Exam 1 study guide Flashcards
The scientific method steps
observations, hypothesis formation, experimentation, data analysis, conclusion
non-polar covalent bonds
atoms with similar electronegativities. Electrons shared equally
-covalent bonds are the strongest bc the atoms thing that the electron shared is theirs so they work hard to keep it
polar covalent bonds
atoms with different electronegativities, pos and neg. Shared unequally Ex:water
Electronegativity – what is it? Why is it significant? How does it relate to bond formation?
Def: ability of nucleus to attract electrons
Electronegativity is significant because
-It explains the stability of chemical compounds.
-It predicts the type of bond (covalent or ionic)
-It makes bonding between atoms possible
Ionic bonds
Ionic bond: is an attraction of positive and negative: definition for test
Electrons transferred, forming ions that are attracted to each other
-positive ion being attracted to negative ion
-ions are atom or molecule with charge
-Cation: pos charge, lost electrons
-Anion: neg charge, gained electrons
-Ionic bond: cation binds to an anion like i said pos being attracted to neg
Hydrogen bonds
Hydrogen bonds:
Electropositive hydrogen from one polar molecule is attracted to an electronegative atom
-water molecules form multiple hydrogen bonds with each other
van der Waals interactions
Van der Waals forces are weak intermolecular forces that are dependent on the distance between atoms or molecules. These forces arise from the interactions between uncharged atoms/molecules.
For example, Van der Waals forces can arise from the fluctuation in the polarizations of two particles that are close to each other.
4 “big picture” properties of water
high specific heat, hydrogen bonding alters the state of water, (cohesion, adhesion, surface tension), -ions and polar molecules dissolve readily in water, hydrophilic, hydrophobic interactions
Cohesion/adhesion
cohesion: (kindergarteners hold each others hands) water molecules are attracted to other water molecules and stick together via hydrogen bonding.
Adhesion: (kindergarteners holding teachers hand) water molecules are attracted to something that is not water (other polar molecules) and stick via hydrogen bonding
surface tension
Surface tension: measure of attraction between molecules at the surface of a liquid (LEARN MORE)
Moderation of temperature by water
Water moderates temperature in the following ways:
Water has a high specific heat, meaning it can absorb a lot of heat before its temperature rises.
Liquid water at the surface takes longer to heat up and cool down compared to air, helping to stabilize temperature.
Coastal areas near bodies of water have more moderate temperatures due to water’s high heat capacity.
Expansion upon freezing
Water expands upon freezing due to the following reasons:
Molecules set themselves in a very open arrangement that contains more space than the water in the liquid state.
Bodies of water freeze on the top first due to the maximum density of water at about 4°C.
Hydration shell
When the solvent is water, it is called a hydration shell or hydration sphere. The hydration shell represents water’s attraction or adhesion to a substance, and the greater the attraction, the greater the number of water molecules involved in the hydration shell.
hydrophobic vs hydrophilic
Hydrophilic: water loving, things that can dissolve in water, often have a charge like polar or ionic. Hydrophobic: water fearing, do not like water, nonpolar, no charge. Amphipathic have hydrophilic and hydrophobic regions, they form micelles when placed into water
Define acid/base and understand the pH scale and what it means in terms of H+ content
As Acidity goes up, pH goes down, H+ donor
Base (akline) when put in water the pH goes higher, H+ acceptors
The term “base” in pH refers to:
A substance that accepts hydrogen ions.
When dissolved in water, it results in a solution with more hydroxide ions than hydrogen ions, making it alkaline.
On the pH scale, values greater than 7 are considered basic.
Buffers- what they do and the example of the buffer system in blood
Buffers: pair of substances that minimize Ph fluctuations in the fluids of living organisms
Most buffers consist of a weak acid and a weak base. They help maintain a given pH even after the addition of an acid or a base. For example, blood contains a carbonic acid (H 2 CO 3)-bicarbonate (HCO 3-) buffer system. In this system, the weak acid dissociates to a small extent, giving bicarbonate ions
Dehydration synthesis & hydrolysis reactions
Hydrolysis reactions: a chemical reaction that breaks apart molecules using water
Dehydration reaction or dehydration synthesis reaction is a chemical reaction in which two molecules join together via a covalent bond, with the removal of a water molecule. . A dehydration reaction is a specific type of condensation reaction and synthesis reaction.
functional groups examples
carboxyl: carbon atom double-bonded to an oxygen atom and single-bonded to a hydroxyl group (–OH), giving it the formula R-COOH where “R” represents the rest of the molecule
hydroxyl: hydroxyl group (―OH), in chemistry, a functional group with one hydrogen and one oxygen atom.
