Download Biophysics II

Biophysics II
… about life & death
By
A/Prof. Xiang Yang Liu
Biophysics & Micro/nanostructures Lab
Department of Physics,
NUS
Key questions to be addressed
Physics Concept: Ordered State vs
Disordered State
Materials and Energy:
{ The ordering of life:
z
z
{
Materials with ordered structures
correspond to some particular
functions.
To maintain ordered structures,
energy is required.
What are the basic characteristics of
living organisms?
Disordered
Ordered
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Physics Concept: Ordered State vs
Disordered State
Physics Concept: Ordered State vs
Disordered State
Disordered
Disordered
Ordered
Ordered
Physics Concept: the 1st law of
thermodynamics-energy conservation
Physics Concept: Ordered State vs
Disordered State
2nd Law of Thermodynamics
Isolated system
System
×
{
No energy and
Materials
exchange
{
Environment
Spontaneous Process
An Ordered State
A Disordered State
E is required
Energy can neither
be created nor
destroyed.
It may exist in a
variety of forms
and may be
transformed from
one type of energy
to another.
A grassland, a terrestrial ecosystem: In an ecosystem, chemical cycling
(gray arrows) and energy flow (yellow-to-red arrows) begin when plants
use solar energy and inorganic nutrients to produce their own food
(organic nutrients).
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How to Define Life: The hierarchy of life
reveals the highest order in the Universe
How to Define Life: The hierarchy of life
reveals the highest order in the Universe
(cont’d)
Living things are organized (ordered)
{
{
Atom: the smallest
part of an element
that still has the
properties of that
element
Molecule (such as
DNA, RNA and
Protein): a cluster of
atoms held together
by chemical bonds.
How to Define Life: The hierarchy of life reveals
the highest order in the Universe (cont’d)
{
Organism: an individual independent
living entity.
{
Organ: a group of cells that perform a
specialized function in an organism.
How to Define Life: The hierarchy of life
reveals the highest order in the Universe
(cont’d)
{
Population: a group of individuals of a
particular organism that inhabits a given
region and interbreeds, ie Human
population, etc.
3
How to Define Life: The hierarchy of life
reveals the highest order in the Universe
(cont’d)
{
Community: Various organisms that
interact in a given region.
How to Define Life: The hierarchy of life reveals
the highest order in the Universe (cont’d)
{
Ecosystem: a living community and
its physical environment.
How to Define Life: The hierarchy of life reveals
the highest order in the Universe (cont’d)
{
Biosphere: a portion of the earth
that contains living organisms.
A View of Life:
Levels of
Biological
organization (1)
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What is the difference?
{
A View of Life:
Levels of
Biological
organization (2)
How to Define Life?
Despite life’s diversity, the
common characteristics of all
life forms …
z
z
z
Food: energy and materials
Energy is the capability to do work
Metabolism
Disordered: The tear and wear of
living things with time.
{ Living things counteract the disorder by
taking energy and materials from their
environment and using them for repair,
growth, and other processes of
survival.
{
How to Define Life?
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Characteristics of Living Organisms
(cont’d)
{
Metabolism- biochemical reactions
that acquire & use energy and
Materials: Organized chemical
steps, by which the breakdown and
buildup of molecules make energy
or build needed parts.
How to Define Life? (cont’d)
3. Living things Respond
(to their
environment).
4. Living Things
Reproduce and
develop.
z
z
How to Define Life? (cont’d)
1. Living things are organized
(ordered)
All life forms …
2… carry out a process called
“metabolism”, which involves the
conversion of different forms of
energy and of chemical
compounds.
Q&A1
Protein crystal growth
Do you think that protein
crystals are alive? Why?
Reproduce-make
another organism like
itself.
Develop-from an
immature to a mature
individual.
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How to Define Life? (cont’d)
5. Living things have adaptations
z
Adaptations are modifications that
make organisms suited to their
way of life.
How to Define Life? (cont’d)
All living things
6. … are made of cells
enclosed by
membranes that
maintain internal
conditions very
different from their
surroundings.
How to Define Life? (cont’d)
All life forms …
7. … have DNA or
RNA as the
genetic
material…
The Chemistry/physics of
Life
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Basic Terminology (1)
DNA
RNA
stands
for
DeoxyriboNucleic Acid
stands
for
RiboNucleic Acid
The Chemistry/physics of Life
{
{
Basic Terminology (2)
For either frogs or Professors…
Where the life starts…
The Chemistry/physics of Life
{
{
{
Where does life start?
… from fertilized eggs.
But what is it in the
fertilized eggs that
directs to the
formation of frogs or
professors?
Or what is it we get
from our parents
which makes us an
individual human or a
frog?
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From Gene to An Organism…
{
Genes
From Gene to An Organism…
Throughout the body - in cells...
{ Our bodies are formed from between 50
and 100 trillion cells (a trillion is a
thousand billion, or a thousand, thousand
million).
{ These cells are organized into tissues,
such as skin, muscle, and bone.
{ Each cell contains all of the organism's
genetic instructions stored as DNA.
However, each cell uses only the
instructions from part of the DNA.
Within the cell - in
chromosomes Each very long
DNA molecule is tightly wound and
packaged as a chromosome.
Humans have two sets of 23
chromosomes in every cell, one set
inherited from each parent. A
human cell therefore contains 46 of
these chromosomal DNA molecules.
From Gene to An Organism…
{
For example, a muscle cell uses the
DNA that specifies the muscle
apparatus, whereas a nerve cell
uses DNA that specifies the nervous
system. It is as if each cell reads
only that part of a book of
instructions that it needs.
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The central question in life sciences…
From Gene to An Organism…
DNA,
Chromosome,
Genome
{
{
{
Gene,
Each DNA molecule that forms a
chromosome can be viewed as a
set of shorter DNA sequences.
These are the units of DNA
function, called genes, each of
which guides the production of
one particular component of an
organism.
A set of human chromosomes
contains one copy of each of the
roughly 30,000 genes in the
human "genome" - the term
used to refer to the complete
genetic
instructions
for
an
organism.
Key message of this lecture
{
The hierarchy of Life…10 levels
Organelles
Cell
Tissue
Lower levels of
organization
Organ
Organ systems
Individual organism
Population
Higher level of
organization
Community
Ecosystem
{
{
How does the gene, or strain moleculeDNA, produce cells, and ultimately
creatures, like frogs and professors…
The answer to the question comes from
the chemistry/physics of life, in
particular the structures and functions
of Proteins.
Key message of this lecture
{ The
essential characteristics of Life…7
key points.
{ What defines the ultimate form of
life…Genes…
{ The central question of Life Sciences…
{ Physics can be applied to study the
underlying mechanisms (why and how)
at all different levels of the hierarchy of
life.
Biosphere
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