1. Replication, Transcription and Translation
DNA and RNA
Replication, Transcription and Translation

2. Griffith’s Experiment
How did Griffith explain this situation? What must have happened? What is

3. Avery’s Experiment
By separating out the materials from the bacteria and mixing them with harmless bacteria only the ones mixed with nucleic acids turned into the lethal strain. So, the hereditary factors had be carried by the DNA.

4. Hershey-Chase Experiment
Alfred Day Hershey and Martha Chase show in their famous blender experiment that DNA, not protein, is the carrier of genetic information.  The blender is not a special scientific instrument, but an ordinary kitchen appliance manufactured by the Waring Corporation.  Hershey and Chase use their Osterizer® model to separate the protein coats of T2 phage viruses from their nucleic acid payloads, and from bacterial cells that the phages have infected.  By labeling the protein coats and then viral DNA with radioactive tracers in separate experiments, Hershey and Chase are able to demonstrate that viral replication in bacterial cells is accomplished by DNA and not proteins - See more at:

5. A typical Bacteriophage –
A bacteriophage (informally, phage) is a virus that infects and replicates within bacteria. The term is derived from 'bacteria' and the Greek φαγεῖν phagein "to devour". Bacteriophages are composed of proteins that encapsulate a DNA or RNA genome, and may have relatively simple or elaborate structures. Their genomes may encode as few as four genes, and as many as hundreds of genes. Phage replicate within bacteria following the injection of their genome into the cytoplasm. Bacteriophage are among the most common and diverse entities in the biosphere.

6. Bacteriophage infection cycle
Since ancient times, reports of river waters having the ability to cure infectious diseases have been documented, such as leprosy. In 1896, Ernest Hanbury Hankin reported that something in the waters of the Ganges and Yamuna rivers in India had marked antibacterial action against cholera and could pass through a very fine porcelain filter. In 1915, British bacteriologist Frederick Twort, superintendent of the Brown Institution of London, discovered a small agent that infected and killed bacteria. He believed the agent must be one of the followingPhages were discovered to be antibacterial agents and were used in Georgia and the United States during the 1920s and 1930s for treating bacterial infections. They had widespread use, including treatment of soldiers in the Red Army. However, they were abandoned for general use in the West for several reasons:
Medical trials were carried out, but a basic lack of understanding of phages made these invalid.
Phage therapy was seen as untrustworthy, because many of the trials were conducted on totally unrelated diseases such as allergies and viral infections.
Antibiotics were discovered and marketed widely. They were easier to make, store and to prescribe.
Former Soviet research continued, but publications were mainly in Russian or Georgian languages, and were unavailable internationally for many years.
Clinical trials evaluating the antibacterial efficacy of bacteriophage preparations were conducted without proper controls and were methodologically incomplete preventing the formulation of important conclusions.

7. The 3 Key Roles of DNA
Storing genetic information.
Copying genetic information.
Transmitting genetic information.

8. DNA is 2 long polymers of covalently bonded nucleotides wound around each other and attracted to each other by hydrogen bonds.
Most DNA molecules are double-stranded helices, consisting of two long biopolymers made of simpler units called nucleotides—each nucleotide is composed of a nucleobase (guanine, adenine, thymine, and cytosine), recorded using the letters G, A, T, and C, as well as a backbone made of alternating sugars (deoxyribose) and phosphate groups (related to phosphoric acid), with the nucleobases (G, A, T, C) attached to the sugars. DNA is well-suited for biological information storage, since the DNA backbone is resistant to cleavage and the double-stranded structure provides the molecule with a built-in duplicate of the encoded information.

