Chapter 7 Cell Structure and Function Unit 3

Cells Cytology: the study of cells

IMPORTANT CELL STRUCTURES

Cell Theory Cells are made from preexisting cells. Cells are the smallest units of life. All living things are made from at least one cell.

Cell History

Brief history Redi (1660’s) Hooke (1660’s) Leeuwenhoek (1670’s) Schleiden & Schwann(1830’s) Virchow (1850’s) Brown (1830’s)

Francesco Redi 1668 Helped disprove spontaneous generation "All life comes from life"

Robert Hooke Mid-1660s Used microscopes to diagram samples of living organisms After looking a thin cuttings of cork, he called the chambers “CELLS” from the rooms found in monasteries

Anton van Leeuwenhoek Mid-1670s Used simple microscopes to observe microscopic life in pond water Made vast improvements to microscope construction

German cell biologists 1830s: Matthias Schleidan: concluded all plants made from cells 1830s: Theodor Schwann: concluded that all animals made from cells

Rudolph Virchow 1855 Concluded that the nucleus was responsible for cell division.

Robert Brown 1883 Recognized that cells contained a prominent feature and named it the nucleus.

Louis Pasteur (1860s) Discovers that Cells come from Cells

Lynn Margulis Recognized for her work done in the 1980s proposed the Endosymbiotic Theory “Organelles in larger, complex cells may have been free-living prokaryotic cells in the past.” In 2000 she received the U.S. National Medal of Science

Cell theory (based on 200+ years of discoveries) Cells are made from preexisting cells. Cells are the smallest units of life. All living things are made from at least one cell. Cells dividing Brief History of Cells

Microscopy the use of microscopes to study cells Different types of microscopes Light microscope Transmission electron microscope Scanning electron microscope

Cells are the basic unit of life Unicellular: organisms made up of only one cell Ex: bacteria, protist, fungus Multicellular: organisms made up of more than one cell Ex: protist, fungus, plant, animal

ALL CELLS CONTAIN THESE FOUR PARTS… Plasma membrane: cell membrane, made of 2 layers of phospholipids Cytosol: a carbohydrate and water based solution located in the cytoplasm that suspends all internal parts of the cell Ribosomes: produces proteins DNA: genetic material made of nucleic acids

Types of cells

There are 2 types of cells Prokaryote: bacteria, archaebacteria Eukaryote: protist, fungus, plant, animal

Prokaryotes & Eukaryotes Bacteria pic – Life, p.459 You carry oats, I eat ‘em! Picture1: Largest known bacterium: Thiomargarita namibiensis relative to “typical” bacteria size Picture2: Animal cells are eukaryotic cells ?What does “kernal” represent? ?Can anyone guess what was going through the greek minds when they named these two cell types? These words reflect the idea that prokaryotic cells evolved BEFORE nuclei developed. Eukaryotic cells have a true nucleus. “Eu” = True “Pro” = Before “Karyote” from Greek karyon = Kernal

Prokaryote (bacteria) cell features No membrane bound organelles (ex: nucleus, mitochondria, etc) Small Simple Plasma membrane, ribosome, cytoplasm, DNA

Prokaryotic (Bacterial) Cell Capsule Label the bacteria cell in IAN on pg. 9

Prokaryotic cell structure Capsule: durable outer covering that some bacteria have for protection against water, acids, and viruses Flagella: movement Cell wall: protective layer around plasma membrane Pili: anchoring and DNA exchange

Eukaryotic Cell Complex 4 basic components + organelles Organelles: “little organs” that carry out specialized functions within a cell Have membrane organelles Many variations

Membranes

Plasma (Cell) Membrane (Phospholipid Bilayer) Outer boundary of cytoplasm Semipermiable (only certain molecules enter & leave) Outside of cell Inside (cytoplasm) Cell membrane Proteins Protein channel Lipid bilayer Carbohydrate chains

Phospholipid bilayer A double layer that is an effective barrier for most molecules Hydrophobic = “water fearing” tails in the center, prevent most things from entering Hydrophilic = “water loving” heads attract water to edges of membrane Outside of cell Inside (cytoplasm) Cell membrane Proteins Protein channel Lipid bilayer Carbohydrate chains

Cell membranes are mosaics of different molecules combined.

