Biology Basics

Cell Structure and Function

• Cells are the basic units of life, with two main types: prokaryotic (bacteria) and eukaryotic (all other living things)
• Prokaryotic cells lack membrane-bound organelles, have a single circular DNA molecule, and free ribosomes and a cell wall
• Eukaryotic cells have membrane-bound organelles, multiple linear DNA molecules, and histones on DNA

Cell Organelles

• Nucleus: holds DNA and nucleolus, where ribosomal subunits are made
• Mitochondria: double membrane, site of cellular respiration, outer membrane is smooth, and inner membrane is folded with enzymes
• Ribosome: site of translation, protein synthesis, made of rRNA and protein
• Endoplasmic Reticulum (ER): connected to nucleus, allows for reactions, membranous, smooth ER for lipids, and rough ER for proteins
• Golgi Complex: packaging in membrane and signals for export
• Cytoskeleton: microfilaments, microtubules, and centrioles; gives shape, movement, and support to the cell
• Vacuoles/Vesicles: storage of water and solutes

Cell Membrane

• Phospholipid bilayer: selectively permeable, amphipathic
• Fluid Mosaic Model: in motion, proteins, cholesterol, glycoproteins, and glycolipids among phospholipids
• Types of transport: simple diffusion, facilitated diffusion, active transport, endocytosis, and exocytosis
• Osmosis: diffusion of water using a selectively permeable membrane

Energy and Metabolism

• Energy: free energy is used for organization, growth, and reproduction
• First law of thermodynamics: energy is not created or destroyed, only converted
• Second law of thermodynamics: entropy increases, organization decreases
• Cellular Respiration: breaks down glucose, produces ATP, occurs in mitochondria, and involves glycolysis, Krebs cycle, and electron transport chain
• Photosynthesis: captures free energy, uses water and carbon dioxide, produces glucose and oxygen, and occurs in chloroplasts

Cell Cycle

• Cell cycle: interphase, cell division, and cytokinesis
• Interphase: growth, synthesis of DNA, and preparation for mitosis
• Mitosis: duplicated chromosomes line up, spindle fibers pull them apart, and cytokinesis divides cytoplasm and reforms cell membrane
• Checkpoints: internal controls, external signals, and DNA damage

Molecular Genetics

• DNA structure: double helix, nucleotides, phosphate, sugar, nitrogen base, and antiparallel strands
• DNA replication: semi-conservative, bidirectional, and involves helicase, DNA polymerase, and ligase
• RNA: single stranded, ribose sugar, uracil instead of thymine, and base pair rules
• Transcription: making mRNA, involves RNA polymerase, and occurs in the nucleus
• mRNA editing: introns are excised, exons are spliced together, and a polyA tail and GTP cap are added
• Translation: mRNA code is read, matched with tRNA, and constructs a polypeptide using the ribosome

Mutations

• Any change in the DNA sequence, can be inheritable if in egg or sperm
• Point mutations: one nucleotide error, substitutions, insertions, or deletions
• Frame shift mutations: one or more bases deleted or inserted
• Silent mutations: substitution codes for the same amino acid or deletion/insertion is of three nucleotides