Cheatsheet: Cell Structure and Function | AP Biology - Grade 9 PDF Download

 Page 1


UNIT II n o i t c n u F d n a e r u t c u r t S l l e C :  
A. Living Things 
? All living things are composed of cells 
? According to cell theory, the cell is life’s basic unit of structure and function 
? Cell is the smallest unit of living material that can carry out all the activities necessary for 
life 
? Why not be a GIANT CELL? 
? Specialization 
? Must maintain high surface area:volume ratio to allow cellular exchanges across the 
membrane! 
¦  
B. Types of Cells and Organelles 
? Invention of electron microscopes allowed scientists to figure out the exact functions of cells 
? Prokaryotic cells 
? Only in domains Bacteria and Archaea 
? Smaller 
? Simpler 
? Circular DNA 
¦ In nucleoid region 
¦ NO NUCLEUS 
? Cell wall 
¦ Made up of peptidoglycans that surround a lipid layer called the plasma 
membrane 
? Filled with semi-fluid cytosol 
? Have ribosomes 
? Can have flagella 
¦ Long projections used for motility 
? May have a thick capsule outside their cell wall to give them extra protection 
? No membrane-bound organelles 
? Eukaryotic cells 
? More complex 
? Organized into smaller structures called organelles 
? DNA in nucleus bounded by a membranous nuclear envelope 
? Cytoplasm between plasma membrane and nucleus 
C. Organelles 
? Each organelle has its own special task 
? Plasma Membrane 
? Outer envelope 
? Complex 
? Phospholipid bilayer 
? Encloses vacuole 
? Regulates movement in/out of cell 
 
 
Page 2


UNIT II n o i t c n u F d n a e r u t c u r t S l l e C :  
A. Living Things 
? All living things are composed of cells 
? According to cell theory, the cell is life’s basic unit of structure and function 
? Cell is the smallest unit of living material that can carry out all the activities necessary for 
life 
? Why not be a GIANT CELL? 
? Specialization 
? Must maintain high surface area:volume ratio to allow cellular exchanges across the 
membrane! 
¦  
B. Types of Cells and Organelles 
? Invention of electron microscopes allowed scientists to figure out the exact functions of cells 
? Prokaryotic cells 
? Only in domains Bacteria and Archaea 
? Smaller 
? Simpler 
? Circular DNA 
¦ In nucleoid region 
¦ NO NUCLEUS 
? Cell wall 
¦ Made up of peptidoglycans that surround a lipid layer called the plasma 
membrane 
? Filled with semi-fluid cytosol 
? Have ribosomes 
? Can have flagella 
¦ Long projections used for motility 
? May have a thick capsule outside their cell wall to give them extra protection 
? No membrane-bound organelles 
? Eukaryotic cells 
? More complex 
? Organized into smaller structures called organelles 
? DNA in nucleus bounded by a membranous nuclear envelope 
? Cytoplasm between plasma membrane and nucleus 
C. Organelles 
? Each organelle has its own special task 
? Plasma Membrane 
? Outer envelope 
? Complex 
? Phospholipid bilayer 
? Encloses vacuole 
? Regulates movement in/out of cell 
 
 
? Flexible due to weak bonds holding it together 
¦ Higher fluidity when more phospholipids have double bonds (causing a bend in 
the tail) since the molecules aren’t as packed  
? Semipermeable 
¦ Only small hydrophobic molecules can pass through unaided 
¦ Anything large/hydrophilic must pass through active/passive transport 
¦ Water can’t move through easily due to its polarity 
? Fluid-mosaic model 
¦ Peripheral proteins are loosely associated with the lipid bilayer 
? Located on inner/outer surface of membrane 
¦ Integral proteins are firmly bound into the plasma membrane 
? Amphipathic to allow anchoring 
? Some extend all the way through the membrane 
¦ Membrane peppered with different proteins/carb chains 
? Adhesion proteins 
¦ membrane proteins form junctions between adjacent cells  
? Receptor proteins 
¦ Serve as docking sites for arrivals at the cell 
¦ Ex. hormones 
? Transport proteins 
¦ Form pumps that use ATP to actively transport solutes across the membrane 
¦ Hydrophilic channel that certain molecules/ions can use as a tunnel 
¦ Specific for substance it moves 
? Carrier Proteins 
¦ Bind to molecules and change shape to shuttle them across the membrane 
? Channel proteins 
¦ Selectively allow the passage of ions/molecules 
? Cell surface marker 
¦ Exposed on cellular surface  
¦ Play a role in cell recognition/adhesion 
¦ Ex. glycoproteins 
? Carbohydrate side chains 
¦ Attached to surface of some proteins 
¦ Found only on outer surface 
? Cholesterol 
¦ Maintain fluidity    
¦ Unsaturated fats also lend membrane fluidity by increasing space between 
phospholipids due to bend 
 
