dna, rna & protein synthesis & genetic engineering

Major Cell Activities Include:• Diffusion • Osmosis• Active Transport• Cell Energy

– Photosynthesis– Cell Respiration– ATP

• DNA Replication• RNA Formation• Protein Synthesis• Cell Division

This unit covers these three

• Pre-Notes, Background Info:• Nucleic acids

A. Store & transmit genetic info

B. DNA & RNAC. Composed of

repeating units called nucleotides

DNA double helix

Pre-Notes, Background Info:Nucleotides consist of:

1. a sugar2. a phosphate group3. one nitrogen base

Nucleotide

DNAmolecule

I. DNA (Deoxyribonucleic Acid)

A. Found in almost all living cells –in the nucleus of eukaryotes (3 Feet/Cell)

B. 2 primary functions1. Control protein (enzyme) production

(ie. ATPase)-These enzymes then control chemical reactions in cells.

2. Duplicate itself for new cells that are created

C.Forms of DNA1.Chromatin –Partially

unwound when? (Normal Situations)

2.Chromosome – tightly wound DNA (Cell division)

D. Structure of DNA1. Consists of two long strands that spiral2. Each strand is a chain of nucleotides3. Three parts to each nucleotide

a. 5 carbon sugar (deoxyribose)b. Phosphatec. Nitrogen base (4 different kinds of bases)

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Nucleic acids are polymers of nucleotides.-nucleotide: sugar + phosphate + nitrogenous base

Nucleotide

DNAmolecule

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Nucleotide

4.All nucleotides have same sugar and phosphate

5. Four different kinds of nitrogen basesa. Adenine – purine – double ring moleculesb. Guanine – purine – double ring moleculesc. Thymine – Pyrimidines – single ring

moleculesd. Cytosine – pyrimidines – single ring molecules

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Segment of DNA

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DNA

6.Double Helix – Spiral laddera. Sides of the ladder = 5 carbon

sugar and phosphatesb. Rungs of the ladder = nitrogen

bases bonded together from each side

Rosalind Franklin’s X-ray Photo (1951)

7. Hydrogen bonds form between purines and pyrimidines creating “steps” of ladder

a. Adenine + Thymine = 2 hydrogen bonds

=2 hydrogen bonds

=3 hydrogen bonds

b. Cytosine + Guanine= 3 hydrogen bonds

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A T

C G

E. DNA ReplicationWHY?

-each cell must get same DNA copy when cells divide.

1. DNA helicase (enzyme) attaches to DNA molecule.

2. Helicase moves along DNA breaking hydrogen bonds- “unzips” DNA into two strands.

3. Each strand now has unpaired nitrogen bases.

4. Free floating nucleotides in the nucleus form hydrogen bonds with unpaired nitrogen bases.

5. DNA Polymerase (enzyme) bonds together nucleotides by connecting Deoxyribose(Sugar) to phosphate

6. Ligase (enzyme) repairs DNA7. Final result = 2 exact copies of DNA

* Each copy = 1 “old” strand and 1 “new” strand

8. Replication occurs at many (1000’s) of sites along DNA – speedy process

9. Replication very accurate – 1 error per billion nucleotides

10. Nitrogen bases:a. Adenine (A) bonds with Thymine (T)b. Cytosine (C) bonds with Guanine (G)

If unzipped old segment = C-C-A-T-G-A-G-T

What will the new segment be?

II. RNA (Ribonucleic Acid)

A. Structure of RNA*Different than DNA in 3 ways1. RNA is a single strand – DNA = Double2. RNA has ribose sugar – DNA =Deoxyribose3. RNA has Uracil instead of ThymineDNA nitrogen bases RNA nitrogen bases

Cytosine Guanine Cytosine Guanine

Adenine Thymine Adenine Uracil

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Nucleic Acids

B.3 types of RNA*All made in the nucleus

and travel to the ribosomes

1. Messenger RNA (mRNA)a. Single straight strandb. Transmits DNA informationc. Serves as template (pattern)

for making proteins

2. Transfer RNA (tRNA)a. Single folded strandb. Complimentary bases pair upc. Also involved in protein synthesis

3. Ribosomal RNA (rRNA)a. Globular formb. Part of ribosome structure

C. Transcription – process of making RNA from DNA

1. Protein enzyme called RNA polymerase binds to DNA.

2. RNA polymerase separates portion of DNA into two separate strands.

3. Free floating nucleotides in nucleus match their nitrogen bases with bases of “unzipped” DNA.

DNA base code = C-G-A-T-A

Complimentary RNA = G-C-U-A-U

4.RNA polymerase forms bonds (hydrogen) between nitrogen bases.

