Midterm 1 Scientific Method, Chemistry of Life, Carbohydrates, Proteins, Nucleic Acids, Lipids

Flashcards covering key vocabulary from the lecture notes on the Scientific Method, Chemistry of Life, Carbohydrates, Proteins, Nucleic Acids, and Lipids.

Characteristics of Living Things

Being composed of cells, replicating/reproducing, containing/processing/responding to information, acquiring and using energy, and evolution.

Scientific Knowledge

Based on evidence, meaning previous ideas can be thrown out or changed due to new evidence.

Scientific Theories

Much more supported by evidence than hypotheses, broader in scope, testable, falsifiable, and offer an explanation of a phenomenon (unlike laws).

Scientific Laws

Show cause and effect relationships but do not offer an explanation of a phenomenon.

Scientific Method

A constant cycle of observation, hypothesis, prediction, testing, and making conclusions.

Hypotheses

Testable and falsifiable, tentative explanations of observations, generally written in present tense.

Predictions

Outline how to test a hypothesis, including independent and dependent variables, generally in future tense with more specifics than hypotheses.

Peer Review

The process scientific studies undergo before being published.

Control Group

A group in an experimental design used for comparison against the treatment group, helping to control for confounding variables.

Placebo

A substance or treatment resembling the real treatment but lacking an active ingredient, used in blind experiments.

Blind Experiment

An experimental design where the experimental subject does not know whether they are receiving the placebo or actual treatment.

Double-Blind Experiment

The best experimental design where neither the person administering the treatment nor the experimental subject knows whether a placebo or actual treatment was given.

Experimental Studies

Studies in which a variable is manipulated by the scientist, tending to yield stronger evidence than observational studies.

Observational Studies

Studies where variables are not manipulated by the scientist, conducted for various reasons despite yielding weaker evidence than experimental studies.

Sample Size

The number of individuals measured in a study; a higher sample size increases confidence in the results.

Statistics

Tools that help determine how confident that the results of a study are meaningful or real.

Confounding Variables

Anything that may affect an experiment other than the independent variable being manipulated.

Nonpolar Covalent Bonds

Chemical bonds characterized by equal sharing of electrons between atoms.

Polar Covalent Bonds

Chemical bonds characterized by unequal sharing of electrons between atoms.

Ionic Bonds

Chemical bonds characterized by a complete transfer of electrons between atoms.

Ion

An atom that has lost or gained one or more electrons, giving it a net electrical charge.

Electronegativity

A measure of the tendency of an atom to attract a bonding pair of electrons, used to predict molecular polarity.

Bond Strength in Biological Systems

Covalent bonds are strongest, followed by ionic bonds, and hydrogen bonds are very weak.

Water (Solvent)

The most common solvent in biological systems, polar and forms hydrogen bonds.

Hydrogen Bonding

An attraction between a partially charged hydrogen atom and another partially charged atom (usually oxygen or nitrogen) within or between polar molecules.

Hydrophilic Molecules

Polar molecules and ions that dissolve easily in water.

Hydrophobic Molecules

Nonpolar molecules that do not dissolve easily in water.

Organic Molecules

Carbon-based molecules generally having a carbon skeleton modified by different functional groups.

Functional Groups

Specific groupings of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules, affecting their behavior and function.

pH

A measure of acidity, essentially the concentration of H+/hydrogen ions/protons; inversely related to acidity on a logarithmic scale.

Energy Storage in Bonds

Nonpolar bonds (like C-C and C-H) usually store more energy than polar bonds (like C-O).

Macromolecules

Large molecules that often consist of several smaller subunits called monomers bound together.

Monomers

Smaller subunits that are covalently bound together to form larger macromolecules.

Carbohydrates

Macromolecules consisting mostly of C, H, and O, usually in a 1:2:1 ratio, often indicated by the '-ose' suffix, used for energy storage and structure.

Monosaccharides

The monomers of carbohydrates; all carbohydrates are made of one or more monosaccharides (e.g., glucose, fructose, galactose).

Glycosidic Linkages

Covalent bonds that link monosaccharides together to form larger carbohydrate molecules.

Disaccharides

Carbohydrates that consist of two monosaccharides linked together (e.g., sucrose, lactose).

Polysaccharides

Many monosaccharides covalently linked together, used for energy storage or structural support.

Starch

A polysaccharide consisting of linked α-glucose molecules, used by plants for energy storage, less branched than glycogen.

Glycogen

A polysaccharide consisting of linked α-glucose molecules, used by animals for energy storage, more branched than starch, leading to faster digestion.

Cellulose

A structural polysaccharide in plants, composed of β-glucose molecules, forming linear parallel strands linked by hydrogen bonds, and indigestible by humans.

Chitin

A structural polysaccharide found in fungi and insect exoskeletons.

Peptidoglycan

A structural polysaccharide found in bacterial cell walls.

