CHAPTER 6A TOUR OF THE CELL

Cytology: science/study of cells

Light microscopy resolving power~ measure of clarity

Electron microscopy TEM ~ electron beam to study cell ultrastructure

SEM ~ electron beam to study cell surfaces Cell fractionation ~ cell separation; organelle study Ultracentrifuge ~ cell fractionation; 130,000rpm

A cell is a living unit greater than the sum of its parts

• While the cell has many structures that have specific functions, they must work together.

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Prokaryotebacteria cellsTypes of cells

Eukaryoteanimal cells

- no organelles

- organelles

Eukaryoteplant cells

Cell Types: ProkaryoticNucleoid: DNA concentrationNo organelles with membranesRibosomes:protein synthesis Plasma membrane: (all cells); semi-permeableCytoplasm/cytosol(all cells)

Cell types: EukaryoticNucleus:membrane enclosed organelle containing

chromosomesMembrane bound organelles of specialized

form and function Generally larger than prokaryotic cells

Cell Size

As cell size increases, the surface area to volume ratio decreases

Rates of chemical exchange may then be inadequate for cell size

Cell size, therefore, remains small

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Why organelles? Specialized structures

specialized functions cilia or flagella for locomotion

Containers partition cell into compartments create different local environments

separate pH, or concentration of materials distinct & incompatible functions

lysosome & its digestive enzymes Membranes as sites for chemical reactions

unique combinations of lipids & proteins embedded enzymes & reaction centers

chloroplasts & mitochondria

mitochondria

chloroplast

Golgi

ER

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Cells gotta work to live! What jobs do cells have to do?

make proteins proteins control every

cell function make energy

for daily life for growth

make more cells growth repair renewal

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Proteins do all the work!

cellsDNA

proteins

organismRepeat after me…

Proteins do all the work!

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Cells functions Building proteins

read DNA instructions build proteins process proteins

folding modifying

removing amino acids adding other molecules

e.g, making glycoproteinsfor cell membrane

address & transport proteins

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Building Proteins Organelles involved

nucleus ribosomes endoplasmic reticulum

(ER) Golgi apparatus vesicles

nucleus ribosome ER Golgiapparatus vesicles

The Protein Assembly Line

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nuclearpores

nuclearpore

nuclear envelopenucleolus

histone protein

chromosome

DNA

Function protects DNA

Structure nuclear envelope

double membrane membrane fused in spots to create pores

allows large macromolecules to pass through

Nucleus

What kind of molecules need to

pass through?

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Nucleolus Function

ribosome production build ribosome subunits from rRNA & proteins exit through nuclear pores to cytoplasm &

combine to form functional ribosomes

smallsubunit

large subunit

ribosome

rRNA &proteins

nucleolus

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smallsubunit

largesubunitRibosomes

Function protein production

Structure rRNA & protein 2 subunits combine 0.08m

RibosomesRough

ER

SmoothER

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Types of Ribosomes Free ribosomes

suspended in cytosol synthesize proteins that

function in cytosol Bound ribosomes

attached to endoplasmic reticulum

synthesize proteins for export or for membranes

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Endoplasmic Reticulum Function

processes proteins manufactures membranes synthesis & hydrolysis of many compounds

Structure membrane connected to nuclear envelope &

extends throughout cell

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Types of ER

rough smooth

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Smooth ER function Membrane production Many metabolic processes

synthesis synthesize lipids

oils, phospholipids, steroids & sex hormones hydrolysis

hydrolyze glycogen into glucose in liver

detoxify drugs & poisons in liver ex. alcohol & barbiturates

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Membrane Factory Build new

membrane synthesize

phospholipids builds membranes

ER membrane expands bud off & transfer

to other parts of cell that need membranes

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Rough ER function Produce proteins for export out of cell

protein secreting cells packaged into transport vesicles for export

Which cellshave lot of rough ER?

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Golgi Apparatus

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Vesicle transport

vesiclebuddingfrom roughER

fusionof vesiclewith Golgiapparatus

migratingtransportvesicle

protein

ribosome

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Any Questions!!