Page 3


UNIT II n o i t c n u F d n a e r u t c u r t S l l e C :  
A. Living Things 
? All living things are composed of cells 
? According to cell theory, the cell is life’s basic unit of structure and function 
? Cell is the smallest unit of living material that can carry out all the activities necessary for 
life 
? Why not be a GIANT CELL? 
? Specialization 
? Must maintain high surface area:volume ratio to allow cellular exchanges across the 
membrane! 
¦  
B. Types of Cells and Organelles 
? Invention of electron microscopes allowed scientists to figure out the exact functions of cells 
? Prokaryotic cells 
? Only in domains Bacteria and Archaea 
? Smaller 
? Simpler 
? Circular DNA 
¦ In nucleoid region 
¦ NO NUCLEUS 
? Cell wall 
¦ Made up of peptidoglycans that surround a lipid layer called the plasma 
membrane 
? Filled with semi-fluid cytosol 
? Have ribosomes 
? Can have flagella 
¦ Long projections used for motility 
? May have a thick capsule outside their cell wall to give them extra protection 
? No membrane-bound organelles 
? Eukaryotic cells 
? More complex 
? Organized into smaller structures called organelles 
? DNA in nucleus bounded by a membranous nuclear envelope 
? Cytoplasm between plasma membrane and nucleus 
C. Organelles 
? Each organelle has its own special task 
? Plasma Membrane 
? Outer envelope 
? Complex 
? Phospholipid bilayer 
? Encloses vacuole 
? Regulates movement in/out of cell 
 
 
? Flexible due to weak bonds holding it together 
¦ Higher fluidity when more phospholipids have double bonds (causing a bend in 
the tail) since the molecules aren’t as packed  
? Semipermeable 
¦ Only small hydrophobic molecules can pass through unaided 
¦ Anything large/hydrophilic must pass through active/passive transport 
¦ Water can’t move through easily due to its polarity 
? Fluid-mosaic model 
¦ Peripheral proteins are loosely associated with the lipid bilayer 
? Located on inner/outer surface of membrane 
¦ Integral proteins are firmly bound into the plasma membrane 
? Amphipathic to allow anchoring 
? Some extend all the way through the membrane 
¦ Membrane peppered with different proteins/carb chains 
? Adhesion proteins 
¦ membrane proteins form junctions between adjacent cells  
? Receptor proteins 
¦ Serve as docking sites for arrivals at the cell 
¦ Ex. hormones 
? Transport proteins 
¦ Form pumps that use ATP to actively transport solutes across the membrane 
¦ Hydrophilic channel that certain molecules/ions can use as a tunnel 
¦ Specific for substance it moves 
? Carrier Proteins 
¦ Bind to molecules and change shape to shuttle them across the membrane 
? Channel proteins 
¦ Selectively allow the passage of ions/molecules 
? Cell surface marker 
¦ Exposed on cellular surface  
¦ Play a role in cell recognition/adhesion 
¦ Ex. glycoproteins 
? Carbohydrate side chains 
¦ Attached to surface of some proteins 
¦ Found only on outer surface 
? Cholesterol 
¦ Maintain fluidity    
¦ Unsaturated fats also lend membrane fluidity by increasing space between 
phospholipids due to bend 
 
 
? Nucleus 
? Largest organelle of cell 
? Directs what  goes on in cell 
? Responsible for cell’s ability to reproduce 
? Home of hereditary information (DNA) 
¦ DN organized into large structures called chromosomes 
? Most visible structure of nucleus id nucleolus, which is where rRNA is made and 
ribosomes are assembled 
? Ribosomes 
? Sites of protein synthesis 
? Manufacture all proteins required/secreted by the cell 
? Consists of RNA and other proteins 
? Bind messenger RNA and transfer RNA to synthesize proteins 
? Round structures consisting of 2 subunits:te large subunit and the small subunit 
? Composed of RNA and proteins 
? Can either be free floating or attached to the endoplasmic reticulum (ER) 
 
