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Cell Theory
Cell Theory The Building Blocks of LifeRobert Hooke – 1665 - Used a “microscope” / magnifying glass to look at cork
- From England
- Discovered what a cell was by looking at a piece of cork
Anot Van Leeuwenhook – 1673 - Dutch inventor who created the microscope that we recognize today
- First person to discover a single celled protozoa
- Protozoa is like pond scum
- He also looked at blood cells
Cell:
The smallest unit of life that can perform all life processes.Cell Theory (Really important - Know This!) - All organisms are made of one or more cells
- The cell is the basic unit of all living things
- All cells come from existing cells
Spontaneous Generation: - The idea that things or organisms just appear.
- AKA – The idea that worms were created out of rain hitting the ground or the idea that flies came from dirty rags and filth.
Protoplasm:
All the living material found in a cell capable of carrying on all the life processes.The Two Major Kinds of Cells:Prokaryote Cell: (1st Major Kind of Cell)
Cells that DO NOT have a cell membrane around their nucleus.
Example – Bacteria- Prokaryotes are molecules surrounded by a membrane and cell wall. Prokaryotic cells lack characteristic Eukaryotic sub cellular membrane enclosed “organelles”, but may contain membrane systems inside a cell wall.
Second kind of Prokaryotes:
Archaebacteria- SAME As bacteria since they lack a nucleus and don’t have membrane bound organelles.
- DIFFERENT in that they have ribosomes that are more like a Eukaryotic cell.
Eukaryotic Cell (2nd Major Kind of Cell)
Cells that have a membrane around their nucleus.Example – Plant and Animal Cells Eukaryotic
Cells usually are 10 times larger than Prokaryote cells.
The basic Eukaryotic cell contains the following:
- Plasma membrane around their nucleus
- Cytoplasm (the semi fluid substance inside the membrane.
- Has a cytoskeleton – the microfilaments and microtubules that suspend organelles, this gives it shape, and allow for the cells motion.
- Has membrane enclosed subsellular organelles.
Parts of the Cell:Organelles: The things or structures (PARTS) inside of a cell that perform the functions necessary for the cell to survive.
- Example: Think about your heart, lungs and liver… They are all organs or organelles inside of your body. The cell has parts like this inside of its cell.
Cell Membrane: Is the protective layer that covers the cell’s surface.
it acts like the fence around a yard. It is like the skin on your body. It keeps some things out and lets some thing in.
Location: - Found in all cells
Description - Plant - inside cell wall
- Animal - outer layer; cholesterol
- Double layer of phospholipids with proteins
- Selectively permeable
Function - Support
- Protection
- Controls movement of materials in/out of cell
- Barrier between cell and its environment
- Maintains homeostasis
Cell Wall: - Found only in PLANT cells
- Gives support to the cell
- Is a second layer or “fence” like the cell membrane.
Location: - Plant, Fungi, & Bacteria, but not animal cells
Description - Outer layer
- Rigid & strong
- Made of cellulose
Function - Support (grow tall)
- Protection
- allows H2O, O2, CO2 to diffuse in & out of cell
Nucleus: - An organelle inside of the cell that directs the activity in the cell.
- It holds the DNA (Deoxyribonucleic acid)
- This is the blue print material (directions) for the cell.
- It tells how to reproduce and perform all of the cells jobs.
nucleolus
Location: - All cells except prokaryotes
Description - Found inside the cell's nucleus
- May have more than one
- Disappear during cell division
Function - Make ribosomes
Nuclear Membrane
Location:- All cells except prokaryotes
Description - Surrounds nucleus
- Double membrane
- Selectively permeable
Function - Controls movement of materials in/out of nucleus
Endoplasmic Reticulum: (ER) - A folded membrane that moves material in the cell
- ER (Endoplasmic Reticulum) is part of the internal delivery system and uses tubes for passageways.
- ER is additionally responsible for moving proteins and other carbohydrates to the Golgi Body.
Location: - All cells except prokaryotes
Description - Network of tubes or membranes
- Smooth w/o ribosomes
- Rough with embedded ribosomes
- Connects to nuclear envelope & cell membra
Function - Carries materials through cell
- Aids in making proteins
Golgi Body (Apparatus)
- consisting of flat, disk-shaped sacs, tubules, and vesicles
- Stacks of sacs that package and move proteins around in the cell.
Location: - All cells except prokaryotes
Description - Stacks of flattened sacs
Function - Modify proteins made by the cells
- Package & export proteins
Mitochondria - The organelle that releases energy in the cell. (The powerhouse of the cell)
- Found in both animal and plant cells.
- Mitochondria produce ATP using energy stored in food molecules.
Location: - All cells except prokaryotes
Description - Peanut shaped
- Double membrane
- Outer membrane smooth
- Inner membrane folded into cristae
Function - Breaks down sugar (glucose) molecules to release energy
- Site of aerobic cellular respiration
Chloroplasts - Organelle that produces chlorophyll. ( The chemical of photosynthesis) to power the plant cell.
- Chlorophyll traps the energy of sunlight, which is then used by the plant cell to make sugar for energy.
- Only found in PLANT cells.
Location: - Plants and algae
Description - Green, oval containing chlorophyll (green pigment)
- Double membrane with inner membrane modified into sacs called thylakoids
- Stacks of thylakoids called grana & interconnected
- Gel like innermost substance called stroma
Function - Uses energy from sun to make food (glucose) for the plant
- Process called photosynthesis
- Release oxygen
Ribosome:
Organelle that makes protein for the cell.
Location: - All cells
Description - Small bodies free or attached to ER
- Made of rRNA & protein
Function - Synthesizes proteins
Vesicle / Vacuole
Small sack that moves material in and out of the cell.
Location: - Plant cells have a single, large vacuole
- Animal cells have small vacuoles
Description - Fluid-filled sacs
- Largest organelle in plant cells
Function - Store food, water, metabolic & toxic wastes
- Store large amounts of food or sugars in plants
Lysosome: - Organelle that eats worn out cell parts.
- It contains digestive enzymes.
- Lysosomes are round membrane surrounded structures that can be found anywhere in the cytoplasm.
- Sometimes they are called suicide bags because they encase the worn out part that is to be digested.
Location: - Animal as well as plant cells
Description - Small and round with a single membrane
Function - Breaks down larger food molecules into smaller molecules
- Digests old cell parts
Cytoplasm - The gel-like material inside of the cell membrane.
- Keeps organelles in place
Location: - All cells
Description - Clear, thick, jellylike material (cytosol)
- Organelles found inside cell membrane
- Contains the cytoskeleton fibers
Function - Supports and protects cell organelles
Cytoskeleton:
Location: - All cells
Description - Made of microtubules - microfilaments
Function - Strengthen cell & maintains the shape
- Moves organelles within the cell
Centrioles
Description - Paired structures near the nucleus
- Made of a cylinder of microtubule pairs
Function - Separate chromosome pairs during mitosis
Location: - Bacterial cells & Protozoans
Description - Arrangement of microtubules
- Long, but few in number
Function - Movement
Cilia
Location: - Animal cells, Protozoans
Description - Arrangement of microtubules
- Short, but numerous
Function - Movement
- Cells lining the human upper respiratory tract are ciliated (have cilia). The cilia move mucous and debris upward to the mouth where it is swallowed
