Molecules make Cells possible:

• Sugars for energy• Proteins for building structures• Lipids for cell membranes• DNA/RNA for making more cells• ATP for making energy possible

Prokaryotes vs. Eukaryotes

•DNA in single loop

•Very small•No organelles

•Live in all environments

•DNA in chromosomes in nucleus•Much larger•Organelles handle complex cell tasks•Live in restricted environments

Prokaryotic cells are structurally simpler than eukaryotic cells

Prokaryotic cell

Nucleoidregion

Nucleus

Eukar yotic cell Organelles

Colo

rized

TEM

15,

000

Figure 4.3A

Surface Area to Volume Ratio

A small cell has a greater ratio of sur face area to volume than a large cell of the same shape

30 m 10 m

30 m 10 m

Surface areaof one large cube 5,400 m2

Total surface areaof 27 small cubes 16,200 m2

Figure 4.2B

Eukaryotic cells—plants, fungi, animals, protists

• Nucleus present

• Membrane surrounds cell

• Cell wall may be present (plants, fungi, but NOT animals)

Plasma membrane• Surrounds entire cell• Made of two lipid layers• Allows certain molecules in/out =

“selectively permeable”

Nucleus—control center

Cytoskeleton—internal ‘skeleton’

Internal membrane system

3 important membranes:

1. Rough endoplasmic reticulum

2. Smooth endoplasmic reticulum

3. Golgi complex

• Smooth endoplasmic reticulum has a variety of functions:1. Synthesizes lipids 2. Processes toxins and

drugs in liver cells3. Stores and releases

calcium ions in muscle cells

Rough endoplasmic reticulum makes membrane and proteins Ribosomes on the sur face of the rough ER produce proteins that are secreted, inserted into membranes, or transported in vesicles to other organelles

• Lysosomes are sacs of enzymes that function in digestion within a cell

• Lysosomes in white blood cells destroy bacteria that have been ingested

• Lysosomes also recycle damaged organelles

The various organelles of the endomembrane system are interconnected structurally and functionally

Moving the cells around

3 ways:1. Flagellum—cell

extends cytoplasm into tail-like structure

2. Cilia—cell extends small hair-like structures

3. Pseudopodia—cell extends itself to move around

Human cells move too!1. Lung cells & fallopian tube cells

use cilia to move things around.

2. Male sperm cells use a flagellum to get to the egg.

3. White blood cells use pseudopodia to move between other cells and get to where they need to be.

Organelles

• Membrane surrounds them• Important organelles:

• Nucleus• Cell membrane• Lysosomes/peroxisomes• Rough endoplasmic reticulum• Smooth endoplasmic reticulum• Golgi apparatus• Special organelles involved in energy:

• Mitochondrion—produces ATP (in all eukaryotes)• In plants and some algae: Chloroplast—produces sugar

from light energy

Mitochondria

Chloroplast

Can human diseases result from organelles? Yes!

• Lysosomes• Mitochondria• Peroxisomes (in plants)• Even Cell Membranes!• Aging?• Chronic Fatigue Syndrome?

Quick Review!• What are 5 organelles in the cell?• In order, what organelles are responsible for

moving the products of DNA to the Golgi Complex?

• What 3 things make up the cell membrane?• What are the 4 foundational theories of

biology?• What are the 4 groups of biologically-

important molecules?