2. Objectives
1. Enumerate the attributes of living matter.
2. Distinguish between prokaryotes and eukaryotes.
3. Identify the important organelles of the cell.
4. Name the common elements and compounds required
by living organisms.
3. What is a Biochemistry?
Biochemistry is the chemistry of biomolecules and their
chemical reactions in living matter at the
molecular and cellular level.
biomolecules molecules involved in the survival of the
living organism.
chemical reactions changes within the organism’s
body usually referred to as biochemical
reactions or metabolism.
Biochemistry seeks to describe the structure, organization, and
functions of living matter in molecular terms.
4. Level of Organization
1. Subatomic Paticles
- an electron, proton, or neutron; three
major particles of which atoms are
composed.
2. Atom
- smallest unit of an element that still
remains the properties of that element.
3. Molecule
- a unit of two or more atoms of the same
or different elements bonded together.
5. 4. Organelle
- any various membraneous sacs or other
compartments inside the cell that separate
different metabolic reactions within the cellular
space and in time. ribosome
5. Cell
- smallest living unit; may live independently or may be part of a
multicellular organism.
6. Tissue
- a group of similar cells and intercellular substances
functioning together in a specialized activity. red blood cell
7. Organ
- one or more types of of tissues interacting as a structural,
functioning unit.
jellyfish
brain
6. 8. Organ system
- two or more organs whose separate functions are integrated int the performance of a
special task.
• The heart is part of the circulatory system,
which carries oxygen and other materials
heart throughout the body. Besides the heart, blood
vessels are organs that work in your
circulatory system.
9. Multicellular organism
- individual composed of specialized,
interdependent cells arrayed in tissues, organs,
and other organ system.
Biochemistry asks how the remarkable
properties of living organisms arise
from the thousands of different lifeless
biomolecules.
7. It can be divided into three principal areas:
1. Structural and Functional Biochemistry: Chemical
structures and 3D arrangements of molecules.
2. Informational Biochemistry: Language for storing
biological data and for transmitting that data in cells
and organisms.
3. Bioenergetics: The flow of energy in living organisms
and how it is transferred from one process to another.
8. When these molecules are isolated and examined individually,
they conform to all the physical and chemical laws that
describe the behavior of inanimate matter - as do all the
processes occurring in living organisms.
The study of biochemistry shows how the collections of
inanimate molecules that constitute living organisms interact
to maintain and perpetuate life animated solely by the physical
and chemical laws that govern the nonliving universe.
Physical and Chemical sciences alone may not completely
explain the nature of life, but they at least provide the essential
framework for such an explanation.
BIOCHEMISTRY
9. Tools to study biochemistry:
All students of life must have a fundamental
understanding of general chemistry, organic chemistry
and biology.
Know chemical structures and reactivities of molecules
that participate in cellular reactions.
Know biological functions of cellular molecules.
Know how all of the pieces and different chemical
reactions fit together.
11. Biochemistry draws its major themes from:
1. Organic chemistry - which describes the properties of
biomolecules.
2. Biophysics - which applies the techniques of physics to
study the structures of biomolecules.
3. Medical research - which increasingly seeks to
understand disease states in molecular terms.
4. Nutrition - which has illuminated metabolism by describing
the dietary requirements for maintenance of health.
5. Microbiology - which has shown that single-celled
organisms and viruses are ideally suited for the elucidation
of many metabolic pathways and regulatory mechanisms.
12. 6. Physiology - which investigates life processes at the tissue
and organism levels.
7. Cell biology - which describes the biochemical division of
labor within a cell.
8. Genetics - which describes mechanisms that give a
particular cell or organism its biochemical identity.
13. Elements of Life
Up to 99+% of the human body
is made of the elements C
(9.5%), H (25.2%), O (63%)
and N (1.4%).
Only 31 chemical elements occur naturally in plants and animals.
14. 99% of the mass of the human body is made up of only six
elements: oxygen, carbon, hydrogen, nitrogen, calcium, and
phosphorus.
Every organic molecule contains carbon. Since 65-90% of
each body cell consists of water (by weight), it is not surprising
that oxygen and hydrogen are major components of the body.
15. Question
What property unites H, O, C and N and renders these atoms
so appropriate to the chemistry of life?
Their ability to form covalent bonds by electron-pair sharing.
