Cells: History, Structure and Function Unit 5

Observation vs. Inference Observation: what you observe using your five senses (see, smell, hear, touch, taste) Observations are objective (unbiased) Examples: Inference: Applying what you know (background knowledge) to what you are observing or experiencing with your senses. Inferences are subjective (biased). Examples: Science is made up of observations and inferences

Video Write down two observations Write down two inferences s/6850.html s/6850.html

Video Observations: Inferences:

What came first: the discovery of cells or the invention of microscopes? Microscopes! Who saw the first cells? In 1665, Robert Hooke looked at cork cells under a microscope. What was he really looking at?__________________. (remember… Capt. Hook wanted to lock Peter Pan in a jail cell)

German discoveries Matthias Schleiden: “All plants are made of cells” Theodor Schwann: “All animals are made of cells” Rudolf Virchow: “New cells can only be made by cells that divide” These discoveries led to the Cell Theory

Cell Theory 1. All living things are made of cells. 2. Cells are the basic units of structure and function in living things. 3. New cells are produced from existing cells.

Unicellular vs. Multicellular All living things are made of cells Unicellular Organism: made of only one cell Examples: Multicellular Organism: made of many cells Examples: What are the advantages of each?

Prokaryotes vs. Eukaryotes Prokaryote: No nucleus Genetic material is not contained in a nucleus in prokaryotic cells. Examples: Eukaryote: Has a nucleus & organelles Eukaryotic cells keep genetic material in a nucleus, separate from the rest of the cell. Think: Eukaryote= has everything in envelopes Examples:

Who came first? Earth’s first cells were prokaryotes. Eukaryotes evolved from prokaryotes Endosymbiotic Theory: A theory that the mitochondria and chloroplasts of eukaryotes originated as free-living prokaryotes that were engulfed (taken in) by primitive eukaryotic cells and become established as permanent symbionts in the cytoplasm Do you think prokaryotes or eukaryotes are more abundant on earth?

Prokaryotic vs. Eukaryotic

Origin of Eukaryotes

Classification: 6 Kingdoms Living Organisms Prokaryotes (No nucleus or organelles) ArchaebacteriaEubacteria Eukaryotes (Has a nucleus and organelles) Plants Fungi Animals Protists

Prokaryotes vs. Eukaryotes Prokaryotes: Bacteria All Single-celled (unicellular) Eukaryotes: Animals, Plants, Fungi, & Protists Unicellular OR Multicellular

Prokaryotic or Eukaryotic?

Prokaryotic Cell Eukaryotic Cell

Practice: Posters At your tables, construct: Prokaryotic Cell Eukaryotic Cell Include information on your poster: Examples of prokaryotes/eukaryotes Answer the question about prokaryotes and eukaryotes: Are they unicellular or multicellular or both? Who came first: Prokaryotes or Eukaryotes? Are prokaryotes or eukaryotes more abundant on earth?

Assignment: Complete the Venn Diagram showing the similarities and differences between Prokaryotic and Eukaryotic cells Use the following words: Nucleus Endoplasmic reticulum Golgi apparatus Lysosomes Vacuoles Mitochondria Cytoskeleton Cell membrane Cytoplasm

Prokaryotes Eukaryotes

Organelles Nucleus: contains DNA (instructions for making molecules) Nucleolus: where ribosomes are made Nuclear membrane: surrounds nucleus Nuclear pores: openings in the membrane to let things in and out. Chromatin = DNA + protein Chromosomes: condensed chromatin

Organelles Ribosomes: make proteins Endoplasmic reticulum (ER): membrane system where lipids & proteins are made and shipped out Rough ER: ribosomes are attached Smooth ER: no ribosomes Rough ER makes proteins Smooth ER makes lipids (fats)

Organelles Lysosomes: full of enzymes to break down molecules and waste. Vacuoles: sac-like, stores water, salts, minerals, proteins and carbohydrates. Plant cells have one large vacuole full of water. This makes the plant strong enough to hold leaves and flowers.

Organelles Mitochondria: convert chemical energy (from food) into a form that can be used by the cell. Chloroplasts: convert sunlight energy into chemical energy (food) during photosynthesis. Chlorophyll: the green pigment in chloroplasts

Cytoskeleton Cytoskeleton: Protein filaments that support the cell. Microfilaments Microtubules

Cell Boundaries Cell Membrane: in all cells, regulates what enters and leaves the cell. Lipid bilayer Cell Wall: in plants, algae, fungi & bacteria, provides support and protection. In plants, made of cellulose