GENETICS- CENTRAL DOGMA OF MOLECULAR BIOLOGY

CENTRAL DOGMA OF MOLECULAR BIOLOGY, GENETICS, HEREDITY,CHROMOSOMAL DISORDERS,

1. GENETICS PART 2

2. UNLOCKING DIFFICULTIES DNA or Deoxyribonucleic acid is double stranded material that carries genetic information for the development and functioning of an organism. RNA or ribonucleic acid is a single stranded material that stores information and helps in the synthesis of proteins in our body. Enzymes are proteins that help speed up chemical reactions in our bodies.

3. UNLOCKING DIFFICULTIES NUCLEOTIDES Nucleotides are organic molecules composed of a nitrogenous base, a pentose sugar and a phosphate. They serve as monomeric units of the nucleic acid polymers

4. UNLOCKING DIFFICULTIES NUCLEOTIDES

5. UNLOCKING DIFFICULTIES

6. CENTRAL DOGMA OF MOLECULAR BIOLOGY

7. CENTRAL DOGMA OF MOLECULAR BIOLOGY The central dogma of molecular biology states that genetic information flows only in one direction, from DNA, to RNA, to protein, or RNA directly to protein. STEPS: Replication, Transcription, and Translation It is suggested that the information present in a DNA is essential to make up all proteins and RNA acts as a messenger that carries information through the ribosomes.

8. CENTRAL DOGMA OF MOLECULAR BIOLOGY REPLICATION TRANSCRIPTION TRANSLATION

9. In DNA replication, the DNA makes multiple copies of itself. STEPS: Initiation, Elongation, Termination Semi-conservative process - the original strand of DNA acts as a template for the newly synthesized strand. Enzymes Used : Helicase, Primase, DNA Polymerase I,II,III, and Ligase REPLICATION

10. DNA Polymerase I, II, III – repairs, extends, and proofreads the DNA during replication. Helicase – unzips/unwinds the DNA strands by breaking the hydrogen bonds between the nitrogenous bases, forms the replication fork . Ligase - enzyme which joins together the Okazaki fragments of the discontinuous DNA strands. ENZYMES IN REPLICATION

11. Primase - This enzyme helps in the synthesis of RNA primer complementary to the DNA template strand. ENZYMES IN REPLICATION

12. DNA REPLICATION

13. DNA REPLICATION: INITIATION The process of replication starts at the origin of replication where the enzyme Helicase unwind/unzip the double stranded DNA creating the replication fork .

14. DNA REPLICATION: ELONGATION As the strands of DNA separates, the DNA polymerase synthesizes the complementary sequence of the strand, the parental strand acts as a template for the new nucleotide sequences.

15. DNA REPLICATION: ELONGATION In this process, one strand is continuous (3’  5’ direction) and follows continuous replication by DNA. It is called the leading strand . The other strand is discontinuous called lagging strand (5’  3’ direction) and form fragments called Okazaki fragments.

16. DNA REPLICATION: TERMINATION During termination, primers are removed and replaced with new DNA nucleotides and the backbone is sealed by the enzyme ligase . After the ligase has connected all the nicks, the newly synthesized DNA molecule is complete.

17. DNA REPLICATION: TERMINATION During termination, primers are removed and replaced with new DNA nucleotides and the backbone is sealed by the enzyme ligase . After the ligase has connected all the nicks, the newly synthesized DNA molecule is complete.

18. CENTRAL DOGMA OF MOLECULAR BIOLOGY REPLICATION TRANSCRIPTION TRANSLATION PROTEIN SYNTHESIS

19. TRANSCRIPTION Transcription is the process by which the information is transferred from one strand of the DNA to RNA by the enzyme RNA Polymerase . The DNA strand that synthesizes the RNA is called the template strand and the other strand is called the coding strand . The RNA polymerase reads and adds nucleotides from 3’ 5 ’ direction.

20. RNA Polymerase - RNA polymerase is a multi-unit enzyme that synthesizes RNA molecules from a template of DNA. ENZYME IN TRANSCRIPTION

21. TRANSCRIPTION: INITIATION RNA polymerase binds to a specific sequence within the gene called promoter . As the RNA polymerase moves along from 3’ 5’ direction, the DNA unwinds. Half of the DNA strand will act as the template strand or the antisense strand and will be used to synthesize the RNA.

22. TRANSCRIPTION: ELONGATION RNA polymerase reads the antisense strand from 3’ 5’ direction and catalyzes the addition of ribose nucleotides to the antisense strand synthesizing the pre-mRNA strand. The RNA strand is built from 5’ to 3’.

23. TRANSCRIPTION: TERMINATION At the end of the gene, RNA polymerase encounters a sequence of DNA called the termination signal. RNA polymerase detaches from the DNA and releases the pre-mRNA molecule.

24. mRNA PROCESSING ADDITION OF 5’ CAP POLYADENYLATION INTRON SPLICING The 5’cap is a modified guanine (G) nucleotide , and it protects the transcript from being broken down. The enzyme poly(A) polymerase adds a chain of 100-250 adenine nucleotides to the pre-mRNA. The enzyme spliceosome cuts the introns (non-coding regions), exons (coding regions are spliced together by the same enzyme.

