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CHAPTER 6: TOUR OF THE CELL - Coggle Diagram
CHAPTER 6: TOUR OF THE CELL
MICROSCOPES AND BIOCHEMISTRY
MICROSCOPY
cells are too small for the naked eye
human eye resolution ≈ 200 μm (0.2 mm)
LIGHT MICROSCOPE (LM)
uses visible light to magnify cells
most plant & animal cells: ~50 μm
bacteria & Archaea: 1–5 μm
EUKARYOTIC VS. PROKARYOTIC SIZE
eukaryotes = 10–50x larger
prokaryotes = much smaller
WHY CELLS ARE SMALL
surface area to volume ratio is critical
small cells = faster nutrient/waste exchange
larger cells = slower exchange, inefficient
CELL FRACTIONATION
breaks cells apart to study organelles separately
helps link organelle structure → function
PLASMA MEMBRANE
phospholipid bilayer with embedded proteins
selectively permeable
regulates O₂, nutrients, and waste movement
EUKARYOTIC CELLS
BASIC FEATURES
have DNA inside a nucleus
contain membrane-bound organelles
have cytoplasm and ribosomes
MAJOR ORGANELLES
nucleus – holds DNA
ER (Rough & Smooth) – builds proteins & lipids
golgi Apparatus – modifies & ships proteins
mitochondria – makes ATP
lysosomes – digest materials
vacuoles – storage
PLASMA MEMBRANE
phospholipid bilayer
proteins = channels, receptors, enzymes
EXAMPLES
Animal Cells: flexible, no cell wall
Plant Cells: rigid, with wall & chloroplasts
CELL SIZE AND EFFICIENC
small cells work better
large surface area-to-volume ratio = efficient exchange
EUKARYOTIC CELL'S GENETIC INSTRUCTIONS
NUCLEUS
nuclear envelope: double phospholipid bilayer
nuclear pores: allow RNA & proteins to pass
chromosomes: DNA molecules containing genes
chromatin: DNA wrapped around histone proteins
nucleolus: produces rRNA for ribosome assembly
nuclear lamina: protein network supporting shape
RIBOSOMES
made of rRNA + proteins
free ribosomes: float in cytosol, make local proteins
bound ribosomes: on rough ER, make export/membrane proteins
two subunits: large & small (“hamburger bun” analogy)
function: protein synthesis
GENE EXPRESSION
DNA - RNA - Protein
ribosomes follow gene instructions to build proteins
ENDOMEMBRANE SYSTEM
DEFINITION
group of connected membranes working together
INCLUDES
nuclear envelope
nuclear envelope
golgi apparatus
lysosomes
vacuoles
plasma membrane
CONNECTIONS
continuous: Nuclear Envelope - Rough ER
vesicular transport: other membranes exchange materials via vesicles
ROUGH ER
ribosome-studded
makes proteins, glycoproteins, and new membrane
packages proteins in transport vesicles
SMOOTH ER
no ribosomes
makes lipids
detoxifies drugs (especially in liver)
stores calcium ions
GOLGI APPARATUS
flattened sacs = cisternae
cis face: receives vesicles
trans face: ships them off
modifies, sorts, and packages proteins
LYSOSOMES
membrane sacs with hydrolytic enzymes
digest macromolecules (hydrolysis)
phagocytosis: engulfing food
autophagy: recycling old organelles
VACUOLES
storage organelles
central vacuole (plants): water & nutrients; maintains pressure
MITOCHONDRIA AND CHLOROPLASTS
MITOCHONDRIA
site of cellular respiration
converts glucose - ATP
found in both plants and animals
has double membrane; inner folds = crustal
CHLOROPLAST
site of photosynthesis
captures sunlight - make sugars
contain chlorophyll (green pigment)
found only in plant cells
inner structures: thylakoids stacked as grand
SHARED TRAITS
both have their own DNA & ribosomes
both have double membranes
support the endosymbiotic theory (origin from ancient prokaryotes)
EXAMPLES
mitochondria = “powerhouse”
chloroplast = “solar panel” of the cell
CYTOSKELETON
PURPOSE
maintains cell shape, supports movement, organizes organelles
COMPONENTS
microtubules
hollow tubes of tubulin
Shape cell, guide organelle movement
Used in cilia, flagella, centrioles
microfilaments
made of actin
support shape, help muscle contraction
intermediate filaments
provide strength
support the nucleus & form nuclear lamina
MICROFILAMENTS
made of actin
support shape, help muscle contraction
INTERMEDIATE FILAMENTS
provide strength
support the nucleus and form nuclear lamina
CENTROSOMES AND CENTRIOLES
found only in animal cells
organize microtubules during division
EXAMPLE
flagella: movement (like sperm cell tails)
cilia: short, hair-like structures for motion or sweeping debris
EXTRACELLULAR COMPONENTS AND CONNECTIONS BETWEEN CEELS
PLANT CELLS
Cell Wall: cellulose layer outside plasma membrane
Provides shape, support, and protection
Plasmodesmata: channels connecting cells - allow molecules to pass
ANIMAL CELLS
no cell wall
Have Extracellular Matrix (ECM):
Made of glycoproteins (like collagen)
Made of glycoproteins (like collagen)
CELL JUNCTIONS
Tight Junctions: seal neighboring cells
Desmosomes: anchor cells (strong connections)
Gap Junctions: allow small molecules to pass (like plasmodesmata)
COMPARISON
Plant cells - rigid, have wall & chloroplasts
animals cells - flexible, have ECM and centrioles
PLANTS VS. ANIMALS CELL COMPARISON
CELL WALL
plant cells: present
animal cells: absent
CHLOROPLASTS
plant cells: present
animal cells: absent
CENTRAL VACUOLE
plant cells: large
animal cells: small/none
CENTRIOLES
plant cells: absent
animal cells: present
SHAPE
plants: boxy/rigid
animals: round/flexible
MITOCHONDRIA
plants: present
animals: present