Cell Organelles Use this presentation in conjunction with the Cell Organelle note-taking worksheet.

Cell Organelles Organelle (“little organ”) = a small structure in the cell that performs a specific function. Membrane-bound organelles are found only in eukaryotic cells

Cytoplasm Everything in a cell except the nucleus is cytoplasm Clear, gelatin-like, watery substance surrounding the organelles. Maintains the shape and consistency of the cell. Allows for chemical reactions necessary in metabolism

Cell Membrane Boundary of the cell Made of a phospholipid bilayer, with protein molecules scattered all over Regulates what comes in and out of the cell, provides for some protection of the cell and its organelles Emphasize word parts here: phospho= phosphate head; lipid= fatty acid tail bi= 2

Nucleus Control center of the cell – has the information needed to oversee the chemical reactions in cells (what is the counterpart in a factory?) Contains DNA (either as chromosomes or chromatin), nucleolus and nuclear envelope Surrounded by a double membrane called nuclear envelope Usually the easiest structure to see under a microscope Usually one per cell, but some cells have many nuclei Cells with more than one nucleus include muscle cells and liver cells, largely because of the massive volume of cytoplasm and number of organelles that need controlling. 5

Nuclear Envelope Boundary of the nucleus “Envelope” – because it a a double-membrane Made of a phospholipid bilayer (like the cell membrane) Regulates what comes in and out of the nucleus, has nuclear pores that allow a large molecule like RNA to move in and out of the nucleus. Emphasize word parts here: phospho= phosphate head; lipid= fatty acid tail bi= 2

Chromosome/ Chromatin Eukaryotic DNA has 2 forms: Chromatin- DNA that is loosely coiled around a protein. When the cell in NOT dividing, DNA is in this form but cannot be seen in most light microscopes. Chromosome- chromatin is condensed into chromosomes when the cell divides (mitosis/ meiosis). Humans have 23 pairs of chromosomes which contain all of your DNA. These are visible in a light microscope. Has the genetic code that directs what proteins get made

Nucleolus A large, dense area in the nucleus Site of ribosome production nucleolus

Ribosome Site of protein synthesis (also known as translation) Found attached to rough ER or floating free in cytoplasm Not membrane-bound Produced in a part of the nucleus called the nucleolus

Endoplasmic Reticulum A.k.a. “E.R.” (endo means inside + cytoplasmic + reticulum means network = network of membranes inside the cytoplasm) Connected to nuclear envelope Rough ER: studded with ribosomes; it chemically modifies proteins Smooth ER: no ribosomes; it makes lipids

Golgi Apparatus Looks like a stack of plates; membrane- bound Stores, transports, and packages proteins Molecules transported to and from the Golgi by means of vesicles AKA Golgi Complex

Which organelles do lysosomes work with? Garbage disposal of the cell Membrane-bound Contain digestive enzymes that break down big molecules and damaged organelles Which organelles do lysosomes work with?

What type of microscope may have been used to take this picture? Vacuoles Large central vacuole usually in plant cells Many smaller vacuoles in animal cells Storage container for water, food, enzymes, wastes, pigments, etc. Membrane-bound The image is 2D, so it must have been a light microscope or TEM. If the cell is very tiny, then a TEM was used. Otherwise, a strong light microscope could have captured this image. What type of microscope may have been used to take this picture?

Mitochondria “Powerhouse of the cell” – found in BOTH plant and animal cells Cellular respiration occurs here to release energy (ATP) for the cell to use Has 2 membranes – outer and inner membranes (the latter is highly folded that increases surface area for cellular respiration Has its own circular DNA and ribosomes (wonder why?)

Chloroplast Found only in plant cells and plant-like protists Site of photosynthesis Bounded by a double membrane – third membrane is “photosynthetic” - contains the green pigment chlorophyll Contains its own DNA and ribosomes (why?) Chloroplasts absorb light, which is the starts the process of photosynthesis.

Cytoskeleton Acts as skeleton and muscle Provides shape and structure Helps move organelles around the cell, or move the cell itself Made of three types of filaments Only in eukaryotes Actin, also found in muscle cells, mainly help maintain cell shape in their cytoskeletal role. Microtubules mostly move organelles around the cell. Intermediate filaments also provide structural support.

Centrioles During cell division – help assemble the spindle apparatus that moves chromosomes Usually found only in animal cells Made of microtubules arranged in a special way Microtubules are also part of the cytoskeleton.

Cilia and Flagella Made of microtubules arranged in a special way (similar to centrioles) Extensions of (some) eukaryotic cells that have no cell wall For movement Cilia in throat cells Cilia in Paramecium Cilia in sperm cells

Cell Wall Found in plant, fungus, and bacterial cells Rigid, protective barrier Located outside of the cell membrane Made of cellulose (fiber) in plant cells 19

Quick Review Which organelle is the control center of the cell? Which organelle is responsible for converting food energy into usable energy and is present in ALL eukaryotic cells? Which organelles are not found in animal cells? Which organelle helps plant cells make food? What does E.R. stand for? Which organelles have something to do with making and packaging proteins? Why are almost all organelles membrane-bound?

Identify the organelles