25. CENTRAL DOGMA OF MOLECULAR BIOLOGY REPLICATION TRANSCRIPTION TRANSLATION

26. TRANSLATION Translation is the process by which the mRNA codes for specific proteins. It is an active process which requires energy. This energy is provided by the charged tRNA molecules. The bases (3s’) on the mRNA (codons) will code for a specific amino acid.

27. mRNA (messenger RNA) - the genetic material that codes for specific amino acids. tRNA (transfer RNA) – helps decode the mRNA, carry amino acids to the ribosome during protein synthesis. Ribosomal units - composed of two subunits with densities of 50S and 30S, translate the codons in mRNA and serve as a factory where a growing polypeptide chain is assembled. MATERIALS FOR TRANSLATION

28. Codon - A sequence of three consecutive nucleotides in a DNA or RNA molecule that codes for a specific amino acid. Amino acids – building blocks of proteins, 20 amino acids make up proteins found in the human body. Polypeptide - is a string of amino acids connected together by peptide bonds . They make up proteins. Proteins - serve as structural support, biochemical catalysts, hormones, enzymes, building blocks, and initiators of cellular death. TRANSLATION TERMINOLOGIES

29. CODONS OF MESSENGER RNA (mRNA) START CODON STOP CODONS AUG UGA UAG UAA

30. TRANSLATION: INITIATION The tRNA (Transfer RNA) brings the corresponding amino acid to each codon as the ribosomal units moves along the mRNA strand.

31. TRANSLATION: TERMINATION Reading of the final mRNA codon (stop codons) which ends the synthesis of the polypeptide chain and release it. The release factor signals the ribosomal units to terminate the translation and release the polypeptide chain.

32. AMINO ACID SEQUENCING

33. AMINO ACIDS An amino acid is an organic chemical with carbon-hydrogen bonds . Amino acids are the monomers that make up proteins. Amino acid chains are bonded by peptide bonds.

34. AMINO ACIDS Chains of amino acids linked by peptide bonds are called polypeptides .

35. AMINO ACIDS Though more than 200 amino acids are identified in nature, only 20 amino acids serve as building blocks of body proteins. They are known as common amino acids.

36. COMMON AMINO ACIDS

37. SAMPLE PROBLEM DNA : TAC CGC TCC GCC GTC GAC AAT AAC ACT mRNA: AA:

38. SAMPLE PROBLEM DNA : mRNA: AUG GUG GGG GCA UAC CGA CCC UAA UAG AA:

39. SAMPLE PROBLEM DNA : TAC TGA TCG ACC CCC ATA ATG AAA ATC mRNA: AA:

40. KARYOTYPING

41. KARYOTYPING Karyotyping is a diagnostic tool used in medical genetics to examine the chromosomes of an individual to detect any abnormalities.

42. KARYOTYPING TECHNIQUES To make a karyotype, scientists take a picture of the chromosomes from a cell and arrange them in terms of: Size Banding pattern Centromere positions

43. KARYOTYPING It involves arranging and analyzing the chromosomes from a cell sample to create a visual representation of the chromosome complement, known as a karyogram . It is an important tool in identifying genetic disorders, determining the sex of an individual, and studying evolutionary relationships between species.

44. LETS TRY! Which of the following is best pair of this chromosome? A B C D

45. LETS TRY! Which of the following is best pair of this chromosome? A B C D

46. LETS TRY! Which of the following is best pair of this chromosome? A B C D

47. CHROMOSOMAL ABNORMALITIES

48. HUMAN CHROMOSOMES Humans typically have 23 pairs of chromosomes, or 46 chromosomes in total. Any missing or excess chromosome results to chromosomal abnormalities.

49. FACTORS OF CHROMOSOMAL ABSNORMALITIES Chromosome abnormalities often happen due to 1 or more of these: Errors during dividing of sex cells ( meiosis ) Errors during dividing of other cells ( mitosis )

50. TRISOMY 21 Down syndrome is a genetic condition where a person is born with an extra copy of chromosome 21. This can affect how their brain and body develop. The majority of Down syndrome cases happen randomly (sporadically).

51. TURNER SYNDROME Turner syndrome happens when a baby assigned female at birth is born with one missing or partial X chromosome. Monosomy X: This type means each cell has only one X chromosome instead of two. Mosaic Turner syndrome: An individual’s cell have a pair of X chromosomes, while other cells only have one

52. TURNER SYNDROME Turner syndrome presents in many ways. It can cause several different characteristics — or features — as well as certain health conditions, which can vary in severity.

53. EDWARDS SYNDROME Trisomy 18, also called Edwards syndrome , is a chromosomal condition associated with abnormalities in many parts of the body. Individuals with trisomy 18 often have slow growth before birth (intrauterine growth retardation) and a low birth weight.

54. PATAU SYNDROME Trisomy 13 , also called Patau syndrome, is a severe chromosomal condition, with multiple malformations due to an additional copy of all or part of chromosome 13. The cause of this additional copy of chromosome 13 is unknown .

55. KLINEFELTER SYNDROME Klinefelter syndrome is a common genetic condition in which people assigned male at birth (AMAB) have an additional X chromosome. Symptoms may include breast growth, infertility, osteoporosis and learning difficulties.