Cells Typical Eukaryotic Cell All living organisms are made of
cells All living organisms are made of cells Adult human body have
10-50 trillion cells! Adult human body have 10-50 trillion
cells!
Slide 4
Components of Cell Carbohydrates (= carbs) : providing energy
to cells and make cellular structures sugars, starches, cellulose,
etc. Carbohydrates (= carbs) : providing energy to cells and make
cellular structures sugars, starches, cellulose, etc. Lipids (aka
fats) : store energy, make cell membranes Lipids (aka fats) : store
energy, make cell membranes Proteins : versatile, essential
molecules of cells Proteins : versatile, essential molecules of
cells Nucleic acids : handling heritable information of cells DNA
and RNA Nucleic acids : handling heritable information of cells DNA
and RNA
Slide 5
DNA Proteins All Earth life have DNA, and DNA is the backbone
of heredity. All Earth life have DNA, and DNA is the backbone of
heredity. o Heredity DNA replication o function of DNA (genes)
protein synthesis Whats protein? Whats protein? o organic compound
made of amino acids in a folded chain o essential part of organisms
and participate in every process within cells enzymes involved in
matabolism make cell stucture cell signaling, immune responses,
etc.
Slide 6
DNA structure http://www.youtube.com/watch?v=qy8dk5iS1f0
Slide 7
DNA replication http://www.youtube.com/watch?v=hfZ8o9D1tu
s
Slide 8
Protein synthesis
http://www.youtube.com/watch?v=XO-2Z933AzM
Slide 9
RNA world? In the beginning of Earth life, the very first life
could not be based on DNA. DNA is way too complicated to be created
by mere lucky chemical reaction. In the beginning of Earth life,
the very first life could not be based on DNA. DNA is way too
complicated to be created by mere lucky chemical reaction. early
life must have used a simpler molecule (e.g., RNA) or, DNA was
introduced externally?!? Although we do not expect DNA or RNA to
appear in life on other worlds, molecules with similar function are
well expected!
Slide 10
Amino Acids Most important monomer! Most important monomer!
Basic building blocks of proteins, nucleotides, and sugars Basic
building blocks of proteins, nucleotides, and sugars Typically, few
hundred amino acids form a protein polymer. There are about 70
different amino acids in the nature, but only ~20 are used in
living organisms. Typically, few hundred amino acids form a protein
polymer. There are about 70 different amino acids in the nature,
but only ~20 are used in living organisms. A strand of amino acids,
part of a protein
Slide 11
Monomer/Polymer Glycogen: the carbohydrate that animals use to
store energy is a polymer made of glucose molecule contains 22
atoms Glycogen: the carbohydrate that animals use to store energy
is a polymer made of glucose molecule contains 22 atoms Most life
forms consist of small number of simple molecule types called
monomers, which can join together in a repetitive sequence to
become larger and more complex molecules called polymers.
glucose
Slide 12
Chirality of Amino Acids Chirality (handedness) Chirality
(handedness) For a given amino acid, there are two geometrical
shapes: left-handed & right-handed right-handed In
non-biological environ: two types are equally found In
non-biological environ: two types are equally found In living
organisms: only left-handed amino acids are found! In living
organisms: only left-handed amino acids are found! All Earth life
forms were originated from an ancestral life using only left-handed
amino acids! All Earth life forms were originated from an ancestral
life using only left-handed amino acids!
Slide 13
Genes a distinct portion of DNA strand representing any single
function (e.g., instruction for one protein) a distinct portion of
DNA strand representing any single function (e.g., instruction for
one protein) SpeciesNo. of genes Virus10 Mitochondria40
Microbe1,000 E coli4,400 Human27,000 Mouse29,000 Rice50,000
Slide 14
Small difference in genes Different human races Different human
races o Any possible distinct genetic differences are now
disappeared by inter-racial breed. o Genetic difference b/w races
< b/w two individuals from one race! Astrobiological
Implication? Astrobiological Implication? o Small genetic
difference huge difference (e.g., Chimpanzee vs. Human) ;
Chimpanzee and human share 98% of the same genes o Is advanced
intelligence an inevitable evolutionary outcome?
Slide 15
Genetic code : a set of rules for reading DNA Codes for most
amino acids really depend on just two letters in the past, genetic
codes were two letter based Genetic words consist of three DNA
bases in a row. For the purpose of protein building, each word
represents either a particular amino acid or start reading or stop
reading. Genetic words consist of three DNA bases in a row. For the
purpose of protein building, each word represents either a
particular amino acid or start reading or stop reading. Genetic
code is same for nearly ALL living organisms on Earth! common
ancestor of all life on Earth! Genetic code is same for nearly ALL
living organisms on Earth! common ancestor of all life on
Earth!
Slide 16
Mutation Replicating the whole ~3 billion bases for human DNA
takes only a few hours Replicating the whole ~3 billion bases for
human DNA takes only a few hours About 1 replication error in
billion chances About 1 replication error in billion chances o
wrong base o deleted base o extra base o etc. Most of these errors
have no effect Most of these errors have no effect Why? about 95%
of human DNA bases are non- coding DNA Most significant change is
from deleted base. Due to this error, every individual living
organism differ each other. Due to this error, every individual
living organism differ each other. Mutation = molecular engine of
the evolutionary adaption! Mutation = molecular engine of the
evolutionary adaption! Any change in the base sequence of DNA Any
change in the base sequence of DNA
Slide 17
Sickle-cell disease Just one base change in one gene (Adenine
Thymine) Just one base change in one gene (Adenine Thymine) Most
mutations are harmful, but occasional good mutations are being
picked up by natural selection Most mutations are harmful, but
occasional good mutations are being picked up by natural
selection
Slide 18
Another evidence of the common ancestor ATP (Adenosine
TriPhosphate). Cells recyle ATP. The ATP molecule gives up energy
when it splits into ADP and a phosphate group. ATP/ADP are like
battery o ATP : fully charged o ADP : fully discharged There are
many other possibilities of different molecular pairs (i.e.,
different batteries), but all Earth life use ATP as the energy
reservoir. common ancestor of all Earth life.
Slide 19
In summary Important Concepts Common ancestor of all Earth Life
(chirality of amino acid, common genetic code, and use of ATP among
all living organisms on Earth) Some non-DNA based life forms in the
beginning? DNA replication Important Terms amino acids / proteins
chirality genes, genetic code mutation Chapter/sections covered in
this lecture : 5.2 & 5.4
