Membrane Transport, Biomolecules, Chromosomes, Protein Synthesis, Cell Metabolism

Passive Transport

Movement of molecules across a membrane without energy

Simple Diffusion

Small nonpolar molecules move down their concentration gradient (e.g., O2, CO2)

Facilitated Diffusion

Molecules move through protein channels or carriers down their concentration gradient

Osmosis

the passive movement of water through aquaporins

Active Transport

Movement against concentration gradient, requires ATP

Sodium-Potassium Pump

Actively pumps Na⁺ out and K⁺ into the cell using ATP

Endocytosis

Cell engulfs large particles by forming vesicles from the membrane

Exocytosis

Cell releases substances by fusing vesicles with the membrane

Effect of Temperature on Diffusion

Higher temperature increases diffusion rate; lower temperature decreases it

Chemical Composition of Chromosomes

Arrangement, type, and ratio of atoms in molecules

Chemical Structure of Chromosomes

Spatial arrangement of atoms within molecules

Diploid Cells

Cells with two copies of each chromosome (46 in humans)

Haploid Cells

Gametes with half the number of chromosomes (23 in humans)

Chromatids

Threadlike strands into which a chromosome divides longitudinally during cell division; each contains a double helix of DNA

Transcription

Occurs in the nucleus; DNA is used as a template to make complementary mRNA

Translation

Occurs in the cytoplasm on ribosomes; mRNA is read to assemble amino acids into proteins

DNA Role in Protein Synthesis

Stores all instructions to make proteins

mRNA Role

Carries the "recipe" from DNA to ribosome

tRNA Role

Brings the correct amino acids to the ribosome

rRNA Role

Makes up the ribosome and ensures proper assembly of proteins

Metabolism

All chemical reactions necessary to maintain life

Catabolism

Breakdown of substances into simpler molecules

Anabolism

Building larger molecules from smaller ones

Glycolysis

Cytoplasm; splits glucose into 2 pyruvate, 2 ATP, 2 NADH; no oxygen needed

Krebs Cycle

Mitochondrial matrix; produces 2 ATP per glucose, 6 NADH, 2 FADH2; requires oxygen

Electron Transport System

Inner mitochondrial membrane; uses NADH/FADH2 to generate ~32 ATP; requires oxygen

Fermentation

Partial oxidation of glucose without oxygen; regenerates NAD⁺

Aerobic Oxidation

Glucose breakdown with oxygen; final electron acceptor is O2

Anaerobic Oxidation

Glucose breakdown without oxygen; other molecules act as electron acceptor

NADH and FADH2

Electron carriers; donate electrons to ETC to generate ATP

Water

Polar molecule, solvent for reactions, regulates temperature, facilitates nutrient/waste transport

Carbohydrates

Composed of C, H, O; simple (monosaccharides) or complex (polysaccharides); main energy source

Lipids

Hydrophobic molecules (fats/oils), triglycerides, energy storage, form cell membranes

Proteins

Composed of amino acids linked by peptide bonds; enzymes, structural support

Minerals

Inorganic elements needed in trace amounts; bone formation, muscle/nerve function

ATP

Nucleotide with three phosphate groups; stores and releases energy for cellular processes

DNA

Double helix of nucleotides; stores genetic information and guides protein synthesis

RNA

Single-stranded nucleotides; mRNA carries code, tRNA brings amino acids, rRNA forms ribosomes

Gap Junction

Small protein channels between cells that allow ions and signals to pass directly

Phagocytosis

“Cell eating” – the cell engulfs large particles or microbes into vesicles for digestion.

Pinocytosis

“Cell drinking” – the cell takes in fluid and dissolved solutes in small vesicles.