Chapter 7 Cells and Transport

Hooke 1665 Observed pieces of cork under a simple microscope. Describe the structure of cork.

Hooke named the structures “CELLS”. He named them after the rooms that monks lived in at monasteries, because they looked like empty rooms.

Leeuwenhoek 1674 He used a primitive microscope to look at many objects. He saw tiny creatures swimming around and called them “animalcules”.

Schleiden 1838 Concluded that all plants were made of cells. →

Schwann 1839 Concluded that all animals were made of cells. →

Virchow 1855 Proposed that all cells must come from existing cells.

The cell theory 1st States that…….. ALL LIVING THINGS ARE COMPOSED OF CELLS.

CELLS ARE THE BASIC UNIT OF STRUCTURE AND FUNCTION IN LIVING THINGS. 2nd States that…. CELLS ARE THE BASIC UNIT OF STRUCTURE AND FUNCTION IN LIVING THINGS.

3rd and Finally states that….. NEW CELLS ARE PRODUCED FROM EXISTING CELLS.

Let’s look at some cells!

List at least 5 differences between these two types of cells.

Prokaryotes vs. Eukaryotes Prokaryotes – Smaller, more primitive cells. Lack a nucleus and organelles. Examples: Bacteria and cyanobacteria Eukaryotes – “True nucleus”. Have membrane-bound DNA and complex organelles. Examples: Animals, plants, fungi, protists (amoeba).

Eukaryotes vs. Prokaryotes: Size A macrophage eating E. coli and human cheek cells with bacteria.

Plant and Animal cells have: Plant cells have: A cell wall Chloroplasts No centrioles Large vacuoles (some) Animal cells have: No cell walls Centrioles Plant and Animal cells have: Mitochondria Cell membranes Nucleus All other organelles

Cellular Organelles:

Organelles found in Eukaryotes Cell membrane- made of a phospho- lipid bi-layer, the membrane protects the cell and regulates what enters and exits the cell

illustrations:

Endoplasmic Reticulum: An extension of the nucleus inside the cell, the ER transports materials inside the cell and serves as a place for protein synthesis (Rough ER). Ribosomes: sites of protein synthesis.

Golgi Body: “flattened pancakes” that take material traveling on the ER and package it and label it for intracellular or extracellular transport.

Nuclear membrane: Surrounds the nucleus and has pores which allow RNA to pass through the cytoplasm Regulates protein messages to the rest of the cell

Nucleus: Contains the DNA on chromosomes. Site of the replication of DNA in the beginning of mitosis.

Mitochondria: The “powerhouse” of the cell. Mitochondria are kidney bean/oval shaped with a wavy internal membrane. ATP (the cell’s energy currency) is formed on this membrane. (Once bacteria??)

Chloroplast: Found only in plants, chloroplasts are oval shaped organelles that gather the sun’s energy to create ATP and assemble carbohydrates for plants to use in the future.

Cell Wall: Also found only in plants (and fungi), the cell wall is a rigid structure made of cellulose and lignin that protects a plant cell and gives it shape.

Peroxizomes: Small vesicles (bags) that contain various enzymes that convert fats to carbohydrates and convert H2O2 into water and oxygen.

Lysosomes: Vesicles that contain digestive enzymes.

Vacuole: A large internal storage place for wastes, food, or water. Common in plant cells.

Cytoskeleton: The internal framework of the cell composed of microtubules that give the cell its shape.

Centrioles: Found only in animal cells, the centrioles set up the framework that moves the chromosomes to opposite sides of the cell during cell division.

Flagella and Cilia: Flagella: Complex cables of microtubules that allow for cellular movement. http://www.microscopyu.com/moviegallery/pondscum/protozoa/peranema/t1/peranema03.html Cilia: Smaller, more numerous flagella in a large area of the cell. http://www.microscopyu.com/moviegallery/pondscum/protozoa/stentor/t1/stentor01.html

Cellular Organelles: Organelles work together to allow the cell to carry out important life functions. Use your notes and your diagrams to help you study. Complete your cell models/activities for side dishes. Include: cell membrane, nucleus, nuclear membrane, rough ER, smooth ER, Golgi body, mitochondria, lysosomes, and centrioles.

The cell membrane regulates what enters and exits the cell. Active transport – the movement of particles across the membrane using energy (ATP). Examples: gated channels, endocytosis, etc.. Passive transport – the movement of particles without using additional energy. Examples: osmosis, diffusion.

A review: Solution – a mixture of two or more substances Solutes – the substances dissolved in the solution. Water – the universal solvent. Concentration – the mass of solvent in a given volume of solution.

Passive transport: Simulation in cells Diffusion – the movement of particles from an area of high concentration to an area of low concentration. When the concentration of the solvent is even throughout, the system has reached equilibrium. Simulation in cells

Passive transport, continued… Osmosis – the diffusion of water through a selectively permeable membrane. Selectively permeable – some particles can pass through while others cannot. Water wants to reach an equilibrium! animation

Osmosis continued… Water moves to “dilute” out the more concentrated solution so the free water content is equal on both sides of the membrane. Isotonic solution – when the amount of solutes and water is the same on both sides of the membrane. Example: RBC’s and plasma. Hypertonic – more concentrated solution. Example: Salt water. Hypotonic – the less concentrated solution. Example: Red blood cell in salt water

Red blood cells in various solutions:

Passive transport, Continued… Facilitated diffusion – Protein channels in the cell help certain molecules (glucose) through the membrane. No energy used. Animation What diffuses? Water, oxygen, carbon dioxide, glucose…

Active Transport: Endocytosis – Uses ATP to “engulf” or take in food/water through the cell membrane. Examples: Pinocytosis – taking in water by pinching in around it. Phagocytosis – taking in food/solids by pinching in. Exocytosis- Uses ATP to expel vesicles (proteins, solids)