Transcript Cell Structures and Functions

Cell Structures and Functions
Plasma Membrane
• Structure
– Phospholipid Membrane:
• Amphipathic
• Forms a Bilayer (hydrophilic heads on interior and
exterior faces of cell)
• Fluid
Plasma Membrane
Function
Maintain homeostasis (allow certain things to
enter/leave cell so internal processes continue)
– Phospholipid bilayer acts as selectively
permeable membrane
– Proteins act as channels
– Carbohydrates act as receptors
– Cholesterol decreases fluidity (stabilizes)
Rough Endoplasmic Reticulum
– Structure
• Lipid Bilayer Network
• Studded with Ribosomes
• In animal cells, associated with the nuclear
membrane
– Function
• Allows cell products (protein) to travel throughout
the cytoplasm
• Protein folding occurs here as well
Smooth Endoplasmic Reticulum
• Structure
– Lipid Bilayer Network
• Function
– Lipid Synthesis
– Allows cell products (lipid primarily) to travel
throughout the cytoplasm
Golgi Apparatus
• Structure
– Layers of Flattened lipid bilayer vesicles
• Function
– Works with Cell Membrane/ER’s to
• Convert lipid/protein products to usable forms
• Transport products throughout/out of cell
Golgi Body: Lysosome
• Structure
– Membrane bound vesicle (golgi body)
– Contains digestive enzymes
• Function
– Digest ingested foods
– Break-up/Recycle used-up organelles
Golgi Body: Microbodies
• Structure
– Small lipid bilayer vesicles
– Example is Peroxisome
• Function
– Associated with mitochondria
– Break up hydrogen peroxide (harmful byproduct
of aerobic respiration)
Cytoskeletal Elements
– Structure
• Protein filaments (3 types)
– Function
• Allows organelles to move throughout the cell
• Move the cell during cell division (or in case of
muscle cell, expands and contracts the cell)
Mitochondria
• Structure
– Double membrane organelle with isolated
compartments
• Function
– Compartments isolate reactions involved with
aerobic respiration
– Function of aerobic respiration is to produce
ATP (usable energy molecule)
Nucleus
• Structure
– Nuclear Membrane and Pores
• Lipid Bilayer w/ associated protein channels
– Chromatin
• DNA + protein (histones)
• Function
– Nuclear membrane and Pores
• Controls access to DNA
– Chromatin
• Keeps Genetic information tightly packed
• Genetic information – info for building proteins
Ribosomes
• Structure
– Made of RNA and Protein
– Large and Small Subunits
• Function
– Site of protein manufacturing
Cytosol
• Structure
• Aqueous solution (mostly water and ions)
• Function
• Fluid medium for chemical reactions
Cilia or Flagella
• Structure
– Protein filaments in a 9+2 arrangement
embedded in the membrane
• Function
– Motile Elements of the Cell
– Allows cell to move or moves substances
around the cell
Vacuoles
• Structure
– Membrane bound vesicles – often made from
in-pocketing of plasma membrane.
– Contain various cell products for storage
• Function
– Store cell products, food, waste, etc.
– In plants, the Central Vacuole contains
enzymes and water. When filled, it maintains
turgor pressure on the cell wall.
Cell Wall
– Structure
• In plants, made of the polysaccharide cellulose as well as the
proteins pectin and lignin. Actually 2 layers, depending on the
cell function, the thicknesses of each vary.
– Contain openings lined with membrane called
Plasmodesmata, that allow things to enter the cell.
• In fungi, made of nitrogen-rich polysaccharide chitin.
– Function
• Provides protection and support in plant and fungi
cells
Chloroplast
• Structure
– Membrane organelle that contains smaller
vesicles called Grana
– Grana’s membrane has high concentration of
chlorophyll
• Function
– Use sunlight energy to produce carbohydrates
Centrosomes
• Structure
– Animal cells (small protein filament bundles
called centrioles)
– Plant cells (associated cytoskeleton elements)
• Function
– Organizes cytoskeleton during cell division to
equally separate chromosomes
– Where all cytoskeleton growth originates