Proteins embedded in membranes can be: Channels “gates” to interior for transporting into & out of cytoplasm Receptors “windows” for gathering information about cell surroundings Markers “name tags” that identify type of cell to others

Nucleus Directs cell activities Nuclear Envelope (with pores) → outer boundary Chromatin/Chromosomes → (DNA) carry genetic information Nucleolus → (contain RNA) produces ribosomes chromatin

Nucleus Stores ______ ______ DNA helps to regulate ______ production. Proteins ______ cellular activity.

Endoplasmic reticulum Ribosomes small structures on endoplasmic reticulum and floating in the cytosol, that function to produce protein Endoplasmic reticulum an interconnecting system of “pathways,” for transport. May be Rough ER (with ribosomes attached) or Smooth ER (without ribosomes attached).

Vacuole Large, sac-like compartment for storing liquids Food, water, salt, or waste In Animal cells they are called vesicles Called vacuoles in plant and Protists cell

Golgi apparatus (body) Modify, package, and sort protein packages for secretion, outside of cell flattened compartments with vesicles for secretion (packaging & shipping)

Lysosome Specialized vacuole that contains digestive enzymes to destroy foreign molecules and waste

Understanding A student drew this recycling symbol on their notebook cover to represent the lysosome; Why would this be an accurate representation?

Mitochondria Organelle responsible for breaking down glucose molecules into ATP energy molecules They are rod-shaped with folds, for releasing energy (ATP) by respiration

Understanding Hypothesize which cells would have more mitochondria, cardiac cells or skin cells. Why?

Chloroplast Organelle in plants and algae that produces sugar molecules by photosynthesis Why are chloroplasts green?

Understanding A student takes a green plant into pitch dark room, closes the door and turns off the light. What color is the plant?

Cytoskeleton Hollow fibers for support & shape and to move cytoplasm Made of Microfilaments Microtubules Cell membrane Endoplasmic reticulum Microtubule Microfilament Ribosomes Mitochondrion

Plant Cell Label the plant cell Plant Cell Smooth endoplasmic Vacuole Nuclear envelope Ribosome (attached) (free) Smooth endoplasmic reticulum Nucleus Rough endoplasmic reticulum Nucleolus Golgi apparatus Mitochondrion Cell wall Cell Membrane Chloroplast Vacuole Plant Cell

Animal Cell Label the animal cell Animal Cell Centrioles Nucleolus Nucleus Nuclear envelope Rough endoplasmic reticulum Golgi apparatus Smooth Mitochondrion Cell Membrane Ribosome (free) (attached) Animal Cell

Surface to volume ratio Because materials must be transported across cell membranes, maximizing the amount of membrane surface area increases transport efficiency. This is why larger organisms are multicellular.

STOP NOTES HERE… GO ONTO THE FOLDABLES AND THE NOTES FOR TRANSPORT AND TONICS

Comparing surface area to volume (Complete the calculations in the margin of your notes) Surface area: 6 mm x 6 mm x 6 sides = ___ mm2 Volume: ___ mm3 S / V = ___ Surface area: 3 mm x 3 mm x 6 sides x 8 cubes = ___ mm2 Volume = ___ mm3 S / V = ___

Passive or Active transport? current (Concentration gradient)

Passive vs Active transport: which requires energy output?

Diffusion across a membrane

Osmosis across a membrane

Osmosis Osmosis - Diffusion of water across a selectively permeable membrane from higher water purity (high concentration) to lower water purity (low concentration) When solutions of varying water concentrations are found across a membrane, the solutions are given names. Hypertonic Hypotonic Isotonic

Achieving equilibrium

Channel vs. Carrier Proteins

Active transport video Click on image to play video.

Types of Active Transport Endocytosis cell brings particles in. Pinocytosis Liquids are brought in.

Phagocytosis Phage means to “eat” large particles (food or bacteria) are surrounded & engulfed by cell. Examples = an ameba feeding & a white blood cell destroying an invader. Why are white blood cells called MacroPhages?

“Cell eating”

Exocytosis cell deposits particles outside of cytoplasm Secretion = cell products given off Excretion = wastes products given off

Cell structure is related to it’s function All cells are different. Cell specialization → different cells have different jobs. Each cell serves different needs. Diversity on a individual scale helps stabilize the organism Diversity on a large scale helps stabilize the ecosystem