Topic 4 Flashcards
parameters for microscopy
- magnification
- resolution
- contrast
magnification
ratio of an objects image sice to real size
resolution
minimum distance of two distingushable points
contrast
visable differences in brughtness between parts of a sample
what are the different types of microscopy
light microscopy
electron microscopy (scanning SEM, transmission TEM)
light microscopy has limit to
resolution
cellular components shared between all cells
- plasma/ cell membrane
- cytosol
- DNA
- ribosomes
prokaryotic cells
- no nucleus
- dna in an unbound region called nucleoid
- no membrane bound organelles
- generally smaller than eukaryotic
eukaryotic cells
- dna in nucleus that is bounded by a double membrane
- membrane bound organelles
- cytoplasm in the region between plasma membrane and nucleus
- generally larger
cellular size ratios
- practical limits to size of cells due to metabolic requirements
- surface area to volume ratio is critical
- as a cell increases in siz its vollume grows proportionally more than surface area
plasma membrane
selective barriier that allows sufficient passage of oxygen, nutruents, and waste
- phospholipid bilayer
we need a large surface area for cellular function due to
plasma membrane components
organelles
membranes separate cell into compartments
present in animal, not in plant
- lysosome
- flagellum
- intermediate filament
- centrosome
present in plant, not animal
- central vacuole
- chroloplast
- plasmodesmata
- cell wall
nucleus
most visable organelle
- contains dna in a eukaryotic cell
- dna is organized into units called chromosomes
nuclear envolope
encloses the nucleus, separating nucleus from cytoplasm
- double membrane, each membrane has a phosholipid bilayer
- pores regulate the entry and exit of molecules from the nucleus - pore complex
pore complex
pores that regulate the entry and exsit of molecules from the nucleus
nucleolus
located within the nucleus
- site of ribosomal RNA (rRNA) synthesis
- ribosomes (protein and rRNA) assembled in nucleolus then they are exported
ribosomes
make proteins via translation
- made of ribosomal RNA and protein
- cells with high protein synthesis have large numbers of ribosomes
where do ribosomes carry out protein synthesis
- in the cytosol (free ribosomes)
- on the endoplasmic reticulum or in the nuclear envelope (bound ribosomes)
endomembrane system
regulates protein traffic and performs metabolic functions in the cell
endomembrane system includes
- nuclear envelope
- endoplasmic reticulum
- golgi apparatus
- lysosomes
- vacuoles
- plasma membrane
components are either continious or connected by vesicles
endoplasmic reticulum
- continous with nuclear envelope
- smooth: lack ribosomes
- rough: studded w ribosomes
smooth ER functions
- syntehsize lipids
- metabolize carbs
- detoxifies drugs and poisons
- stores calcium ions
rough ER functions
- bound ribosomes produce proteins
- make and distribute secretory proteins surrounded by membranes- distrubted by transport vesicles
- membrane factory for cell
golgi apparatus
- consits of flattened membranous sacs called cisternae
golgi function
modifies products of the ER (transported by vesicles) and other molecules
- sorts and packages materials into transport vessicles
flow of golgi
- cis face receiving side, closest to ER
- trans face shipping side.
