Biology Lecture Review: Microscopy, Cells, Chemistry, Energy, Macromolecules, DNA, Transcription, Gene Expression, and Recombinant DNA

Vocabulary flashcards covering topics from Microscopy and Cells to Recombinant DNA Technologies, including chemistry of life, energy use, biological macromolecules, DNA structure and replication, gene expression, and biotechnological applications and ethics.

Optical Resolution of the Human Eye

Approximately 200 microns.

Eukaryotic Cells

Cells ranging in size from 1 micron to 1 cm.

Human Cells

Cells typically ranging in size from 10 to 100 microns.

Organelles

Components of cells such as the nucleus, cytoplasm, mitochondria, ribosomes, endoplasmic reticulum, cytoskeleton, and plasma membrane.

Chemical Symbol

An abbreviation for a chemical element (e.g., C for Carbon).

Atomic Mass

The total number of protons and neutrons in an atom's nucleus.

Atomic Number

The number of protons in an atom's nucleus.

Valence Electrons

Electrons in the outermost shell of an atom that determine its bonding abilities.

Bond Strength

The energy required to break a chemical bond. Single bonds are weaker than double, which are weaker than triple bonds, with an inverse relationship to bond length.

Polar Bond

A covalent bond where electrons are shared unequally between atoms.

Hydrogen Bonds

A type of intermolecular bond resulting from the unequal sharing of electrons in water, or with highly electronegative atoms like Nitrogen and Fluorine.

Hydrophobia

The property of "water hating," characteristic of nonpolar substances.

Hydrophilia

The property of "water loving," characteristic of polar substances.

Cell Membrane

The part of the cell where hydrophobic and hydrophilic interactions are most evident. Its thickness can matter for insulation, like in the myelin sheath.

Myelin Sheath

An insulating layer around axons, formed by cell membranes, that facilitates the conduction of action potentials.

Van der Waals Forces

Weak attractive forces between atoms and molecules that arise from temporary fluctuations in electron distribution, causing transient polarization.

pH

A measure of the concentration of H+ ions in a solution, calculated as -log10([H+/1M]).

Acid

A substance that releases H+ ions into a solution.

Base

A substance that accepts H+ ions from a solution.

Physiological pH

The tightly controlled pH range within living organisms, essential for homeostasis (e.g., blood pH is 7.4).

First Law of Thermodynamics

A principle stating that energy cannot be created or destroyed, only transformed from one form to another.

Second Law of Thermodynamics

A principle stating that for any spontaneous process in an isolated system, the total entropy (disorder) increases.

Entropy

A measure of the degree of disorder or randomness in a system.

Anabolic Reactions

Reactions that consume energy to synthesize larger molecules from smaller ones, generally increasing order and decreasing energy within the molecules.

Catabolic Reactions

Reactions that release energy by breaking down larger molecules into smaller ones, generally decreasing order and increasing entropy within the molecules.

ATP (Adenosine Triphosphate)

The primary energy currency of the cell; energy is released upon removal of a phosphate group via hydrolysis, and energy is required for its addition.

Glycolysis

An anaerobic metabolic pathway that occurs in the cytoplasm, consuming glucose and 2 ATP to produce pyruvate, 4 new ATP, and 2 new NADH.

Pyruvate Oxidation

An aerobic metabolic process occurring in the mitochondrial matrix, converting pyruvate into acetyl CoA, CO2, and NADH.

Citric Acid Cycle (Krebs Cycle)

A metabolic pathway that occurs in the mitochondrial matrix, taking acetyl CoA as input, producing electron carriers (NADH, FADH2), some GTP/ATP, and CO2, and does not directly require O2.

Oxidative Phosphorylation/Chemiosmosis

An aerobic process in the mitochondria where NADH and FADH2 fuel a series of redox reactions to pump protons, creating an electrochemical gradient used by ATP synthase to produce ATP.

Biological Macromolecules

Large molecules composed of smaller repeating building blocks (monomers).