9. The 4 bases are the Purines (adenine and guanine) and the Pyrimidines (Thymine and Cytosine)

10. Guanine bonds with Cytosine. The three bonds are hydrogen bonds!

11. Adenine bonds with Thymine. Here there are two hydrogen bonds.

12. A diagram of DNA

13. The three components of DNA are the phosphate group, sugar and a nitrogen containing base
DNA is composed of two chains of repeating nucleotides. Each nucleotide consists of three components. These components are: Phosphate Group
2-deoxyribose sugar
A nitrogen containing base
cytosine
adenine
guanine
thymine

14. Chargaff's rules state that DNA from any cell of all organisms should have a 1:1 ratio of guanine to cytosine and adenine to thymine.
(base Pair Rule) of pyrimidine and purine bases and, more specifically, that the amount of guanine is equal to cytosine and the amount of adenine is equal to thymine. This pattern is found in both strands of the DNA. They were discovered by Austrian chemist Erwin Chargaff

15. Rosalind Franklin and her X-Ray diffraction picture of DNA
Franklin is best known for her work on the X-ray diffraction images of DNA which led to the discovery of the DNA double helix. According to Francis Crick, her data was key to determining the structure[3] to formulate Crick and Watson's 1953 model regarding the structure of DNA.[4] Franklin's images of X-ray diffraction confirming the helical structure of DNA were shown to Watson without her approval or knowledge. This image and her accurate interpretation of the data provided valuable insight into the DNA structure, but Franklin's scientific contributions to the discovery of the double helix are often overlooked

16. Watson and Crick – DNA is 2 chains wound around each other, each chain going in opposite directions. The two chains are held together with hydrogen bonds.
he following are the features of the DNA molecule as described by Watson and Crick in chains
purine opposite a pyrimidine
chains held together by H-bonds
Guanine is paired with cytosine by three H-bonds
Adenine is paired with thymine by two H-bonds
anti-parallel orientation of the two chains
5' >3' 3'< ' the molecule is stabilized by:
large # of H-bonds
hydrophobic bonding between the stacked bases
Components of DNA
DNA is composed of two chains of repeating nucleotides. Each nucleotide consists of three components. These components are: Phosphate Group
2-deoxyribose sugar
A nitrogen containing base
cytosine
adenine
guanine
thymine

17. Prokaryote vs. Eukaryote DNA.
In prokaryotes (organisms without a nuclear membrane), DNA undergoes replication and transcription and RNA undergoes translation in an undivided compartment. All three processes can occur simultaneously.
In eukaryotes (organisms with a nuclear membrane), DNA undergoes replication and transcription in the nucleus, and proteins are made in the cytoplasm. RNA must therefore travel across the nuclear membrane before it undergoes translation. This means that  transcription and translation are physically separated. The primary transcript, heterogeneous nuclear RNA (hnRNA), undergoes extensive post-transcriptional processing to make a messenger RNA (mRNA)molecule that can pass through the nuclear membrane

18. Eukaryotic chromosomes contain DNA wrapped around proteins called histones. Each package of 8 histones is called a nucleosome

19. The strands are complementary in the sense that each strand can be used to make the other half by the sequence of base pairing.

20. Prokaryote DNA replication

21. Eukaryotes – DNA replication occurs at many places and proceeds in two directions until each chromosome is copied.

22. DNA Replication is carried out by a series of enzymes
DNA Replication is carried out by a series of enzymes. DNA Polymerase joins individual nucleotides to produce a new DNA molecule

23. Gene – coded DNA instruction for the production of a protein.
A gene is a molecular unit of heredity of a living organism. It is widely accepted by the scientific community as a name given to some stretches of deoxyribonucleic acids (DNA) and ribonucleic acids (RNA) that code for a polypeptide.
This stylistic diagram shows a gene in relation to the double helix structure of DNA and to a chromosome (right). The chromosome is X-shaped because it is dividing. Introns are regions often found in eukaryote genes that are removed in the splicing process (after the DNA is transcribed into RNA): Only the exons encode the protein. This diagram labels a region of only 55 or so bases as a gene. In reality, most genes are hundreds of times larger.

