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Chapters 6-7 (Chapter 6: A Tour of the Cell (Concept 6.2: Eukaryotic cells…
Chapters 6-7
Chapter 6: A Tour of the Cell
Concept 6.2: Eukaryotic cells have internal membranes that compartmentalize their functions
surface area vs.volume ratio
cells with greater metabolic requirements are larger
as cell increases in size, volume grows proportionately more than its surface area
surface area increases while total volume remains constant
we are not just made of one cell, but multiple to allow more surface area for metabolic functions
Eukaryotic cells
DNA in nucleus bound by double membrane
membrane-bound organelles
internal membranes divide cell into organelles, compartments
cytoplasm in region between plasma membrane and nucleus
plasma membrane- selective barrier, allows passage of oxygen, nutrients, and waste
gnerally larger than prokaryotic cells
Prokaryotic cells
no nucleus
DNA in an unbound region- nucleoid
no membrane-bound organelles
cytoplasm bound by plasma membrane
bound by cell wall, glycocalyx
and then fimbriae, flagella
basic features of all cells:
semifluid substance - cytosol
chromosomes - carry genes
plasma membrane
ribosomes- make proteins
organelles
Concept 6.4: endomembrane system
golgi apparatus
flattened membraneous sacs, cisternae
modifies products of ER
manufactures certain macromolecules
sorts and packages materials into transport vesicles
lysosomes
membraneous sac of hydrolytic enzymes, digest macromolecule
hydrolytic enzymes and lysosomal membranes made by rough ER, transferred to golgi for processing
lysosome fuses with vacuole, digests molecules
endoplasmic reticulum
more than half of total membrane, continuous with nuclear envelope
two regions
smooth ER, lack ribosomes
metabolizes carbohydrates
detoxifies drugs and proteins
stores calcium ions
synthesizes lipids
rough ER, studded with ribosomes
bound to ribosomes, secrete glycoproteins
distributes transport vesicles, secretory proteins surrounded by membranes
membrane factory
vacuole
large vesicle derived from ER and golgi
food vacuoles formed by phagocytosis
Concept 6.5:
mitochondria - cites of cellular respiration, uses oxygen to generate ATP
mitochondrial matrix and intermembrane
cristae- folded inner membrane
chloroplasts - sites of photosynthesis, plastids
chlorphyll, green pigment
thlakoids - membraneous sacs, grnaum
stroma - internal fluid
Concept 6.3: genetic material
ribosomes
complexes made of ribosomal RNA and protein
protein synthesis
in the cytosol (free ribosomes)
on outside or ER or nuclear envelope (bound ribosomes)
nucleus
contains most of cell's genes
chromosomes: discrete units of DNA
chromatin: one DNA molecule associated with proteins
nucleolus: within nucleus, site of ribosomal RNA(rRNA) synthesis
nuclear envelope: encloses nucleus, separates from cytoplasm, double membrane, both are lipid bilayer
outer membrane
nuclear pores: pore complex, regulate entry and exit form nucleus
inner membrane
nuclear lamina: lines nucleus, composed of proteins, maintains shape
Concept 6.6: cytoskeleton
cytoskeleton - network of fibers extending throughout cytoplasm
support cell, maintain shape
three types of molecular structures
microtubules - thickest, cell shape, motility, chromosome movements
microfilaments - actin filaments, thinnest, cell shape, motility
intermediate filaments - middle range diameter, cell shape, coiled cables, lamina
Concept 6.1: Biologists use microscopes and biochemistry to study cells
types of microscopes:
light microscope (LM): less detail
binocular compound light microscope- 2D
dissecting light microscope- 3D
electron microscope (EM): more detail
transmission electron microscope (TEM)- 2D
scanning electron microscope (SEM)- 3D
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cell fractionation: takes cells apart, separates major organelles
can determine functions of organelles
centrifuges- fractionate cells into component parts
biochemistry & cytology help correlate cell function with structure
parameters in microscopy
contrast: difference in brightness between light and dark areas of an image
resolution: measure of clarity of the image
magnification: ratio of object's image size to its real size
Chapter 7: Membrane Structure & Function
diffusion, passive transport
osmosis - movement of water across membrane
hypotonic - lower concentration of solute
isotonic - balanced concentration of solute
hypertonic - higher concentration of solute
facilitated diffusion - need transport proteins
channel proteins - bridge for molecules to cross
carrier proteins - form to molecules's shapes
tendency fro molecules to spread out evenly into available space
active transport
electrogenic pump
sodium-potassium pump - generate membrane potential
proton pump
cotransport
symport - move in same direction
antiport - opposite direction
bulk transport - large molecules
exocytosis - move molecules out
endocytosis - bring molecules in
phagocytosis - one large single item
pinocytosis - many smaller items
receptor-mediated cytosis - many smaller items, but specific solutues
requires energy, ATP, against concentration gradient
membrane
fluidity
membranes held together by weak hydrophobic interactions
most lipids and proteins can move sideways within membrane
selective permeability
cell must exchange materials with surroundings, controlled by plasma membrane
regulate cell's molecular traffic
lipid bilayer - hydrophobic tails, hydrophilic heads
membrane proteins
fluid mosaic model - protein molecules bobbing in fluid bilayer of phospholipids
peripheral proteins - bound to surface of membrane
enzymatic activity
signal transduction
cell- cell recognition
transport
intercellular joining
integral proteins - penetrate hydrophobic core, one or more nonpolar amino acids
asymmetrical distribution of proteins, lipids, and carbs is determined when ER and golgi build membrane