The World of Cells

1. The World of Cells Source: Biology: The Living Science, Prentice Hall, 1998

2. The Cell Theory • All living things are made up of one or more cells (cell =smallest unit of life). • Cells are the smallest units of life in an organism. • All cells come from preexisting cells by cell division.

3. Main Parts of a Cell • Cell Membrane • Cytoplasm • Nucleus • Organelles(“little organs”) • Cell Wall - found only around plant cells (not really part of a cell but found just on the outside of the plant cells) Source: Biology; Miller, Levine; Prentice Hall, 1998

4. Cell Membrane Structure: • Outermost layer (boundary) of the cell. • Porous (semi-permeable) • Consists of a double layer of fat interspersed with large protein molecules. Source: Biology: The Living Science , Prentice Hall, 1998

5. Cell Membrane Function: • Controls the movement of substances into (nutrients) and out of (wastes) the cell. • Protection • Gives structure (shape) to the cell. Source: Biology: The Living Science, Prentice Hall, 1998

6. Cytoplasm Structure: • A thick, jelly-like substance (protoplasm) found inside plant and animal cells • fills in the space between the nucleus and the cell membrane. Source: Biology: The Living Science, Prentice Hall, 1998

7. Cytoplasm Function • Protects and supports the cell’s organelles (the “little organs” of the cell: ribosomes, mitochondria, E.R., golgi bodies, lysosomes, etc.). Source: Biology; Miller, Levine; Prentice Hall, 1998

8. The Nucleus • Not all cells have a nucleus. Cells that do not have a nucleus are called Prokaryotes. Bacillus bacteria….procaryotic cells Source: Biology Today, CRM Books, 1972 Cells that have a nucleus are called EUCARYOTES. Source: Biology, The Living Science, Prentice Hall, 1998 Elodea…eucaryotic cells

9. Structure of the Nucleus • Large oval structure found usually near the center of Eukaryotic cells • Contains the genetic material (hereditary material) such as chromosomes, genes, DNA, RNA. • Contains the nucleolus a darker area within the nucleus that is thought to store proteins. Source: Biology; Miller, Levine; Prentice Hall, 1998

10. Nuclear Functions: • Controls and regulates all of the cell’s activities such as protein synthesis, energy production, the movement of substances in and out of the cell, cell division (mitosis, and meiosis). • NUCLEUS(electron micrograph…EM image) Source: Biology; Miller, Levine; Prentice Hall, 1998

11. Genetic (Nuclear) Material • Chromatin - all the thread-like material that is the genetic or hereditary material within the nucleus of the cell. Made up of chromosomes. Source: Biology: The Living Science, Prentice Hall, 1998

12. Genetic (Nuclear) Material • Chromosome - individual self-duplicating strands of genetic material. When the cell is dividing, the chromatin becomes thicker and more ‘rod-shaped’...each of these rod shapes is a chromosome (collectively, all the chromosomes in the nucleus comprises the chromatin). Source: Biology: The Living Science, Prentice Hall, 1998

13. Genetic Material • Gene: a hereditary factor/unit found on a chromosome. Thousands of genes are found on each chromosome. Each gene determines one characteristic of the cell or individual (i.e. hair color, eye color, skin color, etc.). Source: Biology: The Living Science, Prentice Hall, 1998

14. Genetic Material • D.N.A. (deoxyribonucleic acid): a very complex molecular structure that is considered the “blueprint” for life. Contains all the necessary information to control all the characteristics and activities of the organism. The DNA ultimately makes up all of the genetic/hereditary material. Source: Biology: The Living Science, Prentice Hall, 1998

15. The Organelles • Mitochondria (mitochondrion is singular) • Vacuoles • Ribosomes • Endoplasmic reticulum (E.R.)…rough…smooth • Golgi bodies (or golgi apparatus) • Chloroplast (plants only) • Lysosomes • Vesicle

16. Mitochondria Structure • Bean-shaped or rod-shaped structure found in the cytoplasm of both plant and animal cells. • Contains A.T.P. (adenosine triphosphate) a complex high energy molecule. • Mitochondrion (singular)…Mitochondria (plural) Source: Biology: The Living Science, Prentice Hall, 1998

17. Mitochondrion Function • Produces energy for the cell (cellular respiration). • “The powerhouse of the cell” • Mitochondria (plural) are very abundant in cells that require lots of energy (i.e. muscle cells). Source: Biology: The Living Science, Prentice Hall, 1998

18. Vacuole Structure • A round fluid-filled sac found in the cytoplasm of both plant and animal cells. • Contents may be liquid or solids. • Many plant cells have large (larger than animals) vacuoles. They may even occupy 50-90% of the cells’ volume. Source: Life A Biological Science, Harcourt, Brace, Jovanovich, 1975

19. Vacuole Functions: • Storage place for food (proteins, fat, carbohydrates), water, wastes, etc. for the cell. • Many plant cells have a large central vacuole in order to store a large amount of water (this is especially true for desert plants...that have very little water resources).

