Biology #1 - Cells

Cells

Smallest and basic structural and functional units of all living organisms, performing essential life processes.

Essential Life Processes (Functions of Cells)

Metabolism, Cellular Respiration, Growth, Reproduction, and Response to Stimuli (MCGRS).

Metabolism

All chemical reactions occurring within a cell.

Cellular Respiration

Breakdown of glucose to produce ATP (energy).

Growth in Prokaryotes

Increase in cell size achieved by producing proteins, lipids, enzymes, etc.

Reproduction

Formation of new cells through mitosis or meiosis.

Response to Stimuli

Ability to react to environmental changes such as light, temperature, chemicals, and touch.

Discovery of Cells

First discovered by Robert Hooke in 1665 observing dead oak bark cells under a microscope.

Antonie van Leeuwenhoek

Observed living cells like bacteria and protozoa in 1674, calling them Animalcules.

Discovery of the Nucleus

Discovered by Robert Brown in 1831; serves as the control center containing genetic material (DNA).

Eukaryotic Cells

Plant and animal cells featuring a true nucleus and membrane-bound organelles.

Prokaryotic Cells

Unicellular, primitive organisms lacking a true nucleus or membrane-bound organelles.

Unicellular Organisms

Made of one cell performing all life functions independently; micro-scopic with simple organelles (e.g., bacteria, amoeba).

Multicellular Organisms

Organisms that are made up of many cells that specialize in different functions, larger complex structures, and interdependent survival (e.g., plants, animals).

Cell Theory

Explained by Theodor Schwann and Matthias Jakob Schleiden in 1830.

In vivo

Biological processes taking place within a living organism (e.g., mouse testing, gamete fusion).

In vitro

Biological processes taking place outside a living organism, such as in laboratory settings (e.g., blood testing).

In silico

Computer-based biological analysis using bioinformatics and computational tools to speed up research.

Human Genome Project (HGP)

A 2004 international project to map and sequence the entire human DNA genome (~20K-25K genes).

DNA

Hereditary double-helix molecule composed of antiparallel strands and nucleotide subunits, containing all genes.

Genes

Specific segments of DNA functioning as units of heredity to produce products like proteins or RNA.

Genome

The complete set of DNAs across all 46 chromosomes (23 pairs) in a human body cell.

DNA Base Pairs

Approximately 6.6 x 10^9 nitrogenous base pairs held together by hydrogen bonds across 46 chromosomes.

Sizes of Biological Structures

Atoms (~0.1 nm), Lipids (1-10 nm), Proteins (1-100 nm), Ribosomes (20-30 nm), Viruses (50-100 nm).

Mutation

A sudden random change in genetic material affecting genes or chromosomes, caused by mutagens.

Mutagens

Chemicals, radiation, consumables, and environmental factors that cause genetic mutations.

Mutation Effects

Can be positive (disease resistance), neutral (no immediate effect), or negative (syndromes, sickle cell anemia).

Coding Mutations

Mutations occurring in coding regions of DNA that affect protein synthesis.

Nucleotide Bases

Nitrogenous building blocks of DNA (A, T, G, C) and RNA (A, U, G, C)

DNA Base Pairing Rules

Adenine pairs with Thymine (2 H bonds); Cytosine pairs with Guanine (3 H bonds).

RNA Base Pairing Rules

Adenine pairs with Uracil (2 H bonds); Cytosine pairs with Guanine (3 H bonds).

Nucleotide Structure

Composed of a nitrogenous base, a pentose sugar (deoxyribose or ribose), and a phosphate group (NSP).

Viruses

Small infectious agents with genetic material encapsulated in a protein shell, acting as a link between living and non-living organisms. They can only survive when in a host cell.

Non-Living Nature of Viruses

Cannot carry out life processes like metabolism or reproduction independently, and can be crystallized.

Living Nature of Viruses

Possess genetic material (DNA/RNA) and can evolve and reproduce inside a host cell.

