AP Exam Review Cells

Prokaryotic vs. Eukaryotic Cells Prokaryote Prokaryote “before” “nucleus” “before” “nucleus” Bacteria Bacteria DNA is concentrated in nucleoid (non membrane-bound) DNA is concentrated in nucleoid (non membrane-bound) No membrane bound organelles No membrane bound organelles Eukaryote Eukaryote “true” “nucleus” “true” “nucleus” Protists, plants, fungi, animals Protists, plants, fungi, animals Nucleus holds DNA Nucleus holds DNA Membrane bound organelles Membrane bound organelles

Cellular Organelles Nucleus: Nucleus: “control center” of the cell “control center” of the cell Surrounded by a nuclear envelope Surrounded by a nuclear envelope DNA DNA Nucleolus: site of ribosome synthesis Nucleolus: site of ribosome synthesis

Cellular Organelles Ribosomes Ribosomes Site of protein assembly Free and bound ribosomes

Cellular Organelles Endoplasmic Reticulum: Endoplasmic Reticulum: Made up of membranous tubules and cisternae (sacs) Made up of membranous tubules and cisternae (sacs) Smooth ER: NO ribosomes attached Smooth ER: NO ribosomes attached Synthesis of lipids Synthesis of lipids Metabolism of carbs Metabolism of carbs Detoxification of drugs and other poisons Detoxification of drugs and other poisons Rough ER: ribosomes attached Rough ER: ribosomes attached Protein assembly Protein assembly

Cellular Organelles Smooth and Rough ER Smooth and Rough ER

Cellular Organelles Golgi Apparatus: Golgi Apparatus: Products of the Endoplasmic Reticulum are modified and stored here Products of the Endoplasmic Reticulum are modified and stored here

Cellular Organelles Lysosomes: Lysosomes: Used by cells to digest macromolecules Used by cells to digest macromolecules Sac of hydrolytic enzymes Sac of hydrolytic enzymes Apoptosis: Apoptosis: Programmed cell death Programmed cell death

Cellular Organelles Vacuoles: Vacuoles: Food vacuoles (storage) Food vacuoles (storage) Contractile vacuoles (pump extra water out of cells in freshwater protists) Contractile vacuoles (pump extra water out of cells in freshwater protists) Central vacuole (plant cells) Central vacuole (plant cells) Stores organic compounds, inorganic ions (K+, Cl-), and water Stores organic compounds, inorganic ions (K+, Cl-), and water

Cellular Organelles Peroxisomes: Peroxisomes: Contain enzymes that transfer hydrogen from various substances to oxygen, producing H 2 O 2 as a byproduct Contain enzymes that transfer hydrogen from various substances to oxygen, producing H 2 O 2 as a byproduct Various functions: Various functions: Break fatty acids down into smaller molecules for cellular respiration Break fatty acids down into smaller molecules for cellular respiration Detoxify alcohol in liver Detoxify alcohol in liver

Cellular Organelles Mitochondria Mitochondria Site of cellular respiration Site of cellular respiration “powerhouse of the cell” “powerhouse of the cell” More metabolic activity = more mitochondria More metabolic activity = more mitochondria

Cellular Organelles Mitochondrial Structure: Mitochondrial Structure: Outer membrane Outer membrane Inner membrane: Inner membrane: Cristae = large surface area Cristae = large surface area Intermembrane space Intermembrane space Mitochondrial matrix Mitochondrial matrix

Cellular Organelles Chloroplasts: Chloroplasts: Found in plants and eukaryotic algae Found in plants and eukaryotic algae Site of photosynthesis Site of photosynthesis Contain the green pigment chlorophyll Contain the green pigment chlorophyll

Cellular Organelles Chloroplast Structure Chloroplast Structure Thylakoids Grana = stacks of thylakoids Stroma Fluid outside the thylakoids

Cellular Organelles Cytoskeleton Cytoskeleton Maintains shape of cell Maintains shape of cell Responsible for movement of cell and movement of organelles within cell Responsible for movement of cell and movement of organelles within cell Railroad idea Railroad idea

Cellular Organelles Components of Cytoskeleton: Components of Cytoskeleton: Microtubules – 25 nm diameter Microtubules – 25 nm diameter Intermediate Filaments – 8 – 12 nm diameter Intermediate Filaments – 8 – 12 nm diameter Microfilaments – 7 nm diameter Microfilaments – 7 nm diameter

Cellular Organelles Microtubules Microtubules Hollow tubes Hollow tubes Made up of A- and B-tubulin Made up of A- and B-tubulin Responsible for: Responsible for: Cell motility (cilia/flagella) Cell motility (cilia/flagella) Chromosome movements (mitosis) Chromosome movements (mitosis) Movement of organelles Movement of organelles Maintenance of cell shape Maintenance of cell shape

Cellular Organelles Intermediate Filaments Intermediate Filaments Made up of fibrous proteins Made up of fibrous proteins Made up of keratin Made up of keratin Responsible for: Responsible for: Structural support Structural support Maintenance of cell shape Maintenance of cell shape

Cellular Organelles Microfilaments Microfilaments Made up of 2 intertwined strands of actin Made up of 2 intertwined strands of actin Responsible for: Responsible for: Muscle contraction Muscle contraction Cytoplasmic streaming Cytoplasmic streaming Cell motility (pseudopodia) Cell motility (pseudopodia) Cell division (cleavage furrow) Cell division (cleavage furrow) Maintenance of/changes in cell shape Maintenance of/changes in cell shape

Cellular Organelles Cell Wall Cell Wall Found only in plant cells Found only in plant cells Protects the cell wall Protects the cell wall Maintains cell shape Maintains cell shape Prevents excessive uptake of water Prevents excessive uptake of water Hold plant up against gravity Hold plant up against gravity

Cellular Organelles Extracellular Matrix: Extracellular Matrix: Found in animal cells Made up of glycoproteins (collagen) & proteoglycans Proteins + carbohydrates Provides support and anchorage for cells Differs from one cell type to another

Intercellular Junctions Neighboring cells are connected to one another Neighboring cells are connected to one another Plant cells: Plant cells: Plasmodesmata: Plasmodesmata: Channels in the cell wall through which strands of cytoplasm pass through and connect the living contents of adjacent cells Channels in the cell wall through which strands of cytoplasm pass through and connect the living contents of adjacent cells

Intercellular Junctions Animal Cells: Animal Cells: Tight junctions Tight junctions Desmosomes Desmosomes Gap junctions Gap junctions

Intercellular Junctions Tight junctions: Tight junctions: Membranes of neighboring cells are fused Form a continuous “belt” around a cell Example: digestive tract

Intercellular Junctions Desmosomes Desmosomes Anchoring junctions Anchoring junctions Act as rivets Act as rivets

Intercellular Junctions Gap junctions Gap junctions Communicating junctions Communicating junctions Cytoplasmic channels between adjacent cells Cytoplasmic channels between adjacent cells Salts, sugars, AAs, etc. can pass through Salts, sugars, AAs, etc. can pass through

Diffusion vs. Osmosis Diffusion: Movement of molecules from high to low concentration until equilibrium is reached. Passive Transport= no energy required What substances may diffuse across membrane? Nonpolar (non-charged) molecules; small polar molecules Osmosis: The passive transport of water across a selectively permeable membrane Hyper-, hypo-, iso- tonic RELATIVE TERMS!! Always referring to solute concentration Water moves from areas of lower concentration of solutes (hypotonic) to areas of higher solute concentration (hypertonic)

Mitosis