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 Made of a phospho lipid bi layer, 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
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
Nuclear Envelope “ Envelope” – because it a a double-membrane Made of a phospho lipid bi layer (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.
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 nucleolus
Site of ribosome production
Ribosome Site of protein synthesis (also known as translation) Found attached to rough ER or floating free in cytoplasm
Produced in a part of the nucleus called the nucleolus
Endoplasmic Reticulum A.k.a. “E.R.” ( endo means inside + cyto plasmic + 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
Lysosomes Garbage disposal of the cell Which organelles do lysosomes work with?
Contain digestive enzymes that break down big molecules and damaged organelles
Vacuoles Large central vacuole usually in plant cells Many smaller vacuoles in animal cells What type of microscope may have been used to take this picture?
Storage container for water, food, enzymes , wastes, pigments, etc.
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 Bounded by a double membrane – third membrane is “photosynthetic” - contains the green pigment chlorophyll
Contains its own DNA and ribosomes (why?)
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
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
Cilia and Flagella Made of microtubules arranged in a special way (similar to centrioles) Cilia in throat cells Cilia in Paramecium Cilia in sperm cells
Extensions of (some) eukaryotic cells that have no cell wall
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
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