Chapter 1.docx

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18 Apr 2012
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Lecture 1ish notes
Chapter 1: Cells and Genomes
Universal feature of cells on earth
- most single celled organism, but other like us multicellular.
All cells store their hereditary info in the same linear chemical code called DNA
DNA is long, double stranded, unbranched polymer chains
4 monomers being Adenine, Guanine, Cytosine, Thymine
All cells replicate their hereditary information by template polymerization
DNA consists of multiple chunks of the following:
Sugar called deoxyribose that has phosphate attached + Base(ATCG).
DNA synthesized by the creation of a complementary strand to fit half of the
double strand, called the template strand
Bonds betweeb base pairs weaker than the sugar phosphate links, which
allows for pulling apart of strand without damaging phosphate backbone
SUMMARY; DNA is information store, template polymerization is way info is
copied.
All Cells transcribe portions of hereditary info into intermediary form RNA
DNA is instruction, in transcription, instruction of DNA guide to the
synthesis of RNA.
RNA, then is also a form of instruction for the creation of proteins, a
process called translation.
RNA FACTS:
- ribose sugar attached to phosphate+ Adenine with Uracil and C+G
- Formation comes about similarly to DNA creation from template single
strand, but instead uracil is used with adenine.
- RNA can be made multiple times from the same template strand. Imagine it
as RNA monomers come to the DNA template strand, attach to form a chain,
then disconnect and leave as a half strand.
- Being single stranded allows for flexibility and makes it able to fold ontop of
itself and be kept through week bonds (localy complementary )
Proteins are catalysts in Cells
Features of Protein:
-long unbranched polymer chains built of monomers called amino acids
-Form most of mass in cell
-20 different type of amino acid monomers.
- Protein molecule called polypeptide which fold into 3D shapes
- 3D shapes have sites on them that allow for reactions with other very specific
molecules.
- proteins are thus enzymes as they have points of reaction, where these reactions
are catalyzed. Some cases molecules covalent bonds are broken by proteins, like in
the case of lysozyme which splits polysaccharide chains.
-Proteins aside from being catalysts also serve to maintain structure, generate
movement and sensing signals.
* important point is that proteins put genetic material into action*
DNA’s template = RNA which directs protein productionproteincatalyses
reactions
Summary: Proteins are macromolecules that
1)perform cell function
2) building blocks for cell structure
3) form enzymes that catalyze reactions
4)regulate gene expression
5) enable cell communication
6)movement
RNA translation into proteins
Goes from 4 letter monomer to 20 proteins
Steps:
a) mRNA strung to rRNA (ribosome)
b) tRNA, which has an amno acid attached to it comes, and accommodates the
specific codon on the mRNA, with the anti codon. Ex. AUG codon with UAC
anti codon
c) match occurs between codon/anticodon, amino acid attached to chain of
amino acids which presided it, and tRNA leaves with nothing.
-Fragment of DNA corresponding to one protein is gene
-One chunk of DNA that makes a certain protein is called a gene.
-DNA expression regulated, cell adjusts rate of transcription and translation
according to need .
- regulatory dna, also called non coding regions bond to special proteins that
control the rate of transcription. Other non-coding DNA exists to serve as
markers for where a protein begins and ends.
- Genome of cell(total genetic information in DNA sequence) dictates nature of
cell protein but when and where there supposed to be made.
Life requires free energy
- for cell to replicate etc... it needs energy from outside environment thus free
energy responsible for propagation of information. If it doesn’t get raw
materials it decays and soon dies
- molecules can be represenrted as spring loaded devices. Once they are
activated and connected by bonds, energy level decreases as the energy is
dissipated as heat.
All cells act as biochemical factories dealing with the same basic molecular building
blocks
Basically, all cells make dna,rna and protein, and commonly, they all need the same
materials as each other. Ex. ATP.
Cells enclosed in plasma membrane where waste and nutrients pass
- Without plasma, cell couldn’t maintain integrity as a chemical system
- Plasma is amphiphillic. Consists of hydrophobic and hydrophilic parts.
Hydrophilic on outside.
- When placed in environment of water, a layer will form. Self assembly
- Hydrocarbon polymers
- DNA thus has an impact on the way cells function because they provide blue
print for proteins that affect transport etc. in cell.
Energy sources powering cells
-Organotrophic- feeding off other living things or things it produces
- Feeding from non-living organisms. A) Phototrophic from sun, and b) Lithotrophic
from rock.
Organotrophs couldn’t survive without latter as they are primary energy converters.
Like secondary consumer stuff
a) algae, oxygen is byproduct of them
b) very tiny, unseen as hidden away. Aerobic and anaerobic
Cells which fix N and C for others
Some cells take carbon and nitrogen in their natural occurrence and ready them to
be used.
- after time , its possible these two things, one dependant on other merge
Prokaryotic cells = greatest biochemical diversity.
Features:
- live indepenantly, not part of organism
- rod shaped/spherical
- no division in cell between components
-live in enormous variety, many capabilities, more than eukaryotes. Organotrophs
and phototrophs are examples
Tee of life has three branches
-Dna analysis helps draw lines
- Prokaryotes branched into bacteria and archaeabacteria
1) Bacteria
2) Eukaryotes: sexual reproduction
3) Archaea: like harsh environments, resemble eukaryotes in the machinery
for handling genetic info, but are more similar to bacteria in there
metabolism and energy conversion. Reason is because of horizontal exchange
Some genes evolve rapidly; others conserved