20. Lysosome Structure • Small round structures found in the cytoplasm of animal cells (not usually found in plants). • Contain digestive enzymes (defined as “organic catalysts”). Source: Biology: The Living Science, Prentice Hall, 1998

21. Lysosome Functions: • Involved in digestive activities including breaking down large food molecules into smaller ones. • Digestion of old cell parts. It might even destroy the cell....thus the nickname: “suicide bag.”

22. Ribosome Structure: • Appear as dots (using a powerful microscope) in the cytoplasm of both plant and animal cells. • Can be attached to the endoplasmic reticulum (E.R.) or ‘free floating’ in the cytoplasm. • Ribosomes are made in the nucleus. Source: Biology: The Living Science, Prentice Hall, 1998

23. Ribosome Functions: • Produces protein (protein synthesis). • The “plan” for protein synthesis comes from the D.N.A. in the nucleus of the cell. The ribosomes “read” the plan and assembles the sequence of amino acids (the building blocks of proteins) to build the proteins.

24. Endoplasmic Reticulum (E.R.) Structure: • A network of of folded membranes that extend from the cell membrane throughout the cytoplasm. • Rough E.R. has ribosomes attached to them. • Smooth E.R. does not have ribosomes attached to them. Source: Biology; Miller, Levine; Prentice Hall, 1998

25. Endoplasmic Reticulum (E.R.) Functions: • Transports proteins produced by the ribosomes. • Transports proteins to regions of the cell where they are needed or to the Golgi bodies to be exported from the cell. Source: Biology; Miller, Levine; Prentice Hall, 1998

26. Golgi Bodies Structure: • Sometimes called golgi apparatus. • Consists of stacks of sacs....like a stack of pancakes or soggy paper plates. • Pinching off from the edges of the Golgi bodies sacs are vesicles. Source: Biology; Miller, Levine; Prentice Hall, 1998

27. Golgi Bodies Functions: • The storage and packaging of materials that will be exported from the cell (the “shipping department” of the cell). (UPS/Fed Ex) • Vesicles pinch off from the golgi apparatus move to the cell membrane carrying the substances stored in the golgi bodies. These substances are then released (secreted). Source: Biology; Miller, Levine; Prentice Hall, 1998

28. Vesicles Structure and Function • Spherical sacs found in the cytoplasm of cells that helps to transport materials around the cell and out of the cell. • Golgi bodies package secretions and the vesicles transport the secretions to the cell membrane for its release from the cell.

29. Chloroplasts Structure: • Oval-shaped green structures found in the cytoplasm of plant cells (notfound in animal cells). • Mostly found in the cells in the leaves of plants. • Contains a green pigment called Chlorophyll. Source: Life A Biological Science, Harcourt, Brace, Jovanovich, 1975

30. Chloroplast Functions: • Site for Photosynthesis. • Chloroplasts use the sun’s energy to make food for the plant. Cross section of a leaf (green = chloroplasts) Source: Life A Biological Science, Harcourt, Brace, Jovanovich, 1975

31. Cytoskeleton • The internal ‘beams’ for support. The microtubules and microfilaments are the internal supports (beams) for the cell. Source: Biology: The Living Science, Prentice Hall, 1998

32. Cell Wall Structure: • Not actually part of a cell. It is found only on the outside of plant cells (just outside of the cell membrane). • Located VERY close to the cell membrane. • Very rigid and strong. • Made up of cellulose (a starch compound). Cell wall Source: Life A Biological Science, Harcourt, Brace, Jovanovich, 1975

33. Cell Wall Functions: • Gives structure and support to the cell (and because plants are made up of cells...gives structure and support to the plant). • Protection for the cell. Source: Biology; Miller, Levine; Prentice Hall, 1998

34. Chlorococcus Source: Life a Biological Science, Harcourt, Brace, Jovanovich, 1975

35. Elodea Source: Biology; Miller, Levine; Prentice Hall, 1998

36. Osteocyte (bone cell) Source: Biology: The Living Science , Prentice Hall, 1998

37. Rotifer Source: Biology: The Living Science , Prentice Hall, 1998