EOC Review Standard 2 - CELLS

1. EOC Review Standard 2 - CELLS

2. B-2.1 Recall the 3 major tenets of the cell theory • All organisms are made of cells. • All cells are produced by other living cells. • The cell is the most basic unit of life.

3. B-2.1 Question • According to cell theory, • A. all multicellular organisms are composed of prokaryotic cells. • B. only cells like the eukaryote can carry out the functions of life. • C. single celled organisms like these are only capable of asexual reproduction. • D. even primitive cells, like the prokaryote, can carry out the functions of life.

4. B-2.2 Summarize the structures and functions of organelles in Eukaryotes • The cell membrane is a highly specialized organelle composed of a phospholipid bilayer. Two layers of phospholipids line up with hydrophilic heads facing out and hydrophobic tails facing in. • The phospholipid bilayer is semi-permeable—meaning it lets some things pass through (small, nonpolar molecules) and restricts the movement of others (large, polar molecules). Thus, it forms a boundary between the inside and outside of the cell and controls what comes in and out. • Nucleus – organelle that holds the cells DNA, which is the code to make proteins. • The nucleus is bound by a double membrane (the nuclear membrane) with special pores that control passage of materials. Inside the nucleus is the genetic material, DNA. • There is also a dense region of RNA called the nucleolus inside that produces ribosomes.

5. Ribosomes link amino acids to form proteins. They are made of RNA. They can be found free-floating in the cytoplasm—the gel-like fluid that fills the cell. • At other times, they are bound to the rough endoplasmic reticulum. The rough ER helps process proteins made on its surface. • The golgi apparatuswill sort and repackage proteins before sending them on…often for export outside the cell. • Transport of materials from ER golgi cell membrane is done by pinching off a sac of membrane called a vesicle—it’s like a vehicle that temporarily carries things around the cell • Lysosomes are small sacs of membrane filled with enzymes that can be used for cell defense or to digest and recycle old bits of cell. • Vacuoles are fluid filled sacs that hold water or materials the cell might need later. • Cilia are small fibers that beat like oars in unison. A flagellum is a long whip like structure that turns like a motor to move a cell through liquid.

6. Mitochondria have two membranes, the inner membrane appears folded. This is the site of cellular respiration where cellular energy (in the form of ATP) is made. • They are found in BOTH plants and animals. • Chloroplasts have two membranes (just like mitochondria) only their inner membrane is made of stacks of membrane disks. They contain the pigment chlorophyll which makes them green and helps to capture energy for photosynthesis.

7. All plants are surrounded by a cell wall that provides rigid support to plant cells. These walls can provide support even after the cell dies! • Plants are also strengthened by their central vacuole. It is a very large vacuole that fills with water and pushes out on the cell wall, keeping the plant cells firm. When you don’t water a plant it wilts because the central vacuole shrinks.

8. B-2.2 QuestionIdentify the following organelles

9. Prokaryotic Single celled Lack a nucleus No membrane bound organelles Divide by binary fission- Complex cell walls made of peptidoglycan Eukaryotic Single or multi-cellular Nucleus surrounded by a membrane containing DNA Membrane bound organelles Divide by mitosis If they have a cell wall, it is made of cellulose or chitin B-2.3 Compare the structures and organelles of prokaryotic and eukaryotic cells

10. B-2.3 Question • Which of the following is found in a eukaryotic cell, but is not found in a prokaryotic cell? A. Cytoplasm B. Cell membrane C. Nucleus D. Flagella

11. B-2.4 Cell Differentiation as the basis for heirarchical organization • Cells • Tissues • Organs • Organ Systems

12. B-2.4 Question • Organize the parts of this body system in order from simplest to most complex according to the levels of organization in a multi-cellular organism. • A. human being  central nervous system  brain  nerve tissue  neuronsB. brain  neurons  nerve tissue  central nervous system  human beingC. neurons  nerve tissue  brain  central nervous system  human beingD. nerve tissue  neurons  brain  central nervous system  human being

13. B-2.5 Explain active, passive, and facilitated transport to maintain homeostasis • Active transport: • Is powered by chemical energy (ATP). • Endocytosis is the process of taking material into the cell. • Exocytosis is the process of expelling material from the cell. *think exit

14. Passive Transport • Does NOT require energy (ATP) from the cell • Diffusion - involves molecules spreading out across a membrane until they reach equilibrium (equal concentrations) • Facilitated Diffusion - uses protein channels (but still no energy) to help things that are normally too big to cross • Osmosis - the diffusion of WATER across a membrane (high water concentration to low water concentration

15. Osmosis • Hypertonic solutions have more stuff (sugar, salt, etc…called the solute) dissolved in them compared to the cell • Hypotonic solutions have less solute dissolved in them compared to the cell • Isotonic solutions have equal amounts of solute. • Water moves from where there is more water (less solute) to less water (more solute)

16. B-2.5 Question • In a hypertonic solution, water will move ____ of the cell, causing the cell to ____. A. In; shrivel B. Out; lyse C. Out; shrivel D. In; lyse

17. B-2.6 Summarize the cell cycle • Interphase • Includes G1, S, and G2 • Cells spend about 95% of their time in this phase • Mitosis • The division of one nucleus into two • Includes prophase, metaphase, anaphase, and telophase • Cytokinesis: often combined with telophase since it occurs at the same time

18. Metaphase: chromosomes line up in the middleof the cell and spindle fibers connect to centromeres Prophase: chromosomes condense, nuclear envelope disappears, and spindle fibers form. • Telophase: the new nuclei form, spindle fibers break down, and chromosomes begin to uncoil. Cytokinesis begins at the end of telophase Anaphase: centromeres split, sister chromatids separate to opposite sides of the cell

19. B-2.6 Question 1 2 3 4 5 Identify each of the following pictures as: Interphase Prophase Metaphase Anaphase Telophase/Cytokinesis

20. B-2.7 Summarize cell regulation and uncontrolled cell regulation • cell cycle control system triggers and coordinates key events in the cell cycle • At certain checkpoints the cell responds to various signals • External signals: like growth factors (chemicals) from surrounding cells and physical signals like being too closely packed or no longer touching another cell where one has died • Internal signals: a cell can receive a signal from its own nucleus/DNA that it is time to grow and divide by the sensing of an external factor that triggers a message sent inside the cell by various enzymes;

21. Tumors – when cell cycle is out of control • Tumor: a lump of cells that divides uncontrollably • Come in two forms: • Benign: essentially harmless, cells stay in the place where the tumor started • Malignant: dangerous, the result of cells that metastasize—or move around the body through the lymph or cardiac systems—and start new tumors elsewhere

22. B-2.7 Question • One difference between a cancer cell and a normal cell is that • A. Cancer cells divide uncontrollably • B. Normal cells divide uncontrollably • C. Cancer cells cannot make copies of DNA • D. Normal cells cannot make copies of DNA

23. B-2.8 Factors that affect the rates of chemical reactions • temperature (speeds up collisions) • pH (how acidic a solution is) can disrupt cell processes • To maintain homeostasis cells use buffers, they keep the pH around neutral • Catalysts: speed up reactions by lowering activation energy • Enzymes are biological catalysts that speed up biochemical reactions by bringing reactants together and positioning them in a way that requires less energy to fuse or break them. • Thus, enzymes lower the energy required for a biochemical reaction to occur (lower the activation energy). • Almost all enzymes are proteins! • Enzymes are very specific—they have an active site that fits only one substrate (reactant)—known as lock and key model.

24. B-2.8 Question • How do enzymes catalyze chemical reactions?