Bond Energy (kJ/mol)
H-H 436
C-H 414
C-C 343
C-O 351
16. The elements of Life
C, the hybridizer Fe, the O2 carrier
H, placeholder and water Na,K depolarizers
builder P, the energy carrier
O, the oxidizer and hydrogen Cl, the neutralizer
bonder S, the linker
N, protein builder Mg, Zn, Cu, Ni, Mo
Ca, the skeletizer
enzyme coordinators
Lithium, Strontium,
Oxygen (65%) Sulfur (0.25%) Aluminum, Silicon,
Carbon (18%) Sodium (0.15%) Lead, Vanadium,
Hydrogen (10%) Magnesium (0.05%) Arsenic, Bromine
Nitrogen (3%) (trace amounts)
Calcium (1.5%) Copper, Zinc, Selenium, Molybdenum,
Phosphorus (1.0%) Fluorine, Chlorine, Iodine, Manganese,
Potassium (0.35%) Cobalt, Iron (0.70%)
17. Biomolecules of Life
1. Proteins
- these are polymers of amino acids linked by peptide
bonds.
- they are also called polypetides.
- they function as transport proteins, structural proteins,
enzymes, antibodies, cell receptors.
2. Nucelic acids
- classified as RNA and DNA, are polymers of
nucleotides linked by phosphodiester bonds.
18. - the nucleotide sequence in these polymers spells out
the genetic information that directs growth,
development and reproduction.
3. Carbohydrates
- also known as polysaccharides which are polymers of
monosaccharides.
- function as storage sources of energy in plants (starch)
and animals (glycogen) and as structural elements in
plants.
- function as storage sources of energy in plants (starch)
and animals (glycogen), as structural elements in
plants, supply carbon for synthesis of other
compounds and used in intercellular
communications..
19. 4. Lipids
- storage of energy in the form of fat
- responsible for the integrity of cellular membranes
(phospholipids), synthesis of hormones and
vitamins, and act as insulator (thermal blanket).
Livingthings are composed of lifeless molecules. When these
molecules are considered individually, they are found to
conform to all the physical and chemical laws that describe the
behavior of inanimate matter.
But when put together in a particular manner, this collection of
lifeless molecules start to exhibit the different attributes of life.
20. What is Life?
Hard to define! Let’s list some of its properties.
Necessary Properties
highly organized and complicated
- all organisms are consist of one or more
cells (atoms connect to form molecules,
molecules make organelles, and
organelles make cells. Cells make up
tissue, tissues organized into organs,
and organs into organ systems.
uses energy
- all organisms acquire and use energy to
perform many kinds of work.
21. sensitive (interacts with its environment)
- plants grow toward light, an animal’s pupils dilate in darkness, amoeba and
paramecia move toward food.
metabolism
- ability to change substances into different substances to get energy.
evolutionary adaptation
- all organisms interact with the environment and other organisms in ways that
influence their survival to better adapt to their environment.
homeostasis
- all organisms maintain ‘relatively’ constant internal conditions like ion
concentration, body fluid, temperature, glucose in the bloodstream, blood
pH, blood pressure, etc.
excretion
- removal of waste products
Likely (but maybe not be necessary) Properties
grows and develops
- normally, all forms of life must grow to allow development and reproduction
22. reproduces
- heriditary molecules (RNA and DNA) ensures production of offspring similar to
previous generation.
mutates and evolves
- long term adaptation, new forms of life are formed from life itself
23. Requirements for Life
1. Energy (need food to function)
a. Autotrophs = make their own food (plants are autotrophs)
b. Heterotrophs = cannot make their own food (animals, people,
dogs, lizards, are heterotrophs).
2. Water – all living things need water to survive.
3. Living Space – need a place to get food, water, and shelter.
4. Homeostasis = Stable Internal Conditions – so when the temperature gets
too cold or hot, or too wet or dry where they live, their body
still stays the same inside.
24.
25. The Cell
All living organisms on earth are made of cells except viruses.
The smallest unit that is capable of life.
multicellur organism, Human
one-celled organism, Bacteria (at least 1014 cells)
26. There are many different types of cells that are usually highly
specialized. The differences could be according to shape and
function.
