Cellular Cellular OrganellesOrganelles

6.3 & 6.46.3 & 6.4

Organelles covered Organelles covered todaytoday

Nucleus & nuclear envelopeNucleus & nuclear envelope

RibosomesRibosomes

Endomembrane systemEndomembrane system Endoplasmic reticulum (ER)Endoplasmic reticulum (ER) Golgi apparatusGolgi apparatus LysosomesLysosomes VacuolesVacuoles

Nucleus - StructureNucleus - Structure

Contains the DNA packaged into Contains the DNA packaged into genesgenes on on chromosomeschromosomes

Nuclear envelope is a double membrane that Nuclear envelope is a double membrane that separates nucleus from separates nucleus from cytoplasmcytoplasm

Pore complex lines each nuclear pore and Pore complex lines each nuclear pore and regulates entry & exit (RNA leaves through the regulates entry & exit (RNA leaves through the pores)pores)

Nuclear Nuclear laminalamina lines inner surface & help lines inner surface & help maintain shapemaintain shape

Nuclear matrix is a framework of Nuclear matrix is a framework of fibersfibers extending throughout the interior of the extending throughout the interior of the nucleusnucleus

Organization of DNAOrganization of DNA

DNA is organized into discrete units called DNA is organized into discrete units called chromosomeschromosomes

Each chromosome is made up of Each chromosome is made up of chromatinchromatin (complex of proteins and DNA)(complex of proteins and DNA)

Chromatin is the Chromatin is the uncoileduncoiled form of DNA form of DNA

Chromosomes is the coiled up form of DNA Chromosomes is the coiled up form of DNA that takes shape when the cell is about to that takes shape when the cell is about to dividedivide

Chromosome NumberChromosome Number

Every human cell has Every human cell has 4646 chromosomes that chromosomes that occur in pairs called homologous pairsoccur in pairs called homologous pairs

So we have 23 So we have 23 homologous pairshomologous pairs of of chromosomeschromosomes

The exception is the sex cells or The exception is the sex cells or gametesgametes (sperm & egg) which have 23 chromosomes.(sperm & egg) which have 23 chromosomes.

This preserves chromosome number from This preserves chromosome number from one one generationgeneration to the next to the next

NucleolusNucleolus

Structure in the non-dividing nucleus – Structure in the non-dividing nucleus – appears as a mass of densely stained appears as a mass of densely stained granules and granules and fibersfibers

RibosomalRibosomal RNA (rRNA) is synthesized from RNA (rRNA) is synthesized from instructions contained in the DNAinstructions contained in the DNA

Proteins imported from the cytoplasm are Proteins imported from the cytoplasm are assembled with rRNA into assembled with rRNA into largelarge and and smallsmall ribosomal subunits ribosomal subunits Small & large subunits Small & large subunits exitexit nucleolus where nucleolus where

they can assemble proteinsthey can assemble proteins

RibosomesRibosomes Made of ribosomal RNA and proteinsMade of ribosomal RNA and proteins

Main function: Main function: carry out protein synthesiscarry out protein synthesis

Cells that make a large number of proteins Cells that make a large number of proteins have a high percentage of ribosomes (example: have a high percentage of ribosomes (example: pancreas)pancreas)

Two types of ribosomes – both contain large & Two types of ribosomes – both contain large & small subunits small subunits FreeFree ribosomes – suspended in the cytoplasm and ribosomes – suspended in the cytoplasm and

make proteins that function within the make proteins that function within the cytoplasmcytoplasm BoundBound ribosomes – attached to the outside of the ribosomes – attached to the outside of the

ER and make proteins that are inserted into ER and make proteins that are inserted into membranes or membranes or exportedexported from the cell. from the cell.

Endomembrane Endomembrane systemsystem

Functions in the cell:Functions in the cell: Synthesis of proteinsSynthesis of proteins Transport of proteins into membranes or out of Transport of proteins into membranes or out of

the cellthe cell Metabolism and movement of lipidsMetabolism and movement of lipids Detoxification of poisonsDetoxification of poisons

System is connected through direct contact System is connected through direct contact or by transfer of vesiclesor by transfer of vesicles

Organelles of the Endomembrane system: Organelles of the Endomembrane system: nuclear envelope, ER, Golgi, lysosomes, nuclear envelope, ER, Golgi, lysosomes, vacuoles, plasma membranevacuoles, plasma membrane

Endoplasmic ReticulumEndoplasmic Reticulum

Extensive network of membranes that is Extensive network of membranes that is continuous with the nuclear envelope continuous with the nuclear envelope (surrounds it)(surrounds it)

