Ch.3 Cells

1. Plasma Membrane

2. Cytoplasm• Entire contents of cell between P.M.

and nucleus • .

3. Nucleus or Nuclear Area• Contains DNA, the genetic material

The 3 Basic Parts of all Cells

– Phospholipids form a two-layer sheet

Figure 5.11B

Water

Water

Hydrophilicheads

Hydrophobictails

Classes of Cells

• Two basic types of cells:1. Prokaryotic cells

2. Eukaryotic cells

Prokaryotic cells are ….

Prokaryotic cell

Nucleoidregion

Nucleus

Eukaryotic cell Organelles

Co

loriz

ed

TE

M 1

5,0

00

Figure 4.3A

Prokaryotic Cell

Nuclear area

Pili

Flagella

Ribosomes

Cell wall

Plasma membrane

Figure 4.3B

Eukaryotic cells Animal Cell

Fig 4.4A

1. The nucleus is the cellular control center

NucleusChromatin

Nucleolus

Pore

Ribosomes

Roughendoplasmicreticulum

Two membranesof nuclearenvelope

Figure 4.5

2. Smooth endoplasmic reticulum, or smooth ER

• Synthesizes lipids

Smooth ER

Rough ER

Nuclearenvelope

Rough ER

RibosomesSmooth ER

TE

M 4

5,00

0

Figure 4.7

3. Rough endoplasmic reticulum or Rough ER– Ribosomes on the surface

Secretory(glyco-) proteininside trans-port vesicle

4Transport vesiclebuds off

Sugar chain3

Rough ER

Glycoprotein2Polypeptide

Ribosome

1

Figure 4.8

4. The Golgi apparatus finishes, sorts, and ships cell products

Figure 4.9

Golgi apparatus

TE

M 1

30

,00

0

Transportvesicle fromthe Golgi“Shipping” side

of Golgi apparatus

Golgiapparatus

“Receiving” side ofGolgi apparatus

Transportvesiclefrom ER

New vesicleforming

5. Vesicles: – Membrane-bound “balloons” that transport and

store substances in cells

6. Lysosomes are sacs of enzymes • function in

digestion within a cell

• recycle damaged organelles

Fig 4.13

•The various organelles of the endo-membrane system are inter-connected structurally and functionally

7. Mitochondria harvest chemical energy from food

– Mitochondria carry out cellular respiration …

Figure 4.14

Mitochondrion

Outermembrane

Intermembranespace

Matrix

Innermembrane

Cristae

TE

M 4

4,8

80

8. Cytoskeleton & related structures -

Actin subunit

Microfilament

7 nm

Fibrous subunits

10 nm

Intermediate filament Microtubule

25 nm

Tubulin subunit

Fig 4.17

– Microfilaments of actin

– Intermediate filaments

– Microtubules give the cell rigidity• And provide anchors for organelles and act as tracks for

organelle movement

Cilia and flagella move when microtubules bend– Eukaryotic cilia and flagella are

LM

60

0

Co

loriz

ed

SE

M 4

,10

0

Figure 4.18

– Tight junctions

– Anchoring junctions

– Gap junctions • allow substances to flow from cell to cell

Anchoring junction

Tight junctions

Gap junctions

Extracellular matrix

Space between cells

Plasma membranes of adjacent cells

Figure 4.18B

Plant Cell –Fig. 4.6b

Plant cells also have:1. Vacuole

• stores water, solutes, waste• Important for growth and rigidity

2. Chloroplasts

3. Cell wall

**Plant cells do not have lysosomes

Vacuoles function in the general maintenance of the cell

Chloroplast

Centralvacuole

NucleusC

olor

ized

TE

M 8

,700

Figure 4.12

Chloroplasts convert solar energy to chemical energy

– convert solar energy to chemical energy in sugars

TE

M 9

,750

Chloroplast

Stroma

Intermembranespace

Inner and outermembranes

Granum

Figure 4.15

Plant cells

• have rigid cell walls made of cellulose

Plasma membrane

Cytoplasm

Plasmodesmata

Vacuole

Layers of one plant cell wall

Walls of two adjacent plant cells

Figure 4.22

Chapter 5: How cells Work

Transporting across membranes• Solvent –

• Solute – – any molecule dissolved in the liquid.

• Selectively permeable – water can move freely through the membrane, but the membrane regulates the passage of solutes

• Diffusion –

• Osmosis – movement of water across a selectively permeable membrane.

Given a membrane that is permeable to water and glucose:

Which way will water move?

Which way will glucose move?

• Hypertonic – high solute concentration, as compared to the other side of a membrane

• Hypotonic –

• Isotonic – equal solute concentrations on both sides of the membrane

Fig. 5.12: Diffusion

Isotonic Solutions

Fig. 5.13

Fig. 5.14

Functions of membrane proteins

Messenger molecule

Receptor

Activatedmolecule ATP

Enzymes Receptors for messages Transport of substances

Two types of transport across membranes

1. Passive transport (or Facilitated diffusion) – a solute moves through a membrane

transport protein in the direction set by its concentration gradient

– Small nonpolar molecules such as

– Other larger or polar molecules do not easily diffuse across the bilayer and transport proteins provide passage across membranes through a process called facilitated diffusion

Figure 5.15

Solutemolecule

Transportprotein

2.Active transport • energy-driven transport proteins move solutes

across membranes against their concentration gradient.

• Why?

• Mechanism: ATP binds to active transport pump, causing a change in its shape. The protein now has energy to pump the solute against its concentration gradient

PP PProtein

changes shapePhosphatedetaches

ATPADPSolute

Transportprotein

Solute binding1 Phosphorylation2 Transport3 Protein reversion4

Cells expend energy for active transport

Figure 5.18

Fluid outside cell

Cytoplasm

Protein

Vesicle

Exocytosis and endocytosis transport large molecules

– To move large molecules or particles into the cell is endocytosis

Figure 5.19A