A Tour of the Cell Flashcards
Resolving Power
minimum distance two points can be separated and still be distinguished as two separate points (clarity of image)
Microscope TEM
reveals internal details
Microscope SEM
reveals surface details
Why is the cell so small ?
-surface area/volume ratio determines how fast material can diffuse in and out of the cell (diffusion fall as cell gets larger)
Prokaryotic Cells
- small 1-5 um long
- lack nucleus
- ribosome and cell wall differ from eukaryotes
- capsule: sticky outer layer
- (pili)= projections
Eukaryotes
- 10-100um long
- membrane bounded organelles
- true nucleus
- cellular metabolism occurs with organelles, increase membrane
- non-membrane structures (cytoskeleton, centrioles)
Nucleus
- largest organelle
- stores, protects, replicates, and expressed genetic info
Nuclear envelope
- double membrane
- contains nucleoplasm
Nucleoplasm contains
chromatin: DNA and protein
- ribosomes synthesis
Nuclear Lamina
- inner nuclear membrane
- shape of nucleus
- protein called lamin
- chromosomes attachment site for organizing the nuclear contents
Nuclear matrix
framework of fibres throughout nucleus
Human eye revolving point
0.1-0.2mm
Cell surface area
how fast materials can diffuse in nutrients or out of cell
What happens when the larger cell gets more surface area to volume ratio ?
volume ratio decreases (bad)
Perinuclear space
space between molecules
nuclear pore complexes
transmits traffic between nucleoplasm
Ribosomes
contains protiens and ribosomal RNA (rRNA) that functions to synthesize proteins
Eukaryotic Ribosomes
four dozen protiens (aka four rRNA molecules)
Free Ribosomes
located in cytosol, makes protien for cytosol, chloroplast, mitochondria, and nucleoplasm
Bound Ribosomes
bound to endoplasmic reticulum make modified protiens active in endomembrane system (transmembrane protiens in golgi network) and secrets protiens
Endomembrane system
membranes whose member are in direct contact with one another or engage in vesicular trafficking togther
- includes double membranes
- excludes paracisomes, chloroplast and mitochondria
Endoplasmic Reticulum (ER)
network of tubes and sacs, interior space= lumen
Smoother ER
- no protein related function
- lipid synthesis
- carbohydrates metabolism
- sequesters CA2+
Rough ER
- protein synthesis
- protein storing
- protein modifications
- membrane biogenesis
- all facilitated by prepare of ribsomes
Golgi Appparatus
series of flattened sacs and associated vesicles consisting of cisternae (flattened membrane disk)
Cis cisternae
cis golgi network= receiving, convex (((
trans cisternae
trans golgi network- shipping concave )))
Golgi Functions
- protein sorting, processing, modifications to oligosaccharides to glyco- protein and lipids
- plant vacuoles
- no synthesis and no ribosomes
Vesicles
transport one part of the endomembrane system to another
Lysosomes
acidic compartments in animal cells containing acid hydrolases
- maintain pH 5
- contain activity of H+ ATP in lysosomal membrane
Heterophagy
digestion of material brought into cell environment
Autophagy
digestion of cells own material (worn out organelles)
Central Vacuoles
occupies most volume of mature plant and fungal cells (only in plants)
- maintains proper pressure to support plant growth
- performs hydrolytic functions, stores waste and toxins
Food vacuoles
contain phagocytosed food
Contractile vacuoles
expell liquid and regulate osmotic pressure
Mitochondria
sites of cellular respiration, perform most oxidation to provide energy to form ATP
Mitochondria features
- double membrane
- hundreds to thousands per cell
Inner mitochondrial membrane
site of eletron transport chain ETC
- increase surface area
- linning of intestines
Mitochondrial matrix
site of citric acid cycle KREBS
Circular DNA
high plants also have linear
binary fission
replication
prokaryotic origin
but no longer able to live independently
- phagocytosis
- origin of alpha protobacteria
Chloroplast
plastids that perform photosynthesis in plants and algae
Chloroplast features
- green due to pigment
- double membrane
thylakoid membrane
site of light absorbtion
- eletron transport produced ATP and NADPH for the calvin cycle
- may be stacked
stroma
fluid between grana site of calvin cycle and CO2 fixation
Chemiosmosis
use by both mitochondria and chloroplast to generate ATP
Endosymbiont theory
eukaryotes took 1st prok (mitochondria ) 2nd prok (chloroplast)
peroxisome
involved in catabolic oxidative processes
peroxisome features
- belong to microbodies
- single membrane
- forms peroxyde (H2O2) toxic and broken down by catalase
- doesnt contain own DNA
cytoskeleton
muscle and bone of the cell containing many proteins
cytoskeleton features
- maintains shape
- facilitates motility
- holds and traffics organelles
- transmits signals
cytoskeleton components
- microtubles
- microfillaments
- intermediate fillaments
Microtubles (large)
tubulin heterodimers that are dynamic (grow and shrink)
- hollow and largest cytoskeletal element
- centrosome ogranize MT,
- dyneins and Kinesisns - walk along MT in a sliding effect where cilia carry cargo
Microfilaments (small)
- actin molecules involved in cell crawling and cytoplasmic streaming
- solid rods
- myosins : ATP dependent, thick filaments
- sarcomere muscle units: thin filaments actin
- muscle movement; myosin and actin
Intermediate filaments (medium)
- durable fibres used in support only
- high tensile strength to withstand mechanical stress
- form nuclear lamina
plant cell wall
-cellulose (polymer of glucose) microfibres in matrix of polysaccharides and proteins
Plasmodesmata
-small threads of cytosol connect between plant cell neighbors = communication
animal cell surface- Intercellular Junctions
tight junctions (diffusion barriers) desmosomes (anchoring junctions) gap junctions (communication junctions)
animal cell surface- Extracellular Junction
- gylcoproteins, proteoglycans cross linked to each other by extracellular adhesion protein
- anchors and supports cells, facilitates tissue formation and gene expression
