1.2 Ultrastructure of cells Flashcards
What are prokaryotes?
Organisms whose cells lack a nucleus
What kingdom do prokaryotes belong to?
Monera
What are the two domains of prokaryotes?
Archaebacteria and eubacteria
What are archaebacteria?
Found in extreme environments like high temperatures, salt conditions and pH
What are eubacteria?
Traditional bacteria including most pathogenic forms
What are the nine typical cellular components in prokaryotes?
Cytoplasm
Nucleoid
Plasmids
Ribosomes
Cell membrane
Cell wall
Slime capsule
Flagella
Pili
What is the cytoplasm?
Internal fluid component of the cell
What is the nucleoid?
Region of the cytoplasm where the DNA is located
What are plasmids?
Autonomous circular DNA molecules that may be transferred between bacteria
What are ribosomes?
Complexes of RNA and protein that are responsible for polypeptide synthesis
What is the cell membrane?
Semi permeable and selective barrier surrounding the cell
What is the cell wall?
Rigid outer covering which maintains shape and prevents bursting
What is the slime capsule?
A thick polysaccharide layer used for protection against drying out and phagocytosis
What is the flagella?
Long slender projections containing a motor protein that enables movement
What is pili?
Hair like extensions that enable adherence to surfaces or mediate bacterial conjugation
What is binary fission?
A form of asexual reproduction used by prokaryotic cells
What is the first stage in the process of binary fissison?
The circular DNA is copied in response to a replication signal
What is the second step in binary fission?
The two DNA loops attach to the membrane
What is the final step of binary fission?
The membrane elongates and pinches off which forms two cells
What are eukaryotes?
Organisms whose cells contain a nucleus
Where did eukaryotes come form?
Prokaryotic cells
What are eukaryotes compartmentalised by?
Organelles
What are organelles?Protista
Membrane bound structures that perform specific roles
What are the four kingdoms of eukaryotes?
Protista
Fungi
Plantae
Animalia
What are protista?
Unicellular organisms or multicellular organisms without specialised tissue
What are fungi?
Have a cell wall made of chitin and obtain nutrition via heterotrophic absorption
What are plantae?
Have a cell wall made of cellulose and obtain nutrition autotrophically
What are animalia?
No cell wall and obtain nutrition via heterotrophic ingestion
What are the twelve structures of an animal cell?
Nucleolus
Nucleus
Cytosol
Ribosomes
Cytoskeleton
Mitochondria
Peroxisome
Golgi apparatus
Lysosome
Plasma membrane
Smooth ER
Rough ER
What are the eleven typical structures of a plant cell?
Ribosomes
Mitochondria
Vacuole
Chloroplast
Plasma membrane
Cell wall
Golgi apparatus
Nucleus
Nucleolus
Rough ER
Smooth ER
What are the three universal organelles?
Ribosomes
Cytoskeleton
Plasma membrane
What is the structure of ribosomes?
Two subunits made of RNA and protein
What size are ribosomes in eukaryotes?
80s
What size are ribosomes in prokaryotes?
70s
What is the function of ribosomes?
Site of polypeptide synthesis
What is the structure of the cytoskeleton?
A filamentous scaffolding within the cytoplasm
What is the function of the cytoskeleton?
Provides internal structure and mediates intracellular transport
What is the structure of the plasma membrane?
Phospholipid bilayer embedded with proteins
What is the function of the plasma membrane?
Semi permeable and selective barrier surrounding the cell
What are the eukaryotic organelles found in both plant and animal cells?
Nucleus
Smooth ER
Rough ER
Golgi apparatus
Mitochondrion
Peroxisome
Centrosome
What is the structure of the nucleus?
Double membrane structure with pores
Contains an inner region called a nucleolus
What is the function of the nucleus?
Stores genetic material as chromatin
What is the function of the nucleolus?
The site of ribosome assembly
What is the structure of the smooth endoplasmic reticulum?
A membrane network that is bare
What is the structure of the rough ER?
A membrane network that is studded with ribosomes
What is the function of the smooth ER?
Transports lipids between organelles
What is the function of the rough ER?
Transports proteins between organelles
What is the structure of the golgi apparatus?
An assembly of vesicles and folded membranes located near the cell membrane
What is the function of the golgi apparatus?
Involved in the sorting, storing, modification and export of secretory products
What is the structure of mitochondrion?
Double membrane structure, inner membrane highly folded into internal cristae
What is the function of mitochondrion?
Site of aerobic respiration/ATP production
What is the structure of peroxisome?
Membranous sac containing a variety of catabolic enzymes
What is the function of peroxisome?
Catalyses breakdown of toxic substances and other metabolites
What is the structure of the centrosome?
Microtubule organising centre
What is the function of the centrosome?
Radiating microtubules form spindle fibres and contribute to cell division
What are the three organelles present only in animal cells?
Chloroplast
Vacuole
Cell wall
What is the structure of chloroplast?
Double membrane structure with internal stacks of thylakoids
What is the function of chloroplast?
Site of photosynthesis
Manufactured organic molecules are stored in various plastids
What is the structure of the vacuole?
Fluid filled internal cavity surrounded by a membrane
What is the function of the vacuole?
Maintains hydrostatic pressure
What is the structure of the cell wall? - plant
External outer covering made of cellulose
What is the only animal cell only organelle?
Lysosome
What is the structure of the lysosome?
Membranous sacs filled with hydrolytic enzymes
What is the function of the cell wall?
Provides support and mechanical strength prevents excess water uptake
What is the function of the lysosome?
Breakdown/hydrolysis of macromolecules
What do electron microscopes use to magnify and resolve microscopic specimens?
Electron beams focused by electromagnets
What do transmission electron microscopes do?
Generate high resolution cross sections of objects
What do scanning electron microscopes do?
Display enhanced depth to map the surface of objects in 3D
What are the two key advantages of electron microscopes when compared to light microscopes?
- higher range of magnification
- higher resolution
What are the disadvantage of electron microscopes?
They cannot display living specimens in natural colours
What is a micrograph?
A photo or digital image taken through a microscope to show a magnified image of a specimen
When talking about micrographs, why may specific shapes vary?
Depending on the location of cross sections
What do cells with many mitochondria typically undertake?
Energy consuming processes
What do cells with extensive ER networks typically undertake?
Secretory activities
What do cells rich in lysosomes typically do?
Digestive processes
What do cells with a lot of chloroplast typically do?
Photosynthesis