Cell Biology

What is a cell? A cell is the smallest structural and functional unit of an organism

Cell Theory Microscopic lenses  discovery of cells Cell theory All living things are composed of cells and their products New cells arise from the division of older cells Cells are the basic building blocks of life

Challenge time! Can you think of something you would call “alive” that isn’t made of cells?

1/9/12 Objective Do Now Do Later

Cells Two major classes of cells Eukaryotic Prokaryotic Have many membrane bound compartments called organelles Animals, plants, fungi Prokaryotic Have no membrane bound compartments Bacteria

Evolution of Cells Tree of life can be divided into 3 domains Bacteria/Archaea = prokaryotes Eukarya = eukaryotes Prokaryotic cells are older/more primitive

Organelles Eukaryotic cells contain membrane bound compartments called organelles Each organelle performs specific jobs to aid the overall function of the cell

Analogy time! If a cell were a factory, what would its organelles be?

Nucleus Region of the cell that contains the DNA Tightly coiled strands of DNA are called chromosomes Nucleoplasm is fluid in the nucleus

Nucleus Have you ever seen a nucleus before? Sure you have!

Recall The nucleus stores DNA, which contains your genetic code. What instructions are contained in this genetic code? Why might you call the nucleus the brain of the cell?

Nuclear Envelope The nucleus is surrounded by a double phospholipid bilayer called the nuclear envelope Proteins form channels through these membranes called nuclear pores

Recall The cell membrane is a single phospholipid bilayer Why do you think the nuclear envelope is a double phospholipid bilayer?

Nucleolus Nucleolus = region of the nucleus Rich in RNA Ribosomes are produced here Then travel out to the cytoplasm

Ribosomes We’ve studied these already What is the function of ribosomes? Genes get transcribed into mRNA copies Ribosomes translate mRNA into proteins Where do ribosomes fit in this scheme?

Structure of Ribosomes Ribosomes have 2 subunits, each containing protein and RNA

Nobel Prize time! Enzymes are molecules that catalyze, or speed up the rate of a chemical reaction Many proteins are enzymes Ex: Digestive enzymes are proteins that speed up the rate of digestion of food molecules

Nobel Prize time! 1989 – Sid Altman wins Nobel Prize in chemistry for showing that RNA can catalyze reactions too Discovered RNA component of ribosomes When RNA was removed from ribosomes, they could no longer perform their job  RNA is involved in the function of ribosomes

Application Question Enzymes catalyze, or speed up, reactions. What reaction do ribosomes catalyze?

1/10/12 Objective: Finish exploring organelles Do Now: Take your matching quiz! (10 min-ish) Do Later: Active reading of section 3.4

Cytoplasm The region outside the nucleus is called the cytoplasm Contains many organelles

Quiz time! Where is the cytoplasm in this egg?

Cytoskeleton How do cells maintain their shape? Structural support from protein rods that are called the cytoskeleton Microfilaments = actin polymers Microtubules = tubulin polymers Imaging microtubules with actin-Green Fluorescent Protein

Nobel Prize time! 2008 – Nobel Prize in Chemistry awarded for discovery of Green Fluorescent Protein Naturally occurring in jellyfish Gene for GFP can be spliced into gene for a protein of interest Makes protein under study fluoresce.

Fluorescent Proteins Extremely useful lab technique

Endoplasmic Reticulum The Endoplasmic Reticulum (ER) is a series of flattened sacs connected to the nucleus Involved in: Transport throughout the cell Protein synthesis Lipid synthesis

Endoplasmic Reticulum Two kinds of ER Rough ER: phospholipid membrane is studded with ribosomes Smooth ER: membrane contains no ribosomes

Extension Question The ER participates in Transport throughout the cell Protein synthesis Lipid synthesis What part of the ER do you think is involved with protein synthesis?

Golgi Apparatus Has a cool name Also a series of flattened sacs Also involved in transport throughout cell processing of proteins

Mitochondria Mitochondria break down sugar to produce energy (ATP) for the cell Have a double phospholipid bilayer Like nucleus Inner and outer membranes Matrix = interior space Cristae = exterior space

Lysosomes “Garbage disposal of the cell” Contain powerful enzymes to break down Nutrients Foreign objects Worn out parts of the cell

Centrosomes 2 in each cell Microtubules grow out from the centrosomes Participate in cell division Centrosomes Centrosomes organize the “Mitotic spindle apparatus”

Cilia and Flagella Cilia are shorter, more frequent Flagella are longer Usually 1 per cell Whip-like projections Structurally supported by microtubules

Vesicles Vesicles are the storage containers of the cell Can hold a great variety of molecules Form by endocytosis Endocytosis = cellular intake of outside materials