Cell Ultrastructure Flashcards
(31 cards)
What are the features of eukaryotic cells?
Have distinct nucleus and membrane bound organelles.
Eukaryotic cells: describe the structure of a cell wall.
Formed on outside of cell membrane.
Structural support is provided by the polysaccharide cellulose (plants) and peptidoglycan (bacteria cells).
Plasmodesmata (narrow threads of cytoplasm) connect cytoplasm of neighbouring plant cells.
Eukaryotic cells: describe the function of a cell wall.
Provide structural support for plant cells.
Eukaryotic cell: describe the structure of the nucleus.
Surrounded by nuclear envelope which is double membraned with nuclear pores (large holes containing proteins).
Interior = nucleoplasm full of chromatin (DNA/protein complex)
Nucleolus = dark region of chromatin involved in making ribosomes.
Eukaryotic cells: describe the function of the nucleus.
Largest organelle
Controls cell division and growth
Contains the cells DNA
Eukaryotic cells: describe the structure of mitochondrion.
Surrounded by double membrane (outer membrane)
Mitochondria matrix = small circular strands of DNA (space enclosed by inner membrane)
Inner membrane studded with stacked particles (enzymes that make ATP)
Eukaryotic cells: describe the function of mitochondrion
Aerobic respiration
Release energy (ATP)
Eukaryotic cells: describe the structure of the chloroplast
Larger than mitochondria
Surrounded by double membrane
Thylakoids (membrane bound compartments) - contain chlorophyll stacks to form grana (maximises light catchment)
Grana joined by lamellae (thin + flat thylakoids)
Eukaryotic cells: describe the function of the chloroplast.
Photosynthesis - chlorophyll for light absorption (different pigments to adsorb different wavelengths)
- stroma contains enzymes
Starch grains/lipid droplets store products
Synthesis proteins - contain DNA and ribosomes
Eukaryotic cells: describe the structure of ribosomes.
Free in cytoplasm or attached to rough endoplasmic reticulum
Larger 80S type
Eukaryotic cells: describe the function of the ribosomes.
Smallest + most numerous organelle
Protein synthesis
Eukaryotic cells: describe the structure of endoplasmic reticulum
Series of interconnected membrane channels
RER - studded with ribosomes
SER - no ribosomes
Eukaryotic cells: describe the function of the endoplasmic reticulum
Synthesis and transport materials
RER - synthesis proteins before being exported via Golgi body
SER - process materials mainly lipids needed by cell
Eukaryotic cells: describe the structure of the Golgi body
Series of flattened stacks of membrane vesicles formed from ER
Eukaryotic cells: describe the function of the Golgi body
Transports proteins from RER to cell membrane
RER fuses with one side of GB membranes and are modified while at other side small vesicles bud off and move towards cell membrane, where they fuse releasing contents by exocytosis
Eukaryotic cells: describe the structure of the vacuole.
Sac in plant cells surrounded by tonoplast (selectively permeable membrane)
In animals cells not permeable and small
Eukaryotic cells: describe the function of the vacuole
Provides structural support
Eukaryotic cells: describe the structure of lysosomes
Small membrane bound vesicles formed from RER
Contain a cocktail of hydrolytic enzymes
Eukaryotic cells: describe the function of lysosomes.
Recycle materials - break down unwanted chemicals, toxins, organelles and even whole cells
Can fuse with vacuole to digest it’s contents
What are the organelles present in eukaryotic cells?
Cell membrane
Cell wall
Nucleus
Mitochondria
Chloroplast
Ribosomes
Endoplasmic reticulum (rough and smooth)
Golgi body
Vacuole
Lysosomes
Prokaryotic cells: describe the structure of plasmid DNA
Smaller circular DNA
Sometimes present in bacteria
Prokaryotic cells: describe the function of plasmid DNA
Can replicate independently and be passed between bacteria
Prokaryotic cells: describe the structure of the capsule
Surrounds cell wall
Gelatinous structure made of polysaccharides
Prokaryotic cells: describe the function of the capsule
Prevents bacteria from being ingested by phagocytes and adhere to surfaces
Can provide protection
