Cell Structure Function Standard 2 Cellular Structure Cell

Cell Structure & Function Standard 2: Cellular Structure

Cell Theory 1. All living things are made up of cells. 2. Cells are the smallest working units of all living things. 3. All cells come from pre-existing cells through cell division.

Definition of Cell • A cell is the smallest unit that is capable of performing life functions. • A cell is the basic unit of life.

Who Discovered the cell? • Robert Hooke – The first person to see cells, he was looking at cork and noted that he saw "a great many boxes. ” (1665)

Who Discovered Cells? • Anton van Leeuwenhock – Observed living cells in pond water, which he called "animalcules" (1673)

Examples of Cells Amoeba Proteus Plant Stem Bacteria Red Blood Cell Nerve Cell

Two Types of Cells • Prokaryotic- primitive, disorganized • Eukaryotic- organized, complicated

Prokaryotic • Do not have structures surrounded by membranes • Few internal structures • One-celled organisms, Bacteria http: //library. thinkquest. org/C 004535/prokaryotic_cells. html

Eukaryotic • Contain organelles surrounded by membranes • Most living organisms Plant http: //library. thinkquest. org/C 004535/eukaryotic_cells. html Animal

“Typical” Animal Cell http: //web. jjay. cuny. edu/~acarpi/NSC/images/cell. gif

“Typical” Plant Cell http: //waynesword. palomar. edu/images/plant 3. gif

Animal vs Plant Cells • ONLY in plant cells: – Chloroplasts- organelle in which photosynthesis occurs – Cell Wall- protects the plant cell and maintains its shape – 1 LARGE Vacuole: used for storage

Cell Parts Organelles

Cell Membrane • Outer membrane of cell that controls movement in and out of the cell • Double layer • Phospholipid bilayer http: //library. thinkquest. org/12413/structures. html

Cell Membrane • Plasma membrane– Regulates the transport of substances across the boundary. – Fluid-like • Composed of mostly proteins and a type of lipid called a phospholipid.

Cell Membrane • Phospholipid Molecule 1. two fatty acids (the tail) 2. Phosphate group (the head)

Cell Membrane • Phospholipid Bilayer– Two-layer “sandwich” of molecules that surrounds a cell.

Cell Membrane • Proteins in the phospholipid bilayer – Enzymes activity – Cell-to-cell recognition – Cell signaling – Transport of materials

Cell Wall • Most commonly found in plant cells • Supports & protects cell • Made of cellulose http: //library. thinkquest. org/12413/structures. html

Nucleus • Controls cell activities- brain of the cell • Separated from cytoplasm by nuclear membrane • Contains genetic material - DNA

Nuclear Membrane • Surrounds nucleus • Made of two layers • Openings allow material to enter and leave nucleus (RNA) http: //library. thinkquest. org/12413/structures. html

Chromosomes • Found in nucleus • Made of DNA • Contain instructions for traits & characteristics (blueprint) http: //library. thinkquest. org/12413/structures. html

Nucleolus • Inside nucleus • Contains RNA to build proteins http: //library. thinkquest. org/12413/structures. html

Cytoplasm • Gel-like mixture • Surrounded by cell membrane • Found in-between each organelle

Endoplasmic Reticulum • Moves materials around in cell • Smooth ER: lacks ribosomes (lipid production) • Rough ER (pictured): ribosomes embedded in surface (contain ribosomes) http: //library. thinkquest. org/12413/structures. html

Ribosomes • Each cell contains thousands • Make proteins • Found on ribosomes & floating throughout the cell http: //library. thinkquest. org/12413/structures. html

Mitochondria • POWERHOUSE of the cell • Produces energy through chemical reactions – breaking down fats & carbohydrates • Controls level of water and other materials in cell • Recycles and decomposes proteins, fats, and carbohydrates http: //library. thinkquest. org/12413/structures. html

Golgi Bodies • Protein 'packaging plant' • Move materials within the cell • Move materials out of the cell http: //library. thinkquest. org/12413/structures. html

Lysosome • Digestion – Breaks down proteins, fats, and carbohydrates • Transports and breaks down undigested material to cell membrane for removal • Cell breaks down if lysosome explodes http: //library. thinkquest. org/12413/structures. html

Vacuoles • Membrane-bound sacs for storage, digestion, and waste removal • Contains water solution • Help plants maintain shape (1 large vacuole) http: //library. thinkquest. org/12413/structures. html

Chloroplast • Found in plant cells • Contains green chlorophyll • Where photosynthesis takes place http: //library. thinkquest. org/12413/structures. html

Peroxisomes • Abundant in liver and kidney cells • Catalyze a variety of biochemical reactions: – Synthesis of bile acids (used to digest fats) – Detoxification of hydrogen peroxide – Break down of certain lipids – Detoxifies alcohol

Vesicle • Small membrane sacs that specialize in moving products into, out of, and within the cell. – Two Processes • 1. Exocytosis-Export of materials • 2. Endocytosis- Import of materials

How do cells move? • Cilia – Shorter and more numerous than flagella. Used for locomotion • Flagella – Long, whip-like structures, with a core of microtubules. Helps propel cells.

How does something pass through the membrane? • Active Transport – ENERGY required! • Passive Transport – NO energy required! – Selective (Semi) permeable membraneallows some substances to cross more easily than others.

Passive Transport • NO energy required! – 1. Diffusion- The net movement of particles of a substance from high concentration to low concentration. • Equilibrium- number of molecules moving in one direction is equal to the number of molecules moving in the other direction.

Passive Transport • NO energy required! – 2. Facilitative Diffusion- transport proteins provide a pathway for certain molecules to pass. • Facilitate means “to help”

Passive Transport • NO energy required! – 3. Osmosis- passive transport of water across a selective permeable membrane. • Hypertonic- higher concentration of solute • Hypotonic- Lower concentration of solute • Isotonic- concentrations of solute are equal

Passive Transport

Passive Transport • Passive Transport

Active Transport • Active Transport – Cell uses energy (ATP) to move molecules or ions across a cell membrane • Pumps in the opposite direction of diffusion (low concentration to high concentration)

Active Transport • 1. Endocytosis 1. Pinocytosis » membrane take in tiny droplets of liquid from their surroundings » Beneficial because the cell can take in water and particles that dissolve in it. 2. Phagocytosis » Membrane engulfs particles from its surroundings

Active Transport • 1. Endocytosis (continued) 3. Vesicle: made of phospholipids

Active Transport • 2. Exocytosis – Reverse of endocytosis. • Vesicles fuse to membrane to get particles OUT of the cell

Active Transport • Na+/K+ pump-Occurs in Nerve cells • Animal cell contains a higher concentration of potassium ions (K+) and a lower concentration of Sodium ions (Na+) in its fluid surroundings.

The Microscope • Types of microscopes – 1. Light Microscopes • Scientists use stains or dyes to show the different structures inside a cell • You are probably most familiar with a compound like microscope

The Microscope • Types of Microscopes – 2. Electron Microscope • Used to study very small things…. shows things are 1 billionth of a meter in size. – Example: DNA