Textbook Notes (280,000)
CA (160,000)
UTSG (10,000)
BIO (600)
BIO130H1 (100)
Chapter 1

BIO130H1 Chapter Notes - Chapter 1: Mutation, Circuit Diagram, Tetraodontidae


Department
Biology
Course Code
BIO130H1
Professor
Wolfgang Moeder
Chapter
1

This preview shows pages 1-2. to view the full 8 pages of the document.
TERM TEST 1 NOTES
CHAPTER ONE OF TEXTBOOK
CELLS AND GENOMES
10 million, perhaps 100 million living species on earth
Most are single celled organisms
ALL CELLS STORE THEIR HEREDITARY INFO IN THE SAME LINEAR CHEMICAL CODE (DNA)
DNA storage of hereditary information, made of long unbranched paired polymer chains,
always made of the same four monomers: A T C G: adenine thymine cytosine guanine
ALL CELLS REPLICATE THEIR HEREDITARY INFORMATION BY TEMPLATED POLYMERIZATION:
Each monomer/nucleotide consists of 2 parts: sugar [deoxyribose] and a base, either ATCG
A binds to T, C binds to G; therefore two complementary sequences forming a double helix
o Bonds between base pairs are weak so the strands can easily be pulled apart without
breaking backbones [sugar and phosphate]; so that each strand can serve as a template
for the synthesis of a fresh strand: DNA REPLICATION
ALL CELLS TRANSCRIBE PORTIONS OF THEIR HEREDITARY INFORMATION INTO THE SAME
INTERMEDIARY FORM [RNA]
DNA must also express information by guiding synthesis of other molecules
Leads to the production of two other polymers, RNAs and proteins
TRANSCRIPTION when segments of DNA are used as templates for the synthesis of
RIBONUCLEIC ACID, or RNA [DNA->RNA]
TRANSLATION when RNA molecules direct the synthesis of polymers of a different chemical
class, the proteins [RNA->protein]
basically, DNA replication > RNA production > protein production
RNA backbone is made of ribose instead of deoxyribose; instead of thymine there’s Uracile
The dna segment can be used over and over again for synthesis, therefore it’s a fixed formation.
RNA transcripts are mass-produced and disposable.
Since these transcripts function as intermediates, they’re called mRNAs or messenger RNA to
guide proteins according to genetic instructions in DNA
RNA molecules are single stranded, therefore they are more flexible to form weak bonds with
other parts of same molecule, e.g. CCCC with GGGG
ALL CELLS USE PROTEINS AS CATALYSTS [things that increase the rate of chemical reaction]
Protein molecules are long unbranched polymer chains formed by stringing together monomeric
building blocks drawn from a standard repertoire that is the same for all living cells
Carry information like DNA and RNA
Monomers of protein [the A G C T equivalents] are called AMINO ACIDS, different from those of
RNA and DNA and there are 20 instead of 4 types
Core around which aminos are built, and a side group that gives each amino acid a chemical
character
Protein molecules are called POLYPEPTIDES and are created by joining aminos in a particular
sequence where it will have reactive sides on its surface
Amino acid polymers bind with high specificity to other molecules and act as enzymes to
catalyze reactions that make or break covalent bonds; they direct the vast majority of chemical
processes in the cell

Only pages 1-2 are available for preview. Some parts have been intentionally blurred.

