Types of Cells There are two broad groups of cells Organelle Prokaryotes Do NOT have membrane-bound organelles Eukaryotes DO have membrane-bound organelles Organelle Structure within a cell that is surrounded by a membrane and has a specific function for cell survival

Prokaryotes No membrane-bound organelles DNA not bound in a nucleus Many prokaryotes are unicellular This cell type includes all bacteria

Eukaryotes Does Contain membrane-bound organelles DNA is bound in a nucleus Eukaryotes may be unicellular (algae and yeast) or multicellular (plants and animals)

Plasma Membrane Boundary of the cell Controls what goes in and out of the cell through the selectively permeable membrane Keeps some things out and lets some things in Maintains cell’s homeostasis

Plasma Membrane Components– Phospholipid Bilayer Two layers of phospholipids give the cell a stable yet flexible boundary Makes up the majority of the plasma membrane Hydrophilic exteriors Water “loving” Hydrophobic interior Water “hating” Why? Structure of the molecule! Phosphate head = hydrophilic, polar Hydrocarbon tails = hydrophobic, non-polar

Plasma Membrane Components– Membrane Proteins Carrier Channel Marker Receptor

Plasma Membrane Components– Fluid Mosaic Model The phospholipids move freely within the membrane (but do not flip to the other side) Fluid The membrane proteins float on and around the membrane like little boats Mosaic These comparisons are why this plasma membrane structure is called the fluid mosaic model

Cell Wall Found outside the cell membrane Gives the cell added support and protection Made of the carbohydrate, cellulose This mesh of cellulose is porous and allows anything to pass through Plants, fungi, and most bacteria (prokaryotes) have cell walls Animals DO NOT

Nucleus and Nuclear Envelope Controls most of the cell processes and contains the DNA (like the brain of the cell) In almost all eukaryotic cells (plants AND animals) Made up of a few parts: Chromatin- tangled strands of DNA bound to protein, spread throughout nucleus becomes visible chromosomes during cell division) Nucleolus- small dense region where assembly of the ribosome begins Nuclear Envelope- double-membrane layer with pores that allow material to move in and out of the nucleus

Mitochondria Transform food energy into high-energy compounds that the cell can use to power growth, development, and movement The “POWERHOUSE” Smooth outer membrane and highly-folded inner membrane The more energy a cell needs, the more mitochondria they may have For example, a muscle cell would need more mitochondria than a bone cell because it requires more energy to do its job In eukaryotic cells

Chloroplast Use energy from sunlight to make energy-rich molecules during photosynthesis Have a double membrane and the green pigment chlorophyll Inner membrane is folded into disks called thylakoids that are arranged in stacks called grana Only found in plants and algae

Ribosomes Function: Produce proteins following coded instructions that come from the nucleus Structure: Made of a large unit and a small unit that only come together when they are making a strand of protein Can be free or on the Rough Endoplasmic Reticulum In eukaryotes AND prokaryotes

Endoplasmic Reticulum (ER) Structure: folded membranes within the cytoplasm “Workplace” of the cell Rough ER Function: modifies the proteins that are made on its ribosomes Smooth ER Function: Contain special enzymes and help to make lipids for the cell membrane. In eukaryotes only

Golgi Apparatus Structure: flattened system of tubular membranes Function: Receives modified proteins form the ER and completes the processing of the proteins, packages them in vesicles, and ships them out to their destinations within or out of the cell. Also organizes lysosomes. In eukaryotes

Lysosomes Small organelles containing digestive enzymes to break down food particles, worn out organelles, bacteria, and viruses into particles that can be used by the rest of the cell The “Wrecking Crew” of a cell In eukaryotes

Vacuoles Sac-like structures that store materials such as water, salts, proteins, and carbohydrates Plants have one large vacuole that also helps give support to flowers and leaves In eukaryotes animal plant

Centrioles Structure: Look like a pair of hollow cylinders which lie perpendicular to each other near the nucleus of the cell. Function: Plays a role in organizing the mitotic spindle during cell division; plays a role in organizing the basal bodies that build cilia and flagella. Only in Animal Cells

Cilia and Flagella Function: Helps to move the cell or its outer environment; some organisms use them to capture food. Cilia – short, numerous, hair-like projections that move in a wavelike motion Flagella – longer projections that move in a whip-like motion Major means of locomotion for unicellular organisms

Cytoskeleton A network of protein filaments that helps the cell maintain its shape and helps with cell movement Microtubules- hollow tubes of protein that maintain cell shape Microfilaments- long, thin fibers that function in movement and support of cell. Smaller than microtubules

Prokaryotes vs. Plants vs. Animals Organelle Prokaryotes Eukaryotes Plants Animals Plasma Membrane Cell Wall Nucleus DNA Mitochondria Chloroplasts Ribosomes                

Prokaryotes vs. Plants vs. Animals Organelle Prokaryotes Eukaryotes Plants Animals Endoplasmic Reticulum Golgi Apparatus Lysosomes Vacuoles Centrioles Cilia or Flagella            

Cell Size Cells will grow larger to a certain point and then their growth will slow down Eventually they will stop growing and divide into two smaller cells These smaller cells will then grow until they divide Why not just keep growing?

Surface Area vs. Volume Materials must move through the cell by diffusion or by vacuole transport The further materials travel, the more time and/or energy must be used to move them Larger cell means a greater surface area for exchanging materials BUT also means a larger volume through which materials must travel Cells must maintain the proper surface area/volume ratio Membranes in the cell are often folded to create greater surface area for exchange Example - Mitochondria