Ch 4 Campbell Biology in Focus HHS AP Biology Eggers Cellular Organelles Ch 4 Campbell Biology in Focus HHS AP Biology Eggers

The Jobs of Cells Three main jobs: Make energy Make proteins Need energy for all cellular activities Need to clean up the waste produced while making energy Make proteins Proteins do the work in cells – enzymes, structure, transport, etc. – so we need LOTS of them Make more cells For growth and development To replace old, damaged or diseased cells

Eukaryotic cells have internal compartments called organelles that make doing all of this work much more efficient Nucleus Ribosomes Endoplasmic reticulum Golgi apparatus Lysosomes Vacuoles Mitochondria Chloroplasts Peroxisomes Cytoskeleton: microtubules, centrosomes and centrioles, cilia and flagella, microfilaments, intermediate filaments

Nucleus Bound by the nuclear envelope which is a double membrane composed of two lipid bilayers Connecting the interior of the nucleus to the cytoplasm are large pores which house a protein pore complex which regulates entry and exit of proteins, RNA and other large molecules. Contains most of the genes in the cell, which are located on units called chromosomes. Chromosomes are a combination of both DNA and organizing proteins all wound up together – this is called chromatin. Within the nucleus, you can see a dense region called the nucleolus, where ribosomal RNA is synthesized.

Ribosomes Located in both the cytosol and also attached to the rough endoplasmic reticulum Composed of ribosomal RNA (rRNA) and protein Their job is to synthesize proteins Free ribosomes synthesize the proteins that will function within the cytosol while the bound ribosomes found on the rough ER synthesize integral membrane proteins and proteins for secretion

Endomembrane system Includes the nuclear envelope, the endoplasmic reticulum, the Golgi apparatus, the lysosomes, vacuoles and vesicles, and the cell’s exterior plasma membrane

Smooth and rough endoplasmic reticulum (ER) Smooth ER – synthesis of lipids, carbohydrate metabolism, drug & poison detoxification, and storage of calcium ions (liver cells are packed with smooth ER). Rough ER – is rough in appearance because it is studded with ribosomes. The rough ER produces glycoproteins for secretion and membrane-bound proteins. Proteins bound for secretion or destined to reside in the cell’s plasma membrane bud off from the rough ER in transport vesicles.

Golgi apparatus/Golgi bodies Transport vesicles from the ER often travel first to the Golgi. In the Golgi apparatus, proteins are modified and stored prior to secretion The flattened stacks of Golgi are called cisternae & are not physically connected. The side of the stacks facing the nucleus and ER is referred to as the cis face – this side receives vesicles. The side of the stack facing the plasma membrane is the trans face – this is where the vesicles exit the Golgi. The Golgi also synthesizes macromolecules such as the polysaccharide pectin in plant cells.

Animated tutorial at: http://www.pol2e.com/at04.02.html

Lysosomes Are membranous sacs of hydrolytic enzymes Carry out intracellular digestion Eg phagocytosis. A nutrient or food particle is engulfed, forming a membranous food vacuole. The lysosome fuses with the vacuole, releasing its contents. The hydrolytic enzymes break down the material within the vacuole and the more simple molecules pass into the cytosol for use by the cell. Lysosomes are also involved in autophagy

Digit formation, programmed cell death, and lysosomes…

Vacuoles Large vesicle derived from the ER & Golgi Performs selective transport of solutes Food vacuole formed by phagocytosis Contractile vacuole found in protists - pumps excess water out of the cell Central vacuole in mature plant cells - stores critical ions and helps the cell to increase in size without the energy expenditure necessary to produce additional cytoplasm

Central vacuole in a plant cell Contractile vacuole in a paramecium Central vacuole in a plant cell Food vacuole in an amoeba

Mitochondria & chloroplasts These organelles provide the usable fuel that keeps cellular processes running = glucose & ATP Mitochondria perform cellular respiration, which converts pyruvate, derived from glucose, into ATP. ALL eukaryotic cells have mitochondria. Chloroplasts, found in photosynthetic organisms, capture the sun’s energy and use this to produce glucose from CO2 and H2O in the process of photosynthesis.

Endosymbiont theory Mitochondria and chloroplasts are structurally different from cell organelles derived from the endomembrane system – they are enclosed by a double membrane and chloroplasts have additional membrane-enclosed structures within them They contain ribosomes and their own DNA, which they use to synthesize proteins specific to their function.

Mitochondria

Plastids in plants Contain pigments for photosynthesis Chloroplasts Chromoplasts Storage = Leucoplasts Amyloplast = starch Elaioplast = lipids Proteinoplast = proteins

Chloroplasts

BOTH animal calls and plant cells have mitochondria to make ATP!! All cells need ATP in order to survive so all eukaryotic cells have mitochondria BOTH animal calls and plant cells have mitochondria to make ATP!!

Peroxisomes Specialized metabolic compartment surrounded by a single layered plasma membrane It contains enzymes that detoxify poisons by removing H+ from them and transferring the hydrogen to O2, producing hydrogen peroxide (H2O2) H2O2 is also toxic, but peroxisomes contain an enzyme called catalase that converts hydrogen peroxide to water

The cytoskeleton The cytoplasm of cells contains a highly organized network of fibers called the cytoskeleton Give mechanical support & maintains cell shape Anchors organelles and cytosolic enzymes Allows for cell motility

Microtubules Microtubules – hollow rods composed of protein subunits called tubulin Motor proteins use ATP to move along microtubules In animal cells, the centrosome, near the nucleus, is the microtubule organizing center which gives rise to the microtubule scaffold.

Microfilaments Solid rods composed of actin molecules Helps support the cell’s shape In muscles, it is actin filaments and another protein called myosin which allow for muscle fiber contraction.

Motor proteins (kinesin & dynein) transport organelles along microtubules

Cilia & flagella 1. axoneme, 2. cell membrane, 3. intraflagellar transport, 4. basal body, 5. cross section of flagellum, 6. triplets of microtubules in the basal body

Cell Fractionation – technique to separate and isolate organelles by size using differential centrifugation

Extracellular Matrix

Cell Junctions – Animal Cells Tight junctions – bound by proteins, forms a continuous seal that prevents leakage across epithelial cells Desmosomes – like rivets, creating strong attachments between cells – in muscles Gap junctions – like plant plasmodesmata, connect cytoplasm to neighboring cytoplasm

Plant plasmodesmata Plasmodesmata – membrane-lined channels that connect adjacent plant cells. Allow for the passage of large molecules

Cell Videos Inner Life of a Cell: https://www.youtube.com/watch?v=B_zD3NxSsD8 Plant cells: https://www.youtube.com/watch?v=9UvlqAVCoqY Animal cells: https://www.youtube.com/watch?v=cj8dDTHGJBY

Diseases of cellular components -- http://www.mhhe.com/biosci/ap/foxhumphys/student/olc/h-reading10.html http://en.wikipedia.org/wiki/Mitochondrial_disease http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3794802/ http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3794802/table/t1-ijms-14-18670/ http://www.sciencedirect.com/science/article/pii/S0092867409013622 http://www.ehow.com/list_6368550_cell-membrane-diseases.html http://en.wikipedia.org/wiki/Peroxisomal_disorder