27. Examples of Cells
Amoeba Proteus
Plant Stem
Bacteria
Red Blood Cell
Nerve Cell
28. All cells are relatively small. They vary in length from 2 µm to 30 µm.
29. Prokaryotic Cell
Do not have structures surrounded by membranes
Few internal structures
No nucleus
30. • Nucleoid region contains the DNA
• Cell membrane and cell wall
• Contain ribosomes (no membrane)
to make proteins in their cytoplasm
31. Eukaryotic Cell (Animal)
Contain organelles such
as a nucleus surrounded
by membranes
Most living organisms
Contain 3 basic cell structures:
• Nucleus
• Cell Membrane
• Cytoplasm with organelles
36. Functions of Organelles
Cell Membrane
A lipid/protein/carbohydrate complex, providing a barrier and
containing transport and signaling systems.
(Serves as security guards or gate keeprs. Decides what can
enter or leaves the cell. It lets in useful substances and lets out
waste.)
Cell wall
Plants have a rigid cell wall in addition to their cell membranes
Cytoplasm
enclosed by the plasma membrane, liquid portion called cytosol
and it houses the membranous organelles.
Nucleus
Double membrane surrounding the chromosomes and the nucleolus.
Pores allow specific communication with the cytoplasm. The
nucleolus is a site for synthesis of RNA making up the ribosome
(Serves as the control center. All the activities inside the cell
are controlled by instructions which comes from the nucleus.)
37. Mitochondrion
Surrounded by a double membrane with a series of folds
called cristae. Functions in energy production through metabolism.
Contains its own DNA, and is believed to have originated as a
captured bacterium.
(Serves as the power house of the cell. The mitochondira releases
energy from food.)
Chloroplasts (plastids)
Surrounded by a double membrane, containing stacked thylakoid
membranes. Responsible for photosynthesis, the trapping of light
energy for the synthesis of sugars. Contains DNA, and like
mitochondria is believed to have originated as a captured
bacterium.
Endoplasmic reticulum (RER)
A network of interconnected membranes forming channels within the
cell. Covered with ribosomes (causing the "rough" appearance) which
are in the process of synthesizing proteins for secretion or
localization in membranes.
(Serves as the construction team of the cell.)
38. Golgi body
A series of stacked membranes. Vesicles (small membrane
surrounded bags) carry materials from the RER to the Golgi
apparatus. Vesicles move between the stacks while the proteins are
"processed" to a mature form. Vesicles then carry newly formed
membrane and secreted proteins to their final destinations including
secretion or membrane localization.
(Serves as the assembly and storage point of the cell. Some of the
substances made in the cells are assembled and stored in the Golgi
body.)
Lysosymes
A membrane bound organelle that is responsible for degrading
proteins and membranes in the cell, and also helps degrade materials
ingested by the cell.
(Serves as the waste disposal unit of the cell. The lysozomes eat
up waste materials and old worn out parts of the cell.)
Vacuoles
Membrane surrounded "bags" that contain water and storage
materials in plants.
39. Peroxisomes or Microbodies
Produce and degrade hydrogen peroxide, a toxic compound that
can be produced during metabolism.
Cytoskeleton
Arrays of protein filaments in the cytosol. Gives the cell its
shape and provides basis for movement.
E.g. microtubules and microfilaments.
41. Assignment
Purpose: To compare the structure and function of cells with a
familiar system.
DIRECTIONS: You will create an analogy (comparison) for a cell
using a factory.
42. Your analogy will include a
(1) drawing or model where you label each part of the city/house/
body/station and its corresponding cell part (organelle), and a
(2) written description of each city/house/body/station part and
how it is similar to its corresponding organelle.
44. Biochemical Reactions
• Metabolism - total sum of the chemical reaction happening in a living
organism (highly coordinated and purposeful activity)
Anabolism – biosynthesis of small molecules to larger molecules
which requires energy.
Catabolism - degradation of fuel molecules and the production of
energy for cellular function
All biochemical reactions occur inside the cell and are catalyzed by
enzymes.
Both anabolism and catabolism may occur simultaneously not only
because they involve different enzymes but also because they ma be
separated in their location within the cell.
45. catabolic • For example:
the degradation of fatty acids to acetyl
CoA occurs by way of exnzym located
within the mitochondria, whereas the
anabolic conversion of acetyl CoA to
anabolic fatty acids occurs in the cytoplasm by
way oif a separate system.
FUNCTIONS OF METABOLISM
1. Acquistion and utilization of energy.
2. Synthesis of molecules needed for cell structure and functioning
(i.e., proteins, nucleic acids, lipids, etc.
