Cells

2.3 – Introduction to Biomolecules The Levels of Organization Organ Systems Organism

Skin Cells and Stomach cells

How did cells get discovered?? 1655 – was the first to identify cells, and he named them because he made better lenses, Leeu observed cells in greater detail – was the first to note that plants are made of cells – concluded that all living things are made of cells – proposed that all cells come from other cells.

The Cell Theory has 3 principles: – All organisms are made of cells.

– The Cell theory has three principles. All organisms are made of cells. All existing cells are produced by other living cells

– The Cell theory has three principles. All organisms are made of cells. All existing cells are produced by other living cells. The cell is the most basic unit of life.

All cells share certain characteristics. Cells tend to be microscopic. All cells are enclosed by a membrane. All cells are filled with cytoplasm. Bacterium (colored SEM; magnification 8800x) cell membrane cytoplasm

There are two cell types:

EUKARYOTES vs PROKARYOTES Eukaryotic cells have a nucleus. Prokaryotes do not have a nucleus. nucleus

EUKARYOTES vs PROKARYOTES Eukaryotic cells have membrane bound organelles. Prokaryotes do not have membrane bound organelles. nucleus organelles

EUKARYOTES vs PROKARYOTES Both Eukaryotic and Prokaryotic cells have cytoplasm and a cell membrane. nucleus organelles cell membrane cytoplasm

Living Things Come in All Sizes How does the size of a cell in a tadpole compare to a blue whale?? – Most cells in a whale are similar in size to those in tadpoles What makes a whale so Much larger than a tadpole? – A whale has far more cells than a tadpole or the frog it Becomes.

Organelles

All cells have a cell membrane – the cell membrane or plasma membrane, forms a boundary between a cell and the outside environment. – Controls the passage of materials into and out of cell – Consists of a double layer of phospholipid molecules. Phospholipid- a phosphate group, 2 fatty acids, glycerol.

Cell Wall ( ONLY IN PLANT CELLS!!!) – A rigid layer that gives protection, support, and shape to the cell – Cell walls can adhere to one another to support an entire organism Example - much of the wood in a tree trunk consists of dead cells whose cell walls continue to support the entire tree – Cell wall composition varies and is related to the needs of each type of organism - tree vs algae – Even though it is tough, it still has channels to allow water and other molecules to cross into and out of the cells survival.

Cells have an internal structure. – Cytoskeleton is a network of proteins (fibers/tubes) that is constantly changing to meet the needs of cells. – The cytoskeleton has many functions. supports and shapes cell helps position and transport organelles provides strength assists in cell division aids in cell movement

Components of a Cytoskeleton: 2 main types of fibers/tubes that make it up. – Microtubules long hollow tubes give cell its shape act as tracks for movement of organelles assist in cell division – Microfilaments smallest of the 2 tiny threads that enable cells to move & divide play important role in muscle cells, allow muscle to contract & relax

Cytoplasm: – Clear, gelatinous fluid inside the cell Mostly made of cytosol – Jelly-like material that consists mostly of water with proteins and carbohydrates – Organelles are found within the cytoplasm

Several organelles are involved in making and processing proteins. – Nucleus – Nuclear envelope – Nuclear pores – Nucleolus – Rough Endoplasmic Reticulum – Ribosomes – Golgi Apparatus – Vesicles

Nucleus – Control center of the cell because it holds the genetic information or DNA – DNA contains the genes that are instructions for making proteins 2 Major demands on DNA 1. DNA must be carefully protected 2. DNA must be available for use at all times Solution for these demands: * Nuclear envelope- a double membrane that surrounds and protects DNA, with tiny nuclear pores that allow certain large molecules in and out.

Nucleolus – Tiny dense region within nucleus – Essential for making ribosomes

Endoplasmic Reticulum – A large part of most eukaryotic cells is filled by the ER. – Interconnected network of thin folded membranes – Numerous processes, including the production of proteins and lipids, occur on both the surface and inside the ER – 2 types of ER: Rough Endoplasmic Reticulum Smooth Endoplasmic Reticulum

Rough ER – its surface is dotted with ribosomes – Proteins are being made on ribosome and the rough ER can modify the protein by adding sugar chains to it which can help it fold into a shape.

