50 to 100 trillion cells. cells carry on all the processes associated with life, such as reproducing and interacting with the environment.

8. microscopes Sizes of cells, viruses, and other small things Biology is a visually rich subject area. However, many of the most interesting biological events and structures are smaller than the unaided human eye can see. In fact, human eyes have a resolution of about 100 µm. On the chart below, notice that of all the structures listed, only the plant cell is within our resolution--just barely

9. EUCARYOTIC CELL STRUCTURE At the most basic level, the cell's overall structure can be viewed as: 1.Cell Membrane 2.Nucleus 3.Organelles 4.Cytoplasm 1.Cell Membrane: the thin layer which separates the cell contents from it's environment. 2.Nucleus: specialized structure within the cell which contains DNA and controls cell functioning and reproduction. 3.Organelles: small bodies with specific structures and functions within the cell. 4.Cytoplasm: the liquid substance between the nucleus and the cell membrane, in which the organelles are located.

10. Eukaryotic Cells liver cell

11. Now Let’s Have a DETAILED look at CELL ORGANELLES The Cell Membrane and the “Fluid Mosaic” Model the cell membrane functions in transport of materials in and out of cell, recognition, communication, and homeostasis. The Fluid Mosaic Model: Model: Cells are surrounded by a thin membrane of lipid and protein. lipid and protein.

12. scientists today agree upon The Fluid Mosaic Model of membrane structure. The cell membrane is a remarkable structure that has properties of a solid and a liquid. It forms a "fluid sea" in which proteins and other molecules like other lipids or carbohydrates are suspended (like icebergs) or anchored at various points on its surface. the “sea” or “fluid” parts composed of side by side phospholipids arranged in a bilayer (called a lipid bilayer). The solid part (the “mosaic”) is the variety of proteins etc. embedded in the bilayer.

13. each phospholipid has a … 1. 1. hydrophobic tail and a 2. hydrophylic head. the membrane has consistency of light machine oil. the membrane is SELECTIVELY PERMEABLE (will let some substances in but not others of the same size). CellMembrane

14. Nucleus

15. Nucleus The nucleus is a large, centrally located organelle surrounded by nuclear envelope. The nuclear envelope is a double membrane (2 phospholipid bilayers) that has pores. Nuclear pores allow proteins into the nucleus and ribosomal subunits out. The envelope is very porous and is a continuation of the membranes of the endoplasmic reticulum.

16. Double-membrane (envelope)Double-membrane (envelope) Numerous poresNumerous pores RNA and other chemicals to pass to cytoplasm, but notRNA and other chemicals to pass to cytoplasm, but notDNA Structure of the nuclear envelope and nuclear pores. Nucleus

17. The Nucleus control center or "brain" of cell. The site where genetic information is stored in chromosomes. Although each cell gets a copy of every gene, only certain ones are turned on in a particular cell. The DNA is contained by a number of chromosomes, which consist of long strands of DNA tightly wound into coils with proteins called histones. The combination of DNA and histone proteins is known as CHROMATIN.

18. Genes contain DNA which works with RNA to bring about the synthesis of proteins The nucleus, therefore, determines the metabolism, growth, differentiation, structure, and reproduction of cell. The nucleolus( 1-2 darker bodies), is the site of rRNA synthesis (protein to from ribosomes). The Nucleus

19. Ribosomes Site for PROTEIN SYNTHESIS !! Ribosomes consist of rRNA and proteins and proteins each ribosome is made of 2 non-identical subunits (small and large) rRNA is produced in the nucleolus and joined with proteins -- then migrate through the nuclear pore to the cytoplasm for final assembly ribosomes attach themselves to the endoplasmic reticulum

20. Endoplasmic Reticulum (ER) the ER is a system of MEMBRANOUS TUBULAR CANALS that begins just outside the nucleus and branches throughout the cytoplasm. Part of the ER is studded with ribosomes and called ROUGH Endoplasmic Reticulum The areas without ribosomes is called SMOOTH Endoplasmic Reticulum.

21. Endoplasmic Reticulum (ER) Both rough and smooth ER are involved in synthesis and modification of macromolecules. Rough ER is the site where PROTEIN SYNTHESIS occurs on the attached ribosomes. Smooth ER produces different molecules depending on the type of cell.

