General Biology & Chemistry Review

Comprehensive practice flashcards covering macromolecules, basic chemistry, properties of water, scientific method, metric system conversions, cell history, cell theory, and biological organization based on course lecture notes.

What four classes of large biological molecules make up all living things?

Carbohydrates, lipids, proteins, and nucleic acids.

What is the difference between a polymer and a monomer?

A polymer is a long molecule consisting of many similar building blocks called monomers, which serve as repeating units.

How do dehydration reactions and hydrolysis reactions differ in polymer synthesis and breakdown?

A dehydration reaction synthesizes polymers by joining two monomers through the loss of a water molecule ($H_2O$), whereas hydrolysis breaks down polymers into monomers by adding a water molecule.

What is the general chemical formula for monosaccharides, and what is the formula of glucose?

Monosaccharides have formulas that are usually multiples of $CH_2O$. Glucose has the formula $C_6H_{12}O_6$ and is the most common monosaccharide.

What type of covalent bond joins two monosaccharides to form a disaccharide, such as in maltose or sucrose?

A glycosidic linkage, formed via a dehydration reaction.

How do starch and glycogen differ in their cellular storage roles and structure?

Starch is a glucose storage polysaccharide in plants stored in plastids (its simplest form is unbranched amylose), while glycogen is a highly branched glucose storage polysaccharide in animals stored mainly in liver and muscle cells.

What structural difference distinguishes starch from cellulose?

Both are glucose polymers, but starch uses $\alpha$ glucose ring forms forming helical linkages, whereas cellulose uses $\beta$ glucose ring forms forming straight, unbranched chains linked into microfibrils by hydrogen bonds.

Where is the structural polysaccharide chitin found in nature?

Chitin is found in the exoskeletons of arthropods and provides structural support for the cell walls of many fungi.

Why are lipids hydrophobic, and what are the three most biologically important types of lipids?

Lipids consist mostly of hydrocarbons that form nonpolar covalent bonds, causing them to mix poorly with water. The three most biologically important types are fats, phospholipids, and steroids.

What chemical components form a triacylglycerol (fat) molecule, and what bond links them?

A fat molecule consists of one glycerol joined to three fatty acids by ester linkages.

What is the structural difference between saturated and unsaturated fatty acids?

Saturated fatty acids have no double bonds between carbon atoms and hold the maximum number of hydrogen atoms, whereas unsaturated fatty acids have one or more double bonds (typically cis double bonds, causing bending).

What is the structural composition of a phospholipid, and how does it behave in water?

A phospholipid consists of two fatty acid tails (hydrophobic) and a phosphate group with attachments (hydrophilic head) attached to glycerol; in water, they self-assemble into a bilayer with heads facing outward and tails facing inward.

What characterizes the structure of a steroid, and what role does cholesterol play?

Steroids have a carbon skeleton consisting of four fused rings. Cholesterol is a component of animal cell membranes and serves as a precursor from which other steroids are synthesized.

What are the monomers of proteins, and what covalent bonds link them into polypeptides?

The monomers are amino acids (20 different types characterized by unique R group side chains), which are linked by covalent peptide bonds.

What characterizes the four levels of protein structure?

Primary structure is the unique linear sequence of amino acids; Secondary structure consists of coils ($\alpha$ helix) and folds ($\beta$ pleated sheet) in the backbone; Tertiary structure is the overall 3D shape from R group interactions; Quaternary structure arises when two or more polypeptide chains form one functional protein.

What is denaturation, and what environmental factors can cause it?

Denaturation is the loss of a protein's native three-dimensional structure (rendering it biologically inactive) caused by alterations in pH, salt concentration, temperature, or other environmental factors.

What is the central dogma of gene expression in eukaryotic cells?

Genetic information flows from DNA to RNA to protein ($\text{DNA} \rightarrow \text{RNA} \rightarrow \text{protein}$), where DNA directs synthesis of mRNA in the nucleus, and mRNA moves to the cytoplasm to direct polypeptide assembly at a ribosome.

What are the three chemical components of a nucleotide?

A nitrogenous base, a pentose sugar (deoxyribose in DNA, ribose in RNA), and a phosphate group. (A nucleoside consists of only the nitrogenous base and the sugar).

How do pyrimidines and purines differ, and which nitrogenous bases belong to each family?

Pyrimidines have a single six-membered ring and include cytosine (C), thymine (T, in DNA), and uracil (U, in RNA). Purines have a six-membered ring fused to a five-membered ring and include adenine (A) and guanine (G).

What structural features distinguish DNA from RNA?

DNA is a double helix with antiparallel strands ($5' \rightarrow 3'$), uses deoxyribose sugar, and pairs A with T and G with C. RNA is typically single-stranded, uses ribose sugar, and pairs A with U instead of T.

Which four elements make up 96% of living matter?

Carbon (C), hydrogen (H), oxygen (O), and nitrogen (N).

How do atomic number, mass number, and atomic mass differ?

Atomic number is the number of protons in an element's nucleus. Mass number is the sum of protons plus neutrons in the nucleus. Atomic mass is the total mass of an atom, approximated by its mass number.

What are isotopes, and what defines a radioactive isotope?

Isotopes are two atoms of an element that have the same number of protons but differ in their number of neutrons. Radioactive isotopes decay spontaneously, giving off particles and energy.

What determines the chemical behavior of an atom?

The distribution of electrons in its electron shells, particularly the valence electrons in the outermost (valence) shell. Elements with full valence shells are chemically inert.

How do nonpolar covalent bonds and polar covalent bonds differ?