3. Removal of waste products.
46. Metabolic Pathway
Metabolism generally occurs by orderly, stepwise, series or sequence of
individual chemical reactions that are dependent on the basic laws of
thermodynamics called as metabolic pathways.
• Also called biochemical pathway, is a multistep reaction within a cell that is
catalyzed by enzymes
An example of a simple metabolic pathway is the single step
conversion of a precursor A to a given product B.
an enzymatic reaction
A enzyme B is reversible.
47. In a multi-steps metabolic pathway, product B could become a
substrate of the second reaction to yield product C and so on.
E1 E2 E3 E4 E5
A B C D E Product
linear metabolic pathway
E’s are enzymes
B, C, D, E are intermediate substances also called metabolites.
E5 E8 E11
E2 C D E Product 1
E1 E3 E6 E9 E12
A B F G H Product 2
E4
E7 E10 E13
I J K Product 3
branched metabolic pathway
48. Primary Metabolic Pathway
A series of metabolism or biochemical reactions that encompasses
reactions involving primary compounds which are formed as part of the
normal anabolic and catabolic processes of plants and animals.
Primary metabolites are compounds commonly produced from primary
metabolic pathways such as proteins, carbohydrates, lipids, nucleic acid
that are directly used for growth and devlopment.
Absence of primary metabolites will cause cells and the whole organism
to die.
Examples:
Glycolysis Electron Transport Chain
Citric Acid Cylce Oxydation of Fatty Acids
51. Secondary Metabolic Pathway
A metabolism of secondary compounds or secondary metabolites other
than primary compunds.
A compound is classified as secondary metabolite if it does not seem to to
directly function in the processes of growth and devlopment of the animal
or plant.
Even though secondary compounds are a normal part of the metabolism of
an organism, they are often produced in specialized cells and tend to be
more complex than primary compounds.
Examples of secondary metabolites
antibiotics alkaloids
52. Even though thousands of reactions sound very large and complex
inside a tiny cell:
1. The type of reactions are small.
2. Mechanisms of biochemical reactions are simple.
3. Reactions of central importance (for energy production and
synthesis and degradation of major cell components) are
relatively few in number.
Frequent reactions encountered in biochemical processes:
1. Nucleophilic substitution
• one atom or group of atoms substituted for another.
2. Elimination reactions
• double bond is formed when atoms in a molecule is removed.
3. Addition reactions
• two molecules combine to form a single product.
• hydration reactions - water added to alkene > alcohol
(common addition reaction).
53. 4. Isomerization reactions
• involve intramolecular shift of atoms or groups
5. Oxidation-Reduction (redox) reactions
• occur when there is transfer of electron from a donor to an
electron acceptor.
6. Hydrolysis reactions
• cleavage of double bond by water.
54.
55.
56. Requirement for Life
MATTER:
PRODUCED IN BIG BANG (H & He) AND STARS
(
(HEAVIER ELEMENTS)
ARE CERTAIN ELEMENTS NEEDED?
STABLE ENERGY SOURCE:
LOW MASS MAIN SEQUENCE STARS (OR SOMETHING
E
ELSE?)
PROTECTED ENVIRONMENT:
PLANETARY OR LUNAR SURFACES
PLANETARY OR LUNAR INTERIORS
THICK PLANETARY OR LUNAR ATMOSPHERES
CHEMICAL SOLVENT (LIQUID):
W
WATER (OR SOMETHING ELSE?)
57.
58.
59. Secondary metabolism:
Metabolism of secondary compounds, defined simply as
compounds other than primary compounds. A compound is
classified as a secondary metabolite if it does not seem to
directly function in the processes of growth and
development. Even though secondary compounds are a
normal part of the metabolism of an organism, they are
often produced in specialized cells, and tend to be more
complex than primary compounds. Examples of secondary
compounds include antibiotics, and plant chemical
defenses such as alkaloids and steroids.
MetaCyc (www.metacyc.org)
Taiz, Lincoln, and Eduardo Zeiger. "Surface Protection and Secondary
Defense Compounds." Plant Physiology. New York: Benjamin/Cummings
Publishing Company, Inc., 1991: 320-345.
[item in sorceforge, should be readdressed via sourceforge]
60. Secondary metabolism:
Processes that result in many of the chemical changes of
compounds that are not required for growth and
maintenance of cells, and are often unique to a taxon. In
multicellular organisms secondary metabolism is generally
carried out in specific cell types, and may be useful for the
organism as a whole. In unicellular organisms, secondary
metabolism is often used for the production of antibiotics or
for the utilization and acquisition of unusual nutrients.
