What is the Scientific Method?
The Scientific Method is a series of steps to uncover the possible explanations to questions; never “PROVEN”, only “supported”. Must be testable & falsifiable.
The steps are as follows:
1.Observation
2.Hypothesis (or Question)
3. Prediction to solve Hypothesis
4. Test the Prediction [Experiment]
5. Draw a conclusion
What is a Chemical Bond?
A chemical bond is the interaction between atoms and holds atoms together. There are a few types of bonds:
Covalent (Polar and Non-Polar): Covalent Bonds share electrons; These are the strongest bonds.
Polar Covalent Bonds is a bond between two non-metals with different electronegativities (for example Hydrogen and Oxygen in H2O). The electrons shared between Hydrogen and Oxygen spend unequal time with Oxygen as they do with Hydrogen. This is because Oxygen has a stronger affinity for the electrons than Hydrogen.
Non-Polar Covalent Bonds are bonds between two atoms with equal affinity (attraction) for electrons, such as two Hydrogen atoms. This bond always happens when two atoms of the same element bond together.
Ionic: Involves a metal and a non-metal. This happens when a metal donates one or more electrons to a non-metal; an example of this is table salt ( Na+Cl -> NaCl ). These bonds are easily broken.
Hydrogen: Hydrogen bonds are bonds between hydrogen and an electronegative atom (such as the Oxygen in H2O). These are very weak bonds. Hydrogen bonds are what gives water it’s fluidity.
What are the properties of Water?
Water is the biological medium on Earth; all living organisms need water more than any other substance. Our cells are surrounded by water, and the cells themselves are made up of anywhere from 70-95% water. Water also is cohesive; that means that hydrogen bonds hold water together. This property aids in the transport of water against gravity in plants. Water also has a high surface tension (or measure of how hard it is to break the surface of a liquid).
Water is also a great moderator of temperature. Water absorbs heat from warmer air and releases heat to cooler air; it can absorb or release a large amount of heat with very little change to it’s own temperature.
What is a Calorie?
A calorie is the amount of heat required to raise the temperature of one gram of water by one degree Celsius.
What is the Structure and Properties of each Functional Group?
The Hydroxyl group is polar (due to the oxygen) and can form hydrogen bonds with water molecules, helping dissolve organic compounds (such as sugars).
The Carbonyl Group is found in sugars; aldoses and ketoses.
The Carboxyl Group has acidic properties because of the polar covalent bond between oxygen and hydrogen. It is found in cells in the ionized form with a negative charge of 1-; it’s specifically called a carboxylate ion.
The Amino group acts as a base. It can pick up H+ from the solution surrounding it (such as water in living organisms).
Phosphate Group w/o R
The Sulfhydryl group can link together with another sulfhydryl group and form a covalent bond; this helps stabilize protein structures.
The Phosphate group (consisting of phosphorus atom bonded to four oxygen atoms; one with a double bond and two which are negative) contributes negative charge to the molecule of which it is a part. It has the potential to react with water, which releases energy.
If a Methyl Group is added to a group of DNA, it can affect gene expression. The arrangement of methyl groups in male and female sex hormones affect their shape and function.
ATP (Adenosine Triphosphate) consists of the organic molecule adenosine attached to a string of three phosphate groups. When a reaction with water occurs, the third phosphate is split off and releases energy that can be used by the cell and ATP become ADP (Adenosine Diphosphate).
What are the four different classes of Macromolecules?
The four classes of macromolecules, or organic carbon backbone, are Carbohydrates, Lipids, Nucleic Acids, and Proteins.
Carbohydrates: Sugars and polymers (or long chains of sugars linked by covalent bonds). This includes monosaccharides (single sugars), disaccharides (consisting of two monosaccharides joined by a glycosidic linkage), and polysaccharides (polymers with hundreds to thousands of monosaccharides).