 
Page 4


UNIT II n o i t c n u F d n a e r u t c u r t S l l e C :  
A. Living Things 
? All living things are composed of cells 
? According to cell theory, the cell is life’s basic unit of structure and function 
? Cell is the smallest unit of living material that can carry out all the activities necessary for 
life 
? Why not be a GIANT CELL? 
? Specialization 
? Must maintain high surface area:volume ratio to allow cellular exchanges across the 
membrane! 
¦  
B. Types of Cells and Organelles 
? Invention of electron microscopes allowed scientists to figure out the exact functions of cells 
? Prokaryotic cells 
? Only in domains Bacteria and Archaea 
? Smaller 
? Simpler 
? Circular DNA 
¦ In nucleoid region 
¦ NO NUCLEUS 
? Cell wall 
¦ Made up of peptidoglycans that surround a lipid layer called the plasma 
membrane 
? Filled with semi-fluid cytosol 
? Have ribosomes 
? Can have flagella 
¦ Long projections used for motility 
? May have a thick capsule outside their cell wall to give them extra protection 
? No membrane-bound organelles 
? Eukaryotic cells 
? More complex 
? Organized into smaller structures called organelles 
? DNA in nucleus bounded by a membranous nuclear envelope 
? Cytoplasm between plasma membrane and nucleus 
C. Organelles 
? Each organelle has its own special task 
? Plasma Membrane 
? Outer envelope 
? Complex 
? Phospholipid bilayer 
? Encloses vacuole 
? Regulates movement in/out of cell 
 
 
? Flexible due to weak bonds holding it together 
¦ Higher fluidity when more phospholipids have double bonds (causing a bend in 
the tail) since the molecules aren’t as packed  
? Semipermeable 
¦ Only small hydrophobic molecules can pass through unaided 
¦ Anything large/hydrophilic must pass through active/passive transport 
¦ Water can’t move through easily due to its polarity 
? Fluid-mosaic model 
¦ Peripheral proteins are loosely associated with the lipid bilayer 
? Located on inner/outer surface of membrane 
¦ Integral proteins are firmly bound into the plasma membrane 
? Amphipathic to allow anchoring 
? Some extend all the way through the membrane 
¦ Membrane peppered with different proteins/carb chains 
? Adhesion proteins 
¦ membrane proteins form junctions between adjacent cells  
? Receptor proteins 
¦ Serve as docking sites for arrivals at the cell 
¦ Ex. hormones 
? Transport proteins 
¦ Form pumps that use ATP to actively transport solutes across the membrane 
¦ Hydrophilic channel that certain molecules/ions can use as a tunnel 
¦ Specific for substance it moves 
? Carrier Proteins 
¦ Bind to molecules and change shape to shuttle them across the membrane 
? Channel proteins 
¦ Selectively allow the passage of ions/molecules 
? Cell surface marker 
¦ Exposed on cellular surface  
¦ Play a role in cell recognition/adhesion 
¦ Ex. glycoproteins 
? Carbohydrate side chains 
¦ Attached to surface of some proteins 
¦ Found only on outer surface 
? Cholesterol 
¦ Maintain fluidity    
¦ Unsaturated fats also lend membrane fluidity by increasing space between 
phospholipids due to bend 
 
 
? Nucleus 
? Largest organelle of cell 
? Directs what  goes on in cell 
? Responsible for cell’s ability to reproduce 
? Home of hereditary information (DNA) 
¦ DN organized into large structures called chromosomes 
? Most visible structure of nucleus id nucleolus, which is where rRNA is made and 
ribosomes are assembled 
? Ribosomes 
? Sites of protein synthesis 
? Manufacture all proteins required/secreted by the cell 
? Consists of RNA and other proteins 
? Bind messenger RNA and transfer RNA to synthesize proteins 
? Round structures consisting of 2 subunits:te large subunit and the small subunit 
? Composed of RNA and proteins 
? Can either be free floating or attached to the endoplasmic reticulum (ER) 
 