MetaCyc (www.metacyc.org)
Taiz, Lincoln, and Eduardo Zeiger. "Surface Protection and Secondary
Defense Compounds." Plant Physiology. New York: Benjamin/Cummings
Publishing Company, Inc., 1991: 320-345.
[item in sorceforge, should be readdressed via sourceforge]
63. Main Players
Enzymes: polymers of amino acids that
act as catalysts that regulate speed of
many chemical reactions in the
metabolism of living organisms; ex.
Phosphoglucoisomerase, aldolase
Metabolites: substance involved or by-
product of metabolism; ex. erythrose 4-
phosphate, sedoheptulose 7-phosphate
65. .
Ribosomes
Protein and RNA complex responsible for protein synthesis
Smooth endoplasmic reticulum (SER)
A network of interconnected membranes forming channels within the
cell. A site for synthesis and metabolism of lipids. Also contains
enzymes for detoxifying chemicals including drugs and pesticides.
Golgi apparatus
A series of stacked membranes. Vesicles (small membrane
surrounded bags) carry materials from the RER to the Golgi
apparatus. Vesicles move between the stacks while the proteins are
"processed" to a mature form. Vesicles then carry newly formed
membrane and secreted proteins to their final destinations including
secretion or membrane localization.
66. Primary (1°) Metabolism
- Construct common biological macromolecules from simple
building blocks found within every cell
- Typically a process of polymerization, stringing monomers
together into a macromolecule that performs a cellular function
sugars polysaccharides
amino acids proteins
fats phospholipid bilayers
- Block production: cell dies (primary metabolites are essential)
67. Metabolism and
Energy Production
Citric Acid Cycle
Electron Transport Chain
ATP Energy from Glucose
Oxidation of Fatty Acids
Metabolic Pathways for Amino Acids
68.
69. Cell Membrane
Outer membrane of cell
that controls movement
in and out of the cell
Double layer
70. Cell Wall
Most commonly
found in plant cells
& bacteria
Supports & protects
cells
http://library.thinkquest.org/12413/structures.html
72. Nucleus
Directs cell activities
Separated from cytoplasm by nuclear
membrane
Contains genetic material - DNA
73. Nuclear Membrane
Surrounds nucleus
Made of two layers
Openings allow
material to enter
and leave nucleus
http://library.thinkquest.org/12413/structures.html
74. Chromosomes
In nucleus
Made of DNA
Contain instructions
for traits &
characteristics
http://library.thinkquest.org/12413/structures.html
76. Cytoplasm
Gel-like mixture
Surrounded by cell membrane
Contains hereditary material
77. Endoplasmic Reticulum
Moves materials around
in cell
Smooth type: lacks
ribosomes
Rough type (pictured):
ribosomes embedded in
surface
http://library.thinkquest.org/12413/structures.html
78. Ribosomes
Each cell contains
thousands
Make proteins
Found on ribosomes
& floating
throughout the cell
http://library.thinkquest.org/12413/structures.html
79. Mitochondria
Produces energy through
chemical reactions –
breaking down fats &
carbohydrates
Controls level of water and
other materials in cell
Recycles and decomposes
proteins, fats, and
carbohydrates
http://library.thinkquest.org/12413/structures.html
80. Golgi Bodies
Protein 'packaging
plant'
Move materials within
the cell
Move materials out of
the cell
http://library.thinkquest.org/12413/structures.html
81. Lysosome
Digestive 'plant' for
proteins, fats, and
carbohydrates
Transports undigested
material to cell
membrane for removal
Cell breaks down if
lysosome explodes
http://library.thinkquest.org/12413/structures.html
82. Vacuoles
Membrane-bound
sacs for storage,
digestion, and waste
removal
Contains water
solution
Help plants maintain
shape
http://library.thinkquest.org/12413/structures.html
83. Chloroplast
Usually found in
plant cells
Contains green
chlorophyll
Where
photosynthesis takes
place
http://library.thinkquest.org/12413/structures.html
84.
85. What is Life Made of?
Physical and Chemical sciences alone
may not completely explain the nature
of life, but they at least provide the
essential framework for such an
explanation.
