Anatomy Chapter 3

ribosome # synthesis of proteins

Which of the following organelles is correctly paired with its specific function?

diffusion

Which of the following would be least affected by defective receptor proteins on a cell membrane?

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22) Molecule X moves across a cell membrane by diffusion. Which row in the chart above best indicates the relationship between the relative concentrations of molecule X and the use of ATP for diffusion?

Carbon dioxide would diffuse out of the cell.

22) The diagram below shows the relative concentrations of molecules inside and outside of a cell. Which of the following statements best describes the general direction of diffusion across the membrane of this cell?

active transport

7) The diagram below represents the movement of a large molecule across a membrane. Which process is best represented in this diagram?

more water moving out of the cell than into the cell

8) A biologist observed a plant cell in a drop of water as shown in diagram A. The biologist added a 10% salt solution to the slide and observed the cell as shown in diagram B. The change in appearance of the cell resulted from

The concentration of O2 will increase inside the cell.

9) The diagram below represents a cell in water. Formulas of molecules that can move freely across the cell membrane are shown. Some molecules are located inside the cell and others are in the water outside the cell. Based on the distribution of these molecules, what would most likely happen after a period of time?

Figure 3.27 Active Transport

Active Transport: Movement of substances across a membrane from region of lower concentration to region of high concentration (against concentration gradient) Uses carrier molecules in cell Membrane Active process; requires ATP energy. Examples: sugars, amino acids, Ca+2, H+, Na+/K+ Pump.

receptors

After a hormone enters the bloodstream, it is transported throughout the body, but the hormone affects only certain cells. The reason only certain cells are affected is that the membranes of these cells have specific

Figure 3.7 Cellular Adhesion Molecules (CAMs)

CAMs: Guide cells on the move Selectins coat white blood cells and anchor them by providing friction. Integrins direct white blood cells through capillary walls toward infection sites. Integrins guide embryonic cells toward maternal cells to form placenta and establish Connections between nerve Cells.

Cell Membrane Structure

Cell membrane framework is a phospholipid bilayer: - Water-soluble (hydrophilic) heads from surfaces. - Water-insoluble (hydrophobic) tails form interior. Bilayer is permeable to lipid-soluble substances, but impermeable to water-soluble substances. Cholesterol stabilizes membrane, helps keep it impermeable to water-soluble substances. Some lipids and proteins can move; "fluid mosaic" properties. Membrane proteins have many functions: Pores, channels, receptors, enzymes, cell contact and identification, CAMs (Cell Adhesion Molecules). Carbohydrates: Cell recognition and interaction, self markers.

Figure 3.15 Other Cellular Structures

Centrosome: - "Central body;" consists of 2 centrioles. - In cytoplasm, near nucleus. - Centrioles are cylindrical, composed of microtubules. - Centrioles produce spindle fibers during cell division, which distribute chromosomes to forming daughter cells.

Figure 3.16 Other Cellular Structures

Cilia: - Motile extensions of cell membrane. - Consist of microtubules in cylindrical pattern. - Form a "fringe" on surface of certain epithelial cells. - Shorter than flagella, but very abundance when present. - Beat back and forth in coordinated manner. - Propel mucus in respiratory tract, propel egg toward uterus.

Figure 3.18 Cell Nucleus

Contains genetic material and controls cell activities. Nuclear envelope: - Porous double-layered membrane. - Separates nucleoplasm from cytoplasm. - Nuclear pores allow passage of certain substances. Nucleolus: - Dense body of RNA and protein. - Sit of ribosome production. Chromatin: - Consists of cell's chromosomes, each containing DNA wound around proteins. - Stores information for protein synthesis.

Cytoplasm

Cytoplasm consists of networks of membranes and organelles suspended in cytosol. Cytoplasm = cytosol + organelles - Cytosol: fluid portion of the cytoplasm. - Organelles: tiny solid structures with specific functions in the cell. Cytoplasm contains the cytoskeleton, a supporting framework of protein rods and tubules.

Figure 3.23 Osmosis

Osmosis: movement of water across a selectively permeable membrane from region of higher water concentration to region of lower water concentration Water moves into a region containing higher impermeant solute concentration. This is a passive process; no ATP is required.