Ribosomes – Tiny organelles that link amino acids together to form proteins. – Both the site of protein synthesis and actively participates in the process. – Ribosomes themselves are made up of proteins and RNA. – After ribosomes are made in the nucleolus, they pass through the nuclear pores into the cytoplasm where they can attach to the rough ER or just float. – 2 types of ribosomes: Attached ( on ER) Free ( floats in cytoplasm)

Golgi Apparatus – Closely layered stacks of membrane-enclosed spaces that process, sort, and deliver proteins. – Its membranes contain enzymes that make additional changes to proteins – Packages proteins and stored for later use – Transports proteins to other organelles – Transports proteins to membrane where they are secreted outside the cell.

Vesicles – Small membrane-bound sacs that divide some materials from the rest of the cytoplasm – Transport these materials from place to place within the cell – Generally short-lived and are formed and recycled as needed. **after proteins have been made, part of the ER pinches off to form a vesicle surround it. **the protein can then be safely transported to the golgi apparatus. ** After being modified in Golgi, Vesicles form ( pinch off) to take proteins out of cell.

Overview of Protein Synthesis: Ribosomes are made in nucleolus Ribosomes leave through the Nuclear pores on the nuclear membrane Some attach to ER, while others remain free floating Ribosomes begin attaching Amino Acids together to form proteins Proteins enter into Rough ER to be modified and folded (shaped) into structures

Overview of Protein Synthesis: Vesicles form from Rough ER and carry proteins to Golgi apparatus There proteins are packaged, sorted and/ or stored in Golgi Once the proteins are ready to leave, vesicles form to transport proteins throughout the cell and to other cells.

Other organelles have various functions – Smooth Endoplasmic Reticulum – Mitochondria – Lysosomes – Centriole – Vacuole – Chloroplasts

Other type of ER: Smooth ER – its surface does not contain ribosomes – Makes lipids – Breaks down drugs and alcohol (liver cells) – Calcium storage (muscle cells)

Mitochondria (powerhouse) – Supplies energy to the cell – chemical reactions take place within the inner folds and convert molecules from the food you eat into usable energy – Unlike most organelles, mitochondria have their own ribosomes and DNA. This suggests that they were originally free-living prokaryotes that were taken in. – Found in cells that are very active (muscle cells)

Lysosomes (garbage disposal) – Membrane-bound organelle that contain enzymes to break down worn-out cell parts and debris. – They also defend a cell from invading bacteria and viruses – They are numerous in animal cells and their presence is still questioned by scientists in plant cells.

Centriole – Are cylinder-shaped organelles made of short microtubules arranged in a circle. – Located in a small region in the cytoplasm called the centrosome that produces these microtubules. – Both Plant and Animal cells have a centrosome region, but only Animal cells form centrioles. – Help divide DNA during cell division – Help form cilia (little hairs) and flagella (whip/tail) for cells.

Vacuole – A fluid-filled sac used for storage of materials needed by a cell. – These materials include water, food molecules, inorganic ions and enzymes – Most animal cells contain small vacuoles – All plant cells have a large central vacuole that strengthens the cell and helps to support the entire plant.

When a plant wilts, its leaves shrivel because there is not enough water in the vacuole to support its normal structure A plants vacuole may also contain substance that are toxic to harm predators, waste products, and pigments that give color to cells – such as those in the petals of flowers. Milkweed

Chloroplasts – Organelles that carry out photosynthesis – Like mitochondria, they have their own ribosomes and DNA so scientist believe they too were taken in by larger cells – ONLY IN PLANT CELLS!!!

Centriole Centrosome Golgi Appratus Vesicle Small Vacuole Nucleolus Nuclear Pores Nucleus Lysosome Cytoskeleton Rough ER Cytoplasm Mitochondria Smooth ER Cell Membrane Ribosome (attached)

Centrosome Golgi Appratus Vacuole Cell Wall Nucleolus Nucleus Nuclear Pores Vesicle Cytoskeleton Rough ER Ribosomes Cell Membrane Smooth ER Mitochondria Chloroplast

Prokaryotes Eukaryotes Cell membrane Ribosomes Genetic Material Cytoplasm Nucleus ER Golgi apparatus Vesicles Lysosomes (animal) Vacuoles Mitochondria Cytoskeleton Chloroplast (plant) Venn Diagrams No Nucleus Genetic material not in nucleus No membrane bound organelles

Animal Cells Plant Cells Lysosomes centrioles Cell membrane Ribosomes Nucleus Nucleolus ER Vesicle Golgi apparatus Vacuoles Mitochondria Cytoskeleton Cytoplasm centrosome Venn Diagrams Cell Wall Chloroplasts