Mol Biol Course VE Mod

8/8/2019 Mol Biol Course VE Mod

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MOLECULAR BIOLOGY

The term molecular biology is somewhat a misnomer, butcommonly used in science. All aspects of biology can be

studied at the molecular level, the term molecular biology is

usually restricted to mean the biology of molecules related to

genes and gene products and heredity.



Studying«..

«at the molecular level

«using quite different sources

«employing really cool technologies «understanding the what, why, and how

«integrating findings into products

«it¶s actually molecule level genetics

«generally, life today is dependent uponthe findings and advancements thereof



Eukaryotic Cell



Weird Looking ³Thing´



Molecular basis of heredity«genes

Basic unit

Responsible for a single inherited propertyor characteristic of the organism

Most properties due to combined actionsof multiple genes

Made of DNA

Is a polymer of linear arrangements of nucleotides

Ranges: bacteria, animal cells«..



Genome sizes

Organism Common name DNA (Mb) Chromosomes Genes

H. influenzae influenza virus 1.8 1 1,749

E. coli bacterium 4.6 1 4,288

S. cerevisiae yeast 12 16 ~6,000 A. thaliana plant 115 ? ~2,500

C. elegans roundworm 100 6 ~20,100

D. melanogaster fruit fly 140 8 ~12,000

M. musculus mouse 3300 40 13,767

O. sativa rice 430 12 ~45,000

H. sapians human 3200 23 pairs ~35,000



DNA structure

Composed of nucleotides

Each consists of 3 components: a phosphate,deoxyribose, and base

Bases: Adenine (A), thymine (T), guanine (G), and cytosine (C)

A + G = purines and T + C = pyrimidines

Nucleotides are linked via the phosphate on the 5¶ end of the deoxyribose of one to the 3¶position of the next

Forms a spiral or helical structure, right-handed doublehelix arrangement



DNA General Video



Human DNA

The DNA found in each human cell is

almost 2 meters long. If all the DNA in a

human adult (that¶s 100 trillion cells) were

laid end to end, the DNA would stretch

113 billion miles. That would take you to

the sun and back 610 times.



Changes or mutations

As scientists learn to read the instructions in our genes, they are discovering that much of our DNA is riddled with errors.

Fortunately, most of these errors are harmless. Considering the difficulties involved²the 6 feet of DNA in a human cell consists of 6 billion subunits, or base pairs, coiled and tightly packed into 23pairs of chromosomes, all of which must be duplicated every time a cell divides²our general stateof health is something of a miracle.

We each inherit hundreds of genetic mutations from our parents, as they did from their forebears.In addition, the DNA in our own cells undergoes an estimated 30 new mutations during our lifetime, either through mistakes during DNA copying or cell division or, more often, because of damage from the environment.

Bits of our DNA may be deleted, inserted, broken, or substituted. Most mutations affect only theparts of DNA that do not contain instructions for making a gene, so we need not worry about them.Problems arise only when an error in certain protein occurs.

To stay alive and functioning , the human body requires a daily crop of billions of fresh proteinmolecules²about 40 ,000 different kinds of proteins that must be supplied in the right quantities, at the right times, and in the right places. We need hemoglobin to carry oxygen through thebloodstream, antibodies to fight foreign substances, hormones to deal with stress,

neurotransmitters to evoke movements, emotions, and thought, and many other proteins to givestructure to organs or speed up chemical reactions.

Much of the recent progress in reading DNA has come from analyses of genetic errors. From: Maya Pines



DNA packaging(eukaryotes)

Cell nucleus is ~5um diameter

DNA sizes from millions to billions of bases«wide range,long, huge task

~500X more DNA than bacterial cells

Folding starts around highly positive charged proteins,histones, which neutralize the negative chare of the DNA

The combination is referred to as chromatin

200 bp around 9 histones = a nucleosome

Chromosome folding: DNA double helix to beads, to

fibers, to super-coiled fibers, to chromosomes Result, the appearance of bands ~1,000,000 per

chromosome



Eukaryote Folding



DNA supercoiling (eukaryote vs prokaryote)

More DNA found as chromosomes in the

nucleus

10-20 X more genes but most DNA (up to95%) not for coding

Human diploid cell has 5.6 X 10+9 bp in

46 chromosomes



DNA structure, cont.

Base pairing occurs A to T and C to G

Hydrogen bonding between the bases, 2 in AT and 3 in CG , holds the two chainstogether

Knowing a base on one strand you thenknow it¶s opposite on the other strand or

complementary base pairing -A-A-T-G-G-C-C-T-A- ³known´ sequence

-T-T-A-C-C-G-G-A-T- ³complementary´



Chromosomes

Genes are linearly located on the chromosomes

DNA segmented into genes, regulatory regions, and intergenic regions

Bacterial chromosome is a single circular molecule with 2,000-4,000 genes and very shortintergenic regions

Animal chromosomes are linear with 10,000 to50,000 genes and multiple; humans - 2 duplicate

sets of 23 different, or 46 total Locations: prokaryotes-cytoplasm; eukaryotes-

nucleus







Codons



Resolution: standard / high

Figure 3.

DNA fragmentation detected with agarose gel electrophoresis of DNA extracted from X-ray (6 Gy) irradiated cells. A and B represent with and withoutglycerol (0.6 M), respectively. C, no irradiation; Lanes 12, 24. 36 and 48, incubation periods (h) after X-ray irradiation. Lane M, øX174 DNA Hae III fragments as size markers.Ohnishi et al. Molecular Cancer 2002 1:4 doi:10.1186/1476-4598-1-4

Download authors' original image



Gel Analysis



FLUORESENCE-CAPILLARY

SEQUENCING



F & r GREEN PROTEIN

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Mol Biol Course VE Mod