Cell Structure 1

Chapter 4:Cell Structure

Topics you are not responsible for:Bacterial cell walls and the ArchaeaCell-to-cell interactions

End of Chapter questions:Understand: allApply: allSynthesize: 1, 3, 4

Do all mQuiz questions

TEM of Platinum/Carbon replicas of HeLa cell cytoplasm showing clathrin-coated vesicles and microtubules

Inner Life of The Cell

Cell Structure 2

What happens to Aafter it forms?

External Amyloid plaques

Internal Neurofibrillary tangles -- Tau protein

“Trafficking” of membrane components Exportto cell surface

-- APP, secretases, etc. Import into cell

QuestionsDo plaques and/or tangles cause Alzheimer’s Dis.?

Why do neuro. tangles form?

Cells and Organs 3

Leukocyte Rolling

Leukocyte Homing

Cells of you immune system circulate continuously through your body

Circulation of cells and Interstitial fluid

-- antigens / pathogens-- immune cells

Cell extravasation-- Chemokines-- receptors-- adhesion proteins

Cell Structure 4

Light Microscopy (A-C)

A

Bright Field DIC

B

DIC Video

Confocal 3D imaging

Electron Microscopy

D E

TEM SEMFluorescence

C

Microscopy

Normal Light Microscopy

Tick and Sick-2 5

Keratocyte DanceDIC $$

Microscopy, cont

Tick and Sick-2 6

Confocal $$$$Fluorescence $$$

Electron Microscopy

SEM vs TEM $$$$$

Tick and Sick-2 7

Cell Structure 8

Examples of Electron Microscopy

D. TEM (Transmission Electron Microscopy) of neurons (cross-section) showing internal cellular structures. ttp://visualsunlimited.photoshelter. com/image/I00005SIGjGWwl9U

E. SEM (Scanning Electron Microscopy) of neurons showing external surface structures.http://www.med.nus.edu.sg/ant/histonet/txt/nervsem/nerv03.sem.html

Examples of Light Microscopy

A. Standard Bright Field Microscopy of Histological section of brain stained to show Neurofibrillary Tangles (>) and Aβ plaques (*). http://www.microscopy-uk.org.uk/mag //artsep06/mc-Alzheimer.html

B. DIC (Differential Interference Microscopy) of Neocortical neurons in primary culture. Note accentuation of edges and 3D-like appearance Adapted from http://www.ipmc.cnrs.fr/cgi-bin/standard.cgi?descriptif=mantegazza.txt&dossier1=equipes&dossier2=mantegazza&site=inter&menu=1&ssmenu=14&lang=uk

C. Fluorescence Microscopy of fibroblast cell culture stained for proteins of the nucleus, mitochondria, and peroxisomes, as well as the filamentous actin and intermediate filaments. http://learn.hamamatsu.com/galleries/ digitalimages/muntjac/muntjaclarge10.html

Growing Cells

Advantages over whole organism

•Individual cell type•Controlled conditions

•Easier analysis•Stem cell culture & tissue

regeneration

Limitations•Individual cell type•Genetic changes

Tick and Sick-2 9

Cell Structure 10

How do Eukaryotic cells differ from Prokaryotic cells?

Prokaryotes = bacteriaEukaryotes = everything else

Size

Cytoplasm organization

Structure of chromosomes

We will discuss other differences later

Eukaryotic cell cytoplasm

Cell Structure 11

How big are cells?

Why are cells so small?

Surface to volume (S/V) ratio

How Big is It?

Cell Structure 12

What are some functionalregions of cells?

Cytoplasm

Cell membrane (plasma membrane)

Extracellular structures

Cell wall

Cilia & flagella

EC matrix

Cell Structure 13

What are the components of eukaryotic cytoplasm?

Membrane bound compartments

-- Cytoplasm vs “cytosol”

Molecular building blocks

Proteins/enzymes-- Cytoskeleton

Ribosomes

Cell Structure 14

What is the structure of the nucleus?

Large nuclear pores-- two membranes

Chromosomes

Nucleolus

Cell Structure 15

How do molecules move through the cell?

1) Diffusion

2) Endomembrane transport system

What is transported?

Where to?

Endocytosis & exocytosis

MolecularDiffusion

Know this!

Cell Structure 16

What is the structure and function of the ER?

Beginning of endomembrane transport

Rough ERProtein: -- synthesis (Ribosomes)

-- folding-- modifications (glycosylation)

Smooth ERLipid synthesisCa++ storage

Transport to Golgi

Cell structure

Transportvesicles

Cell Structure 17

What is the structure & function of the Golgi?

Protein modifications-- e.g., glycosylation

Sorting & Packaging into vesicles

View these animation Virtual cell -- Protein Trafficking

Virtual cell – Protein modificationLinks on Class resource page

How are proteins transported Through the Golgi?

Intracellular Transport 18

How are proteins modified within the golgi?

How are enzymes ‘tagged’ for transport to lysosomes?

-- hydrolytic enzymes -- NAcGluAm-P transferase-- mannose-6-P-- M-6-P receptors

Cell Structure 19

What is the function of lysosomes?

Breakdown of:

Intracellular materials

Extracellular materials

How are materials transported to lysosome?

Hydrolases from Golgi

Materials from inside and outside the cells

Cell Structure 20

Mutations to transport processes underlie some genetic diseases

I-cell diseases Accumulation of lysosomesMental retardation

Metabolic abnormalitiesFatal

Mucolipidosis IINAcGluAm-P transferase deficiencyWhat is expected effect?

Tay-Sacks diseaseganglioside GM2 lipase deficiency

-- lipid recycled from cell surfaceWhat is expected effect?

Lymphocytes of Mucolipidosis II

Cell Structure 21

What are functions of chloroplasts and mitochondria?

What are distinctive properties

Double membrane

Presence of DNA

What is the origin of these organelles?

“Endosymbiosis”

70S vs 80S ribosomes

Endosymbiosis

Cell Structure 22

What proteins comprise the cell cytoskeleton?

Intermediate filaments

Microtubules

Actin filaments

How is the “cytoskeleton” differentfrom a animal skeleton?

Organization and functionof Intermediate filaments

Mechanical strength

Cell Structure 23

What are the organization and functions of microtubules?

cytoplasmic transport

chromosome movements

movements of flagella and cilia -- “9+2” structure

Cytoplasmic streaming

Closer view onmicrotubules

Flagella Cilia

Cell Structure 24

What are the organization and functions of actin filaments?

Various types of cell movements

Membrane contractions

muscle contraction

Crawling motions

Interacts with “myosin”

Heart CellMembrane ruffling

Cell Structure 25

How do plant cells differ from animal cells?

Chloroplasts

Cell Wall

Vacuole

Cell Structure 26

How are viruses different from cells?

Much smaller

Protein coat – ‘capsid’

Often no membrane

No metabolism

Why are virus infectionsVery difficult to treat?