Eukaryotic Cell Structures All About Cells Eukaryotic Cell Structures

The Basics of a Cell Much like our bodies are made up of organs, cells are made up of smaller parts called organelles. Eukaryotic cells are divided into two major parts: The nucleus The cytoplasm – the portion of the cell outside the nucleus

The Nucleus The nucleus: Is the control center of the cell Contains almost all of the cell’s DNA The nucleus contains codes that allows it to make proteins and other important molecules

The Parts of the Nucleus Nuclear envelope – the two membrane structure that surrounds the nucleus Nuclear pores – pores on the surface of the nuclear envelope that allow material to move in and out of the nucleus Chromatin – consists of DNA bound to protein, and is spread throughout the nucleus; when the cell divides the chromatin condenses to form Chromosomes. Chromosomes – contain the genetic material that is passed from one generation to the next. Nucleolus – where the assembly of ribosomes begins

Ribosomes Ribosomes are small particles of RNA and protein found throughout the cytoplasm They produce proteins by following the instructions of the nucleus Can be found: Attached to membranes of cell organelles Free floating

Endoplasmic Reticulum The site of where lipid components of the cell membrane are assembled, along with proteins and other materials that are exported from the cell

Types of Endoplasmic Reticulum There are two types of Endoplasmic Reticulum, or ER: Rough ER – which is involved in the synthesis of proteins Called rough ER because of the ribosomes found on its surface Smooth ER – in many cells, contains enzymes that perform specialized tasks, including the synthesis of membrane lipids and the detoxification of drugs Called smooth ER because of the lack of ribosomes found on its surface

Golgi Apparatus Proteins produced in the Rough ER move into the Golgi Apparatus The function of the Golgi Apparatus is to modify, sort, and package proteins and other materials from the ER for storage in the cell or secretion outside the cell

Lysosomes Filled with enzymes One function is the digestion, or breakdown, of: Lipids Carbohydrates Proteins This allows the rest of the cell to use this fuel They also function to breakdown other organelles that have reached the end of their usefulness

Vacuoles Storage in the cell Store materials such as: Water Salts Proteins Carbohydrates In many plants, there is a single fluid filled vacuole This feature in plants make is possible for them to support heavy structure such as leaves and flowers Also can be found in some animals and unicellular organisms

Mitochondria Organelles that convert the chemical energy stores in food into compounds that are move convenient for the cell to use Considered the “power house” of the cell Enclosed by two membranes; the inner membrane is folded up Your mitochondria is inherited from your mother!

Chloroplasts Organelles that capture energy from sunlight and convert it into chemical energy in a process called photosynthesis The biological equivalent to a solar power plant Surrounded by two membranes Inside the organelle are stacks of other membranes with contain the green pigment chlorophyll

Cytoskeleton Supporting structure and transportation system in the cell A network of protein filaments that helps the cell to maintain its shape Also involved in movement Two principle proteins filaments make up the cytoskeleton: Microfilaments Microtubules

Microfilaments Threadlike structures made of a protein called ACTIN Form an extensive network in some cells and produce a tough, flexible framework that supports the cell Also can help the cell move

Microfilaments In animal cells, structures known as centrioles are formed from tubulin Centrioles: Are located near the nucleus Help aid in cellular division

Microfilaments Microtubules also help to build projections from the cell surface that enable cells to swim rapidly through liquids These projections are: Cilia/Cilium Flagella/Flagellum

Microtubules Hollow structures made up of proteins known as TUBULINS Play critical roles in maintaining cell shape Also important in cell division – they help separate the chromosomes

Analogies A comparison between two different things in order to highlight some point of similarity For example: science writer Claudia Kalb relies on the computer to explain how our brains process memories: Some basic facts about memory are clear. Your short-term memory is like the RAM on a computer: it records the information in front of you right now. Some of what you experience seems to evaporate--like words that go missing when you turn off your computer without hitting SAVE. But other short-term memories go through a molecular process called consolidation: they're downloaded onto the hard drive. These long-term memories, filled with past loves and losses and fears, stay dormant until you call them up. ("To Pluck a Rooted Sorrow," Newsweek, April 27, 2009)

The Cell As A Factory Membrane – the walls, floor and roof of the factory Cytoplasm – the air in the factory Nucleus– the main office in a factory Ribosomes – small machines, turning out proteins on the orders of its ‘boss” – the nucleus

The Cell As A Factory Endoplasmic Reticulum: Rough ER - Assembly line, gets proteins from the ribosomes and modifies them Smooth ER – Specially trained workers Golgi Apparatus – Customization shop, putting the finishing touches on proteins and readying them for shipment, then ships the proteins to the parts of the cell where they are needed Lysosomes – the cleanup crew of the factory

The Cell As A Factory Vacuoles – the storage room Mitochondria – the powerhouse of the factory, converting one form of energy into another Chloroplasts – solar power plants, providing energy to the factory Cytoskeleton – the steel or cement beams and columns that provide the factory’s structure