Animal Cell

Eukaryotic cell characterized by an irregular shape, lack of cell wall, presence of centrioles/lysosomes, and numerous small vacuoles.

Plant Cell

Eukaryotic cell featuring a rectangular shape, rigid cell wall, chloroplasts, plastids, and a large central vacuole.

Parts of an Animal Cell

Consists of a cell membrane and protoplasm (which is divided into cytoplasm and nucleus).

Types of Animal Cells

Nerve, muscle, blood, epithelial, bone, fat, reproductive, and immune cells.

Cell / Plasma Membrane

A semi-permeable, fluid-mosaic lipid bilayer bounding all cells, controlling transport and maintaining homeostasis.

Singer & Nicolson (1972)

Proposed the Fluid Mosaic Model describing membrane flexibility, selective permeability, and lateral mobility.

Phospholipid Bilayer Core

Composed of hydrophilic polar phosphate heads facing outward and hydrophobic fatty acid tails facing inward.

Integral Proteins

Proteins embedded within the phospholipid bilayer, responsible for transport and ion regulation.

Peripheral Proteins

Proteins attached to the inner or outer membrane surfaces providing enzymatic activity and structural support.

Glycocalyx

Gel-like sugar coating formed by glycoproteins and glycolipids on the outer membrane layer for cell recognition and adhesion.

Cholesterol in Animal Cells

Steroid positioned between phospholipid tails to maintain fluidity, stability, and proper thickness across temperatures.

Aquaporins

Specialized integral protein water channels facilitating rapid, selective water transport across cell membranes.

Homeostasis

The biological process of maintaining a stable, regulated internal environment despite external changes.

Cytoplasm

Colorless part of the protoplasm, jelly-like semi-liquid substance consisting of 90 percent water and various organic molecules, housing organelles.

Cytoplasmic Inclusions

Temporary, non-living stored materials in the cytoplasm such as glycogen granules and lipid droplets.

Nucleus Structure

Spherical cell control center containing a dense nucleolus, nucleoplasm, chromatin, and a double nuclear membrane with nuclear pores.

Nucleolus

A dense, non-membrane-bound part of the nucleus rich in protein and RNA responsible for ribosome synthesis and assembly.

Chromatin

Unwound, jumbled complexes of DNA and histone proteins found within the nucleus during growth and maintenance phases.

Mitochondria

Double-membrane rod-shaped organelles known as the powerhouse of the cell, generating ATP via cellular respiration.

Mitochondrial Outer Membrane

Smooth, porous membrane of the mitochondria containing porins that allow passage of small ions and molecules.

Mitochondrial Inner Membrane

Folded into cristae to increase surface area, housing ATP synthase enzymes for oxidative phosphorylation.

Mitochondrial Matrix

Inner gel-like space containing enzymes, mitochondrial DNA, and ribosomes involved in protein synthesis and metabolism.

Oxysomes (F0F1 Particles)

Complex ATP synthase enzymes on mitochondrial cristae that synthesize ATP from ADP and inorganic phosphate using proton gradients.

Ribosomes

Dense, spherical ribonucleoprotein granules composed of two subunits, serving as the sites for protein synthesis.

Endoplasmic Reticulum (ER)

A large network of fluid-filled interconnecting tubules serving as the cell's intercellular transportation and production system.

Rough Endoplasmic Reticulum (RER)

Cisternae studded with ribosomes, continuous with the nuclear membrane, specializing in protein synthesis and folding.

Smooth Endoplasmic Reticulum (SER)

Tubular membranes lacking ribosomes, responsible for lipid synthesis, detoxification, and calcium ion storage.

Golgi Apparatus

Flat, smooth layered sacs near the nucleus involved in modifying, packaging, and sorting proteins and lipids into vesicles.

Vacuole

Membrane-bound organelle involved in maintaining cell shape and storing water, food, and wastes.

Lysosomes

Single-membrane bound organelles containing hydrolytic digestive enzymes; known as suicide bags for triggering cell lysis.

