Cell Biology Quest 1 Study Guide

Robert Hooke

Discovered cells by observing cork under a microscope

Anton van Leeuwenhoek

First to observe living cells; called them "animalcules"

Matthias Schleiden & Theodor Schwann

Proposed the Cell Theory; all living things are made of cells

Rudolf Virchow

Proposed that all cells come from preexisting cells

Shinya Yamanaka

2012 Nobel Prize for discovering Induced Pluripotent Stem Cells (iPS cells)

Lynn Margulis

Developed the Endosymbiont Theory of eukaryotic cell evolution

Properties of Cells

1) Highly organized, 2) Use energy, 3) Respond to stimuli, 4) Reproduce, 5) Maintain homeostasis

Light Microscopy

Uses light to magnify images; lower resolution but can view living cells

Electron Microscopy

Uses electron beams for higher resolution; cannot view living cells

Prokaryotic vs. Eukaryotic Cells

Prokaryotes lack a nucleus & membrane-bound organelles; Eukaryotes have both

Three Domains of Life

Bacteria, Archaea, Eukarya

Microbiome

Collection of microorganisms living in a specific environment

Metagenomics

Method to sequence all genetic material in a sample to study microbiomes

Differentiation

Process where cells specialize into different types despite identical DNA

Stem Cell Benefits & Issues

Embryonic: Pluripotent but ethical concerns; iPS: No ethics issues but risk of mutations

Sources of Stem Cells

Embryos, bone marrow, umbilical cord blood, reprogrammed adult cells (iPS)

Direct Cell Reprogramming

Converting one cell type directly into another without going through a stem cell stage

Six Model Organisms

Yeast, E. coli, Fruit Fly, C. elegans, Mouse, Zebrafish—used for genetic research

Eukaryotic Cell Size

10-100 µm

Bacterial Cell Size

1-10 µm

Mitochondria Size

0.5-2 µm

Virus Size

20-300 nm

DNA Width

2 nm

Hydrogen Atom Size

0.1 nm

Unit Conversions

1 cm = 10 mm, 1 mm = 1000 µm, 1 µm = 1000 nm, 1 nm = 10 Å, 1 Å = 100 pm

Synthetic Biology

Genetic engineering to create new biological systems

Mirror Life

Artificial life forms with mirrored molecular structures; potential for new drugs & biohazards

Viruses

Non-living entities made of DNA/RNA and protein; require a host to reproduce

Viroids

Infectious RNA molecules that lack a protein coat

Endosymbiont Theory

Eukaryotic cells evolved from symbiotic relationships with bacteria (evidence: mitochondria & chloroplasts)

Most Common Elements in Life

C, H, O, N, P, S

Covalent Bonds

Strong bonds where atoms share electrons

Single, Double, Triple Bonds

1, 2, or 3 shared electron pairs

Noncovalent Bonds

Weak bonds like hydrogen bonds, ionic bonds, hydrophobic interactions

Carbon's Importance

Forms 4 covalent bonds, allows complex molecules to form

Polar vs. Nonpolar Molecules

Polar = Unequal electron sharing (H₂O); Nonpolar = Equal sharing (O₂)

Dipole

Separation of charge within a molecule due to electronegativity differences

Highly Electronegative Elements

Oxygen, Nitrogen, Fluorine

Anions

Negatively charged ions (Cl⁻)

Cations

Positively charged ions (Na⁺)

Free Radicals

Unstable molecules that cause aging and disease

Ionic Bonds

Bonds between charged ions (NaCl)

Hydrogen Bonds

Weak bonds between H and electronegative atoms (DNA base pairs)

Hydrophobic Interactions

Nonpolar molecules clustering in water (lipid bilayers)

Van der Waals Forces

Weak attractions due to temporary charge shifts

Properties of Water

High heat capacity, solvent abilities, cohesion, adhesion, surface tension

Acid

Donates H⁺ in solution (HCl)

Base

Accepts H⁺ or donates OH⁻ (NaOH)

Buffer

Resists pH changes by stabilizing H⁺/OH⁻ levels (bicarbonate)

Functional Groups

Methyl (-CH₃), Hydroxyl (-OH), Carboxyl (-COOH), Amino (-NH₂), Phosphate (-PO₄), Carbonyl (-C=O), Sulfhydryl (-SH)

Macromolecules

Proteins, nucleic acids, polysaccharides, lipids

Macromolecule Building Blocks

Amino acids (proteins), Nucleotides (nucleic acids), Monosaccharides (polysaccharides), Fatty acids (lipids)

Stereoisomers

Molecules with the same formula but different spatial arrangement

L vs. D Isomers

Life uses D-sugars and L-amino acids

Glycosidic Bonds

Bonds linking sugar molecules in carbohydrates

Disaccharides

Sucrose, Lactose, Maltose

Polysaccharides

Glycogen, Starch, Cellulose

Types of Lipids

Fats, Steroids, Phospholipids

Amino Acid Structure

Contains an amino group (-NH₂), carboxyl group (-COOH), and R group

Amino Acid One-Letter Codes

20-letter abbreviations for amino acids

Amino Acid Properties

Polar charged, polar uncharged, nonpolar, or unique properties

Special Amino Acids

Glycine (smallest), Cysteine (disulfide bonds), Proline (rigid structure), Alanine (used in mutagenesis)

Protein Structure Levels

Primary (sequence), Secondary (alpha helices, beta sheets), Tertiary (3D shape), Quaternary (multi-subunit)

Determining Protein Structure

X-ray Crystallography, Cryo-electron Microscopy, AI-based predictions

Protein-Protein Interactions

Essential for cellular functions like signaling and transport

Protein Folding

Chaperones assist in proper protein folding

Denaturation

Protein unfolding due to heat, pH, or chemicals

Protein Misfolding

Leads to diseases like Alzheimer's and Parkinson's

Prions

Misfolded proteins that cause infectious diseases