Monomer

A single, repeating molecular unit that can be linked to form a polymer.

Polymer

A large molecule (macromolecule) composed of many repeating monomer units.

Condensation Reaction (Dehydration Synthesis)

A reaction where two molecules are joined by a covalent bond with the removal of a water molecule, typically an anabolic process.

Hydrolysis

A reaction where a covalent bond is broken by the addition of a water molecule, typically a catabolic process.

Carbohydrates

Biological macromolecules including monosaccharides, disaccharides, oligosaccharides, and polysaccharides, primarily used for energy and structural support.

Monosaccharide

A single sugar monomer, the simplest form of carbohydrate.

Disaccharide

Two sugar monomers linked by a glycosidic bond.

Oligosaccharide

Short-chain sugars (e.g., fructose, galactose).

Polysaccharide

Long chains of sugar monomers (e.g., starch, glycogen, cellulose, chitin).

Glycosidic Bond

A covalent bond formed by dehydration synthesis that links sugar units in carbohydrates.

Lipids

A diverse group of biological macromolecules, including fatty acids, triglycerides, phospholipids, and steroids, characterized by their insolubility in water.

Fatty Acids

Long hydrocarbon chains that are a component of many lipids, classified as saturated (straight, solid) or unsaturated (kinked, liquid).

Triglyceride

A lipid composed of a glycerol molecule and three fatty acids, primarily used for energy storage.

Phospholipid

A lipid composed of a glycerol, two fatty acids, and a phosphate group, crucial for forming cell membranes.

Steroid

A lipid characterized by four fused carbon rings (e.g., cholesterol, testosterone, estradiol).

Proteins

Biological macromolecules composed of amino acids linked by peptide bonds, performing diverse functions in the cell.

Amino Acids

The 20 types of building blocks that make up proteins, each characterized by a unique R group.

Peptide Bond

A covalent bond formed between two amino acids via dehydration synthesis.

Polypeptide

A long chain of amino acids linked by peptide bonds.

Denaturation

The loss of a protein's specific three-dimensional shape and function, often caused by changes in temperature or pH.

Primary Protein Structure

The unique linear sequence of amino acids in a polypeptide chain.

Secondary Protein Structure

Localized folding patterns of a polypeptide chain, such as alpha-helices or beta-sheets, formed by hydrogen bonding of the peptide backbone.

Tertiary Protein Structure

The overall three-dimensional folding pattern of a single polypeptide chain, resulting from interactions between side chains (R groups).

Quaternary Protein Structure

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

Chaperones (Proteins)

Proteins that assist in the proper folding of other proteins.

Enzymes

Protein catalysts that speed up biochemical reactions.

Hormones (Proteins)

Protein or steroid signaling molecules that regulate physiological processes.

Structural Proteins

Proteins that provide shape and support to cells and tissues.

Transport Proteins

Proteins that shuttle other molecules across membranes or throughout the body.

Nucleic Acids

Biological macromolecules (DNA and RNA) that carry genetic information.

Nucleoside

A molecule composed of a nitrogenous base covalently linked to a sugar (ribose or deoxyribose), without a phosphate group.

Nucleotide

The monomer unit of nucleic acids, consisting of a nitrogenous base, a sugar (ribose or deoxyribose), and one or more phosphate groups.

Ribose

The sugar component of RNA nucleotides.

Deoxyribose

The sugar component of DNA nucleotides, lacking an oxygen atom on the 2' carbon.

Phosphodiester Linkage

A covalent bond that links nucleotides together to form polynucleotide chains in DNA and RNA.

DNA (Deoxyribonucleic Acid)

A double-helix polynucleotide chain containing deoxyribose sugar, bases A, T, C, G; stores hereditary information.

RNA (Ribonucleic Acid)

A single-stranded polynucleotide chain containing ribose sugar; includes mRNA, rRNA, tRNA.

Transcription

The process of synthesizing RNA from a DNA template.

