Cell Structures- 7.2 Animal Cell Plant Cell

The Outer Cell Cell membrane- a thin, flexible barrier around the cell. Cell membranes are semi-permeable, meaning that they allow certain materials in and out of the cell Cell Wall- Thick, outer covering of plant cells, bacteria cells, fungi cells and algae cells. Cell walls provide support and protection for the cell. Made of cellulose (plants) and chitin (fungi)

Picture It! Cell Membrane Cell Wall

The Nucleus Scottish botanist Robert Brown first identified the nucleus in 1831 The nucleus controls much of the cell’s activity and contains the cell’s hereditary information in the form of DNA (Deoxyribonucleic Acid) Almost all eukaryotic cells including plant and animal cells contain a nucleus Prokaryotic cells like bacteria have no nucleus

The Nucleus, Cont. An Actual Nucleus Model of a Nucleus “Matrix” Nucleus

Inside the Nucleus Chromatin- the granular material inside the nucleus. It is made of DNA bound to protein, and carries the hereditary information in the cell Chromosomes- chromatin condenses to form chromosomes during cell division Nucleolus- Small dense region inside the nucleus that is responsible for the assembly of ribosomes, which make proteins Nuclear membrane- outer covering of the nucleus, allows a steady stream of RNA in and out.

Chromatin Nucleolus Chromosomes

Cytoskeleton Network of protein filaments that helps the cell maintain its shape Also involved in many forms of cellular movement Microtubules are hollow protein tubes that maintain cellular shape and serve as “tracks” on which organelles can travel Microfilaments- protein filaments that provide structure for the cell

Organelles in the Cytoplasm The cytoplasm is the liquid “goo” like material inside the cell. It is made of water and salts, and contains all the cell organelles (little organs) Ribosomes are made of RNA and protein. They assemble proteins following the coded information stored in the nucleus. Electron Microscope image of Ribosomes

Endoplasmic Reticulum Internal membrane system in which cell membrane components are made and proteins are modified Smooth ER- does not contain ribosomes Rough ER- “studded” with ribosomes Smooth ER Rough ER

More Cytoplasmic Organelles Golgi Apparatus- packages and ships materials, attachs necessary carbohydrates and lipids to proteins. This organelle is a stack of sac-like membranes Lysosomes- breaks down carbohydrates and lipids, also “eats” dead organelles- cleans up the cell Vacuoles- store food and water for cells to use, plant cells have huge organelles

Can you find the vacuole?

Energy! Energy! Energy! Mitochondria- Found in both animal and plant cells. Breaks down glucose (food) to release energy Chloroplasts- Found in plant, algae and some bacteria cells. Autotrophic, the organelle that converts sunlight into glucose

Putting it All Together

An Amazing Journey Tiny little cells are so very complex! Imagine taking a magic journey inside one of your cells… what would you see????

Movement Through the Membrane Section 7.3 Movement Through the Membrane

Cell Membrane The cell membrane is the flexible outer covering found on the outside of cells It regulates what enters and leaves the cell and also provides protection and support Cell membranes allow food and water in and gases and wastes out They are semi-permeable, which means that some things are allowed through, and others are not

Cell Membrane, Cont. The core of the cell membrane is a lipid bi-layer (a double layer of lipids) Proteins act as channels through the membrane Carbohydrate chains are there for cell identification

Diffusion Every cell is in a liquid environment– with a liquid interior and surrounded by liquid. The cell membrane separates these two liquid environments. Concentration of a solution is the mass of the solute that is dissolved in a certain volume of solvent In a solution, molecules move constantly. Across a membrane, they move from a high to a low concentration. This is called diffusion

Diffusion, Cont. Diffusion causes many substances to move across the cell membrane, but it does not require energy Diffusion happens automatically, when there is a concentration difference or the solutions are in equilibrium (equal concentrations on both sides) In equilibrium, however, the molecules move rapidly in both directions

Osmosis Osmosis is diffusion, but not all diffusion is osmosis. Osmosis is the movement of water across a semi-permeable membrane Water moves from an area of high water to an area of low water concentrations When equilibrium is reached, it moves in both directions

Osmotic Pressure Osmosis exerts pressure on a certain side of the cell membrane HyPERtonic- Area of high concentrations of particles such as salt or sugar (high PERticles) HypOtonic- Area of high concentration of water (high H2O-- hypOtonic) Isotonic- concentrations of particles and water are equal

Solution Types If you place a cell (like an egg) in a high- particle solution (Hypertonic) then water will rush out of the egg and the egg will shrivel In a Hypotonic (High water) solution, water will rush into the egg and the egg will swell In a Isotonic solution, no change will be noticed because the water will move in both directions, in and out of the egg

Facilitated Diffusion The word facilitate means to “assist” or to “help” In facilitated diffusion, proteins that are embedded in the membrane help bigger molecules go through by acting as a channel There must be a concentration difference, meaning this will not take place in equilibrium Extra energy is not needed

Active Transport “Active” implies that you need energy This is transport that needs energy in order to take place Endocytosis- food is taken into a cell– Phagocytosis is a type of this, it is literally “cell eating” Exocytosis is the exit of materials out of a cell– usually waste

Define Vocabulary 7.3 and 7.4 on page 196 Homework Define Vocabulary 7.3 and 7.4 on page 196 Due Tuesday Also: Progress Report