Cell Structure and Function Chapter 7 Cell Structure and Function

7-2 Eukaryotic Cell Structure Objectives Describe the function of the cell nucleus. Describe the functions of the major cell organelles. Identify the main roles of the cytoskeleton.

7-2 Eukaryotic Cell Structure Divided into two major parts that work together: Nucleus Cytoplasm – outside the nucleus

7-2 Eukaryotic Cell Structure Organelles (“little organs”) - Specialized Nucleus (Both) Ribosomes (Both) Endoplasmic Reticulum (Both) Golgi apparatus (Both) Lysosomes (Both) Vacuoles (Both, but mostly plants) Mitochondria (Both) and Chloroplasts (Plants) Cytoskeleton (Both) Cell membrane (Both) Cell wall (Plants)

7-2 Eukaryotic Cell Structure Nucleus Directs most of cell’s activities Contains information needed to make proteins Stores genetic material - DNA Chromatin chromosomes Surrounded by the nuclear envelope Nucleolus – small, dense region where assembly of ribosomes begins

7-2 Eukaryotic Cell Structure Ribosomes In cytoplasm Small particles of RNA and protein Make proteins following coded instructions from the nucleus

7-2 Eukaryotic Cell Structure Endoplasmic Reticulum Rough – ribosomes on surface Smooth – no ribosomes on surface

7-2 Eukaryotic Cell Structure Endoplasmic Reticulum Membrane system Lipid parts of cell, proteins and other materials that are exported are assembled Moves proteins & Carbohydrates to the Golgi Body.

7-2 Eukaryotic Cell Structure Golgi apparatus Stacks of flattened sacs Modify proteins made by the cells Package, sort & export proteins from the ER

7-2 Eukaryotic Cell Structure Lysosomes Break down compounds into small particles that the cell can use. Remove “junk” that clutter cell

7-2 Eukaryotic Cell Structure Vacuoles Saclike structures Store materials: Water proteins, Salts carbohydrates

7-2 Eukaryotic Cell Structure Mitochondria and Chloroplasts Sources of energy From food and/or from the sun

7-2 Eukaryotic Cell Structure Mitochondria Releases energy in the cell. (The powerhouse of the cell) Produce ATP (high energy compound) from food. Plants DO have these.

7-2 Eukaryotic Cell Structure Mitochondria The powerhouse of the cell.

7-2 Eukaryotic Cell Structure Chloroplasts Uses energy from sunlight to make food molecules (photosynthesis). Found in plants and some other microscopic organisms

7-2 Eukaryotic Cell Structure Cytoskeleton Network of protein filaments that helps the cell maintain shape. Involved in movement Made of two different structures: Microfilaments Microtubules

7-2 Eukaryotic Cell Structure

7-2 Eukaryotic Cell Structure

7-2 Eukaryotic Cell Structure

7-2 Eukaryotic Cell Structure

7-2 Eukaryotic Cell Structure Objectives Describe the function of the cell nucleus. Describe the functions of the major cell organelles. Identify the main roles of the cytoskeleton. End of Section 7-2

7-3 Cell Boundaries Objectives Identify the main functions of the cell membrane and the cell wall. Describe what happens during diffusion. Explain the processes of osmosis, facilitated diffusion, and active transport.

7-3 Cell Boundaries Cell Membrane Thin, flexible barrier Protection Support Regulates what enters/leaves the cell

The Cell Membrane is known as a “Lipid Bilayer” 7-3 Cell Boundaries The Cell Membrane is known as a “Lipid Bilayer” I wonder Why?

7-3 Cell Boundaries Cell Walls Support Protection Plant cellulose cell walls from the ragweed plant anther. The rigid cell wall of plants is made of fibrils of cellulose.

7-3 Cell Boundaries Diffusion Through Cell Boundaries Particles move from an area of high concentration to an area of low concentration. Concentration – the mass of solute in a given volume of solution. Equilibrium – concentration is the same throughout a solution.

A simple rule to remember: 7-3 Cell Boundaries Osmosis – diffusion of water through a selectively permeable membrane. hypertonic = more solute concentration hypotonic = less solute concentration isotonic = same solute concentration A simple rule to remember:

7-3 Cell Boundaries

It lets the water through but not the spaghetti. 7-3 Cell Boundaries selectively permeable What? It lets the water through but not the spaghetti.

7-3 Cell Boundaries Facilitated Diffusion facilitated diffusion - diffusion through a membrane with help from a transport protein. Because…some molecules just can’t get across that membrane on their own. Different proteins allow particular molecules. Does not require energy.

7-3 Cell Boundaries Facilitated Diffusion

7-3 Cell Boundaries Active Transport Transport proteins within the membrane must use energy (ATP) to move substances either to the inside or outside of the membrane. (Against a concentration gradient.) endocytosis Phagocytosis Pinocytosis exocytosis

7-3 Cell Boundaries Active Transport

7-3 Cell Boundaries Phagocytosis “CELL EATING” takes in large particles by engulfing them

pinch off to form vacuoles. 7-3 Cell Boundaries Tiny pockets form along cell membrane fill with liquid, pinch off to form vacuoles.

Vacuole fuses with membrane 7-3 Cell Boundaries Vacuole fuses with membrane forces contents out.

7-3 Cell Boundaries Objectives After this section, can you… Identify the main functions of the cell membrane and the cell wall. Describe what happens during diffusion. Explain the processes of osmosis, facilitated diffusion, and active transport. End of Section 7-3