Cell Structure and Function I will explain what the cell theory is I will describe how researchers explore the living cell I will distinguish between eukaryotes and prokaryotes

Cell Theory ALL living things are composed of cells Cells are the basic units of Structure Function in living things New cells are produced from existing cells

Cell Theory Single Cell Organisms Multicellular Organisms Many of the cells are specialized to do particular jobs

Two Cell Types Prokaryotic Cells Eukaryotic Cells Have genetic material that is NOT contained in the nucleus Eukaryotic Cells Have genetic material that IS contained in the nucleus (separated from rest of cell)

Two Cell Types Prokaryotes many diverse forms, including all bacteria thought to be the oldest forms of life most do not have internal membranes (no compartments) small in size (0.2-10 micrometers) found in Domain Archaea and Domain Bacteria (page 1072)

Two Cell Types Eukaryote DO have internal membranes; they posses compartments surrounded by membranes called organelles larger in size (10 - 1000 micrometers) found in Domain Eukarya (pages 1072-1077)

Eukaryotic Cell Structure organelle: cell structures that have special functions (jobs) cytoplasm: everything between the plasma membrane and the nucleus cytosol: the fluid portion of the cell; more jellylike than water like because there are many sugars and proteins and minerals, etc. dissolved in this fluid

Nucleus Nuclear Pore Nuclear Membrane Nucleolus Chromatin

Nucleus Nucleus (Nuclei = plural) a round body surrounded by two membranes contains hereditary material and nucleoli Controls the activities of the cell Nuclear Envelope: two membranes surrounding the nucleus isolates the DNA from the rest of the cell. Nuclear Pores: holes in the envelope allows messages to enter and leave the nucleus. Nucleolus: (Nucleoli = plural) spherical structure inside the nucleus. assembles the pieces that make up ribosomes. Chromatin = Hereditary material: DNA of cell instructions that tell the cell what proteins to create; proteins (enzymes) control the activities of the cell. Each individual strand of DNA in a nucleus is called a chromosome. Chromosomes become visible with a light microscope when a cell divides because they condense. All the chromosome strands within a nucleus = chromatin.

Ribosomes

Ribosomes very small, dot like, even in electron microscope photos. found in all cells including prokaryotes, extremely numerous. where proteins are assembled. most float free in the cytoplasm, some are attached to membranes

Endoplasmic Reticulum

Endoplasmic Reticulum a complex network of membranes that form flattened sheets, sacs, and tubes that tend to lie parallel to one another.

Endoplasmic Reticulum they synthesize and transport lipids and proteins. attached to both plasma and nuclear membranes. RER = rough endoplasmic reticulum = has attached ribosomes for synthesis of proteins SER = smooth endoplasmic reticulum = no attached ribosomes; contains enzymes to perform special tasks such as synthesizing lipids and detoxifying drugs

Golgi Apparatus

Golgi Apparatus membranes organized as a series of closely stacked flattened sacs. receives, modifies, sorts, and packages proteins/lipids from endoplasmic reticulum. cells that secrete hormones, enzymes, and other proteins are loaded with Golgi apparatus

Lysosome

Lysosome Typically only in animal cells small organelle; contains digestive enzymes removes "junk" from the cell breakdown lipids, carbohydrates, proteins and cell organelles that have outlived their usefulness merge with food vacuoles to digest food merge with bacteria to break down bacteria

Vacuole

Vacuole spherical membrane bound organelle. stores water, minerals, salts, proteins and carbohydrates in most mature plant cells it takes up most of the central portion of the cell single celled freshwater organisms often contain a specialized vacuole called a contractile vacuole. pumps excess water out of the cell. (another example of homeostasis)

Mitochondria

Mitochondria oval or rod shaped structures composed of an inner and an outer membrane inner membrane has many folds (cristae) which increases the surface area of the inner membrane the cells powerhouse contain enzymes that split sugar molecules (glucose) and transfer the energy to other molecules (ATP) that the cell can use this process is called cellular respiration

Chloroplast

Chloroplast oval shaped structure composed of an inner and an outer membrane the inner membranes, thylakoids, are arranged in stack like layers called grana

Chloroplast chlorophyll (green pigment) and all the enzymes necessary to convert light energy, carbon dioxide, and water into chemical energy (sugars) in a process called photosynthesis is packed within the thylakoids all chloroplasts have their own DNA Lynn Margulis, an American biologist, proposed in 1970 that mitochondria and chloroplasts are actually the descendents of prokaryotes that took up a symbiotic relationship in eukaryotic cells. This idea is called the endosymbiotic theory.

Centriole

Centrioles two small organelles near the nucleus (at right angles to each other) microtubules made of tubulin organizes cell division

Cytoskeleton a network of protein microtubules and microfilaments that help maintain shape and are involved in movement within the cell microtubules: hollow tubes of tubulin that maintain cell shape

Cytoskeleton microfilaments: threadlike actin fibers, which can contract (shorten) and therefore change the shape of the cell, move cytoplasm, and provide a framework that is flexible, yet supports the cell.