The Plasma Membrane The Gateway to the Cell

GPS SB1. Students will analyze the nature of the relationships between structures and functions in living cells. A. Explain the role of cell organelles for both prokaryotic and eukaryotic cells, including the cell membrane, in maintaining homeostasis and cell reproduction D. Explain the impact of water on life processes (i.e., osmosis, diffusion)

Recall that The process of maintaining balance in an organism’s internal environment is called---homeostasis! Essential to survival One of the primary structures for this is the… PLASMA MEMBRANE!

Vocabulary Homeostasis Cell or plasma membrane Semipermeable Phospholipid Hypo-, Hyper-, Isotonic Diffusion Passive Facilitated Active transport

Phospholipids TAILS HEAD Phospholipids have a hydrophilic end and a hydrophobic end. Hydrophilic = water loving Hydrophobic = water hating TAILS HEAD

The Hydrophilic ends rotate outward toward the water. The Hydrophobic ends rotate inward toward each other. This makes a double layer of phospholipids—phospholipid bilayer!

Structure of Cell Membrane PHOSPHOLIPID  PHOSPHOLIPID BILAYER (CELL) Cell Membrane 

Selective Permeability Chapter 7 Cellular Structure and Function 7.2 The Plasma Membrane Selective Permeability The plasma membrane controls the movement of substances into and out of the cell. Plasma Membrane Controls the amount of a substance entering the cell Controls the amount of a substance leaving the cell

Thin, flexible boundary between the cell and its environment Chapter 7 Cellular Structure and Function 7.2 The Plasma Membrane Plasma Membrane Thin, flexible boundary between the cell and its environment Allows nutrients into the cell Allows waste to leave the cell

The plasma membrane is composed of the phospholipid bilayer. Chapter 7 Cellular Structure and Function 7.2 The Plasma Membrane The plasma membrane is composed of the phospholipid bilayer. A phospholipid molecule is composed of a glycerol backbone, two fatty acid chains, and a phosphate group.

This membrane got moves! Structure is not fixed (like a brick wall) but moves around – called a fluid mosaic

Chapter 7 Cellular Structure and Function 7.2 The Plasma Membrane Fluid Mosaic Model The phospholipid bilayer allows other molecules to “float” in the membrane. Other Components Proteins Cholesterol Carbohydrates

Membrane Proteins Marker Proteins – like nametags to identify the cell to other cells. Works with the immune system Transport Proteins – Move materials into and out of the cell Receptor Proteins – Allows the cell to interact with other cells.

Protein Channel

Ok, recap!!! Selective permeability allows the membrane to control what enters and leaves the cell Plasma membrane composed of 2 layers of phospholipid molecules Cholesterol and transport proteins aid in function of membrane Fluid mosaic model describes it

Fill in the blanks The axillary border of the scapula is ________ to the vertebral border. The hips are __________ to the shoulders. The knee is ___________ to the ankle. The cranium is __________ to the scalp.

How important is the receptor in a negative feedback system?

Sinoatrial (SA) node?

Name that quadrant. ?

Movement of Molecules Across the Cell Membrane Passive Transport – requires no cellular energy Active Transport – Requires cellular energy

Types of Passive Transport Diffusion – Molecules move with a Concentration Gradient, from high concentration to low concentration. Requires no energy Molecules continue to move until an equilibrium is reached

7.4 Cellular Transport Diffusion in a Cell Cellular Structure and Function 7.4 Cellular Transport Diffusion in a Cell

Osmosis The Diffusion of Water Across a Selectively Permeable Membrane

Osmotic Pressure Gradients In general, water moves toward the area with a higher solute concentration because it has a lower water concentration.

Hypertonic Solutions Contain a higher concentration of solute outside of the cell than inside of the cell. When a cell is placed in a hypertonic solution, the water diffuses out of the cell, causing the cell to shrivel.

Solute concentration is higher outside the cell. Chapter 7 Cellular Structure and Function 7.4 Cellular Transport Hypertonic Solution Solute concentration is higher outside the cell. Water diffuses out of the cell. Plant Cell Blood Cell 13,000x

Hypotonic Solutions Contain a low concentration of solute outside of the cell as compared to inside of the cell. When a cell is placed in a hypotonic solution, the water diffuses into the cell, causing the cell to swell and possibly explode.

Solute concentration is higher inside the cell. Chapter 7 Cellular Structure and Function 7.4 Cellular Transport Hypotonic Solution Solute concentration is higher inside the cell. Water diffuses into the cell. Plant Cell Blood Cell 13,000x

Isotonic Solution The concentration of solute inside of the cell is equal the concentration of solute outside of the cell. Therefore, water move equal into and out of the cell.

Chapter 7 Cellular Structure and Function 7.4 Cellular Transport Isotonic Solution Water and dissolved substances diffuse into and out of the cell at the same rate. Plant Cell Blood Cell 11,397x

Facilitated Diffusion Diffusion with help!! Uses Transport Proteins to move large molecule across the plasma membrane Molecules move with the concentration gradient. Downhill !!

Carrier Proteins Channel Proteins 7.4 Cellular Transport Chapter 7 Cellular Structure and Function 7.4 Cellular Transport Carrier Proteins Channel Proteins

Active Transport Move molecule against the concentration gradient. Uphill!! Known as solute or ion pumps

Active Transport Using Carrier Proteins 7.4 Cellular Transport Cellular Structure and Function Active Transport Movement of particles across the cell membrane using energy Active Transport Using Carrier Proteins

2 Special Types of Active Transport Endocytosis - large molecules are engulfed by cell. Phagocytosis – cell eats Pinocytosis – cell drinks Exocytosis – large molecules are removed from the cell.

Process by which the cell surrounds and takes particles into the cell Cellular Structure and Function 7.4 Cellular Transport Endocytosis Process by which the cell surrounds and takes particles into the cell Exocytosis Secretion of material out of the plasma membrane