All students of life must have a
fundamental understanding of organic
chemistry and biology
87. BOTTOM LINE:
THE ELEMENTS THAT MAKE UP TERRESTRIAL
LIVING ORGANISMS ARE VERY COMMON IN
STARS AND IN THE INTERSTELLAR
MATERIAL FROM WHICH STARS AND
PLANETS ARE FORMED.
IN LIVING THINGS, THE ATOMS OF THESE
ELEMENTS ARE ORGANIZED IN ORGANIC
MOLECULES, MANY OF WHICH ARE LARGE
AND COMPLEX.
88. BASIC FACTS ABOUT LIFE ON EARTH
LIVING ORGANISMS ON EARTH ARE MADE OF
CELLS.
EXCEPTION: VIRUSES
A CELL IS TINY DROP OF WATER AND VARIOUS
ORGANIC MOLECULES, SURROUNDED BY A
MEMBRANE. SOME CELLS CONTAIN CERTAIN
STRUCTURES, TO BE DISCUSSED LATER. SOME
ORGANISMS (BACTERIA, FOR EXAMPLE) ARE
SINGLE-CELLED, AND OTHER ORGANISMS
(HUMANS, FOR EXAMPLE) ARE MULTICELLULAR. A
CELL CAN DIVIDE, RESULTING IN TWO CELLS.
89.
90. Bio-molecules
Just like cells are building blocks of tissues likewise molecules are
building blocks of cells.
Animal and plant cells contain approximately 10, 000 kinds of
molecules (bio-molecules)
Water constitutes 50-95% of cells content by weight.
Ions like Na+, K+ and Ca+ may account for another 1%
Almost all other kinds of bio-molecules are organic (C, H, N, O, P, S)
Infinite variety of molecules contain C.
Most bio-molecules considered to be derived from hydrocarbons.
The chemical properties of organic bio-molecules are determined by
their functional groups. Most bio-molecules have more than one.
91. Major Classes of small Bio-molecules
• Building blocks of proteins.
1. Amino • 20 commonly occurring.
acids: • Contains amino group and carboxyl group
function groups (behavioral properties)
• R Group (side chains) determines the
chemical properties of each amino acids.
• Also determines how the protein folds and
its biological function.
• Individual amino acids in protein connected
by peptide bond.
• Functions as transport proteins, structural
proteins, enzymes, antibodies, cell
receptors.
92. Sugars
Carbohydrates most abundant organic molecule
found in nature.
Initially synthesized in plants from a complex series
of reactions involving photosynthesis.
Basic unit is monosaccharides.
Monosaccharides can form larger molecules e.g.
glycogen, plant starch or cellulose.
Functions
Store energy in the form of starch (photosynthesis in
plants) or glycogen (in animals and humans).
Provide energy through metabolism pathways and cycles.
Supply carbon for synthesis of other compounds.
Form structural components in cells and tissues.
Intercellular communications
93. Fatty acids
Are monocarboxylic acid contains even number C atoms
Two types: saturated (C-C sb) and unsaturated (C-C db)
Fatty acids are components of several lipid molecules.
E,g. of lipids are triacylglycerol, streiods (cholestrol, sex
hormones), fat soluble vitamins.
Functions
Storage of energy in the form of fat
Membrane structures
Insulation (thermal blanket)
Synthesis of hormones
94. Energy for Cells
Living cells are inherently unstable.
Constant flow of energy prevents them from
becoming disorganized.
Cells obtains energy mainly by the oxidation of bio-
molecules (e- transferred from 1 molecule to another
and in doing so they lose energy)
This energy captured by cells & used to maintain
highly organized cellular structure and functions
95. How do complex structure of cells maintain high internal order?
n Synthesis of bio-molecules
2. Transport Across Membranes
- Cell membranes regulate the passage of ions and molecules
from one compartment to another.
3. Cell Movement
- Organised movement- most obvious characteristics of living
cells. The intricate and coordinated activities required to
sustain life require the movement of cell components.
4. Waste Removal
- Animal cells convert food molecules into CO2, H20 & NH3. If
these not disposed properly can be toxic.
99. Year
1944 Proteins were thought to
carry genetic information
1897
Mie s c he r d is c o ve re d D NA
1828 Interweaving of the
historical traditions
of biochemistry,
cell biology,
and genetics.
100. Living things are composed of lifeless molecules. When these molecules
are considered individually, they are found to conform to all the physical
and chemical laws that describe the behavior of inanimate matter.