Carbohydrates
Carbohydrates: sugars, usually long chains
-composed of C,H, and O atoms (carbon with water)
Monosaccharides
Monosaccharides: simplest sugar
e.g. glucose, fructose, ribose
Disaccharides
Carbohydrates composed of 2 monosaccharides
e.g. sucrose
Polysaccharides
many monosaccharides
e.g. glycogen, starch, cellulose, chitin
Lipids: know the 3 classes of lipids
(fats, phospholipids, steroids)
Unsaturated fatty acids
-describe bonding
Unsaturated fatty acids: 2 or more carbons in the fatty acid contain a double bond, each double bond forms a kink, forms a tail, lower melting point, liquid at room temp like oils, found in plants
Saturated fatty acids
-describe bonding
Saturated fatty acids: all single linked carbon covalent bonds, carbons are filled with hydrogen, No double bonds, flat straight structure, higher melting point, solid at room temp, found in animals
ex:butter
Proteins – overall functions of proteins
support muscle contraction, digest enzymes, hormones, DNA
Structure of a general amino acid
A central carbon atom is bound to an amino group. carboxyl group, side chain, and a hydrogen atom
peptide bonds
The covalent bond that forms between the carboxyl group of 1 amino acid is called a peptide bond
Four levels of protein structure
Primary, secondary, tertiary, and quaternary
Determinants of protein structure
Primary: the linear sequence of its polypeptide
secondary: consists of spirals (a-helix) and sheets (B-pleated), created by hydrogen bonding in peptide backbone
Tertiary: Polypeptide fold and reforms upon itself to assume a 3-dimensional shape
Quaternary: the association of 2 or mire polypeptides to form a protein
What is standard deviation?
the dispersion of values from the average or mean, how spread out the data is, larger standard deviation means data is more spread out, lower is data is more clustered around mean
Null hypothesis definition
Explain when you would use a null hypothesis
Null hypothesis: proposes that NO statistical significance exists among a given set of observations ex: fertilizer does no affect plant growth
-null = no difference
It is useful because it can be tested and found to be false, which implies a relationship between the observed data3.
T-test definition
Understand when to use a t-test
tells us how true the calculated mean and standard deviation from the experiment are according to the population (does data from sample go to the whole population)
-To do a T-test you need the mean, standard deviation and N (sample number for each group)
Comparing the means of two groups (pairwise comparison).
Wanting to determine if differences in means could have happened by chance.
Be able to interpret the meaning of a p-value and how it relates to a null
hypothesis
P-value: how valid are my results, p value should be LESS than 0.05 to be valid, it means that you are 95% positive that the two groups are statistically different, means if you repeated the experiment you would be likely to get the same results
Statistically significant: if experiment was repeated would you get the same result
The null hypothesis (H0) states no relationship exists between the two variables being studied.
The p-value indicates how believable the null hypothesis is, given the sample data.
Discovery based science
Collection and analysis of data without the need for a preconceived hypothesis, goal is to gather more info. Ex: test drugs to look for action against a disease
How much difference in electronegativity between 2 elements for it to be considered polar?
If the difference in electronegativity is greater than 1.8, the bond is ionic.
If the difference in electronegativity is between 0.4 and 1.8, the bond is polar covalent.
When the difference is very small or zero, the bond is covalent and nonpolar
Monounsaturated
1 C=C
Polyunsaturated
multiple double bonds?
Protein composition
Carbon. hydrogen, nitrogen, oxygen and small amounts of other elements like sulfur
Phospholipid function
Membrane formation
Triglycerides function
Energy storage
Steroid ring structure function
Hormone production
Waxes functions
Water storage
What type of fat is trans fat?
Trans fats are synthetic unsaturated fats
Saturated fats - plants or animals?
Animals
Unsaturated fats - plants or animals?
plants
Polypeptides
linear strings of amino acids
3 categories that amino acids go into:
nonpolar hydrophobic: does not want to interact with polarity of water (look for H and CH like hydrocarbons, that tells you that it is hydrophobic and nonpolar.)
Polar (uncharged) hydrophilic: look for NH or OH in the blue side chains bc that tells u its in this group
Polar (Charged) hydrophilic: look for physical charge in side chain either acidic or basic
Hydrolysis
taking water and breaking it apart, breaking bonds
Dehydration synthesis:
Allow connect monomers to make polymers: dehydration reaction
-dehydration reaction produces water
-taked 1 hydroxyl and 1 hydrogen to make water
Primary structure of protein
string of amino acids, peptide bonds hold these together, determined by genes(DNA)
Tertiary structure of protein
3D shape of a SINGLE polypeptide, gives overall shape, determined by interactions among various side chains (R groups)
Secondary structure of protein
consists of spirals (a-helix) and sheets (B-pleated), created by hydrogen bonding in peptide backbone
Quaternary structure of protein
present if protein has interactions between multiple polypeptide chains
ex: hemoglobin has quaternary structure: has 4 subunits: 2 alpha, 2 beta
5 factors critical for protein folding and stability:
Hydrogen bonds: contributes to A helix, and B sheets
Ionic bonds and other polar interactions: ionic interacting with other partially charged things
Hydrophobic effect: Carbonhydrogens are hydrophobic so the nonpolar side chains hide in the middle of a protein
Van der Waals dispersion forces: you have your molecules that if they are in a specific distance of each other they will be attracted to each other for a bit
Disulfide bridges: a covalent bond forms between 2 cysteine side chains and is very strong
What causes protein denaturation?
Changes in protein’s pH, temp, ionic concentration
What are the two classes of nucleic acids?
Deoxyribonucleic acid (DNA) and Ribonucleic acid (RNA)
What are the 3 components of a nucleotide?
Phosphate group, pentose sugar (Ribose or deoxyribose), and a base
What are the 4 nitrogenous bases present in DNA?
Adenine, guanine, thymine, cytosine
In DNA molecules what 2 are being paired?
Adenine and thymine
Guanine and cytosine
