Chapter 4 - Cell Structure Flashcards
Scientific units
Cm - 1m = 100cm Mm - 1m = 1000mm Um - 1m = 1,000,000um Nm - 1m = 1,000,000,000nm A - 1m = 10,000,000,000A
Fathers of cell biology
Schleiden + Schwann: proposed cell theory. Schleiden= plant cell
Schwann= animal cell
Hooke+Oken: hooke discovered and named cells (cork)
Oken: believed that all living things are made of cells
Virchow: contributed 3rd point in cell theory ( cells divide)
Cell theory
1) all organisms are made of 1 or more cells. Metabolism+heredity occur inside cells
2) cells are the smallest living things
3) cells arise only from division of previously existing cells.
Magnification
How many times bigger than life the object viewed appears
Combination of power of ocular+objective lens
Resolution
The ability to distinguish between 2 objects which are separate
Something that changes with each type of microscope used
Light microscope
Light passes through specimen+lenses
Lenses magnify and focus image
Light-condenser-slide-magnifier-ocular lens
Light shines from bottom
Resolution= approx. 0.2um or 200mm
Light microscope
Tissue prep
1) kill specimen
2) fix it (preserve with chemicals)
3) embed in wax or plastic
4) slice with microtome
5) stain it
Electron microscope
Electrons pass through or to specimen
Wavelength is shorter than light microscope - shorter wavelength increases resolution
Electron source on top of microscope
Uses magnets as lenses
Scanning electron microscope (SEM)
Specimen @bottom
Electrons go through 3 sets of magnetic lenses-through the coil-bounces off specimen-image read by detector-image goes through black box and to viewing screen.
Resolution= 10nm - creates 3D image
Transmission electron microscope (TEM)
Specimen goes after 1st electromagnetic lens-acts as condenser
Electrons pass to objective lens+to the projective lens
Viewing screen is @ bottom where image can be viewed
Resolution: 0.2nm - 1000x better than light microscope
Much larger than light and requires a vacuum
TEM
Tissue prep
1) kill specimen
2) dehydrate specimen
3) slice + put in plastic
4) stain with heavy metals
Prokaryotic cells
Before nucleus Small,simple,unicellular No membrane bound organelles Live anywhere eukaryotes live,but can live many place eukaryotes can't Most abundant Oldest No nucleus Nucleoid region (DNA)
Eukaryotic cells
After nucleus Larger than prokaryote Complex-specialized cells Some uni but most multicellular Have membrane bound organelles Has nucleus Complex DNA (in nucleus)
Prokaryotes
Bacteria
Structures
Ribosomes Plasmid Flagellum Cytoplasm/protoplasm No nucleus/nucleoid region instead Little structure Rod/spherically shaped Plasma membrane Pili Cell wall (peptidoglycan)
Bacteria
Gram staining (+/-)
Gram + bacteria: thick cell wall-crystal violet stain makes cell wall purple
Gram - bacteria: thin cell wall-crystal violet does not stain-use another stain which turns it pink
Cytoplasm/protoplasm
Semi fluid matrix
Fills interior of cell
Contains all sugars, amino acids, and proteins cell needs
Jello-like consistency
Pilus
Hair-like extensions
Allows cell to transfer genetic materials from one cell to another
Nucleoid region
The area near the centre of the cell that contains most of the genetic material DNA
In cells with no nucleus
Ribosomes
Circular shape
Organelles that carry out protein synthesis
Made of 2 subunits that are made of rRNA and proteins
On RER
Subunits only join to make proteins
Plasmid
A small fragment of circular double stranded DNA that replicates on its own.
Flagellum
Long thread-like structures On the surface of cell Used for movement Rotates like tails' foxy tails Doesn't whip back and forth
Capsule
A gelatinous layer surrounding the cell wall.
Prokaryotic cells
Cell wall
Bacteria is made of peptidoglycan
Plants= cellulose
Fungi=chitin
Primary cell wall-outermost wall
Middle lamella-glues plant cells together
Secondary cell wall- when cell matures inside primary cell wall
Plasma membrane
Separates cell from outside environment Surrounds the cytoplasm. Consists of a single phospholipid bilayer Proteins embedded in it Selectively permeable Cholesterol gives flexibility Receptor/transmembrane sites Interior protein network Cell surface markers
Prokaryotes
2 kingdoms
Bacteria
Archaea
Archaea
No peptidoglycan in cell wall
Less flexible but have membranes that allow them to live in extreme environments.