Proteins

Macromolecules composed of amino acids (monomers), performing a wide variety of functions including structure, defense, signaling, movement, and transport.

Amino Acids

The monomers of proteins, characterized by a central carbon atom bonded to an H, an amino group (NH2), a carboxyl group (COOH), and an R group/side chain.

R Group (Side Chain)

The unique part of an amino acid that differentiates it from others and gives it specific properties (e.g., acidic, basic, polar, nonpolar).

Primary Protein Structure

The linear sequence of amino acids connected by strong, inflexible peptide bonds.

Peptide Bonds

Covalent bonds connecting the carboxyl group of one amino acid to the amino group of the next, forming the primary structure of proteins.

Secondary Protein Structure

Local folding patterns (e.g., alpha-helices, beta-pleated sheets) due to hydrogen bonding between the amino and carboxyl groups of nearby amino acids.

Tertiary Protein Structure

The overall three-dimensional shape of a single polypeptide chain, resulting from interactions between R groups/side chains and between side chains and the amino acid 'backbone'.

Quaternary Protein Structure

The arrangement of multiple polypeptide chains (subunits) in a protein complex.

Protein Function

Determined by the specific amino acid sequence, which dictates the protein's three-dimensional shape.

Denaturing (Protein)

The disruption of a protein's three-dimensional structure (mostly weaker bonds) due to factors like high temperature or changes in chemical environment, without breaking the primary sequence.

Enzymes

Proteins that act as biological catalysts, speeding up specific chemical reactions without being consumed in the process.

Active Site

A specific region on an enzyme with a distinctive shape, size, and chemical properties that allows it to interact only with specific substrates for catalysis.

Essential Amino Acids

Amino acids that cannot be produced by the human body and must be consumed in food to make all necessary proteins.

Nucleic Acids

Macromolecules like DNA and RNA, composed of nucleotide monomers, crucial for storing and transmitting genetic information.

Nucleotides

The monomers of nucleic acids, consisting of a phosphate group, a 5-carbon sugar, and a nitrogenous base.

Deoxyribose

The 5-carbon sugar found in DNA, containing one less oxygen atom than ribose.

Ribose

The 5-carbon sugar found in RNA.

Nitrogenous Bases

Components of nucleotides including adenine (A), guanine (G), cytosine (C), thymine (T - found in DNA), and uracil (U - found in RNA).

Activated Nucleotides

Nucleotides made more reactive by the addition of extra phosphate groups.

ATP (Adenosine Triphosphate)

An activated nucleotide that serves as the most commonly used direct source of energy for cells.

Phosphodiester Linkages

Covalent bonds that connect nucleotides to form nucleic acid strands.

DNA (Deoxyribonucleic Acid)

A nucleic acid that stores genetic information, composed of nucleotides A, C, T, and G, forming a stable double helix of two antiparallel strands.

Base Pairing

The specific bonding of nitrogenous bases in nucleic acids: C with G (forming 3 hydrogen bonds), and A with T (in DNA) or U (in RNA) (forming 2 hydrogen bonds).

RNA (Ribonucleic Acid)

A nucleic acid with a wide variety of uses, including acting as an intermediate between DNA and protein synthesis, usually single-stranded and less stable than DNA.

Ribozyme

An RNA molecule that can act as a catalyst, similar to an enzyme.

Lipids

Macromolecules characterized by not dissolving well in water, lacking common monomers, and including triglycerides, steroids, and phospholipids.

Triglycerides (Fats)

Extremely non-polar lipids used as long-term energy storage, composed of a glycerol molecule with three fatty acids.

Saturated Fatty Acids

Fatty acids that have no double bonds, usually solid at room temperature due to their straight structure, found often in animal-based foods.

Unsaturated Fatty Acids

Fatty acids that have double bonds, usually liquid at room temperature due to the kinks formed by the double bonds, found often in vegetable and fish oils.

Trans Fatty Acids

Fatty acids with double bonds that do not form kinks, making them solid at room temperature, unnatural, hard to digest, and found in highly-processed foods.

Steroids

Lipids composed of four linked carbon/hydrogen rings.

Cholesterol

The most common steroid, a component of cell membranes and used to make steroid hormones.

Amphipathic Molecules

Molecules that have distinct polar/hydrophilic and non-polar/hydrophobic regions, naturally forming membranes.

Phospholipids

Amphipathic lipids composed of a glycerol, two fatty acids, and a head group that includes a phosphate, forming lipid bilayers.

Lipid Bilayers

A selectively permeable membrane formed by phospholipids, only allowing certain molecules to cross easily (small and non-polar).

Membrane Fluidity/Permeability

Properties of lipid bilayers affected by the proportion of unsaturated fatty acids (more unsaturated = more fluid/permeable) and temperature (increased temperature = increased fluidity/permeability).