The Cell Cell Anatomy Parts and Function

The Cell

Cell Anatomy: Parts and Function Animal Cell • Basic teaching tool • 2 -D Drawing, in real life, cells are 3 -D • In real cell, not all organelles would be present (depending on type of cell) • Some organelles would cover others, so we wouldn’t be able to see every single organelle

Cell Membrane (not an organelle) • Function: Provides shape and flexibility Moves materials and waste products into and out of cell • Selectively Permeable- allows certain substances to cross into cell easily and blocks others from entering at all

Cell Membrane • Once thought that the cell membrane was stationary, now due to advancements in technology (SEM) determined that the cell membrane is constantly moving/changing, this is known as the fluid mosaic model. • Example of flexibility: RBC is too big for capillary but can still squeeze through

Cytoplasm (not an organelle) • (Protoplasm, Cytosol) • Found between cell membrane and nucleus (contributes to shape and flexibility) • Mostly water (aqueous solution) in which organelles are found/bathed

Cytoplasm • In this solution, there are some proteins, amino acids, carbohydrates and dissolved salts • Also serves as temporary storage site of raw materials • Used to transport materials from one part of the cell to another

Ribosomes **Site of Protein Synthesis** • Most numerous organelle in many cells • Composed of RNA and protein molecular constituents

2 Types of Ribosomes • Cytoplasmic • (found in cytosol) • makes proteins used within cell (ex: repair proteins) • Endoplasmic • (attached to endoplasmic reticulum) • makes proteins that will be exported (ex: insulin)

Lysosomes *Only found in animal cells • Phospholipid/protein membrane bound organelle • produced by the Golgi Apparatus and contain digestive enzymes • “garbage disposal unit” of the cell clears out unnecessary or broken parts

Lysosomes • Function determined by the type of cell • Ex: White Blood Cells can ingest invading bacteria thereby protecting you and providing nourishment for the WBC

Endoplasmic Reticulum (ER) • Phospholipid/protein membrane * Stretches throughout cytoplasm* • System of folds, sacs, tunnels “Highway System of the Cell” • Efficiently moves materials safely through cell (enzymes in cytoplasm could damage), or can be used for temporary storage

2 Types of ER Rough ER (ribosomes attached) -found in cells that export lots of proteins Smooth ER (no ribosomes attached) -can produce lipids, helps break down toxins in liver

Golgi Apparatus (Complex, Body) • phospholipid/protein membranes more a stacking of tunnels • sections are not connected (membranes between each) • “Post Office/Shipping Dept. ” of cell Anything leaving cell goes through Golgi

Golgi Complex **processing, packaging, secreting organelle • Assembly line, works closely with the ER, and modifies proteins for export by the cell • Also makes lysosomes in animal cells

Cytoskeleton • Function: Support structure that maintains shape and size of cell • Participates in movement of organelles in cytosol • Network of long protein strands in cytosol • Can be assembled and disassembled quickly (when cytoskeleton is absent, cell just rolls or flows • Ex: WBC when it engulfs bacteria, disassembles cytoskeleton

2 Components of Cytoskeleton Microfilaments -small, solid threads of protein that contribute to cell movement Microtubules -larger, hollow tubes of protein

Nucleus • “Brain, Boss” of cell • Function: Main control center of cell • Surrounded by double membrane called nuclear envelope • Contains fine strands of chromatin • Chromatin- combination of DNA and protein -contains genetic information in DNA • DNA also contains information on how to build and run cell

Nucleus • Site where RNA is copied from DNA then transported through nuclear pores to cytosol where it can direct protein synthesis • nuclear pores- small holes in nuclear envelope • most nuclei also contain at least one nucleolus • nucleolus- spherical area, site where ribosomes are synthesized and partially assembled before they pass through the nuclear pores to the cytoplasm • some cells have more than one nucleoli

Mitochondria “Powerhouse of cell” • Function: site of chemical reactions that convert energy from organic molecules (lipids, carbohydrates, proteins) to ATP (the usable form of cellular energy for most cells) • large, bean-shaped organelle • usually more numerous in cells with high energy requirements (i. e. liver cells and muscle cells) *can be as many as 2500 mitochondria in each liver cell*

Mitochondria • Have own DNA and only produce new mitochondria when old ones grow and divide

Cilia and Flagella * NEVER BOTH FOUND ON THE SAME CELL * **Only found in animal cells • made of microtubules (protein)

Cilia • Cilia- small, hair-like organelles, present in large numbers • Cells lining the respiratory tract contain cilia that trap particles and debris from air we inhale. • As they move, the cilia sweep the trapped materials back up to throat where they are removed when you swallow.

Flagella • Flagella- (flagellum is singular) longer and less numerous than cilia • Function in moving unicellular organisms from place to place or in moving specialized cells (i. e. sperm cells)

Cilia and Flagella • Both cilia and flagella have a similar internal structure: Both are composed of 9 pairs of microtubules arranged around a central pair

Cell Wall -Rigid structure (supports and protects plant) -Prevents expansion when excess H 20 enters cell -Protects against pathogens and environment -Store of carbohydrates

Cell Wall • Older cell is, thicker cell wall will be • Completely impermeable except where pores are • Composed of cellulose and pectin

Vacuoles • Store enzymes and metabolic wastes • Get larger with age • Large organelles (up to 90% of cell’s volume) • Some wastes are toxic and must be kept away from rest of cell

Vacuoles • Other things stored in vacuoles: Poisons- acacia trees Water- cactus Waste materials- onions

Plastids • Surrounded by 2 membranes (like nucleus and mitochondria) • Thought to be own organism and joined with other cells in symbiotic relationship • Can replicate themselves

3 Types of Plastids 1. Chloroplast- produce and store chlorophyll -Site of photosynthesis -Have own DNA

3 Types of Plastids 2. Chromoplast- produce and store other photosynthetic pigments (carotenes, xanthophylls) -Help photosynthesize other wavelengths of light -Petals of flowers and fruits contain chromoplasts

3 Types of Plastids 3. Leukoplast- colorless plastid -Store “food” anything that can be converted to energy by mitochondria Ex: Potatoes have lots of leukoplasts– store starch