24. Protein Synthesis an overview

25. The three main types of RNA
The DNA is kept safe in the nucleus. It is the master plan. mRNA carries bits of the plan out into the cytoplasm to make Proteins with the help of rRNA and tRNA.

26. DNA and RNA nucleotides are very similar in structure.

27. A central tenet of biology describes the two-step process, transcription and translation, by which the information in genes flows into proteins: DNA → RNA → protein.
Transcription is the synthesis of an RNA copy of a segment of DNA. RNA is synthesized by the enzyme RNA polymerase.

28. Because there is no nucleus to separate the processes of transcription and translation, when bacterial genes are transcribed, their transcripts can immediately be translated
In a prokaryotic cell, transcription and translation are coupled; that is, translation begins while the mRNA is still being synthesized. In a eukaryotic cell, transcription occurs in the nucleus, and translation occurs in the cytoplasm.

29. Transcription and translation are spatially and temporally separated in eukaryotic cells; that is, transcription occurs in the nucleus to produce a pre-mRNA molecule

30. Transcription – the production of RNA molecules from parts of the DNA molecule
Requires RNA polymerase which binds to DNA and separates the DNA strands. RNA then uses one strand of DNA as a template from which nucleotides are assembled into a strand of RNA

31. Promoters are regions of DNA that tell RNA polymerase where to start
Promoters are regions of DNA that tell RNA polymerase where to start. Similar signals tell RNA polymerase to stop

32. . The pre-mRNA is processed in the nucleus to remove the introns and splice the exons together into a translatable mRNA. That mRNA exits the nucleus and is translated in the cytoplasm.
Most eukaryotic protein-coding genes contain segments called introns, which break up the amino acid coding sequence into segments called exons. The transcript of these genes is the pre-mRNA (precursor-mRNA)

33. The steps of pre-mRNA splicing (intron removal)
The steps of pre-mRNA splicing (intron removal) are as follows:
• The intron loops out as snRNPs (small nuclear ribonucleoprotein particles, complexes of snRNAs and proteins) bind to form the spliceosome. • The intron is excised, and the exons are then spliced together. • The resulting mature mRNA may then exit the nucleus and be translated in the cytoplasm

34. The basic building block of a protein is the amino acid.

35. There are 20 amino acids; each one differs in its R group
There are 20 amino acids; each one differs in its R group. Below are four amino acids showing the differences in R groups.

36. Amino acids are joined together in proteins by peptide bonds.
A peptide bond forms between the carboxyl group of one amino acid (amino acid 1 in the figure below) and the amino group of the adjacent amino acid (amino acid 2).

37. The language of RNA to the language of protein: The genetic code is a triplet code in which three nucleotides in RNA specify one amino acid in protein.
Note the different amino acids and how many have more than one three letter code.
AUG is the start codon and also codes for the amino acid methionine.
UAA, UAG, UGA: stop codons; used for the stop signal.
Degenerate: in most cases, more than one codon per amino acid to a maximum of six.

38. Translation is the process of decoding an mRNA message into a polypeptide chain. It all starts with mRNA
mRNAs vary in length. Sequences of mRNAs vary because amino acid coding sequences (reading frames) differ, and because leader and trailer sequences differ.

39. Ribosomes, the organelles on which the mRNA is translated, consist of two subunits, each of which contains rRNA and ribosomal proteins.
In translation, the mRNA passes through the ribosome, where the codons are recognized by tRNAs carrying the specified amino acids. Each ribosomal subunit consists of rRNA (ribosomal RNA, encoded by rRNA genes) and ribosomal proteins. In eukaryotes, the large subunit is 60S (named for how fast it sediments during centrifugation) and contains 28S, 5.8S, and 5S rRNAs plus about 50 ribosomal proteins. The small subunit is 40S and contains 18S rRNA plus about 30 proteins.

