Biology 1-2 Unit 2 Reading Cells:

Prokaryotes and Eukaryotes There are two general classes of cells, both of which clearly affect human health and are essential for maintaining life as we know it. Both types of cells have a cell membrane that surrounds the cytoplasm of a cell and physically separates the inner components from the outside environment.

Prokaryotes Simple, smaller organisms. Bacteria are prokaryotes. They are found only in single-celled and colonial organisms. LACK A NUCLEUS

Eukaryotes Complex and larger organisms. They have organelles with their own membranes. Plants, animals, protists, and fungi are eukaryotes. Eukaryotic organisms can be either single-cellular or multicellular. HAVE A NUCLEUS

Prokaryotes and Eukaryotes: Key Differences The most important difference between prokaryotes and eukaryotes is that eukaryotes have:

Prokaryotes Eukaryotes A true nucleus Prokaryotes do not have a true

nucleus. DNA floats freely in the cytoplasm.

Eukaryotes have a true nucleus. DNA is held within a membrane-bound nucleus.

Membrane-bound organelles

Prokaryotes do not have membrane-bound organelles, but do have ribosomes, which float freely.

Eukaryotes have membrane-bound organelles. These organelles are highly specialized structures that allow them to exhibit more sophisticated intracellular division of labor than is possible in prokaryotic cells.

Size

Small. Eukaryotic cells are, on average, ten times the size of prokaryotic cells.

DNA composition and length

Simple and circular. The DNA of eukaryotes is much more complex and therefore much more extensive than the DNA of prokaryotes.

Cytoskeleton Prokaryotes do not have a cytoskeleton as they are so small they do not need the extra support

Eukaryotes have a cytoskeleton which maintain the shape of the cell as well as anchoring organelles, moving the cell and controlling internal movement of structures.

ANIMAL CELL PLANT CELL

Osmosis and Diffusion

Diffusion Diffusion is the net passive movement of particles (atoms, ions or molecules) from a region in which they are in higher concentration to regions of lower concentration. It continues until the concentration of substances is uniform throughout. Some major examples of diffusion in biology: • Gas exchange at the alveoli — oxygen from air to blood, carbon dioxide from blood to air. • Gas exchange for photosynthesis — carbon dioxide from air to leaf, oxygen from leaf to air. • Gas exchange for respiration — oxygen from blood to tissue cells, carbon dioxide in opposite direction.

Fluids move or diffuse in response to solute concentration gradients. Fluids move toward areas where they are LEAST concentrated. Fluids continue to diffuse until they reach equilibrium (even distribution of particles).

Osmosis Osmosis is a special example of diffusion. It is the diffusion of water through a partially permeable membrane from a more dilute solution to a more concentrated solution Some major examples of osmosis • Absorption of water by plant roots. • Re-absorption of water by the kidney • Re-absorption of tissue fluid into the blood capillaries. • Absorption of water by the stomach, small intestine and the colon.

A solute is a dissolved material, like salt. A solvent is the fluid that the solute is dissolved in.

A high concentration of a solute makes a solution hypertonic relative to the concentration of solutes in a cell.

A low concentration of a solute makes a solution hypotonic to the concentration of solutes in a cell.

rela

A concentration of a solute that is the same as the concentration of solute inside of the cell is isotonic.

Macromolecules Carbohydrates

The two kinds of carbohydrates we will be testing for today Simple Sugars for example glucose Complex Sugars for example starch

Carbohydrate Definition Simple Sugar---CH2O formula-for storage of energy Complex Sugar---CH2O formula-for storage of energy and for structural support

Carbohydrate Monomer Simple Sugar- A monomer would be glucose for example,,, when you bond glucose and fructose you get sucrose Complex Sugar- A monomer would be glucose for example,,, when you bond many glucoses together you get starch (a storage molecule found in plants) or cellulose (a structural molecule--forms cells walls)

Carbohydrate Examples Examples of sugars: Used for energy in the cell---

Simple Sugar--glucose, sucrose, fructose, Complex Sugar--starch Used for structural support---

Complex Sugar--Cellulose (plant cell walls) and chitin (exoskeletons and fungus cell walls) Proteins Definition

Long chain of amino acids that form a polypeptide chain The polypeptide chain is folded into a specific structure so it can function properly

Protein Monomer Single subunit for all proteins is an amino acid

Protein Examples Some examples of proteins are

--enzymes-which speed up chemical reactions --hemoglobin-used to carry oxygen to the cells in your body

Lipid Definition One of the four classes of organic macromolecules. They function in the long-term storage of biochemical energy insulation, structure and control.

Lipid monomer The single unit of a lipid is a glycerol with three fatty acids attached. These molecules do not attach to each other to form polymers, they simply exist as monomers.

Lipid Examples Examples include the fats, waxes, oils and steroids

Nucleic Acids Definition Genetic instructions found in all cells

Nucleic Acid Monomer Nucleotide

-These are composed of a sugar a nitrogen base and a phosphate group Nucleic Acid Example

DNA-deoxyribonucleic acid RNA-ribonucleic acid

Controls and Indicators The molecules presented at the beginning of the lesson are so important that scientists have devised tests to determine if these molecules are present in a sample. You will first learn to use the indicators listed below to determine if these molecules are present. You will then test several foods using these indicators to determine what molecules are in the food. Before you test your food items, you will first need to observe positive and negative controls. A positive control will demonstrate the color of the indicator when a certain macromolecule is present, whereas a negative control will demonstrate the color of the indicator when a certain macromolecule is not present. Benedicts-Tests for the presence of simple sugars (carbohydrates) in a solution -It will remain blue if there is no sugar present and will turn green/yellow/red if sugar is present -A negative control for benedicts would be water and a positive control would be glucose Lugols-Tests for the presence of the complex sugars (carbohydrates) specifically starch -It will remain gold if there is no starch present and will turn black if starch is present -A negative control for lugols would be water and a positive control would be starch Biurets-Tests for the presence of protein in a solution -It will remain blue if there is no protein present and will turn pink/purple is protein is present -A negative control for biurets would be water and a positive control would be protein (egg white) Paper Bag-Tests for the presence of fats in a solution -It will remain unchanged if there is no fat present and will turn translucent (clear/shiny) if fat is present -A negative control for the paper bag would be water and a positive control would be fat (butter) Enzymes Enzyme structure and function

An enzyme speeds up a chemical reaction by lowering the activation energy. An enzyme is a protein.

Factors that affect enzyme function. -pH---all enzymes have an optimal pH, changing the pH away from optimal may cause stress on the bonds in the enzyme causing it to denature (change shape) and not work -temperature—all enzymes have an optimal temperature, for example the enzymes in our body work best at 37C—changing the temperature away from optimal, may cause the reaction to slow if it is very cold, or cause stress on the bonds in the enzyme if it is very hot causing it to denature

-Concentration of Enzyme-increasing the amount of enzyme in the reaction will speed up the reaction because there are more available to react with the substrate-conversely if you decrease the concentration of the enzyme you will slow down the reaction -Concentration of the Substrate-Increasing the amount of substrate will speed up the reaction because there is more to react with- conversely if you decrease the concentration of the substrate you will slow down the reaction because it takes longer for the enzyme to ‘find’ the substrate Enzyme Inhibition

Dehydration (condensation): remove water to add Hydrolysis: add water to break polymers apart monomers together (digestion)