Lipids: Lipids are hydrophobic (water-fearing; they do not mix well, if at all, with water). Lipids are fats (glycerol and fatty acids). Fats have two times as much energy as starch (a polysaccharide)! There are three types of fats; Saturated, which are solid at room temperature and have no double bonds. Saturated fats are unhealthy. Unsaturated fats tend to be liquids and have double bonds; they are healthy. Trans fats need liquids to be solid; they can’t be broken down by the body naturally because they’re not naturally found in nature. Trans fats are VERY bad for you.
Nucleic Acids: Consist of DNA and RNA. DNA stores genetic information and is made up of four base pairs: Adenine (A), Thymine (T), Guanine (G), and Cytosine (C) which always pair up A-T and G-C [Base Pairing Rule]. The double helix of DNA is made up of a Sugar-Phosphate “handrail”. RNA translates language from Nucleic Acid to Protein language. RNA is made up of four base pairs as well: Adenine (A), Guanine (G), Cytosine (C), and Uracil (U) which pair up A-U and G-C.
Proteins: Proteins account for 50% of the dry mass of most cells. Proteins are made up of Amino Acids, which can be broken down into three groups: Polar, Non-Polar, and Electrically Charged (basic or acidic). A protein’s structure determines it’s function; the sequence and length of Amino Acids determines a proteins three-dimensional shape. Enzymes are made up of 99% proteins (cofactor is only non-protein part). If an enzyme is denatured, or changes its shape due to intense temperatures or pH, it will not work.
What is the Cell Theory?
The Cell Theory states that all living things are composed of cells and that all cells come from pre-existing cells. Cells are the basic organizational unit of life.
What are the major differences between Eukaryotic and Prokaryotic Cells?
Besides for size (Eukaryotic cells are much larger than Prokaryotic cells), there are three main differences between Eukaryotic (“True Nucleus“) and Prokaryotic (“Before Nucleus“) Cells:
Prokaryotic Cells do not have a nucleus or nuclear envelope while a eukaryotic cell does.
Prokaryotic cells do not have membrane-bound organelles while Eukaryotic cells do.
Eukaryotic cells have Cytoplasm between plasma membrane and nuclear envelope, while Prokaryotic cells have cytoplasm bound by the plasma membrane.
What are the structures and functions of the major organelles of the Eukaryotic cell?
The difference in organelles between plants and animals: Plants have Vacuoles, a Cell Wall, and Chloroplasts while Animal cells have Lysosomes and Centrioles.
Nucleus: Houses DNA and RNA and controls cell reproduction. The Nucleolus makes Ribosomes.
Ribosomes: Made up of Protein and rRNA. Ribosomes aid in protein synthesis and are made in the nucleolus. Ribosomes are either free-floating or attached to the Rough E.R.
Endoplasmic Reticulum [E.R.]: The E.R. is a complex network of membranes and is continuous with the Nuclear Membrane. There are two distinct sections; the Rough E.R., which makes proteins, and the Smooth E.R., which makes Lipids and Carbs.
Golgi Apparatus: Consists of cisternae, which are flattened membranous sacs. The function of the Golgi is to modify proteins and carbs, then sort, package, and ship them out via transport Vesicles to various parts of the cell. The Golgi also manufactures some macromolecules.
Lysosomes: The stomach of the cell. Lysosomes contain digestive enzymes and are only found in Animal cells.
Vacuoles: The central vacuole helps maintain pressure in plants.
Plasma Membrane: Semi-permeable. The membrane is made up of a phospholipid bilayer with hydrophobic (water-fearing) tails and hydrophilic (water-loving) heads.
Mitochondria: In both plants and animals, it is the site of Cellular Respiration. Mitochondria contains its own DNA.
Chloroplasts: Plastids family; is only found in plants. It is the site of photosynthesis and is a double membrane organelle. The chloroplast structure includes the Thylakoids and the Stroma.
Cytoskeleton: The Cytoskeleton is a network of fibers though the Cytoplasm. Three types of Cytoskeleton: Microtubules, or the structure the separates chromosomes; Microfilaments, for structure, support, and movement (muscles); and Intermediate Filaments, for structure.
What are the mechanisms by which molecules pass through plasma membranes? Which require energy/transport proteins?