Two sections of the ERTwo sections of the ER Smooth ER – contains no ribosomesSmooth ER – contains no ribosomes Rough ER – surface is covered with ribosomesRough ER – surface is covered with ribosomes

Smooth ERSmooth ER

Functions of the Smooth ER:Functions of the Smooth ER: Synthesis of Synthesis of lipidslipids (oils, phospholipids, steroids) (oils, phospholipids, steroids) Metabolism of Metabolism of carbohydratescarbohydrates DetoxificationDetoxification of drugs and poisons by adding of drugs and poisons by adding

hydroxyl groups to make them more soluble and hydroxyl groups to make them more soluble and easier to flush from the bodyeasier to flush from the body How does this relate to addiction? More drugs & How does this relate to addiction? More drugs &

alcohol = more smooth ER and enzymes to alcohol = more smooth ER and enzymes to increase the rate of detoxification. This increases increase the rate of detoxification. This increases tolerance to the drugs which means you need tolerance to the drugs which means you need more of it to achieve desired effect.more of it to achieve desired effect.

Rough ERRough ER

Functions of Rough ERFunctions of Rough ER

Transport of Transport of proteinsproteins out of the cell out of the cell Ribosomes are attached that undergo protein Ribosomes are attached that undergo protein

synthesissynthesis Make proteins that will be secreted from the cellMake proteins that will be secreted from the cell These proteins leave ER in a These proteins leave ER in a vesiclevesicle (little vehicle) (little vehicle)

Membrane factory for the cellMembrane factory for the cell It grows in place by adding membrane proteins It grows in place by adding membrane proteins

and and phospholipidsphospholipids to its own membrane to its own membrane

GolgiGolgi

Manufacturing, warehousing, sorting, and Manufacturing, warehousing, sorting, and shipping shipping center for the cellcenter for the cell

Products of the ER are modified and stored Products of the ER are modified and stored and then sent to their final destinationand then sent to their final destination

Consists of Consists of flattenedflattened membranous sacs membranous sacs

Vesicles are concentrated around the golgi Vesicles are concentrated around the golgi bringing things to it and away from itbringing things to it and away from it

Sides of the GolgiSides of the Golgi

The golgi has two sides to it:The golgi has two sides to it: Cis face – Cis face – receivingreceiving department department

Side facing the ERSide facing the ER Trans face – Trans face – shippingshipping department department

Side facing the plasma membraneSide facing the plasma membrane Proteins come from the ER in transport Proteins come from the ER in transport

vesicles and fuse to the Cis face and are vesicles and fuse to the Cis face and are modified and leave in vesicles from the trans modified and leave in vesicles from the trans face (alphabetical order C – T)face (alphabetical order C – T)

LysosomesLysosomes Sac of Sac of hydrolytichydrolytic enzymes that an animal cell enzymes that an animal cell

uses to digest macromoleculesuses to digest macromolecules

Sacs are highly Sacs are highly acidicacidic and enzymes are and enzymes are designed to work best theredesigned to work best there

If a sac breaks open no damage is done because If a sac breaks open no damage is done because cytoplasmic pH is cytoplasmic pH is neutralneutral

Made by the Made by the roughrough ER ER

Intracellular digestion of nutrients & Intracellular digestion of nutrients & damageddamaged organellesorganelles

Disorders: Tay-Sachs – a Disorders: Tay-Sachs – a lipidlipid digesting digesting lysosome is missing and the brain becomes lysosome is missing and the brain becomes impaired by lipid buildup.impaired by lipid buildup.

VacuolesVacuoles

Compartments for Compartments for storagestorage

Types:Types: Food vacuolesFood vacuoles Contractile vacuoles (water pumps)Contractile vacuoles (water pumps) Central vacuoles (water storage in plants)Central vacuoles (water storage in plants)

Central VacuoleCentral Vacuole

TonoplastTonoplast surrounds the central vacuole surrounds the central vacuole

Stores organic compoundsStores organic compounds

Stores potassium & chloride (inorganic Stores potassium & chloride (inorganic compounds)compounds)

Disposal sites for Disposal sites for harmfulharmful compounds compounds

Contain Contain pigmentspigments that color the cells to help that color the cells to help attract pollinatorsattract pollinators

Contain poisonous compounds to help Contain poisonous compounds to help protect against protect against herbivoresherbivores

Major role in the Major role in the growthgrowth of plants of plants

Review of the Review of the Endomembrane SystemEndomembrane System