Figure 3.24 Osmotic Pressure

Osmotic Pressure = ability of osmosis to generate enough pressure to lift a volume of water Osmotic pressure increases as the concentration of impermeant solutes increases. - Isotonic Solution: same osmotic pressure Cells in an isotonic solution have no net gain or loss of water. - Hypertonic Solution: higher osmotic pressure Cells in a hypertonic solution loses water. - Hypotonic Solution: lower osmotic pressure Cells in a hypotonic solution gain water.

Movements Into and Out of the Cell

Physical (Passive) Processes: Do not require ATP - Diffusion. - Osmosis. - Facilitated diffusion. - Filtration. Physiological (Active) Processes: Require ATP - Active transport. - Endocytosis. - Exocytosis. - Transcytosis.

Figure 3.8 Cytoplasmic Organelles

Ribosomes: - Composed of protein and RNA. - Free in cytoplasm or on RER. - Provide structural support and enzyme activity to link amino acids in protein synthesis. Endoplasmic Reticulum (ER): - Membrane-bound sacs, canals, vesicles. - Tubular transport system. - Rough ER contains ribosomes, conducts protein synthesis. - Smooth ER does not have ribosomes; conducts lipid synthesis.

requires less energy than thyroid tissue

Studies of fat cells and thyroid cells show that fat cells fewer mitochondria than thyroid cells. A biologist would most likely infer that fat tissue

receptor molecules in the cell membrane

The ability of certain hormones to attach to a cell is primarily determined by the

A Composite Cell

There is no typical cell, but a composite cell shows the components found in most cells. 3 Major Parts of a Cell: - Nucleus. - Cytoplasm. - Cell membrane. Cytoplasm consists of organelles, with specific functions, suspended in a liquid called cytosol.

Figure 3.33 Transocytosis

Transocytosis: - Involves receptor-mediated endocytosis followed by exocytosis. - Quickly transports substance from one end of cell to the other. - Moves substance across barriers formed by tightly connected cells. - Example: Transport of HIV across lining of anus or vagina.

Figure 3.9 Cytoplasmic Organelles

Vesicles: - Membranous sacs. - Store or transport substances. Golgi Apparatus: - Sacs of flattened, membranous sacs. - Refines, packages, and delivers proteins made on the RER.

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21) Which row in the chart below best describes the active transport of molecule X through a cell membrane?

Figure 3.1 Cells are the Basic Units of the Body

(a) A nerve cell's long extensions enable it to conduct electrical impulses from one body part to another. (b) The sheetlike organization of epithelial cells enables them to protect underlying cells. (c) The alignment of contractile proteins within muscle cells enables them to contract, pulling closer together the structures to which they attach.

Figure 3.22 Facilitated Diffusion

- Diffusion across the cell membrane through ion channels or transporters. - Water-soluble substances (Na+, K+, Cl-, glucose, amino acids). - Passive process; no ATP required.

Figure 3.20 Diffusion

- Membrane is permeable to both water and the solute. - Equilibrium is reached when the concentrations of water and the solute are equal in both compartments.

Figure 3.19 Diffusion

- Movement of atoms, molecules, or ions, from region of higher concentration to region of lower concentration. - Occurs due to constant motion of atoms, molecules, ions. - Only substances that the cell membrane is permeable to: oxygen, carbon dioxide, and other lipid-soluble substances. - Passive process; no ATP required. A dissolving sugar cube is an example of diffusion.

Cell (Plasma) Membrane

- Outer boundary of the cell. - Maintains integrity of cell. - Regulate entry and exit of substances, meaning it is selectively permeable. - Signal transduction: permits cell to receive and respond to messages. - Consists mainly of lipids and proteins, with some carbohydrates.

Cells Are the Basic Units of the Body

- The cell is the basic unit of structure and function in the body. - Cells are measured in micrometers, - Cells that have developed specialized characteristics are said to be differentiated. - Cells vary in size and shape; structure and function are inter-related.

cell A, only

13) In the diagram below, the dark dots indicate small molecules. These molecules are moving out of the cells, as indicated by the arrows. The number of dots inside and outside of the two cells represents the relative concentrations of the molecules inside and outside of the cells. ATP is being used to move the molecules out of the cell by

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16) In the diagram below, which structure performs a function similar to a function of the human lungs?

cell B to cell A because cell A is able to recognize signal 1

19) Cellular communication is illustrated in the diagram below. Information can be sent from

active transport

20) The graph below shows the relative concentrations of different ions inside and outside of an animal cell. Which process is directly responsible for the net movement of K+ and Mg++ into the animal cell?