Translation

The process of synthesizing protein from an mRNA template.

Polynucleotide

A long chain composed of many nucleotide units.

Purine

A double-ring nitrogenous base found in nucleic acids (Adenine, Guanine).

Pyrimidine

A single-ring nitrogenous base found in nucleic acids (Cytosine, Thymine, Uracil).

Mass Contribution of Macromolecules

Proteins contribute 50-60% of dry mass, followed by nucleic acids (20%), lipids (10-20%), and carbohydrates (5-10%). Carbohydrates ultimately dominate in mass when considering overall biological systems.

Monomer Size Comparison

The average relative size of monomers is Nucleotide (~330 Da) > Fatty Acid (~256 Da) > Glucose (~180 Da) > Amino Acid (~120 Da).

Polymer Length Comparison

DNA polymers can be billions of nucleotides long, polysaccharides up to 50,000 glucose units, proteins 50-2,000 amino acids, while lipids assemble into bilayers rather than long chains.

Macromolecule Turnover Rate

RNA has the fastest turnover (minutes-hours), followed by proteins (hours-days), then lipids (slower, continuous remodeling), and carbohydrates (depends on metabolic state).

DNA (Deoxyribonucleic Acid) Structure

A double helix with antiparallel strands, composed of nucleotides (deoxyribose + phosphate + base A, T, G, C) where A pairs with T (2 H-bonds) and G pairs with C (3 H-bonds).

B-DNA

The main, most common form of DNA found in cells, a right-handed helix.

A-DNA

A more compact, dehydrated form of DNA.

Z-DNA

A left-handed DNA helix, often found in repetitive GC-rich regions.

Nucleosome

The basic unit of chromatin, consisting of 147 base pairs of DNA wrapped around an octamer of histone proteins.

Euchromatin

Loosely packed chromatin that is transcriptionally active.

Heterochromatin

Densely packed chromatin that is transcriptionally inactive.

Epigenetic Modifications

Heritable changes in gene expression that do not involve alterations to the underlying DNA sequence, such as DNA methylation and histone acetylation.

DNA Replication

The process by which DNA is copied, typically occurring in a semiconservative manner where each new DNA duplex contains one parental and one newly synthesized strand.

Semiconservative Replication

The mechanism of DNA replication where each daughter DNA molecule consists of one original (parental) strand and one newly synthesized strand.

Origin of Replication

A specific DNA sequence where DNA replication begins.

Replication Fork

A Y-shaped structure formed when DNA helicase unwinds the double helix during DNA replication.

Leading Strand

The DNA strand that is synthesized continuously in the 5' to 3' direction towards the replication fork.

Lagging Strand

The DNA strand that is synthesized discontinuously in short pieces (Okazaki fragments) in the 5' to 3' direction, away from the replication fork.

Okazaki Fragments

Short DNA fragments synthesized on the lagging strand during DNA replication.

DNA Ligase

An enzyme that seals the gaps between DNA fragments (e.g., Okazaki fragments) by forming phosphodiester bonds.

DNA Helicase

An enzyme that unwinds the DNA double helix at the origin of replication, forming a replication fork.

Topoisomerase

An enzyme that prevents the overwinding of the DNA double helix ahead of the replication fork by relieving supercoiling.

DNA Polymerase III

The primary enzyme responsible for synthesizing new DNA strands, using the parent DNA strand as a template.

Single-Stranded Binding Proteins (SSB)

Proteins that bind to single-stranded DNA to prevent it from reannealing during DNA replication, especially important for Okazaki fragments.

RNA Primase

An enzyme that synthesizes short RNA primers, which provide a 3'-OH group for DNA polymerase to begin DNA synthesis.

DNA Polymerase I

An enzyme that removes RNA primers and replaces them with DNA.

DNA Proofreading

A function of DNA polymerase that allows it to detect and correct errors (mispaired nucleotides) during DNA synthesis, reducing the error rate.