Can’t adapt well
Has good thermal stability
Membrane has bilayer
Pseudomuran?
Bacteria in a light microscope
4 classifications
1) gram stain
2) flagella
3) cell shape
4) aggregations
Identifying cell shape
Circle - coccus (sing.) cocci (pl.)
Oval - bacillus (sing.) bacilli (pl.)
Comma - vibrios (pl.)
Spiral - spirillium (sing.) spirilla (pl.)
Aggregation
One cell - shape name
2 cells - diplo+shape name
Group of cells - stephalo+shape name
Strand of cells - strepto+shape name
Origin of eukaryotic cells
2 reasons why prokaryotes existed before eukaryotes
1) prokaryotes date 2 billion yrs. before eukaryotes -fossil record
2) complexity of eukaryotes compared to prokaryotes - first thing that changed was the separation of DNA functions and protein building (nucleus)
Endosymbiosis theory
Large prokaryote underwent unfolding
Small prokaryotes engulfed by large prokaryote without being digested
Aerobic=mitochondria
Photosynthetic=chloroplasts
Lead to protoeukaryotic cell - transition cell
Small cells became endosymbionts - both benefits
Nucleus
Controls all cell activities Contains DNA,RNA+proteins Largest organelle Spherical Some have cytoplasmic skeleton to hold it in place. Nucleoplasm-cytoplasm inside nucleus
Chromatin
A complex structure of protein organized chromosomes
Nucleolus
Region of nucleus where intensive synthesis of ribosomal RNA takes place.
Nuclear membrane
2 phospholipid membranes
Nuclear pores - allows ions+small molecules to diffuse between nucleus+rest of the cell
Outer membrane connects to ER
Mitochondria
Oval shaped
Energy metabolism
Double membrane
Own DNA+ribosomes
Both plant+animal cells
Does own cell division
Thought to have arisen from endosymbiosis.
Cristae (christa sing.) - Inner folded membrane. Has proteins that carry out oxidative metabolism(making ATP)
Matrix-inside inner membrane
Intermembrane space- between the 2 membranes.
Chloroplasts
Oval shape
Only in plants
Thought to have arisen by endosymbiosis
Make their own food
Energy metabolism
Double membrane
Own DNA/ribosomes
Contains chlorophyll which makes plants green
Grana (granum sing.)-stacked closed compartments inside inner membrane.
Grana have thylakoids-disk shaped structures.
On surface of thylakoids-light capturing pigments -photosynthesis-chlorophyll.
Stroma- fluid matrix surrounding thylakoids.
Endosymbiosis
When a free-living cell is eaten by another cell but not digested.
Vacuole
Oval shaped Only in plants Tonoplast membrane Stores useful molecules and wastes Plant cells grow by expanding the vacuole Contractile vacuoles - can pump water
Tonoplast
The membrane surrounding a vacuole
Contains channels - lets water in and out
Maintains tonicity/osmotic balance
Vesicles
Circular shape
Membrane bounded sac
Various substances are transported or stored.
Microbodies
Circular shape One membrane Contains a variety of enzymes Peroxisomes Glyoxysomes
Peroxisomes
A microbody that breaks down hydrogen peroxide by catalase
Glyoxysomes
A microbody that contains enzymes that convert fat into carbohydrates.
Plants
Lysosomes
Digestive vesicles Come from Golgi apparatus Contains enzymes that catalyze the break down of proteins, lipids,carbohydrates and nucleic acids Recycle old organelles Eliminates engulfed cells
Plastids
Circular shape
In plants
Site of photosynthesis and starch storage
Leukoplasts
A colourless plastid in which starch grains are stored; usually found in cells not exposed to light.(root cells)
Endoplasmic reticulum
ER
Phospholipid bilayer embedded with proteins
Provides surface for protein and lipid synthesis
Rough (RER)
Smooth(SER)
Rough endoplasmic reticulum
RER
Many ribosomes imbedded
Proteins synthesized on the surface are exported from the cell,sent to lysosomes or vacuoles,or embedded in plasma membrane
Proteins can be modified by adding short chain carbohydrates majoring glycoproteins.
Proteins enter the cisternal space (facing the nucleus)
Smooth endoplasmic reticulum
SER
The membrane contains many embedded enzymes.
The enzymes synthesize carbohydrates and lipids.
Steroid hormones are also synthesized
Stores intracellular calcium.
Modifies foreign substances to make them less toxic