Figure 3.29 Endocytosis

Endocytosis: Movement of a substance into the cell inside vesticle Substances too large to enter by other methods can enter cell this way. There are 3 types of endocytosis: - Pinocytosis: membrane engulfs droplets of liquid. - Phagocytosis: membrane engulfs solid particles. - Receptor-mediated endocytosis: membrane engulfs specific substances, which have bound to receptor proteins on the membrane.

Figure 3.32 Exocytosis

Exocytosis: - Release of substances/particles from cell. - Vesicles containing particles fuse with cell membrane and release contents. - Example: Release of neurotransmitters from nerve cells.

Figure 3.26 Filtration

Filtration: Process that forces molecules through membranes by exerting pressure. - Used to separate solids from water, or small particles from large ones. - Example: When blood plasma leaves capillaries, water and small solutes are filtered, but large plasma proteins are not. - Passive process; no ATP requires.

Figure 3.17 Other Cellular Structures

Flagella: - Another type of motile extension from cell membrane. - Similar in structure to cilia, but much longer. - Flagellum causes the entire cell to move. - Tail of a sperm cell is the only flagellum in a human cell. - Each cell has only 1 flagellum.

metabolic process

In a cell, all organelles work together to carry out

ribosomes

In a cell, information that controls the production of proteins must pass from the nucleus to the

receptor molecules

In multicellular organisms, cells must be able to communicate with each other. Structures that enable most cells to communicate with each other are known as

Figure 3.12 Cytoplasmic Organelles

Lysosomes: Small membranous sacs Contain enzymes that digest proteins, carbohydrates, nucleic acids, bacteria, debris, worn out cell parts "Garbage disposals" of cell. Peroxisomes: Membranous sacs similar to lysosomes Contain enzymes that digest lipids, alcohol, hydrogen peroxide.

Clinical Application 3.2 Disease at the Organelle Level

Melas: - Mutant gene in DNA of mitochondria. - Person cannot extract maximum energy from nutrients. Krabbe Disease: - Caused by inability to produce one lysosomal enzyme. - Person cannot produce myelin for nerve cells, which leads to severe damage to the nervous system. Adrenoleukodystrophy (ADL): - Caused by lack of a protein in membrane of peroxisomes. - Fatty acid buildup destroys myelin sheaths of nerve cells. - Nerve cells cannot transmit nerve impulses fast enough.

Figure 3.14 Other Cellular Structures

Microfilaments, Microtubules & Intermediate Filaments: - Thread-like structures in cytoplasm. - Create the cytoskeleton. Microfilaments: tiny rods of actin; provide cellular movement, such as muscle contraction. Microtubules: - Larger tubes of tubulin. - Rigidity maintains cell shape. - Make up cilia, flagella, and centrioles. - Help move organelles. Intermediate filaments: - Composed of several proteins. - A cytoskeleton structure. - Support nuclear envelope.

Figure 3.10 Cytoplasmic Organelles

Milks secretion is an example of organelle interaction and the transport of substances by vesicles.

Figure 3.11 Cytoplasmic Organelles

Mitochondria: Membrane-bound, fluid-filled sacs House chemical reactions that extract energy from nutrients (cellular respiration, which produces ATP) Called the "powerhouse of the cell".

the nuclei of body cells of an individual

Most of the hereditary information that determines the traits of an organism is located in

have a greater demand for energy than the muscle cells of nonathletes

Muscle cells in athletes often have more mitochondria than muscle cells in nonatheletes. Based on this observation, it can be inferred that the muscle cells in athletes

Clinical Application 3.1 Faulty Ion Channels Cause Disease

Mutations in NA+ Channels can cause inability to feel pain or extreme pain conditions. Mutations in K+ Channels can disrupt electrical activity of the heart and disturb heart rhythm, and/or impair hearing. Abnormal Cl- Channels are the cause of Cystic Fibrosis: production of thick mucus which causes difficulty breathing, clogged pancreas, salty sweat.

The cell membrane forms a barrier that keeps all substances that might harm the cell from entering the cell.

Which statement regarding the functioning of the cell membrane of all organisms is not correct?

mitochondria

While viewing a slide of rapidly moving sperm cells, a student concludes that these cells require a large amount of energy to maintain their activity. The organelles that most directly provide this energy are known as