CH. 3 ~ CELLS

CELL STRUCTURE AND ORGANELLES

Eukaryotic and Prokaryotic Cells Organisms that are Prokaryotic: Organisms that are Eukaryotic: Every organisms that is not bacteria: Animals Plants Fungus Protists Every bacterial cell Eubacteria Archeabacteria

Eukaryotic vs. Prokaryotic Cells Eukaryotic Cells Prokaryotic Cells Large Have chromosomes Have membrane-bound organelles Nucleus Mitochondria Centrioles (theory of endosymbiosis) Small No chromosomes, only small circle of DNA (plasmid) No membrane-bound organelles. Eukaryotic Cells are Larger than Prokaryotic cells

Cell Wall A rigid structure found on the outside of plant, fungal and bacterial cells Permeable – allows most substances to enter freely Composed of cellulose and protein Located OUTSIDE of the cell membrane Structure relates to function: The rigid structure of the cell wall provides support and structure for the organisms

Cell Membrane Surrounds ALL cells Semi-permeable – only allows certain substances to pass through Contains proteins that help to pass materials through. “Phospholipid bilayer” Flexible and “fluid”

Cytosol/Cytoplasm Fluid inside the cell that contains the organelles and allows reaction to occur Composed mostly of water and plays a role in diffusion of materials across the cell membrane.

Nucleus Membrane-bound organelle Found only in Eukaryotes Controls the cell functions and processes Contains DNA that directs the formation of necessary proteins. (genetic blueprint)

Nucleolus An organelle within the nucleus that produces ribosomes and RNA

Ribosomes small organelles that are sites of protein synthesis Take information from the DNA (delivered to the ribosome by RNA) and use it to make protein Sometimes found on the ER (or the rough endoplasmic reticulum), but also found in the cytoplasm of ALL cells

Endoplasmic reticulum (ER) – Endoplasmic reticulum (ER) – detoxification and transport. Attached to the nuclear membrane and zigzags through the cell Rough or smooth Rough = has ribosomes Smooth = no ribosomes

Golgi Apparatus (Bodies) Packaging and distribution Flattened, layered, sac-like organelles which are located near the nucleus.

MITOCHONDRIA “Powerhouse” of the cell Converts food into energy (ATP) Inner and outer membrane Has it’s own DNA (endosymbiotic theory) Found in Eukaryotes only Found in both plants and animals

CHLOROPLASTS Converts sunlight, water and carbon dioxide to sugar and oxygen through photosynthesis Has chlorophyll – pigment that captures the sun’s light. Inner and outer membrane Found in Eukaryotes only Found only in plants (producers/autotrophs)

Lysosomes Contain enzymes to break down old organelles or kill the cell. Centrioles only in animals cells. Make the spindle for cell reproduction

VACUOLE Contains water (Can also store nutrients, waste products) Large in plants, small in animals Controls “turgor pressure” in plants.

Flagella – long whip-like tail for movement Cilia – short hairs for movement

Animal Plant Cell wall Chloroplasts Large vacuole No centrioles No cell wall No chloroplast Small vacuoles Has centrioles

MITOCHONDRION – these are spherical to rod shaped organelles with a double membrane. Its inner membrane lies in many folds to make projections called cristae. They convert energy stored in glucose into ATP (adenosine triphosphate). CYTOPLASM – it is a jelly-like material around the nucleus containing the organelles. AMYLOPLAST- it is a starch-storing, colorless plastid which occurs only in plant storage tisues. CENTROSOME – it is a small body containing centrioles. It provides the microtubules and helps in cell-division. ROUGH ENDOPLASMIC RETICULUM – it is a complicated system of interconnected, membranous, infolded, convoluted sacks that are located in the cell’s cytoplasm. Its rough appearance is due to the ribosomes that cover it. It transfers materials through the cell and produces proteins in sacks called cristernae. SMOOTH ENDOPLASMIC RETICULUM – it is similar to the rough ER, infact it buds off from it. The space within it is called the ER lumen. It contains enzymes and produces and digests fats and membrane proteins. RIBOSOMES – these are small organelles composed of RNA-rich cytoplasmic granules and are sites of protein synthesis. GOLGI BODY – these are flattened, layered, sac-like organelles which are located near the nucleus.

CELL MEMBRANE - this thin surrounding layer is made up of proteins and fats. It is semipermeable i.e. it allows a few substances to pass through while blocking the others. LYSOSOME – also known as cell vesicles, they are round organelles surrounded by a membrane and help in the digestion of cell nutrients as they contain the digestive enzymes. NUCLEUS – it is spherical in shape and contains the DNA chromosomes alongwith the nucleolus and many other organelles. It controls the protein synthesis thereby controlling many important functions the cell. It is surrounded by a nuclear membrane. NUCLEOLUS – it is an organelle within the nucleus and produces the RNA (ribonucleic acid). NUCLEAR MEMBRANE – it is the membrane surrounding the nucleus. VACUOLE – it is a large space filled with fluid within a plant cell which helps the cell to maintain its shape.

MITOCHONDRION – these are spherical to rod shaped organelles with a double membrane. Its inner membrane lies in many folds to make projections called cristae. CENTROSOME – it is a small body containing centrioles. It provides the microtubules and helps in cell-division. CYTOPLASM – it is a jelly-like material around the nucleus containing the organelles. ROUGH ENDOPLASMIC RETICULUM – it is a complicated system of interconnected, membranous, infolded, convoluted sacks that are located in the cell’s cytoplasm. Its rough appearance is due to the ribosomes that cover it. It transfers materials through the cell and produces proteins in sacks called cristernae. SMOOTH ENDOPLASMIC RETICULUM – it is similar to the rough ER, infact it buds off from it. The space within it is called the ER lumen. It contains enzymes and produces and digests fats and membrane proteins. GOLGI BODY – these are flattened, layered, sac-like organelles which are located near the nucleus. SOME MORE CELL ORGANELLES: PEROXISOMES – cell organelles containing enzymes that catalyze the production and breakdown of Hydrogen Peroxide.