Cell-cell biology

7/27/2019 Cell-cell biology

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A Tour of the Cell

Chapter 6


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Objectives

Be familiar with the regions of the cell andthe overall role of each region

Be familiar with the basic organelles and

their function

Be familiar with the way neighboring cells

can communicate


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Cell Types

All living organisms

are made of cells Two kinds of cells

Prokaryotic: lacks

membrane boundstructures other than

plasma membrane

Bacteria

Eukaryotic: contains

membrane bound

organelles enablingcompartmentalization

leading to

specialization animals, plants, protists,fungi


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Cell Size

Limits on cell sizedetermined by ability

to perform metabolic

processes Lower: can all

necessary components

fit Upper: can we regulate

supplies adequately

(surface to volumeratio)


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Regions of a Eukaryotic Cell

Nucleus: contains genetic material (DNA)necessary for cell regulation. Reference

library

Cytoplasm: consists of cytosol (cell fluid)

and organelles (specialized structures that

carry out metabolic activities of cell) Plasma Membrane: contains the cell and

regulates movement of materials into/out ofthe cell


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Cell Overview


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Nucleus

Control center of cell Dual membrane

system that fuse to

form nuclear pores DNA and Protein

complexes called

Chromatin

Nucleolus: region of

RNA within theNucleus


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Nuclear Pore Structure

To get materials into the

nucleus there is a 27

Amino Acid tag (zip code)

added onto molecules and

are assisted by proteinscalled importins

To leave the nucleus

exportin proteins, aspecific zip code, GTP

and Ran are required


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Import Summary


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Ribosomes

Sites of Proteinsynthesis

May be free or bound

Free make proteinstypically used in the

cell

Bound are attached tomembrane (ER) and

make proteins typically

for export


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Endoplasmic Reticulum (ER)

Part of theendomembrane system

Smooth ER: site of

lipid synthesis, detox,carbohydrate

metabolism

Rough ER: site of

protein synthesis

(contains bound

ribosomes)


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Golgi ApparatusWhen it absolutely, positively, has to leave the cell

Finishes, sorts, andpackages

manufactured products

of the cell cis: receives products

from ER

trans: ships materials

to other parts of cell

(often the plasma

membrane)


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Lysosomes

Membrane boundstructures responsible

for the degradation of

spent organelles andfood items

Contain hydrolytic

enzymes


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Vacuoles

Membrane bound

storage areas for

resources

Named after theresource they contain


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Mitochondria, Chloroplast

Mitochondria: site of

most ATP synthesis

Chloroplast: site of

carbohydrate synthesis


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Peroxisomes

Modify molecules

through redox

reactions (fatty acid)

Produce peroxide as aresult (H2O2)

Split into two as they

grow


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Cytoskeletal

elements

Provide structuralframework for the cell

Movement of materialsinside and on the surface ofthe cell

Microtubules

grow from centrosome

load bearing Microfilaments

pulling forces

Intermediate filaments pulling forces


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Organelles of Motility

Flagellum: moves the entire cell

Cilium (cilia): moves things along the surface of

the cell


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Extracellular Surfaces

Most cells have a

combination of proteins,

lipids and sugars that form

an extracellular matrix Plants have a cell wall


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What distinguishes one cells

function from another?

The quantity and type

of organelles

determine how the cell

can function.


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Communication is Critical Connections between cellsare called junctions

Tight junctions: leak-proof connections

between cells

Desmosomes: fastencells together

strengthening the tissue

Gap junctions:provide cytoplasmic

channels between cells

Plasmodesmata: plantcell channels

In order for many cells to

function as a unit (as in

multicellular organisms)there must be a minimal

level of communication


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Cell-cell biology