In a nonpolar covalent bond, atoms share electrons equally. In a polar covalent bond, one atom is more electronegative and pulls shared electrons more strongly, creating partial positive ($\delta^+$) and partial negative ($\delta^-$) charges.

How does an ionic bond form, and what are cations and anions?

An ionic bond forms when an atom strips electrons from its bonding partner, creating oppositely charged ions that attract each other. A cation is a positively charged ion, and an anion is a negatively charged ion.

What is a hydrogen bond?

A weak bond formed when a hydrogen atom covalently bonded to one electronegative atom (usually oxygen or nitrogen in living cells) is also attracted to another electronegative atom.

What are the four emergent properties of water that contribute to Earth's suitability for life?

Cohesive behavior, ability to moderate temperature, expansion upon freezing, and versatility as a solvent.

What is the difference between cohesion and adhesion in water?

Cohesion is hydrogen bonding holding water molecules together (helping transport water against gravity in plants), whereas adhesion is the attraction between water and different substances, such as plant cell walls.

Why does ice float on liquid water, and at what temperature does water reach its greatest density?

Ice floats because stable hydrogen bonds keep molecules further apart in a crystal lattice, making ice less dense than liquid water. Water reaches its greatest density at $4\,^\circ\text{C}$.

What is a hydration shell?

A sphere of water molecules that surrounds each ion when an ionic compound dissolves in water.

How are acids, bases, and pH defined?

An acid increases the $H^+$ concentration ($pH < 7$), a base reduces $H^+$ / increases $OH^-$ ($pH > 7$), and pure water has equal $[H^+]$ and $[OH^-]$ ($pH = 7$).

What is the function of a biological buffer?

Buffers minimize changes in concentrations of $H^+$ and $OH^-$ in a solution to keep internal cell pH near 7, typically consisting of a weak acid and its corresponding base.

What is the difference between qualitative data and quantitative data?

Qualitative data is descriptive, whereas quantitative data includes numerical measurements.

How do inductive reasoning and deductive reasoning differ?

Inductive reasoning derived generalizations from collecting and analyzing a large number of specific observations, whereas deductive reasoning flows from general premises to predicted and specific results.

What are the roles of independent, dependent, and controlled variables in an experiment?

The independent variable is manipulated or changed by the experimenter; the dependent variable is measured to test the effect; controlled variables are held constant by the researcher.

In scientific investigations, what is the difference between an experimental group and a control group?

The experimental group receives the treatment that the researcher wishes to study, while the control group does not receive the treatment.

What are the base units for length, mass, volume, temperature, and time in the metric system?

Meter ($m$) for length, gram ($g$) for weight/mass, liter ($L$) for volume, degrees Celsius ($^\circ\text{C}$) for temperature, and second ($s$) for time.

What mnemonic is used to remember metric prefixes, and what factors do those prefixes represent?

"Kids Have Dropped Over Dead Converting Metrics" stands for kilo- ($1000\times$), hecto- ($100\times$), deka- ($10\times$), Base ($1\times$), deci- ($\frac{1}{10}$), centi- ($\frac{1}{100}$), and milli- ($\frac{1}{1000}$).

What were the main contributions of Robert Hooke and Anton von Leeuwenhoek to cell biology?

Robert Hooke examined cork under a compound microscope in the 1600s, coined the term "cells", and published Micrographia in 1665. Anton von Leeuwenhoek built simple microscopes, observed living organisms in pond water and teeth scrapings, and described chloroplasts.

Who formulated the three tenets of Cell Theory, and what are those tenets?

Matthias Schleiden (1838) and Theodor Schwann (1839) proposed the first two tenets: 1) All organisms are made of cells, and 2) The cell is the structural unit of life. Rudolf Virchow (1855) added the third tenet: 3) Cells can arise only by division from a preexisting cell.

What significant discoveries were made by Friedrich Wöhler and the Buchner brothers regarding cell chemistry?

Friedrich Wöhler (1828) was the first to synthesize an organic compound (urea) from inorganic compounds. Eduard and Hans Buchner (1897) discovered that enzymes in yeast cell extracts cause fermentation without living cells.

Which scientists provided the key evidence proving that DNA, and not protein, is the genetic material?

Frederick Griffith (1927) discovered the transforming principle; Oswald Avery, Colin MacLeod, and Maclyn McCarty (1944) demonstrated DNA carries genetic information; and Alfred Hershey and Martha Chase (1952) provided final proof using radioactive isotopes.

What are the seven fundamental properties shared by all living organisms?

Order, reproduction, growth and development, energy processing, response to the environment, regulation, and evolutionary adaptation.

What is the hierarchy of biological organization from largest to smallest level?

Biosphere $\rightarrow$ Ecosystem $\rightarrow$ Community $\rightarrow$ Population $\rightarrow$ Organism $\rightarrow$ Organ system $\rightarrow$ Organ $\rightarrow$ Tissue $\rightarrow$ Cell $\rightarrow$ Organelle $\rightarrow$ Molecule.

At what level of biological organization do the properties of life emerge, and at what level does evolution occur?

Life's properties emerge at the cell level (the lowest level meeting all life properties). Evolution occurs at the population level (the lowest level where evolution takes place).

What structural features are shared by all cells, and how do prokaryotic and eukaryotic cells differ?

All cells are enclosed by a plasma membrane, use DNA as genetic information, and contain ribosomes. Prokaryotic cells (Bacteria and Archaea) are smaller, simpler, and lack a membrane-enclosed nucleus or organelles. Eukaryotic cells are larger, more complex, and contain membrane-enclosed organelles including a nucleus.