22. Smooth Endoplasmic Reticulum Function 1: Synthesis of lipids: Ex. Smooth ER is abundant in testes and adrenal cortex, both of which produce steroid hormones (e.g. testosterone) Ex. Smooth ER is abundant in testes and adrenal cortex, both of which produce steroid hormones (e.g. testosterone) Sometimes referred to as the cell’s membrane factory b/c it is where phospholipids are synthesized. Function 2: Detoxification of Drugs: Ex. In liver cells the smooth ER is capable of releasing enzymes that can detoxify substance such as alcohol. It does this through attached peroxisomes that contain detoxification enzymes).

23. Endoplasmic Reticulum (ER) Most of the macromolecules (proteins, lipids, etc) leaving the endoplasmic reticulum are still not mature. They must undergo further processing in another organelle, the Golgi apparatus, before they are ready to perform their functions within or outside the cell. (fig. 3.6 p. 55)

24. Golgi Apparatus The Golgi Apparatus (“X” in diagram), are stacks of flattened, hollow cavities enclosed by membranes, which are enclosed by membranes, which are often continuous with the membranes of the endoplasmic reticulum. located near to the nucleus and ER. Looks like a flattened stack of hollow tubes. Looks like a flattened stack of hollow tubes.

25. Golgi Apparatus Thus, the Golgi apparatus functions in protein … 1. Modification (i.e. addition of a carbohydrate or phosphate group) 2. Packaging (often in secretory vesicles that move to plasma membrane) 3. Secretion (of substances to cytoplasm or export from the cell) it receives newly manufactured protein (from the ER) on it's inner surface. Within the Golgi apparatus, the proteins are sorted out, labeled, and packaged into vesicles that "pinch off" the outer surface into vesicles. These vesicles can then be transported to where they are needed within the cell, or can move to the cell membrane for export to the outside of the cell by exocytosis (i.e hormone secretion) These vesicles can then be transported to where they are needed within the cell, or can move to the cell membrane for export to the outside of the cell by exocytosis (i.e hormone secretion) See figure 3.6 in text

26. Vacuoles and Vesicles: Storage & Transport a VACUOLE is a large membrane-enclosed sac a VESICLE is a small membrane-enclosed sac vacuoles and vesicles are formed by: 1) pinching off from the Golgi apparatus or ER 2) Endocytosis (pinching in of cell membrane to import) are used for transport and storage of materials lysosomes are examples of a vesicle peroxisomes are an example of a vacuole peroxisomes are an example of a vacuole

27. Lysosomes Lysosomes Lysosomes: Cellular “Stomachs” specialized vesicles which are formed by the Golgi apparatus. contain powerful hydrolytic enzymes functions in : 1)cellular digestion 2)autodigestion or disposal of damaged cell components like mitochondria. (e.g. in development of embryo- fingers) 3) breakdown of a whole cell (by releasing their contents into the cell cytoplasm). For this reason, they are sometimes called “suicide sacs.”

28. Lysosomes Lysosomes Lysosomes are known to contain over 40 different enzymes that can digest almost anything in the cell, including proteins, RNA, DNA, and carbohydrates. Lysosomes help destroy invading bacteria.

29. Peroxisomes PEROXISOMES are also single-membrane organelles (Vacuoles). contain enzymes which are able to react with toxic substances and break them down. Detoxify contain enzymes which are able to react with toxic substances and break them down. Detoxify i.e. alcohol in liver cells

30. Mitochondria Mitochondria The Cell’s Powerhouse generates energy (ATP) for the cell by ‘burning’ sugar (glucose). Mitochondria are the largest organelles in an animal cell, after the nucleus (about the size of bacteria). Are sausage-shaped or filamentous structures surrounded by a double-layered membrane.

31. Mitochondria Mitochondria The mitochondrion has two membranes: an outer and an inner. The inner is convoluted into shelf-like folds called cristae. The enzymes responsible for cellular respiration are arranged, in assembly- line fashion, on the cristae. The enzymes responsible for cellular respiration are arranged, in assembly- line fashion, on the cristae.

32. Mitochondria Mitochondria Function = AEROBIC ENERGY METABOLISM (AKA CELLULAR RESPIRATION). Converts glucose and fatty acids to ATP ENERGY! The overall formula for cellular respiration is: Carbohydrate + O 2 CO 2 + H 2 O + ENERGY In the end, 38 molecules of ATP (adenosine triphosphate) are formed for every molecule of glucose that is used up in respiration. cristae matrix