Electrons–In living organisms, chemical energy is stored in atoms/molecules by using it to move electrons to more distant orbits.

Think of energy storage this way...• Imagine a molecule as a paper bag, with the nucleus in blue & the

electrons on the outside of the bag—the bag is the orbital space around the atomic nucleus:

Electrons nowfurther away

Energy absorbed

Chemistry is life

• Molecules make up components of cells• Four major organic molecule types:

1. Carbohydrates (sugars, starches)

2. Lipids (fatty acids)

3. Proteins

4. Nucleic acids (DNA, RNA, ATP)

1. Carbohydrates• Carbon + Hydrogen +

Oxygen• Ex. sugars/starches• composed of single sugar

units called monosaccharides, ex. glucose.

• can bond to form more complex compounds like table sugar, ex. sucrose (1 glucose + 1 fructose); 2 sugar units=disaccharide.

C C

C

C

C

C

glucose

C

C

CC

C

Carbohydrates• Some important CHO’s are:–glycogen (how animals store food)

–starch (how plants store food)

–cellulose (plant cell wall compound)—most common CHO on planet

–chitin (shells of bugs and some cells in fungi)

2. Lipids (Fats)• Usually made of fatty acids and a

molecule called glycerol• fats are either saturated or

unsaturated• saturated fats, like lard, are the worst for

humans• unsaturated fats, like fish oils and plant

oils, are better, and can be bonded together to make more complex fats called polyunsaturated fats.

Lipids/Fats (cont.)• Lipids are extremely

important: cell membranes

• lipids make other molecules like hormones (estrogen, testosterone)

• Ex.cholesterol is a lipid byproduct used to make hormones

The cell membrane is a fluid mosaic

of phospholipids and proteins

Figure 5.12

Fibers of the extracellular matrix Carbohydrate

(of glycoprotein)

Glycoprotein

Microfilamentsof cytoskeleton

Phospholipid

CholesterolProteins

Plasmamem-brane

Glycolipid

Cytoplasm

3. Proteins• Composed of units called

amino acids• only 22 amino acids exist,

with 20 used for amino acids• all share a similar structure• amino acids form a peptide

bond or sulfur bond with others

• as these chains of peptides form, they either form a spiral or a flattened sheet.

Amino acid

3. Proteins• protein spirals or

sheets form complicated compounds

• Ex. hemoglobin in your red blood cells that carry oxygen:

Hemoglobin

How proteins fold to become more complex proteins:

Modified proteins: enzymes

•Enzymes are amazing!•Modified proteins•Names end in –ase

ex. Glucose is sugar, glucase is enzyme that breaks it downex. Amylose is starch, amylase is enzyme

•Speed up chemical reactions•Break compounds apart•Put compounds together

Enzymes can break apart molecules OR put them together!

How enzymes work

• Two models: lock&key or induced fit• Lock&key: exact fit of compounds to

enzyme• Induced fit: enzyme can “wrap” around

compounds

4. Nucleotides• 3 parts• 1. phosphate

molecules (phosphorus + oxygens)

• 2. a sugar• 3. a base that

contains nitrogen

Sugar

OH

O P O

O

CH2

H

O

H H

OH H

H

N

N

H

N

N H

HHN

Phosphategroup

Nitrogenousbase (A)

Examples of Nucleotides:•DNA (deoxyribonucleic acid)—holds genetic information•RNA (ribonucleic acid)—takes information from DNA and makes proteins•ATP (adenosine triphosphate) is important in transferring electrons; major energy carrier for cells

ATP uses Electrons to store/release energy

– In living organisms, chemical energy is stored by using it to move electrons to more distant orbits.

– ATP powers nearly all forms of cellular work– The energy in an ATP molecule lies in the bonds

between its phosphate groups

Phosphategroups

ATP

EnergyP P PP P PHydrolysisAdenine

Ribose

H2O

Adenosine diphosphateAdenosine Triphosphate

++

ADP

Figure 5.4A

Structure of DNA

Figure 2.21a

Nucleotide = N-containing base, a pentose sugar, and a phosphate groupFive nitrogen base types – adenine (A), guanine (G), cytosine (C), thymine (T), and uracil (U)

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

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?