40. tRNA’s bring amino acids to the ribosomes during translation to be assembled into polypeptide chains.
tRNAs are encoded by tRNA genes.
All tRNA molecules are simiar in size and shape.
All tRNAs have CCA at the 3’ end to which the amino acid attaches.
At the other “end” of the tRNA molecule is the anticodon, which during translation, “reads” the matching codon on the mRNA.

41. Adding an Amino Acid to tRNA The correct amino acid is added with the help of an enzyme.
The correct amino acid is added to its tRNA by a specific enzyme called an aminoacyl-tRNA synthetase. The process is called aminoacylation, or charging.

42. Initiation of Translation
An initiation complex for translation forms by the assembly of the ribosomal subunits and initiator tRNA (met-tRNA) at the start codon on the mRNA.

43. Translation begins when an mRNA attaches to a ribosome
Translation begins when an mRNA attaches to a ribosome. Each codon is matched by an anticodon with tRNA. The tRNA brings in the correct amino acid for that codon.

44. Elongation of the polypeptide chain begins by the appropriate tRNA binding to the codon in the A site of the ribosome

45. At a stop codon, a release factor reads the triplet, and polypeptide synthesis ends
the polypeptide is released from the tRNA, the tRNA is released from the ribosome, and the two ribosomal subunits separate from the mRNA.

46. Several ribosomes can translate an mRNA at the same time, forming what is called a polysome.
More than one ribosome can translate an mRNA at one time, making it possible to produce many polypeptides simultaneously from a single mRNA.

48. genetics, a mutation is a change of the nucleotide sequence of the genome of an organism, virus, or extrachromosomal genetic element.
The above is an example of a point mutation that is a substitution. One base has been replaced by another.
There can also be substitutions or deletions where a base is missing or added.

49. A frameshift mutation (also called a framing error or a reading frame shift) is a genetic mutation caused by indels (insertions or deletions) of a number of nucleotides in a DNA sequence that is not divisible by three.
Due to the triplet nature of gene expression by codons, the insertion or deletion can change the reading frame (the grouping of the codons), resulting in a completely different translation from the original.

50. Cystic Fibrosis is an example of a frame shift mutation.
The name cystic fibrosis refers to the characteristic scarring (fibrosis) and cyst formation within the pancreas, first recognized in the 1930s.[2] Difficulty breathing is the most serious symptom and results from frequent lung infections that are treated with antibiotics and other medications. Other symptoms--including sinus infections, poor growth, and infertility--affect other parts of the body.CF is caused by a mutation in the gene for the protein cystic fibrosis transmembrane conductance regulator (CFTR). This protein is required to regulate the components of sweat, digestive fluids, and mucus. CFTR regulates the movement of chloride and sodium ions across epithelial membranes, such as the alveolar epithelia located in the lungs. Most people without CF have two working copies of the CFTR gene, and both copies must be missing for CF to develop, due to the disorder's recessive nature. CF develops when neither copy works normally (as a result of mutation) and therefore has autosomal recessive inheritance.

51. Shaking Vest treatment for Cystic Fibrosis
Shaking Vest treatment for Cystic Fibrosis. The vest helps to loosen the thick mucus and allow some of it to be expelled from the lungs.

52. Chromosomal Mutations This involves changes in the number or structure of chromosomes.

53. Down syndrome (DS) or Down's syndrome, also known as trisomy 21, is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21.
[1] Down syndrome is the most common chromosome abnormality in humans.

54. Down syndrome (DS) or Down's syndrome, also known as trisomy 21, is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21.[1] Down syndrome is the most common chromosome abnormality in humans.[2] The CDC estimates that about one of every 691 babies born in the United States each year is born with Down syndrome.[3] It is typically associated with physical growth delays, a particular set of facial characteristics and a severe degree of intellectual disability.[1] The average full-scale IQ of young adults with Down syndrome is around 50 (70 and below is defined as the cut-off for intellectual disability), whereas young adult controls have an average IQ of 100.