Other functions include maintaining structure, generating movements, sensing signals, they put
the cell’s genetic info into action
Polynucleotides specify amino acid sequences of proteins > proteins catalyze reactions including
the ones where DNA molecules are synthesized, creating a loop that is the basis of autocatalytic,
self-reproducing behaviour of living organisms
ALL CELLS TRANSLATE RNA INTO PROTEIN THE SAME WAY
Complex process going from 4 letters genetics to 20 of proteins
Information in a sequence of messenger RNA is read out in groups of three nucleotides at a
time. Each triplet, or codon codes for a single amino acid in a protein. There are 64 [4x4x4]
possible codons, but only 20 amino acids... therefore, several codons correspond to the same
amino acid
TRANSFER RNAS, tRNAs codes are read out by these, a class of small RNA molecules. Each
tRNA attaches to an amino acid, and displays at other end a sequence of nucleotides,
ANTICODON, that enables it to recognize, through base pairing, a particular codon or subset of
codons in mRNA
for synthesis of protein, succession of tRNA molecules charged with appropriate aminos have to
be brought together with an mRNA molecule and matched up. Aminos then have to be linked
together to extend growing protein chain, then released
process is carried out by the ribosome, formed of two main chains of RNA, called ribosomal
RNAs, rRNAs and like 50 proteins
this thing latches onto the end of an mRNA molecule and then trundles along it, capturing tRNAs
and stitching together the amino acids they carry to create a new protein chain
THE FRAGMENT OF GENETIC INFORMATION CORRESPONDING TO ONE PROTEIN IS ONE GENE
DNA molecules are very large because they contain the specification for thousands of proteins
Individual segments of entire DNA are transcribed into separate mRNA molecules, with each
segment coding for a different protein. Each segment is called a GENE.
Complications that RNA molecules can be transcribed in more than one way so there are
alternative versions of a protein
A gene is therefore defined more generally, as the segment of DNA sequence corresponding to a
single protein or set of alternative protein variants
In all cells, the expression of individual genes is regulated: instead of manufacturing all proteins
at once, the cell adjusts the rate of transcription and translation of genes independently,
according to need
REGULATORY DNA are spread across the segments and the areas that don’t code have the
purpose of binding to proteins to create a structure that controls the rate of transcription; also
acting as punctuation, deciding when and where the protein begins and ends
Quantity of regulatory DNA varies, but the basic process is universal
The GENOME of the cell all of the genetic info as embodied in the complete DNA sequence,
dictates both the nature of the proteins as well as when/where they’ll be made
LIFE REQUIRES FREE ENERGY
Living cell is a dynamic chemical system that operates far from its chemical equilibrium
Cells must take in free energy. This is fundamental. When cells die, they decay towards
chemical equilibrium
Genetic info is also fundamental. Free energy is required for the propagation of info. E.g.
choosing between protein possibilities requires energy: molecules captured put in their proper
places, bonded, linked, put on a template etc.
You're Reading a Preview

Unlock to view full version

Only pages 1-2 are available for preview. Some parts have been intentionally blurred.

ALL CELLS FUNCTION AS BIOCHEMICAL FACTORIES DEALING WITH THE SAME BASIC
MOLECULAR BUILDING BLOCKS
Since all cells make DNA RNA and protein, their molecules must be similar like sugars,
nucleotides and amino acids
All cells require ATP atenosine triphosphate as building block for synthesis of RNA and DNA; also
carries free energy and phosphate groups for other chemical reactions
While all cells operate similarly biochemically, the details of their molecules differ
Some organisms are simpler than others e.g. plants make their own organic stuff, whereas
animals feed off others so their cells come ready-made
ALL CELLS ARE ENCLOSED IN A PLASMA MEMBRANCE ACROSS WHICH NUTRIENTS AND WASTE
MATERIALS MUST PASS
This plasma membrane is universal and essential to cell life
Acts as a selective barrier for collecting outside nutrients and containing inside ones
Molecules forming this membrane are amphiphilic consisting of one part that is hydrophobic
and one part that is hydrophilic [water-soluble] where these molecules, when exposed would
cluster the hydrophobic mol. While keeping hydrophilic exposed
Aggregate in water to form a bilayer that creates small closed vesicles
Hydrophobic tails are hydrocarbon polymers CH2-CH2-CH2- and their assembly into a bilayered
vesicle is an example of: cells produce molecules whose chemical properties cause them to
self-assemble into the structures that a cell needs
Proteins in the membrane that transport nutrients; some have been so well preserved we can
recognize the family resemblance between even distant organisms
Transport proteins choose which molecules enter, and the proteins inside choose the reactions
of those molecules. Thus, since proteins are manufactured, the genetic info recorded in the
DNA sequence dictates the entire chemistry of the cell; also its structure and behaviour
A LIVING CELL CAN EXIST WITH FEWER THAN 500 GENES
What are the minimum requirements for life?
The bacterium mycoplasma genitalium has the smallest known genomes; lives as a parasite, has
only 480 genes in its genome of 580070 nucleotide pairs, representing 145018 bytes of info
Minimum number of genes viable is probably not less than 200-300, although 60 shared cells
between species
THE DIVERSITY OF GENOMES AND THE TREE OF LIFE
Microorganisms make up most of the living matter on earth
It’s easy to characterize organisms, easy to consider the routes by which the cells obtain matter
and energy, how they depend on others, basic chemical needs
CELLS CAN BE POWERED BY A VARIETY OF FREE ENERGY SOURCES
Different ways of obtaining free energy
ORGANOTROPHIC feeds on other things, PHOTOTROPHIC feeds on sunlight, makes oxygen
LITHOTROPIC feeds on rock, microscopic, places where humans don’t frequent, some get
energy from aerobic reactions [getting molecules in the air]; organotrophic cannot exist without
the last two
SOME CELLS FIX NITROGEN AND CARBON DIOXIDE FOR OTHERS
Making living cells requires matter in addition to energy
You're Reading a Preview

Unlock to view full version