Unit B – Section 2.0 Biology

Structures and Function of Cell Organelles Cell Membrane Selectively Permeable Keeps contents Nucleus Most obvious organelle in any eukaryotic cell Surrounded by a double membrane Control Center of Cell Contains DNA Surrounds Nucleolus, which produces ribosomes Cytoplasm Aka cytosol Jelly like substance that surrounds and holds other organelles in place Consists of mostly water, and many proteins responsible for cell metabolism Vacuoles Endoplasmic Reticulum Continuation of the outer nuclear membrane 2 types Rough ER – has ribosomes on outside – synthesizes proteins Smooth ER – synthesizes lipids and membrane proteins Ribosomes Synthsize Protein Lysosomes - Golgi apparatus Membrane bound structure (single membrane) Stack of Vesicles that package molecules for transport elsewhere in the cell Mitochondria ‘Mighty Mouse’ Power House of the Cell Provides Chloroplasts Cell Wall

Similarities and Differences between plant and animal cells Plant Cell Animal Cell Cell Wall (composed of cellulose) and Cell Membrane Cell Membrane only (No Cell Wall) Chloroplasts producing chlorophyll No Chloroplasts Large Vacuole Small Vacuoles & Vesicles Undergo Photosynthesis and Cellular Respiration Only Cellular Respiration No Centrioles Centrioles

Cell Composition Elements: C, H, O, N Lipids (fats and oils) Carbohydrates (sugars and starches) Proteins (muscles fibres and enzymes) Nucleic Acids (DNA, RNA)

Cell Equilibrium The cell membrane is sometimes referred to as the plasma membrane. The plasma membrane is made up of a phospholipid bilayer and some proteins 2 layers Hydrophobic Tails and hydrophilic heads

2.2 – Transport through cell – Particle Theory of Matter All matter is made up of particles. Different substances will have different size and composition of particles Particles are constantly moving. Solids least, Gases, most. Change in energy to substance will change movement. Particles are attracted to each other and may form bonds Particles have spaces between them (least in solids, most in gases) Exception: Ice.

Vocabulary Selectively Permable – Controls what enters and exits cells (aka semi-permeable) Diffusion – materials go from high concentration to low concentration. Perfume spreading through a room. Rate of Diffusion – Can be increased by adding energy and increasing molecular movement

More Vocab. Concentration Gradient – Determines direction of water or solution will move. Osmosis – water going from high concentration to low across a semi-permeable membrane (selectively permeable).

More Vocab! Dialysis – solutes going from high concentration to low across a semi-permeable membrane. Facilitated diffusion- molecules transported across the semi-permeable membrane with the use of channel or carrier proteins. All of the above go with the concentration gradient (high to low) All of the above don’t require energy

Even more Vocab! Active transport – carries molecules across the semi-permeable membrane against the concentration gradient (low to high). This requires energy and carrier molecules. The energy that a cell uses is ATP (adenosine triphosphate)

Types of Solutions Solutions that cells are placed in are categorized into 3 types depending on the concentration of solute the solution has to the cell. Hypertonic Hypotonic Isotonic

Isotonic – Same Concentration

Hypotonic – Less Solute

Hypertonic – More Solute

Cells can also bring in large objects: Endocytosis – Cell pinches off small chunks of material  Exocytosis – Cell dumps out small chunk

2.3 Medical Applications Liposomes - create an artificial membrane that can house medicines and carry them throughout the cell. Insulin – (naturally made) glucose controls cells in the pancreas to release insulin by exocytosis. Insulin increases the intake of glucose into cells Peritoneal dialysis – filtering the blood by diffusion Desalination – reverse osmosis – force water out of a membrane so that it goes against the osmotic gradient.

Cell Size Why cells are roughly the same size no matter what they do or are located? Cells are roughly cube like in shape and as the cell grows in size the Surface Area :Volume ratio gets smaller. This is bad for the cell. Surface area determines how much material can come in and how much can leave. Materials come in via diffusion across the membrane. You want lots of this. Volume represents how much stuff is needed (food and necessary gases) and how much must be gotten rid of (wastes solids and gases). Materials come in via diffusion across the membrane. The cell also responds to slowly to its environment if it gets too large

Calculating Surface Area to Volume Ratio Before we calculate the ratio of surface area to volume…we need to review how to calculate Surface Area and volume independently…

Calculating Surface Area You should recall from math: Surface Area = Sum of the AREAS of each side. For example: This rectangle has 6 sides. Short sides = 3cm each, Long side = 5cm 1. So calculate the area of each side : Short = 3cm x 3cm = 9cm2 Long = 3cm x 5cm = 15cm2 2. Multiply each by the number of sides: Short = 2 sides x 9cm2 = 18cm2 Long = 4 sides x 15cm2 = 60cm2 3. Add them together: 18cm2 + 60cm2 = 78cm2

Calculating Volume Again…recall from math Volume = length x width x height Which for the same rectangle: 5cm x 3cm x 3cm = 45 cm3 **Note –> 1 cm3 = 1 mL

Now we can show the ratio of surface area to volume Back to the same rectangle: We always show the ratio as: surface area: volume SO = 78cm2 : 45 cm3 Reduced to = 78:45 AND IT MUST BE IN THAT ORDER!! Your notes show: This is an example calculation that will only work for cubes that are the same size on each side.

Example #1 Calculate the surface area:volume ratio Side length: 1.0 cm  Area of each side: 1.0 cm x 1.0 cm = 1.0 cm2 Surface Area: 1.0cm2 x 6 sides = 6.0cm2 Volume: 1.0cm x 1.0cm x 1.0cm = 1.0cm3 Answer: 6.: 1

Example #2 Surface Area: Volume for a cube: Each side is 2.5 cm Area: 2.5cm x 2.5cm = 6.25cm2 6 sides x 6.25cm2 = 37.5cm2 Volume: 2.5cm x 2.5cm x 2.5cm = 15.63cm3 Answer = 38 : 16 reduce it = 19: 8

Example #3 Surface Area: Volume for a cube: Each side is 4.0 cm Area: 4.0cm x 4.0cm = 16cm2 6 sides x 16cm2 = 96cm2 Volume: 4.0cm x 4.0cm x 4.0cm = 64cm3 Answer = 96 : 64 reduce it = 3 : 2

Homework: Practice problems in Text pg 289 #1-3 Check and Reflect p294 – even #’s Section 2.0 quiz on Tuesday!!