flows for cis to trans
lysosome
- membranous sacs of hydrolytic enzymes that can digest molecules
- works best in acidic
- break down amterial
-PHAGOCYTOSIS engulfing smaller particles
lysosome responsible for
cellular recycling
- autophagy- acidic enzymes RECYCLE cells own organelles and macromolecules
vacuoles
large vesicles derived from the ER and golgi apparatus
food vacuoles
formed by phagocytosis (engulfing smaller particles)
contractile vacuoles
found in many freshwater protisist, pump excess water out of cells
central vacuole
found in many mature plant cells, hold organic compounds and water
mitochandria chem
sites of cellular respiration
- uses O2 to generate ATP
chloroplasts chem
found in plants and algae
- site of photosynthesis
- converts solar enegry to chem energy
mito and chloro similarites
- enveloped by double membrane
- contain free ribosomes and circular dna molecules
- grow and reporduce independently in cells
LEAD TO ENDOSYMBIONT THEORY
ENDOSYMBIONT theory
early ancestor of eukaryotes englufed an oxygen using nonphotosyntehtic cell
- engulfed cell formed relationship with host cell
- evolved into mitochandria
- then it took up photosyntehtic prokayote which evolved into chloroplast
mito function
- found in all eurkayotic cells
- dynamic organelle
- smooth outer membrane, folded inside membrane CRISTAE
what is cristae, function
inner layer of mitochandria, creates a large surface area for enzymes that synthesize ATP
inner layer of mito creates what
intermembrane space and mitochandrial matrix
mitochandrial matrix does what
some metabolic steps of cellular respiration are catalyzed in the matrix
- contains mitochandrial DNA and ribosomes
the chloroplast is one group of plant organelles called
plastids
chroloplast contains what
green pigment called chlorphyll
- includes enzymes and other molecules that function in photosythesis
chloropplast structure includes
thylakoids: double membrane sacs
- granum: stacks of thylakoids
- stroma: internal fluid, contains DNA and ribosomes
perosisome
oxidative organelles
- not part of endomembrane system
- contain enzymes which produce hydrogen peroxide then convert to water
- break down fatty acids and reactive oxygen species
cytoskeleton
- network of fibers that organizes the cells structure and activities
- anchors organelles
- dynamic: constantly reassembling
- throughout cytoplasm
what does the cytoplasm do
helps support the cell and maintain its shape
- interacts with motor proteins to produce cell mobilityu
- organelles and vvesicles can travel along tracks provided by the cytoskeleton
components of cytoskeleton
- microtubules (thickest part)
- microfilaments (also called actin, thinniest)
- intermediate filament (fibers with diameters in a middle range)
microtubules
- hollow rods made of tubin dimers
- largest
microtubule function
- shaping cell, withstand compression
- guiding movement of organeeles
- separating chromosomes during cell division (centrosome/centrioles)
- cell mobility (cilia, falgella)
microfilaments
- solid twisted double chain of actin filaments
- support cells shape
function of microfilaments
- withstand tension (pulled or stretches)
- cellular mobility and contraction
- celluar extensions allow for crawling
- cytoplasmic streaming in plants
intermediate filaments
- in the middle
- more permanent cytoskeleton fixtures
- made up of various sub units
function of intermediate filaments
- support cell shape, withstand tension
- anchor organelles
- formation of nuclear lamina
extracellular components of cells
- most cells synthesize and secrete materials that are external to plasma membrane
- these extracellular materials and structures are involved in many cellular functions
cell wall
an extracellular structure that distingushes plant cells from animal cells
function of cell wall
- protects plant cell
- maintain shape, helps resist force of gravity
- prevents excessive uptake of water
what is the cell wall composed of
cellulose fibers embedded in other polysaccarides and proteins
cell wall layers
- middle lamella: thin layer between primary walls of adjecent cells
- primary cell wall: relatively thing and flexable
- secondary cell wall: added between the plasma membrane and primary cell wall
extracellular matrix
- animal lack cell walls but are covered by an elaborative extracellular matrix (ECM)
the ECM is made up of
glycloproteins such as collagen, proteoglycans and fibronectin
ECM binds to what
receptor proteins called integrins
- integrins are attaached to cytoskeleton
neighbouring cells need to do what
adhere, interact and communicate through direct physical contact
plasmodesmata
PLANTS
are channels that perforate plant cell walls
- cytosol can pass between cells
- joins most of plant into one licing continuum
tight junctions
animal
- membrane of neighbouring cells are pressed toegther
- prevents leakage of extracellular fluid
desmosomes (anchoring junctions)
animal
- fasten cells together into strong sheets
gap junctions (communicating junctions)
animal
- provide cytoplasmic channels between adjecent cells
