All Organisms Are Made of Cells The Cell Theory All living things are composed of cells Cells are the basic unit of structure and function in living things All cells come from pre- existing cells

Overview Of Animal & Plants Organelle Plasma membrane “Mini-organ” Most are membrane bound & perform specific functions Outer covering that defines the boundary Regulates things going in and out Crucial for homeostasis

Overview of Plant & Animal Cells Nucleus Cytoplasm Membrane bound structure that houses the DNA Fluid that fills entire cell and suspends the organelles

Two Major Classes of Cells Prokaryotic Cells Lack a nucleus and other membrane bound organelles  Bacteria  Archaea  Earliest cells in Earth’s fossil record Cell wall

Two Major Classes of Cells Eukaryotic Cells True nucleus Membrane bound organelles Much bigger in size

Is It Alive? Viruses ? Some characteristics of life Smallest infectious agents Composed of mostly protein and genetic material Coat called capsid Some have envelope similar to cell membrane Cell Size

Structure of Cell Membrane Membrane Structure Phospholipid molecule Phosphate head  Hydrophilic  Contains arrangement of atoms attached to glycerol including phosphate group Lipid tail  Hydrophobic  Two fatty acid chains Polar Group Phosphate Glycerol Hydrophilic head (polar) fatty acid chain Hydrophobic tail (non-polar)

Structure of Cell Membrane Organization of phospholipids Bilayer (2 layers) Hydrophobic tails make up inside layer Hydrophilic heads face extra- cellular space and intra-cellular space

Structure of Cell Membrane Proteins within the membrane  Enzymes- carry out reactions  Facilitate communication between cells and allows for recognition between cells  Assists in the transport of molecules across the membrane (like water & sugars)

Membranes Regulate the Traffic of Molecules 2 ways materials such as water, salts, sugar, and nutrients move across the cell membrane, in order to maintain homeostasis PASSIVE TRANSPORT 1. Passive transport 2. Active transport Molecules move from an area of high concentration to an area of low concentration No energy required

Equilibrium Movement of molecules continues, across the membrane, but at the same rate in both directions Molecules are equally dispersed  BALANCE

Types of Passive Transport Simple diffusion: Small molecules (oxygen & carbon dioxide) pass through the membrane from an area of high concentration to an area of low concentration Facilitated diffusion: Larger molecules use protein channels to move across the membrane from an area of high concentration to an area of low concentration

Moving Molecules against a Gradient ACTIVE TRANSPORT When molecules are moved from an area of lower concentration to area of higher concentration Cell expends energy Usually performed to prevent equilibrium from occurring Example: Neuron

Passive Transport Continued Osmosis Solutions Passive transport of water across a selectively permeable membrane Water moves from an area of high concentration to an area of low concentration A solution is made up of two things : Solute and Solvent Solute: Substance in a solution that is dissolved & present in a lesser amount Solvent: Substance in a solution that dissolves the other substance & is present in a greater amount

Types of solutions Hypertonic solution Hypotonic solution Isotonic solution Hyper = over Hypertonic solution is a solution that has a high concentration of solutes Hypo= under Hypotonic solution is a solution that has a low concentration of solutes Iso= same Isotonic solutions are ones that have an equal concentration of solutes and water in and outside of the cell

Osmosis in Different Cells Turgor Pressure: The pressure produced inside the cell from a hypotonic solution Plasmolysis: When the cell membrane shrinks away from the cell wall.

Organs of the Urinary system- Chapter 32.2  Kidneys  Ureters  Urinary bladder  Urethra

Urinary System 4 Organs Kidneys  2 Bean shaped structures  Excrete waste products & regulate water and salt balance  Filter the blood Produce urine = Liquid composed of water, urea, and other nitrogen containing waste products Ureters (2)  Tubes that extend from each kidney carrying urine to the urinary bladder

Urinary System 4 Organs Urinary Bladder  Collapsible sac that temporarily holds urine until it is eliminated from the body Urethra  Urine leaves the bladder through another tube called the urethra

Urinary System Primary Goal of the Kidney Excrete waste products and regulate water and salt balance Two Roles  Clean out toxins from blood  Restore water

4 Steps Involved when Blood is Processed & Urine is Excreted Step #1 = Filtration  Blood pressure forces water and small solutes, including urea, into the Bowman’s Capsule Step #2 = Reabsorption  Active Transport reabsorbs Glucose, amino acids, and other ions from the filtrate back into the blood  Water solution left behind is hypotonic causing osmosis to move water back into the blood

4 Steps Involved when Blood is Processed & Urine is Excreted Step #3: Secretion  The following substances are transported from the blood back into the filtrate Nitrogenous waste products Urea Uric Acid Toxins Excess Water

4 Steps Involved when Blood is Processed & Urine is Excreted Step #4: Excretion  Remaining filtrate is transported to the bladder to leave the body

Regulating Water Balance Mechanisms of homeostasis regulate the amount of water reabsorbed by the kidney  Example: Negative Feedback Loop How the body responds to a stimulus, in order to create a balance again…

Regulating Water Balance Decrease water level in your body  Increase concentration of solutes in your blood  Thirst center in your brain is activated Motivates you to drink ADH (anti-diuretic hormone) is released  ADH travels in the blood to the kidneys  stimulates the nephrons to reabsorb more water  Result: Decrease in solute concentration in the blood to within the normal range Water content of urine decreases  Yellow; concentrated

Regulating Water Balance Drink too much water  Solute concentration in blood drops below the normal range  Less ADH is released from the brain  Lower level of ADH, decreases the amount of water reabsorbed in the nephrons  Result: Urine contains more water  lighter in color

Transporting Large Molecules Endocytosis Exocytosis Moving large molecules into the cell within vesicles  Vesicles: Small membrane bound sacs specialized in moving materials in and out of cell oMoving large molecules out of the cell within vesicles