55. Polyploidy in Plants. Certain fruits have been developed that have are triploid,(3N) or tetraploid (4N). The extra chromosomes cause the fruit to be larger and stronger than the normal 2N or diploid plant.

56. Operon An operon is a group of genes that operate together
The lac operon for a bacterium causes the bacterium to produce the enzyme lactase. This enzyme would be needed by the bacterium if lactose was the available food. If the food was glucose, though, lactase would not be needed.
The lac genes are turned off by repressors and turned on by the presence of lactose.

57. Lac genes in E. coli. When lactose is not present, the repressor binds to the operator region preventing transcription.
Lactase causes the repressor to be released from the operator region.

58. Eukaryotic Gene Regulation The TATA box helps to position RNA polymerase by marking a point just before transcription. Promoters are found just before the TATA box.

59. Transcription factors – a protein that binds to a specific DNA sequence, controlling the transcription of mRNA. They can either activate or block RNA polymerase.
In molecular biology and genetics, a transcription factor (sometimes called a sequence-specific DNA-binding factor) is a protein that binds to specific DNA sequences, thereby controlling the flow (or transcription) of genetic information from DNA to messenger RNA.[1][2] Transcription factors perform this function alone or with other proteins in a complex, by promoting (as an activator), or blocking (as a repressor) the recruitment of RNA polymerase (the enzyme that performs the transcription of genetic information from DNA to RNA) to specific genes

60. RNA interference – small RNA molecules connected to proteins form a Silencing complex. This complex destroys any mRNA it meets with that has a complementary code.
RNA interference (RNAi) is a biological process in which RNA molecules inhibit gene expression, typically by causing the destruction of specific mRNA molecules.
Two types of small ribonucleic acid (RNA) molecules – microRNA (miRNA) and small interfering RNA (siRNA) – are central to RNA interference. RNAs are the direct products of genes, and these small RNAs can bind to other specific messenger RNA (mRNA) molecules and either increase or decrease their activity, for example by preventing an mRNA from producing a protein. RNA interference has an important role in defending cells against parasitic nucleotide sequences – viruses and transposons. It also influences development.
Cells can trim double stranded RNA to form small inhibitory RNA (siRNA). An siRNA can be processed to the single strand anti-sense RNA and used to target mRNAs for destruction. Several proteins (colored ovals) are required for efficient RNA interference. The protein-containing complex was named "RNA-induced silencing complex", RISC.

61. Hox genes Control the differentiation of cells and tissues in the embryo.
In flies, the hox genes are located side-by-side in a single cluster as shown above.
Other similar clusters exist in the DNA of other animals, including humans.
Hox genes tell the cells of the body how they should differentiate as the body grows.
Common patterns of genetic control suggest that these genes have descended from a common ancestor.

62. Homeotic genes cause the development of specific structures in plants and animals. i.e. they are involved in determining where , when and how body segments develop in flies.
Homeotic genes cause the development of specific structures in plants and animals. They include many of the Hox and ParaHox genes which are important for segmentation,[1] They also include the MADS-box-containing genes involved the ABC model of flower development.[2] Not all homeotic genes are Hox genes; the MADS- box genes are homeotic but not Hox genes. Thus, the Hox genes are a proper subset of homeotic genes.
Homeotic genes are genes involved in developmental patterns and sequences. For example, homeotic genes are involved in determining where, when, and how body segments develop in flies. Alterations in these genes cause changes in patterns of body parts, sometimes causing dramatic effects such as legs growing in place of antennae or an extra set of wings or, in the case of plants, flowers with abnormal numbers of parts. An individual carrying an altered (mutant) version of a homeotic gene is known as a homeotic mutant

63. Pax6 gene from a mouse inserted onto a fruit fly causes eyes to grow in unusual places.
The fly gene and the mouse gene are similar enough to trade places and still function even though they come from animals that have not shared a common ancestor for at least 600 million years!