 
? Endoplasmic Reticulum (ER) 
? Continuous channel that extends into many regions of the cytoplasm 
? Lipid proteins synthesis/transport 
? Rough ER 
¦ Attached to nucleus 
¦ Studded with ribosomes 
¦ Proteins generated here are trafficked to/across plasma membrane, or used to  
build Golgi bodies, lysosomes, or the ER. 
? Smooth ER 
? Lacks ribosomes 
? Makes: 
? Lipids 
? Hormones 
? Steroids 
? Breaks down toxic chemicals 
? Golgi Bodies 
? Process proteins 
? Once the ribosomes on the rough ER have completed synthesizing proteins, the Golgi 
bodies modify, process, and sort the products 
? packaging/distribution centers for materials destined to be sent out of cell 
? Package final products into vesicles 
¦ Carry products to plasma membrane 
? Involved in production of lysosomes 
? Mitochondria 
? “PoWeRhOUsE oF ThE cElL” 
? Responsible for converting the energy from organic molecules into useful energy for the 
cell 
? Energy molecule in the cell is adenosine triphosphate (ATP) 
? Unique oblong shape and characteristic double membrane consisting of an inner portion 
and an outer portion 
? Inner membrane forms folds called cristae 
¦ Separates innermost area (called the matrix) from the intermembrane space 
¦ Outer membrane separates the intermembrane space from the cytoplasm 
¦ Production of ATP done on the cristae 
 
 
 
 
Page 5


UNIT II n o i t c n u F d n a e r u t c u r t S l l e C :  
A. Living Things 
? All living things are composed of cells 
? According to cell theory, the cell is life’s basic unit of structure and function 
? Cell is the smallest unit of living material that can carry out all the activities necessary for 
life 
? Why not be a GIANT CELL? 
? Specialization 
? Must maintain high surface area:volume ratio to allow cellular exchanges across the 
membrane! 
¦  
B. Types of Cells and Organelles 
? Invention of electron microscopes allowed scientists to figure out the exact functions of cells 
? Prokaryotic cells 
? Only in domains Bacteria and Archaea 
? Smaller 
? Simpler 
? Circular DNA 
¦ In nucleoid region 
¦ NO NUCLEUS 
? Cell wall 
¦ Made up of peptidoglycans that surround a lipid layer called the plasma 
membrane 
? Filled with semi-fluid cytosol 
? Have ribosomes 
? Can have flagella 
¦ Long projections used for motility 
? May have a thick capsule outside their cell wall to give them extra protection 
? No membrane-bound organelles 
? Eukaryotic cells 
? More complex 
? Organized into smaller structures called organelles 
? DNA in nucleus bounded by a membranous nuclear envelope 
? Cytoplasm between plasma membrane and nucleus 
C. Organelles 
? Each organelle has its own special task 
? Plasma Membrane 
? Outer envelope 
? Complex 
? Phospholipid bilayer 
? Encloses vacuole 
? Regulates movement in/out of cell 
 
 
? Flexible due to weak bonds holding it together 
¦ Higher fluidity when more phospholipids have double bonds (causing a bend in 
the tail) since the molecules aren’t as packed  
? Semipermeable 
¦ Only small hydrophobic molecules can pass through unaided 
¦ Anything large/hydrophilic must pass through active/passive transport 
¦ Water can’t move through easily due to its polarity 
? Fluid-mosaic model 
¦ Peripheral proteins are loosely associated with the lipid bilayer 
? Located on inner/outer surface of membrane 
¦ Integral proteins are firmly bound into the plasma membrane 
? Amphipathic to allow anchoring 
? Some extend all the way through the membrane 
¦ Membrane peppered with different proteins/carb chains 
? Adhesion proteins 
¦ membrane proteins form junctions between adjacent cells  
? Receptor proteins 
¦ Serve as docking sites for arrivals at the cell 
¦ Ex. hormones 
? Transport proteins 
¦ Form pumps that use ATP to actively transport solutes across the membrane 
¦ Hydrophilic channel that certain molecules/ions can use as a tunnel 
¦ Specific for substance it moves 
? Carrier Proteins 
¦ Bind to molecules and change shape to shuttle them across the membrane 
? Channel proteins 
¦ Selectively allow the passage of ions/molecules 
? Cell surface marker 
¦ Exposed on cellular surface  
¦ Play a role in cell recognition/adhesion 
¦ Ex. glycoproteins 
? Carbohydrate side chains 
¦ Attached to surface of some proteins 
¦ Found only on outer surface 
? Cholesterol 
¦ Maintain fluidity    
¦ Unsaturated fats also lend membrane fluidity by increasing space between 
phospholipids due to bend 
 
