microscopes and cell composition Flashcards
light microscope
visible light is passed through a specimen and then through glass lenses - lense bends light so image is magnified
- sees bigger things
- larger EM waves
- living cells
- cane stiane for flagged
parameters of microscopy
magnification, resolution, and contrast
organelles
membrane-enclosed compartments
scanning electron microscopes (SEMs)
focus a beam of electrons onto the surface of a specimen, image that looks 3-D
- looks at surface
- dead cells
transmission electron microscopes (TEMs)
focus a beam of electrons through a specimen
- internal structure
- dead cells
cell fractionation
breaks up cells and separates the components, using centrifuge
- largest parts pellet first
prokaryotic cells
bacteria and archea
- no nucleus
- DNA in unbound region called nucleic (small circular duplex)
- no-membrane bound organelles
- unicellular, small
- rigid cell wall
- small internal organization, little compartmentalization
- divide by fission
eukaryotic cells
protists, fungi, animals, plants
- DNA in nucleus bound by double membrane
- internal membranes that divide cell into organelles
- nucleus
nucleus
contains most of cell’s genes and most obvious organelle
- nucleus envelope
- double membrane (lipid bilayer)
- nucleus pores
difference in plant and animal cells
animal: centrosome
plant: central vacuole, chloroplasts, cell wall
the endomembrane system
regulates protein traffic an performs metabolic functions in the cell
- nucleus envelope
- ER
- Golgi apparatus
- lysosomes
- vacuoles
- plasma membrane
these are either continuous or connected through transfer of vesciles
all cells
- plasma membrane
- cytosol
- chromosomes
- ribosomes
ratio of SA(n2) to V(n3) is critical
small cells have greater SA to V ratio (SA increases while V remains constant)
Ribosomes
complexes of ribosomal RNA and protein
- carry out protein synthesis
- free (cytosol) and bound (ER or nucleus envelope)
The endoplasmic reticulum
accounts for more than half go the total membrane - continuous with nucleur envelope
- Smooth ER (no ribosomes)
- Rough ER (ribosomes)
smooth ER function
- synthesizes lipids
- detoxifies drugs and poisons
- stores calcium ions
rough ER function
- secrete glycoproteins (covalently to bonded proteins and carbs)
- distributes transport vesicles
- is a membrane factory
The Golgi Apparatus
flattened membranous sacs called cisternae
- modifies products of ER
- makes macromolecules
-sorts and packages materials into transport vesicles
-cis face (received) and trans face (ships)
Lysosome
a membranous sac of hydrolytic enzymes that can digest macromolecules
- work best in acidic environment and 3-D shape protects them
- Tay-Sachs disease: lysosomes can’t degrade certain glycolipids due to defect in enzyme
Vacuoles
large vesicles derived from the ER and Golgi
- solution inside differs from cytosol
- Food Vacuoles: formed by phagocytosis
- Contractile Vacuoles: fresh aware protists, pumps out excess water
- Centra Vacuoles: plant cells, holds organic compounds + water
- enzymatic hydrolysis
Mitochondria
the sites of cellular respiration
- smooth outer membrane, folder inner membrane called cristae
-cristae divided into inter membrane space and mitochondrial matrix
cellular respiration
a metabolic price that uses oxygen to generate ATP
Chloroplasts
green pigment chlorophyll and enzymes and other molecules that function in photosynthesis
Peroxisomes
specialized metabolic compartments bounded by a single membrane
- produce hydrogen peroxide and converts to water
