Important Vocabulary Many cells have a variety of internal structures called organelles or mini organs. Most cells are surrounded by a cell membrane. Many cells have a large organelle called the nucleus. Cells that contain organelles and a nucleus are called eukaryotic cells. Cells that DO NOT contain organelles and a nucleus are called prokaryotic cells.
What’s the difference here? Let’s compare three items: a eukaryotic cell, a prokaryotic cell and a virus. What are the similarities? What are the differences?
Prokaryotes Vs. Eukaryotes Vs. Viruses No membrane Nucleus with • No nucleus bound nucleus membrane Only plants have • No membranes Has a cell wall cell wall Only a few • No organelles Contains many organelles or organelles • Cannot none at all. Has a lipid bi- reproduce on Has a capsule layer membrane its own surrounding it surrounding it. Specialized by • Generally not Three main thousands of considered types. different sizes alive by most and shapes. standards
Parts of the Eukaryotic Cell Cell Membrane Cytoplasm (cytosol) Mitochondria Ribosome Endoplasmic reticulum (rough and smooth) Golgi apparatus Lysosome Cytoskeleton Cilia and Flagella Nucleus Nucleolus Cell wall Vacuole Chloroplast
Plant Cells Vs. Animal Cells Contain chloroplasts for No cell wall photosynthesis No chloroplasts Have a cell wall to maintain structure and rigidity Contain lysosomes and Usually do not contain peroxisomes lysosomes and peroxisomes Contain cilia and/or Cells are square and rigid or flagella geometric shaped Cells are fluid and flexible, Limited movement many shapes Have one large central vacuole Cells can move around. Has small vacuoles
Parts of Eukaryotic CellYou are required to know the parts, what they look like and their function for the test!
Cell Membrane The cell membrane is selectively permeable which means some substances can cross and others cannot cross. Cell membranes are made of primarily lipids and proteins. Cell membranes are made of a lipid bi-layer. A cell membrane is called a fluid mosaic because it behaves more like a liquid than a solid. It is flexible and provides an effective barrier and transport function.
Cytoplasm This lies between the cell membrane inside of the cell. It is a fluid that all the organelles float in. It is sometimes called the cytosol.
Mitochondria Mitochondria are the powerhouses of the cell. Mitochondria create ATP for the cell to use as energy. One cell many have thousands of mitochondria depending on its function. Mitochondria have two membranes and have their own DNA which only comes from the mother.
Ribosomes Ribosomes are the most numerous of the cell’s organelles. Ribosomes are made of proteins and RNA. Ribosomes are responsible for creating proteins. Ribosomes are found free in the cytoplasm and also attached to the rough ER. (endoplasmic reticulum)
Endoplasmic Reticulum The ER comes in two varieties, the rough ER and the smooth ER. The rough ER contains ribosomes and makes proteins. The smooth ER does not contain ribosomes and makes lipids such as steroids. The rough and smooth ER are sometimes attach to each other. Both ER are involved in cell product transport of proteins and lipids.
Golgi Apparatus The golgi is the processing, packaging and transport system. It is a system of membranes that work closely with the ER. The golgi modifies the products for transport throughout the cell.
Lysosomes Lysosomes contain enzymes that help digest proteins, carbohydrates, lipids, DNA and RNA. These enzymes can also digest old organelles, viruses and bacteria. Lysosomes are rare in plant cells.
Cytoskeleton Cytoskeleton’s are made of two parts: the microtubules and the microfilaments. The microtubules assist in cell division by moving the cells apart. Microfilaments are made of protein and help with muscle contractions. Both help support the cell and give structure but do allow for movement.
Cilia and Flagella Some cells have flagella. They usually only have one. Many cells have cilia Cilia which can number in the thousands. A flagella is like a whip. Cilia are like tiny paddles. Flagella Cilia and flagella are made of microtubules.
Nucleus The nucleus is surrounded by a membrane called the nuclear envelope. The nucleus contains all the DNA for the cell. It directs all the activities of the cell. The nuclear envelope contains pores so that RNA can pass into the cytoplasm during protein synthesis.
Nucleolus The nucleolus is found inside the nucleus. It is responsible for making the ribosomes. There is usually only one.
Cell Wall Found in plant cells and bacteria only. Not found in animal cells. Helps maintain structure and protection. Does contain small pores to move water and oxygen and carbon dioxide in and out.
Vacuoles These are fluid filled and store many different things such as water, waste, enzymes and poisons. In plants vacuoles take up 90% of the space. Vacuoles are small in animal cells.
Chloroplast This also called a plastid. Chloroplasts have their own membrane and their own DNA. Chloroplasts are found only in plant cells and some protists. (little animals) Chloroplasts do photosynthesis and contain chlorophyll which make them green. Photosynthesis creates sugar from sunlight for the plant to use.