Anabolism is a term for all of the body's _______ reactions. A) decomposition B) hydrolytic C) exergonic D) endergonic E) metabolic

Energy is released during an endergonic reaction A. True B. False

A non-competitive inhibitor influences the function of enzymes by: A) binding the substrate before it can bind to the enzyme. B) causing a permanent change in the enzyme's structure. C) temporarily binding to the enzyme's active site. D) permanently binding to the enzymes's active site. E) doing both B and D.

Why does the enzyme reaction rate decrease at high temperatures?

Cell Membranes

Cell Membrane Parts Phospholipids –Structure –Function –Motion Proteins –Structure –Function

Model of a Cell Membrane

Amphiphilic = Both hydrophobic and hydrophilic Phospholipid Structure

Cell Membrane Parts Phospholipids –Structure –Function –Motion Proteins –Structure –Function

Phospholipids are Amphiphilic

Hydrophobic molecules pass through membrane Hydrophilic molecules bounce off Getting into the Cell

Soap is also Amphiphilic Soap removes grease because it is amphiphilic Not Jon’s Dishes

Some materials easily enter the cell Some materials cannot enter easily Plasma Membrane is Selectively Permeable

Types of Molecular Transport Passive transport –Requires no energy Active transport –Requires energy

Let’s Do an Experiment!

Types of Passive Transport Diffusion –Requires no energy –Movement of molecules from an area of high concentration to an area of lower concentration

What Causes Diffusion? Why do you think diffusion occurs?

Types of Passive Transport Osmosis –Diffusion of water

Types of Passive Transport Osmosis –Diffusion of water –Water moves towards area of high solute concentration OSMOSIS ANIMATION

Types of Passive Transport Osmosis –Diffusion of water –Water moves towards area of high solute concentration –Osmotic Pressure The force with which water moves toward the area of low concentration

Types of Passive Transport Facilitated Diffusion –Molecules cannot pass through membrane unaided

Types of Passive Transport Facilitated Diffusion –Molecules cannot pass through membrane unaided –Need protein channel to facilitate transport into the cell May be too large to pass through Polar Hydrophilic

Facilitated Diffusion at the Bar Gonna need to see some ID to facilitate your transport in.

Facilitated Diffusion at the Bar Hydrophilic, eh? Fine, enter through the protein channel.

Types of Molecular Transport Passive transport –Requires no energy Active transport –Requires energy

Active Transport at the Bar This joint is packed with hydrophilic molecules. I need ID and $5 to go against the gradient.

Active Transport Pumps ATP is used for power

Active Transport Pumps ATP is used for power Work against osmotic or electrical gradient

Active Transport Pumps ATP is used for power Work against osmotic or electrical gradient Move from low to high concentration

Phagocytosis Cell engulfs a particle

Phagocytosis Cell engulfs a particle Allows very large objects to enter cell

White Blood Cells use Phagocytosis WBC Bacteria

Cell Membrane Parts Phospholipids –Structure –Function –Motion Proteins –Structure –Function

Fluid-Mosaic Model Membrane molecules are in continuous motion (= fluidity) FLUID MOSAIC ANIMATION

Phospholipid Movement Phospholipids often move laterally

Phospholipid Movement Phospholipids often move laterally Phospholipids seldom flip –Heads would have to pass through hydrophobic space

Fluid-Mosaic Model Membrane molecules are in continuous motion (= fluidity) Type of phospholipid determines fluidity

Phospholipid Tails Influence Fluidity Unsaturated fatty acid tails are more fluid

Saturated fatty acid tails are less fluid Phospholipid Tails Influence Fluidity

Fluid-Mosaic Model Membrane molecules are in continuous motion (= fluidity) Type of phospholipid determines fluidity Cholesterol and proteins are embedded in bilayer

Cholesterol helps stabilize phospholipid movement Fluidity of Membranes

Cell Membrane Parts Phospholipids –Structure –Function –Motion Proteins –Structure –Function

Protein Structure Trans-Membrane Proteins –Pass through the membrane

Protein Functions 1.Identification 2.Anchor cells together 3.Catalyze reactions (Enzymes) 4.Bind chemical messengers (receptors) 5.Transport hydrophilic molecules

Proteins are Molecular Name Tags Protein tags identify cell Biological marker of “self or non-self” Bacteria Recognition Sperm finding egg

Protein Markers Determine Blood Type Body responds to “foreign” markers A Antigens onlyB Antigens onlyA and B AntigensNo Antigens A Antibodies onlyB Antibodies only A and B Antibodies

Rh Antigens are Proteins Mother’s body attacks Rh+ blood proteins Most common with 2 nd child

Protein Functions 1.Identification 2.Anchor cells together 3.Catalyze reactions (Enzymes) 4.Bind chemical messengers (receptors) 5.Transport hydrophilic molecules

Proteins Hold Cells Together

Protein Functions 1.Identification 2.Anchor cells together 3.Catalyze reactions (Enzymes) 4.Bind chemical messengers (receptors) 5.Transport hydrophilic molecules

Protein Enzymes in Membranes

Protein Functions 1.Identification 2.Anchor cells together 3.Catalyze reactions (Enzymes) 4.Bind chemical messengers (receptors) 5.Transport hydrophilic molecules

Chemical messengers Cause secondary signals to be sent in the cell Small changes in chemical shape send the signals

Protein Functions 1.Identification 2.Anchor cells together 3.Catalyze reactions (enzymes) 4.Bind chemical messengers (receptors) 5.Transport hydrophilic molecules

Transport of Hydrophilic Molecules Facilitated Diffusion Active Transport

1. Proteins change shape to move molecules across membrane. 2. Proteins can cooperate to transport molecules.

Summary Membranes are formed by the amphiphilic nature of phospholipids Membrane molecules are in constant flux, creating a fluid and dynamic layer Membrane proteins serve a number of functions, including regulating the passage of molecules into and out of the cell