Section 3.2 Cell Organelles

The Framework of the Cell Cytoskeleton Cytoplasm Nucleus Ribosome Endoplasmic Reticulum Golgi apparatus Vesicle Vacuoles Lysosome Centrioles Mitochondrion Chloroplast Each eukaryotic cell has a cytoskeleton, which is a network of proteins that is constantly changing to meet the needs of a cell There are three kinds of fibers (next slide)

Three types of cytoskeleton fibers Microfilaments—long, thin fibers that are made of actin (a protein) that are attached to the cell membrane and play an important role in muscle contraction and relaxation Microtubules—thick, hollow fibers that are made of tubulin (a protein) that give the cell its shape and act as “tracks” for the movement of organelles Intermediate fibers—moderately thick and mainly gives a cell its strength (actin and tubulin) Watch protein building video

Cytoskeleton

Cytoplasm It is an important contributor to cell structure Cytoskeleton Cytoplasm Nucleus Ribosome Endoplasmic Reticulum Golgi apparatus Vesicle Vacuoles Lysosome Centrioles Mitochondrion Chloroplast It is an important contributor to cell structure Fills the space between the nucleus and cell membrane Made up mostly of water called cytosol Suspends the organelles in a cell

Directing Cellular Activity Almost all cellular activity depends on the proteins that the cell makes. DNA instructions are copied as RNA messages, which leave the nucleus. In the cytoplasm, ribosomes use the RNA messages to assemble proteins.

Nucleus Cytoskeleton Cytoplasm Nucleus Ribosome Endoplasmic Reticulum Golgi apparatus Vesicle Vacuoles Lysosome Centrioles Mitochondrion Chloroplast The nucleus is the storehouse for most of the genetic information or DNA Surrounded by a double membrane called the nuclear envelope Inside the nucleus is the nucleolus which makes ribosomes Materials are able to leave and enter the nucleus through nuclear pores

Nucleus

Ribosomes Made of RNA and many proteins Cytoskeleton Cytoplasm Nucleus Ribosome Endoplasmic Reticulum Golgi apparatus Vesicle Vacuoles Lysosome Centrioles Mitochondrion Chloroplast Made of RNA and many proteins Some are free-floating while others are attached to other organelle membranes for protein transport out of the cell Ribosomes make proteins using the instructions from the nucleus

Endoplasmic Reticulum Cytoskeleton Cytoplasm Nucleus Ribosome Endoplasmic Reticulum Golgi apparatus Vesicle Vacuoles Lysosome Centrioles Mitochondrion Chloroplast The endoplasmic reticulum (ER) is a system of internal membranes that produce proteins and lipids The membrane of the ER is interconnected to the outer membrane of nuclear envelope There are two types of ER (next slide)

Two Types of ER Rough ER—ribosomes are attached (giving it a bumpy appearance); membrane makes vesicles around proteins to send them elsewhere Smooth ER—has no attached ribosomes; makes lipids and breaks down toxic substances like drugs and alcohol

Endoplasmic Reticulum

Golgi Apparatus (Body) Cytoskeleton Cytoplasm Nucleus Ribosome Endoplasmic Reticulum Golgi apparatus Vesicle Vacuoles Lysosome Centrioles Mitochondrion Chloroplast The golgi apparatus is a set of flattened, membrane-bound sacs that modifies, sorts, and packages cell products for distribution

Golgi Apparatus

Protein Processing The endoplasmic reticulum and the golgi apparatus are organelles that prepare proteins from extracellular export. A vesicle is a small, often spherical-shaped sac that divide some materials from the rest of the cytoplasm and transport materials from place to place within the cell The cell packages the proteins made by the ribosomes in vesicles to be sent out of the cell Cytoskeleton Cytoplasm Nucleus Ribosome Endoplasmic Reticulum Golgi apparatus Vesicle Vacuoles Lysosome Centrioles Mitochondrion Chloroplast

Vacuoles Many plant cells contain a single large, membrane-bound compartment called the central vacuole which stores water, ions, nutrients, and waste When the central vacuole is full, it allows the plant to stand upright, when the vacuole loses water, the plant wilts A contractile vacuole pumps water out of a cell and is found in some protist cells Cytoskeleton Cytoplasm Nucleus Ribosome Endoplasmic Reticulum Golgi apparatus Vesicle Vacuoles Lysosome Centrioles Mitochondrion Chloroplast Make sure to reiterate that there can be more than one of each organelle

Plant’s Central Vacuole

Lysosomes Cytoskeleton Cytoplasm Nucleus Ribosome Endoplasmic Reticulum Golgi apparatus Vesicle Vacuoles Lysosome Centrioles Mitochondrion Chloroplast A lysosome is a vesicle that contains specific enzymes that break down large molecules Can digest food particles, old damaged or unused organelles, and recycle materials in the cell Also defend cells from invading bacteria and viruses Lysosomes are made by the Golgi apparatus

Centrioles Cytoskeleton Cytoplasm Nucleus Ribosome Endoplasmic Reticulum Golgi apparatus Vesicle Vacuoles Lysosome Centrioles Mitochondrion Chloroplast Centrioles which are cylindrical in shape and function in the reproduction of the cell

Energy Production The energy for cellular functions is produced by chemical reactions that occur in the mitochondria and chloroplasts Nearly all eukaryotic cells contain mitochondria however, chloroplasts are found only in plants and some plant-like protists ATP is the form of energy that fuels almost all cell processes

Mitochondrion Cytoskeleton Cytoplasm Nucleus Ribosome Endoplasmic Reticulum Golgi apparatus Vesicle Vacuoles Lysosome Centrioles Mitochondrion Chloroplast A mitochondrion (mitochondria-plural) is an organelle that uses energy from organic compounds to make ATP (energy) Double-membraned and has many folds to increase surface area Unlike most organelles, mitochondria have their own ribosomes and DNA

Mitochondrion

Chloroplast Cytoskeleton Cytoplasm Nucleus Ribosome Endoplasmic Reticulum Golgi apparatus Vesicle Vacuoles Lysosome Centrioles Mitochondrion Chloroplast A chloroplast is an organelle that uses light energy to make sugar from carbon dioxide and water; carries out photosynthesis Found only in plant cells and some plant-like protists

Chloroplast

Check for Understanding What is the cytoskeleton made of? Which organelle is found attached to the nucleus? Which organelle is responsible for breaking down large particles? Describe the process and organelles involved in protein processing.

Prokaryote vs. Eukaryote

Diversity in Prokaryotes Many prokaryotes have flagella which is a long, threadlike structure that rotates to quickly move a cell Many prokaryotes have pili which are short, thick outgrowths that allow prokaryotes to attack to surfaces or to other cells

Prokaryotic Cell

Diversity in Eukaryotic Cells Some types of eukaryotic cells include fungi, plant, animal, and protist cells Plant cells have chloroplasts, a large central vacuole, and a cell wall outside of the cell membrane made of cellulose Animal cells have centrioles

Plant Cell vs. Animal Cell

Body Types A multicellular organism is composed of many individual, permanently associated cells that coordinate their activities Only occurs in eukaryotic cells Some unicellular organisms can thrive independently but others live in groups A colonial organism has a collection of identical cells that are permanently associated with but do not work together

Levels of Organization Plants and animals have many highly specialized cells that are arranged into tissues, organs, and organ systems A tissue is a distinct group of cells that have similar structures and functions Different tissues may be arranged into an organ, which is a specialized structure that has a specific function Various organs that carry out a major body function make up an organ system

Levels of Organization Example What would come before cell in this image?