Molecules pass through plasma membranes because they are selectively permeable due to their hydrophobic tails and hydrophilic heads. Movement of particles across a membrane can be done by osmosis or diffusion. Osmosis is the passive (no energy is required) transport of water across a membrane. Diffusion is the movement of particles across a membrane. There are a few different types of diffusion: Facilitated diffusion, which is diffusion of particles from high to low and requires no energy; Active Transport, which goes against the concentration gradient (or flow of materials, in this case high to low) and requires ATP; Endocytosis, which is the process of getting large things into the cell, such as liquids (pinocytosis) or particles (phagocytosis) and Exocytosis, the process of getting thing out of the cell.
What is Osmosis?
Osmosis is the diffusion of water across a membrane. The rate of osmosis (or diffusion) depends on the concentration gradient (flow of materials from high to low), Environmental Factors such as temperature, pressure, and humidity, and the size of the molecules being diffused.
What is Metabolism?
Metabolism is the sum of all chemical reactions in an organism.
What are anabolic and catabolic pathways?
An anabolic pathway is the series of chemical reactions that constructs larger molecules from smaller molecules, usually requiring ATP. Catabolic pathways, in contrast, is the series of chemical reactions that break down larger molecules into smaller molecules, usually releasing energy while doing so. Here is a great way to remember what Anabolic and Catabolic is; watch this video.
What is an Enzyme and what is its Function? How does an Enzymes Structure relate to its Function?
An enzyme is made up of 99% protein and a non-protein cofactor. Proteins lower the activation energy of a reaction by having a substrate bind to the enzyme’s active site. An enzyme’s shape is substrate specific, like a key into a lock.
What are the factors that affect enzyme activity?
Some factors that affect enzyme activity are:
Substrate Concentration: The more substrate that is present, the quicker a reaction will take place.
Temperature/pH: Extreme temperature and pH can denature an enzyme, rendering it (most times) permanently useless.
Co-Factors: Some enzymes require co-factors, which are non-protein molecules to function correctly.
Competitive Inhibition: The active site is blocked.
Non-Competitive Inhibitors: Something binds to the allosteric site
Allosteric Inhibitors: An allosteric inhibitor is something that binds to the allosteric site on the enzyme, making the enzyme useless for the time being. This can happen via Feedback Inhibition.
What is Fermentation/Aerobic Cellular Respiration?
Fermentation is when oxygen is absent. Fermentation occurs when there is a build up of pyruvate; it continues to produce ATP and NADPH. Aerobic Cellular Respiration is when oxygen is present; in this case, Glycolysis. The goal of Glycolysis is to make ATP, not Pyruvate.
What is Cytokinesis and how is it different in Plants and Animals?
Cytokinesis is the separation of the cytoplasm and divides the cell. In Plants, this is done by building a Cell Plate right down the middle of the cell; in Animals, it is done by Cleavage Furrow, which looks like a string being pulled around the center of a balloon until is pinches off into two smaller balloons.
Compare/Contract Mitosis to Meiosis:
Mitosis conserves the number of chromosome sets, producing cells that are genetically identical to the parent cell while Meiosis reduces the number of chromosome sets from two (diploid) to one (haploid), producing cells that differ genetically from each other and from the parent cell.
Three events are unique to Meiosis, and all three occur in Meiosis I: Crossing over in Prophase I (when homologous chromosomes physically connect and exchange genetic information), At the Metaphase Plate, there are paired homologous chromosomes (also called Tetrads) instead of individual replicated chromosomes, and in Anaphase I, it is homologous chromosomes instead of sister chromatids that separate.
The mechanism for separating sister chromatids is virtually identical in Meiosis II and Mitosis.
What are the Four Ways to Attain Genetic Variation?
Crossing Over (In Prophase I), Random Fertilization (Sperm meeting Egg), Independent Assortment (During Metaphase I; Each chromosome will assort independently of all other chromosomes into its respective sex cell), and Mutation (the ULTIMATE source of Genetic Variation).
Popularity: 6% [?]
