1.2 Ultrastructure Of Cells Flashcards
Ultrastructure
Structures of a biological organism that are at least one nanometer in their smallest dimension
Essential idea (ultrastructure)
Eukaryotes have a more complex cell structure than prokaryotes
Difference between an electron and light microscope
Light microscope magnification limited by visible light spectrum, electron microscope has better resolution. Light microscope allows observation of cell structure, while electron microscope allows observation of ultrastructure
Resolution
The shortest distance between two points that can be distinguished
Prokaryote
Cell that does not contain a nucleus with a simple structure and no compartmentalization. Simplest system that allows life.
Nucleoid
General area within a prokaryote where genetic information is stored
Binary fission
Process through which prokaryotes divide wherein the DNA is replicated semi-conservatively, the cell elongates and pinches off into two genetically identical daughter cells
Eukaryotes
Cells that possess both a nucleus and a complex ultrastructure with compartmentalization
Benefits of compartmentalization
- localized and controlled enzyme conditions = efficient metabolism
- localized conditions
- toxic substances can be isolated
- numbers and locations of organelles can be changed
Nucleus
Spherical membrane possessing double membrane with pores for mRNA passage. Stores genome and transcribes mRNA.
Mitochondria
Possessing a double membrane consisting of a folded inner membrane called cisternae, responsible for cell respiration and the production of ATP. Site of RNA.
Free ribosomes
80S ribosomes that are larger than prokaryotes, responsible for the synthesis of proteins used within the cell
Rough endoplasmic reticulum
80S ribosomes attached, site of protein synthesis, those proteins transported by vestibules to Golgi apparatus for excretion cells. Located close to the nucleus.
Golgi apparatus
Flattened membrane sacs, close to plasma membrane. Modifies, or folds proteins to prepare them for excretion.
Lysosome
Containing strong digestive enzymes that break down food waste and recycle organelles. Due to high enzymatic concentration they stain dark under a microscope.
Vacuoles
Storage units with a single membrane. Central vacuole in a plant occupies majority of space and provides structure.
Flagellum
Unique to animal cells, tail like structure used for movement
Scilla
Animal only hairlike fibers on the outside of a cell that aid in movement and response
Microtubules
Cylindrical fibers that have a variety of functions and play a role in cell division
Chloroplasts
Possessed by many but not all plant cells, site of chlorophyll. Surrounded by a double membrane, containing stacks of thylakoids that increase surface area. Site of photosynthesis and glucose production.
Excess glucose
Stored as starch
Cell wall
Extra cellular, not considered an organelle. Secreted by all plant cells, consisting of permeable and strong cellulose that is difficult to digest.
Difference between eukaryotes and prokaryotes
- eukaryotes have separate membrane bound nucleus
- prokaryotes had free flowing DNA in the cytoplasm
- eukaryotes have complex compartmentalized membrane bound organelles
Plasma membrane
Controls and regulates material exchange
Pili
Protein filaments on cell wall that help cell adhesion and DNA transfer
Difference between prokaryotic and eukaryotic ribosomes
Eukaryotic ribosomes are 80S ribosomes (bigger) while prokaryotic ribosomes are 70S (smaller)
Plasmids
Small circles of DNA that carry a few genes, often responsible for antibiotic resistance + creation of genetically modified bacteria
Semi-conservative chromosome replication
One complete strand of each double helix is directly derived from parental unit
Four kingdoms of eukaryotes
Protocisa, fungi, plantae, animalia
Compartmentalization
The formation of compartments within the cell by membrane bound organelles
Nucleolus
Production of ribosomes
Smoot endoplasmic reticulum
Producing and storing lipids including steroids
Hydrolytic enzymes
Break down proteins, lipids, nucleus acids, carbs, fats etc into their smallest form