Chloroplasts

Plastids in plant cells containing chlorophyll to convert light energy into chemical energy via photosynthesis.

Centrosome

Organelle consisting of microtubule triplets forming centrioles, responsible for organizing spindle fibers during cell division.

Microtubules

Hollow, dynamic protein filaments providing structural support, intracellular transport tracks, and chromosome segregation.

Chromosomes

Linear eukaryotic or circular prokaryotic DNA structures carrying hereditary data, visible during cell division.

Chromosome Structure

Includes sister chromatids, a central centromere, inner chromomere DNA strand, and kinetochores for spindle attachment.

Central Dogma of Biology

Genetic flow where DNA replicates itself, is transcribed into RNA, and RNA is translated into proteins.

Cell Wall

Tough, semi-transparent, protective extracellular layer lying outside the plasma membrane in plants, fungi, and bacteria.

Middle Lamella

Outermost plant cell wall layer composed of pectin, cementing adjacent plant cells together.

Primary Cell Wall

First-formed, thin, elastic layer in young plant cells rich in cellulose fibers and water to allow cell expansion.

Secondary Cell Wall

Rigid, thick inner layer formed after maturity, strengthened by lignin deposition and sometimes waterproofed with suberin.

Plasmodesmata

Microscopic channels passing through plant cell walls, connecting adjacent cell cytoplasms for molecular transport.

Active Transport

Energy-intensive biological movement of molecules against a concentration gradient utilizing ATP and protein pumps.

Passive Transport

Natural molecular movement along a concentration gradient without energy consumption via diffusion or osmosis.

Simple Diffusion

Movement of substances from high to low concentration regions until equilibrium is reached.

Facilitated Diffusion

Transport of water-soluble molecules across cell membranes using channel and carrier transport proteins.

Filtration

Energy-independent process of separating solids from liquids/gases along a gradient, utilized biologically in kidneys.

Osmosis

Net movement of solvent water molecules across a semi-permeable membrane from low to high solute concentration.

Hypertonic Solution

Compartment with higher solute and lower water concentration, causing cellular exosmosis.

Hypotonic Solution

Compartment with lower solute and higher water concentration, causing cellular endosmosis and swelling.

Isotonic Solution

Solutions of equal solute and water concentrations resulting in no net water movement.

Plasmolysis

Shrinkage of plant cell protoplasm away from its cell wall due to severe exosmosis in a hypertonic environment.

Adenosine Triphosphate (ATP)

Cellular energy currency nucleotide composed of adenine, ribose sugar, and three phosphate groups.

ATP Hydrolysis

Exergonic reaction where ATP synthase breaks phosphoanhydride bonds to release energy, producing ADP and inorganic phosphate.

Cellular Respiration

Metabolic process breaking down glucose using oxygen inside mitochondria to produce ATP, carbon dioxide, and water.

Bulk Transport

Active transport process moving large macromolecules or particles across membranes via vesicles.

Endocytosis

Bulk transport moving particles into a cell by enclosing them in plasma membrane vesicles (includes phagocytosis and pinocytosis).

Exocytosis

Bulk transport mechanism where internal vesicles fuse with the plasma membrane to expel materials.

Micromolecules

Small biological monomers with low molecular weight (monosaccharides, nucleotides, water, etc.).

Macromolecules

Large polymer molecules formed by polymerized monomers (carbohydrates, nucleic acids, proteins, lipids).

Proteins as Polypeptide Chains

Complex polymers formed by amino acids joined together by peptide bonds between carboxyl and amino groups.

Chromoplasts

Colored, lipid-rich plastids lacking chlorophyll that store carotenoid pigments to impart red, yellow, and orange colors.

Leucoplasts

Non-pigmented storage plastids found in non-photosynthetic plant tissues like roots and tubers (e.g., amyloplasts, elaioplasts).

Growth in Eukaryotes

An increase in the number of cells (achieved by mitosis or meiosis)