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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
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
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”
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
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.
Lecture Assignment 2
• Pages 485-511 in back of textbook • Topic is cancer• 1 page summary, handwritten, in your own
words, due Thursday, April 17, at the beginning of class
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
Can human diseases result from organelles? Yes!
• Lysosomes• Mitochondria• Peroxisomes (in plants)• Even Cell Membranes!• Aging?• Chronic Fatigue Syndrome?