 
? Nucleus 
? Largest organelle of cell 
? Directs what  goes on in cell 
? Responsible for cell’s ability to reproduce 
? Home of hereditary information (DNA) 
¦ DN organized into large structures called chromosomes 
? Most visible structure of nucleus id nucleolus, which is where rRNA is made and 
ribosomes are assembled 
? Ribosomes 
? Sites of protein synthesis 
? Manufacture all proteins required/secreted by the cell 
? Consists of RNA and other proteins 
? Bind messenger RNA and transfer RNA to synthesize proteins 
? Round structures consisting of 2 subunits:te large subunit and the small subunit 
? Composed of RNA and proteins 
? Can either be free floating or attached to the endoplasmic reticulum (ER) 
 
 
? Endoplasmic Reticulum (ER) 
? Continuous channel that extends into many regions of the cytoplasm 
? Lipid proteins synthesis/transport 
? Rough ER 
¦ Attached to nucleus 
¦ Studded with ribosomes 
¦ Proteins generated here are trafficked to/across plasma membrane, or used to  
build Golgi bodies, lysosomes, or the ER. 
? Smooth ER 
? Lacks ribosomes 
? Makes: 
? Lipids 
? Hormones 
? Steroids 
? Breaks down toxic chemicals 
? Golgi Bodies 
? Process proteins 
? Once the ribosomes on the rough ER have completed synthesizing proteins, the Golgi 
bodies modify, process, and sort the products 
? packaging/distribution centers for materials destined to be sent out of cell 
? Package final products into vesicles 
¦ Carry products to plasma membrane 
? Involved in production of lysosomes 
? Mitochondria 
? “PoWeRhOUsE oF ThE cElL” 
? Responsible for converting the energy from organic molecules into useful energy for the 
cell 
? Energy molecule in the cell is adenosine triphosphate (ATP) 
? Unique oblong shape and characteristic double membrane consisting of an inner portion 
and an outer portion 
? Inner membrane forms folds called cristae 
¦ Separates innermost area (called the matrix) from the intermembrane space 
¦ Outer membrane separates the intermembrane space from the cytoplasm 
¦ Production of ATP done on the cristae 
 
 
 
 
? Lysosomes 
? Tiny sacs that carry digestive enzymes 
? Break down old/worn out organelles/debris/large ingested particles 
? Cells clean-up crew 
? Keep cytoplasm clear of unnecessary flotsam 
? Sometimes contain hydrolytic enzymes that function only at an acidic pH, which is 
enclosed inside the lumen of the lysosome 
 
? Centrioles 
? Small. Paired, cylindrical structured often found within microtubule organizing centers 
(MTOCs) 
? Most active during cellular division 
¦ When  cell is ready to divide, centrioles produce microtubules, which pull the 
replicated chromosomes apart and move them to opposite ends of the cell 
? Common in animal cells but not in plants 
? Vacuoles 
? Latin for “empty cavity” 
? Fluid-filled sacs that store water/food/wastes/salts/pigments for later use/removal 
? Larger in plant cells 
? Peroxisomes 
? Breakdown of long fatty acids through beta-oxidation 
? Cytoskeleton 
? Network of fibers that maintain cell shape 
? Most important: 
¦ Microtubules 
?  Made up of protein tubulin 
? Participate in cellular division/movement 
? Integral part of centrioles/cilia/flagella 
¦ Microfilaments 
? Important for movement 
? Composed of protein actin 
? Actin monomers joined together and broken apart as needed to allow 
microfilaments to grow and shrink 
? Assist during cytokinesis/muscle contraction/formation of pseudopodia 
extension during cell movement 
? Cilia and Flagella 
? Allow motion in single-celled organisms 
? In respiratory tract, cilia sweep constantly back and forth to keep out pathogens/dust 
? Every sperm cell has flagellum, enabling it to swim through the female reproductive 
organs to fertilize the waiting ovum