7.3 Structures and Organelles

7.3 Structures & Organelles Division of Laborcells have a division of labor and contain special structures that work together to carry out life processes

Internal Structure· eukaryotic cells are highly organized structures· surrounded by a membrane and contain membrane-bound organelles that perform specific functions· the organelles are anchored in the cytoplasm by the cytoskeleton - a network of protein fibers· ROLE: structural support and to help move organelles

microtubules (long hollow tubes) - act as tracks for organelle movement...also help in cell division

microfilaments (tiny threads) - enable cells to move, muscle contraction· cytoplasm fluid is know as cytosol and is mostly water

Organelles involved in Protein Production

· much of the cell is devoted to making proteins· proteins are made of amino acids and have unique characteristics (size, polarity, acidity)· since proteins carry out critical functions, they need to be made correctly

Nucleus· the nucleus stores the DNA· DNA contains instructions for making proteins

ROLE: Two major demands of the nucleus1. DNA must be protected2. information must be available

· surrounded by double membrane called the nuclear envelope· nuclear envelope has holes called nuclear pores that are used for transport· most nuclei contain a small spherical area called a nucleolus (site where ribosomes are assembled form proteins and RNA)

Ribosomes· ribosomes are tiny organelles that link amino acids together to make proteins· can be free or attached to ER· ROLE: manufactures proteins

7.3 Structures and Organelles

Endoplasmic Reticulum (ER)· the endoplasmic reticulum(ER) is an interconnected network of thin folded membranes· ROLE: modifies proteins and cellular pathways

Rough ERcovered with ribosomesmakes the bulk of proteins and modifies them for export

Smooth ERmakes lipidsbreakdown toxins

Golgi Apparatus· ROLE: processing, packaging, and secreting organelle of the cell· system of membrane stacks (like pancakes)· works with ER in modifying proteins

Vesicles· vesicles - small membrane-bound sacs that divide materials in the cytoplasm and transport materials within the cell

Mitochondria· ROLE: supply energy to the cell· processes your food energy into cellular energy your cells can use· bean shaped and has two membranes

outer - barrier from cytosolinner - membrane is folded to increase surface area

(cristae)· have their own ribosomes and DNA· cells that require more energy contain more mitochondria

Vacuoles· fluid-filled organelles· ROLE: store water, food, inorganic ions, enzymes, and wastes· animal cell vacuoles are small· in plants they contain one very large vacuole (up to 90% of the cell)

animal cell plant cell

Lysosomes· small circular organelle· ROLE: contains collective enzymes that break down lipids, carbs, proteins, DNA and RNA, bacteria, viruses, and old cell parts· common in animals, fungi, protists...not usually in plants

7.3 Structures and Organelles

Centrosomes and Centrioles· centrosomes ROLE: produce microtubules· in animal cells it contains two small structures called centrioles· centrioles - short microtubules that help with cell division· centrioles can also form cilia and flagella cell wall

cell membrane

Cell Wall· lies outside of cell membrane· ROLE: support, protections, and shape· found in algae, plants, and bacteria· made of cellulose in plants and algae

Chloroplasts· photosynthesis reactions (solar energy --> food energy)· two membrane system and contain ribosomes and DNA· contain membrane stacks - thylakoids· contain chlorophyll (green)

chloroplastscell wall

largevacuole

centrioles

lysosome

small vacuole

animal cells plant cells· centrioles· lysosomes· small vacuole

· chloroplasts· cell wall· large vacuole