GenBio Lesson 1

DNA

molecule of life

Deoxyribonucleic Acid

made up of nucleotides

3 billion DNA subunits (ACTG)

molecule that carries the genetic instructions of living organisms and many viruses

double stranded/helix (unlike RNA w/ single strand/helix)

nucleotides

subunits w/ nitrogenous bases A, C, T, G

made up of nitrogenous bases, sugar, and phosphate group

cells

trillions of cells

each cell - 2 meters of DNA, 46 human chromosomes

approx 30,000 genes code for proteins that perform most life functions

1% of DNA

makes us unique humans (we share the other 99% w/ everything else) → characteristics are determined by single-nucleotide polymorphism (SNP; genomic variant at a single base position in the DNA)

components of DNA

5-carbon sugar (deoxyribose; 1 less oxygen than the ribose in RNA) - phosphate backbone of dna along w/ the phosphate grp

Nitrogenous bases (Adenine+Thymine, Cytosine+Guanine)

phosphate grp

RNA nitrogenous bases

Adenine+Uracil

Cytosine+Guanine

Central Dogma of Molecular Biology

Describes the flow of genetic info w/in a biological system

states that DNA is transcribed into mRNA, which travels into ribosomes where the transcription is then translated using codons into polypeptides (proteins)

discovery of restriction enzymes

Werner Arber, Hamilton Smith, and Daniel Nathans discovered the defense mechanism of certain bacteria in resisting infection by bacteriophages (viruses)

These bacteria have restriction enzymes, which cut the DNA at specific nucleotide sequences

Restriction enzymes

Different restriction enzymes cut DNA at different sites.

Each restriction enzyme recognizes a specific DNA sequence, typically 4-6 base pairs long, and cuts the DNA within that sequence

restriction enzyme example

enzyme EcoRI, which comes from the human gut bacterium E. coli, recognizes the sequence GAATTC and cuts the DNA between the guanine (G) and adenine (A)

this causes sticky ends

Sticky ends

fragment of DNA (often produced by a staggered cut on the DNA using restriction enzymes) in which the terminal portion has a stretch of unpaired nucleotides

these lead to the formation of recombinant DNA (vector DNA + foreign DNA) using ligase

basis of recombinant DNA technology

all cells follow the same physical and chemical laws of DNA

DNA technologies

Recombinant DNA

DNA Cloning

DNA Libraries

Polymerase Chain Reaction (PCR)

Gel Electrophoresis

DNA Profiling

DNA Sequencing

Recombinant DNA

a piece of DNA is combined with another DNA from another source for practical purposes.

1st stage of DNA Cloning

DNA CLONING

methods that uses living cells to mass-produce targeted DNA fragments

DNA libraries

collection of DNA fragments that have been cloned into vectors so that researchers can identify and isolate the DNA fragments that interest them for further study

making insulin from recombinant DNA

get insulin-producing gene from a human cell → insert it into a bacteria host to form recombinant bacteria → fermentation tank → recombinant bacteria produce insulin → insulin harvested and purified → medicine

genetic engineering

process of making changes on the genetic code of an organism.

products are called GMOs or transgenic organisms

GENETICALLY MODIFIED ORGANISM (GMO)

organisms whose genetic material has been altered using genetic engineering techniques.

Bt Technology

Gene for Bt toxic protein was incorporated into crop plants, which enables plants to produce the toxin (led to more yield and less pests)

Bacillus thuringiensis

POLYMERASE CHAIN REACTION (PCR)

used to rapidly mass-produce (millions to billions) copies of a specific DNA sample

3 steps (denaturing, annealing, extending)

amount of DNA created grows exponentially

denaturing

DNA is heated until the strands separate from each other

annealing

the DNA is cooled down to attach primers (short nucleic acid sequence that provides a starting point for DNA synthesis) that help extend the nucleotide sequence

extending

DNA is heated and a new strand is made by Taq polymerase (enzyme involved in the attachment of nucleotides to synthesize DNA)

base DNA strands are extended (by adding nucleotides) starting with the primer

gel electrophoresis

used to separate DNA fragments based on their size/length

An electric voltage is applied to the agarose gel

the negatively charged DNA molecules move toward the positive end of the gel.

related to DNA profiling

DNA profiling

used to distinguish between individuals of the same species using only samples of their DNA

DNA sequencing

laboratory technique used to determine the exact sequence of bases (A, C, G, and T) in a DNA molecule to investigate the functions of genes.

Human Genome Project

spanned 13 years, from 1990 to 2003, with a budget of approximately $3 billion.

primary goals were to identify the complete set of human genes, determine their functions, and make this information accessible for further biological study, and also to determine the complete sequence of DNA bases in the human genome

Gene Therapy

part of genetic engineering

involves the transfer of a gene into an individuals body cells, with the intent to correct a genetic disorder or treat a disease

uses recombinant DNA