5.Polymerase connects nucleotides by bonding sugars to phosphates

6.Enzyme releases new RNA strand when it reaches “stop sign” on DNA.

GENE

III. Protein Synthesis – ribosomes make proteins using information coded in RNA“AKA Translation”

A.Proteins1. Many amino acids linked by

peptide bonds2. 100’s to 1000’s of AA’s per protein3. 20 different AA’s 4. Sequence of AA’s determine

structure and function of each protein

B. Codon – a group of 3 sequential nitrogen bases of an mRNA molecule.1. 64 different combinations = 64

codons2. mRNA u c u u a g c u a g c g

-How many codons?3. Each codon codes for:

a. 1 of the 20 amino acidsb. Start or stop codons

C. Anticodon-Region of tRNA that consists of

bases which are complimentary to codon bases of mRNA

D.Translation – putting amino acids (AA’s) together to build protein from information encoded in mRNA1. mRNA and tRNA transcribed from

DNA in nucleus.2. This RNA exits the nucleus

through pores. 3. mRNA travels to ribosomes.

4. Free floating AA’s are brought to ribosomes by tRNA.

5. Protein always starts with methionine (aug) AA

6. A second AA on tRNA enters ribosome. Codon and anticodon pair up and peptide bonds form between AA’s.

*This process of linking AA’s continues until ribosome reaches a stop codon on mRNA.

What are the stop codons?uaa uag uga

Biotechnology

A. Plasmids: circular double-stranded DNA1. Separate from chromosomal DNA2. Contain genes which code for less essential traits

(ex. Adaptive traits)3. Common in bacteria

A. Recombinant DNA– This is the union of

DNA from 2 different organisms

A. Restriction endonuclease (RE): enzymes in cells which cleave (cut) DNA into pieces

– We can use this enzyme to cut and splice genes

A. Procedure of recombinant DNA technology1. Isolate desired gene from a donor cell2. Cut out desired gene using RE3. Extract plasmid from bacterium using lysozyme4. Using RE cut out DNA segment from plasmid

creating sticky ends5. “paste” desired gene “sticky” ends into plasmid

opening

6. Insert recombinant plasmid into healthy bacterium

7. Allow bacteria to multiply (cloning) by incubating with nutrients

8. Bacteria will transcribe and translate new gene, producing desired proteins

9. What are some desired proteins?

a) Insulinb) Vaccinesc) Hemoglobin

Hemoglobin Protein Molecular Formula:

C3032H4816O872N780S8Fe4

Glycine (typical AA): C2H5N1O2

Some Products Made Using Biotechnology• Human growth hormone is used to treat dwarfism. It previously took the pituitary glands from over 50 cadavers to

make one dose.• Human Insulin is used to treat diabetes.• Tissue plasminogen activator dissolves blood clots in heart attack victims.• Clotting factor VIII will soon be available. Most cases of hemophilia are due to the absence of this factor.• Human lung surfactant is used in premature infants with respiratory distress syndrome.• Atrial natriuretic hormone can be used to treat hypertension.• Bovine growth hormone (bGH) increases milk production in cows by about 10%.• A vaccine for hepatitis B is now produced using biotechnology.• Vaccines for chlamydia, malaria and HIV are being developed.• Vaccines for hoof-and-mouth disease and scours (a form of dysentery) have been developed for farm animals.• Bacteria have been produced that inhibit the formation of ice crystals. These bacteria have been released onto crop

plants to protect them from frost damage.• A bacteria species that normally colonize corn roots have been given a gene that enables it to produce an insect-killing

toxin.• Bacteria are being developed that do a better job at breaking down oil. • Bacteria have been developed that are capable of removing some kinds of toxins from the air and water.• Bacteria have been engineered to extract metals from low-grade ore (bioleaching). • there are 50 types of genetically engineered plants that resist insects, viruses, and herbicides. • A weed called mouse-eared cress has been designed to produce a biodegradable plastic called polyhydroxubutrate

(PHB).• Pharmaceutical companies are developing techniques to produce chemicals using animals. The drug is produced in the

milk of females. For example, goats have been developed to produce antithrombin III, used to prevent blood clots. Clinical trials of this drug will begin soon.

• A pig has been produced that can produce human hemoglobin. Artificial blood may soon be a reality.

B. DNA fingerprinting1. Analysis of DNA sequences to

determine identity