MCAT Biology Section 1: Cells
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New York University Abu Dhabi
Andy
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Summary
This document provides a detailed overview of cell biology concepts, including cell theory, eukaryotic cell structures (nucleus, mitochondria, etc.), prokaryotic cells (bacteria, archaea), and viruses. The information is organized into sections for each type of cell and touches on their structures and functions, suitable for MCAT preparation. Key biological processes are also detailed.
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MCAT - Biology Section 1. Cells 1.1. Cell Theory All organisms are made out of cells Cells are the basic functional unit of life Cells come from pre-existing cells Cells carry genetic info (DNA) 1.2. Eukaryotic Cells Nucleus ○ Double-layered envelope containing DNA ○ Nucleolus synthesizes rRNA Mitoc...
MCAT - Biology Section 1. Cells 1.1. Cell Theory All organisms are made out of cells Cells are the basic functional unit of life Cells come from pre-existing cells Cells carry genetic info (DNA) 1.2. Eukaryotic Cells Nucleus ○ Double-layered envelope containing DNA ○ Nucleolus synthesizes rRNA Mitochondria ○ Outer membrane, intermembrane space, inner membrane, matrix ○ Proton-motive force: H+ pumped from matrix to intermembrane space ○ Apoptosis via release of cytochrome C from ETC Lysosomes ○ Autolysis via release of hydrolytic enzymes from cells Endoplasmic reticulum ○ Rough ER Studded ribosomes and translates secreted proteins ○ Smooth ER Lipid synthesis, detoxification, protein transport Golgi apparatus ○ Modify materials from ER Peroxisomes ○ H2O2 production to break down VLCFA ○ Assists in phospholipid synthesis and pentose phosphate pathway Cytoskeleton ○ Microfilaments (actin rods) Protection, muscle contraction (w/ myosin), cleavage furrow ○ Microtubules (tubulin tubes) Motor protein pathway (kinesis and dynein) and centrioles Cilia (cell surface movement) and flagella (overall cell movement) 9+2 structure found only in eukaryotes ○ Intermediate filaments (keratin, desmin, vimentin, lamins) Cell-cell adhesion, maintain cytoskeleton, cell rigidity, anchor organelles Types of tissues ○ Epithelial Lines body/cavities and forms parenchyma Squamous, cuboidal, columnar Simple, pseudostratified, stratified ○ Connective Supports body and forms framework for epithelia, forms stroma Secretes collagen/elastin to form ECM ○ Cardiac (more info in Cardiovascular System) ○ Nervous (more info in Nervous System) 1.3. Prokaryotic Cells Bacteria ○ Structure (cocci → spheres, bacilli → rods, spirilla → spiral) Single circular chromosome in nucleoid Envelope (cell wall and plasma membrane) Gram staining Flagella (filament, hook, basal body → chemotaxis) ○ O2 requirement Obligate aerobes (no oxygen → death) Facultative anaerobes (switch between O2 or no O2) Microaerophiles (tolerates only low amounts of oxygen) Aerotolerant anaerobes (can tolerate oxygen) Obligate anaerobes (oxygen → death) ○ Recombination Transformation (acquired from environment) Conjugation (transferred between bacteria) Transduction (acquired by viruses) ○ Growth stages Lag phase Log phase Stationary phase Death phase Archaea (compared to bacteria) ○ Similarities Singular circular chromosome, similar structure (no LPS/PDG), binary fission ○ Differences Start translation w/ methionine, histones, and similar RNA pol to eukaryotes 1.4. Viruses Virions (nucleocapsid) ○ DNA viruses (DNA genome, nucleus, host machinery) dsDNA (identical to host DNA) Host replication and transcription ssDNA Host replication and transcription ○ RNA viruses (RNA genome, cytoplasm, own machinery) dsRNA (occurs in eukaryotes if targeted) Replication w/ RdRp inside capsid, no transcription ssRNA(+) Replication w/ RdRp, no transcription ssRNA(–) RdRp performs replication and transcription ○ Retroviruses (two copies of ssRNA, has reverse transcriptase → cDNA from RNA) ○ Life cycle (bacteriophages only) Lytic (virulent, virus replicates fast and lyses host cell) Lysogenic (temperate, virus integrated into host genome) Viroids (small circular ssRNA w/ no capsid, affects plants except for Hep. D in humans) Prions (misfolded proteins, α helices to β-pleated sheets → solubility ↓, degradation ↓)