1. DNA structure and replication

2. DNA DISCOVERY STORY DISCOVERY: Rosalind Franklin: Was too nice!
She shared her discoveries with Watson and Crick who then were the first to publish and get recognized
She confirmed the helical structure, the sugar-phosphate backbone
Rosalind Franklin used X-ray diffraction to get information about the structure of DNA.
She aimed an X-ray beam at concentrated DNA samples and recorded the scattering pattern of the X-rays on film.

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The Double Helix 
Using clues from Franklin’s pattern, James Watson and Francis Crick built a model that explained how DNA carried information and could be copied.
Watson and Crick's model of DNA was a double helix, in which two strands were wound around each other.

4. DNA: Deoxyribonucleic acid DNA: stores our genetic instructions
What is dna?
DNA: Deoxyribonucleic acid
Deoxyribose: Sugar ( -ose means sugar)
DNA: stores our genetic instructions
All the information that programs all of our cells activities
Code that provides the assembly instructions for everything that lives

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DNA and Chromosomes
Many eukaryotes have 1000 times the amount of DNA as prokaryotes.
Eukaryotic DNA is located in the cell nucleus inside chromosomes.
The number of chromosomes varies widely from one species to the next.

6. DNA and Chromosomes Chromosome Structure
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DNA and Chromosomes
Chromosome Structure
Eukaryotic chromosomes contain DNA and protein, tightly packed together to form chromatin.
Chromatin consists of DNA tightly coiled around proteins called histones.
DNA and histone molecules form nucleosomes.
Nucleosomes pack together, forming a thick fiber.

7. Eukaryotic Chromosome Structure
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DNA and Chromosomes
Eukaryotic Chromosome Structure
DNA double helix
Eukaryotic chromosomes contain DNA wrapped around proteins called histones. The strands of nucleosomes are tightly coiled and supercoiled to form chromosomes.

9. Cells
Somatic Cells: Body cells (any cells that are used in the body besides your sex cells)
Replicate with mitosis
Mitosis creates two exact copies
Interphase, Prophase, Metaphase, Anaphase, Telophase and Cytokinesis

10. Gametes: Sex cells Cells Replicate with meiosis
Meiosis combines genetic material, not an exact copy, creates four cells
Two cycles:
Interphase I, Prophase I, Metaphase I, Anaphase I, Telophase I and Cytokinesis I
Interphase II, Prophase II, Metaphase II, Anaphase II, Telophase II and Cytokinesis II

11. Humans have 46 chromosomes
Chromosomes: arrangements of nucleic acids and proteins that are located in the nucleus of cells and carry genetic information in the form of genes.
Genes: unit of heredity that is transferred from a parent to offspring and is held to determine some characteristic of the offspring
Each of the 46 chromosomes contain one DNA molecule packed tightly with proteins in the nucleus

12. Nucleic acid
Nucleic acid: macromolecule (like lipid, proteins, and carbohydrates)
Made up of many small repeating units called nucleotides
Nucleotides:
are made up of: 5-carbon sugar, a phosphate, and 1 of 4 nitrogen bases
Nitrogen Bases: Adenine, Cytosine, Thymine, and Guanine

13. Dna strand 5-carbon sugar 5-carbon sugar Backbones
Two different directions one side goes up the other points down
Phosphate
Phosphate
Nitrogen Base's
Double Helix

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DNA is a double helix in which two strands are wound around each other. Each strand is made up of a chain of nucleotides. The two strands are held together by hydrogen bonds between adenine and thymine and between guanine and cytosine.

15. Nitrogen bases
The most significant coding in your DNA comes from these bases
They are held together by weak hydrogen bonds
They can only be paired with certain bases
Adenine Thymine (apples in tree)
Cytosine  Guanine (car in garage)
This principle is called base pairing.

16. Decode the matching each of the base pairs
Quick check in
Decode the matching each of the base pairs
AGGTCCG
TCCAGGC

17. RNA RNA: ribonucleic acid, a nucleic acid present in all living cells.
Acts as a messenger carrying instructions from DNA for controlling the synthesis of proteins,
although in some viruses RNA rather than DNA carries the genetic information

19. Similarities and differences in dna and rna
RNA is a single strand while DNA is the double helix
Meaning one back bone
Sugar is called ribose and has one more oxygen atom
RNA does not contain thymine, instead it has uracil which bonds with adenine
Similarities:
Both have sugar-phosphate backbone
Both have the nucleotides

20. RNA: is important for producing protein and crucial in replicating DNA
RNA’S ROLE
RNA: is important for producing protein and crucial in replicating DNA
DNA: carries your genetic traits and creates………you

21. SIMILARITIES AND DIFFERENCES BETWEEN DNA AND RNA

23. DNA Replication DNA Replication
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DNA Replication
DNA Replication
Each strand of the DNA double helix has all the information needed to reconstruct the other half by the mechanism of base pairing.
In most prokaryotes, DNA replication begins at a single point and continues in two directions.

24. Cells are constantly dividing
DNA REPLICATION
Cells are constantly dividing
Most of them through mitosis (exact copies)
This is a benefit as you would not want a skin cell to be created in your blood
Every cell in the body has the same DNA
It all started with an original and then copies itself trillions of times in your lifetime
Each time it replicates itself ½ of the original DNA is used as a template to build a new molecule

25. DNA replication
Helicase: unwinds the double helix, slicing open the loose hydrogen bonds between each of the base pairs

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DNA Replication
In eukaryotic chromosomes, DNA replication occurs at hundreds of places. Replication proceeds in both directions until each chromosome is completely copied.
The sites where separation and replication occur are called replication forks.

27. DNA Replication Duplicating DNA
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DNA Replication
Duplicating DNA 
Before a cell divides, it duplicates its DNA in a process called replication.
Replication ensures that each resulting cell will have a complete set of DNA.

28. DNA Replication
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During DNA replication, the DNA molecule separates into two strands, then produces two new complementary strands following the rules of base pairing.
Each strand of the double helix of DNA serves as a template for the new strand.

29. DNA Replication How Replication Occurs
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DNA Replication
How Replication Occurs
DNA replication is carried out by enzymes that “unzip” a molecule of DNA.
Hydrogen bonds between base pairs are broken and the two strands of DNA unwind.

30. DNA replication
Replication Fork: this is the point where splitting stars and creates a leading strand (top) and a lagging strand (bottom)

31. Dna replication
Now the unwound sections can be used as templates to create 2 new complimentary strands in opposite directions

32. Replicating the leading strand:
Dna replication
Replicating the leading strand:
An enzyme called DNA polymerase is used to add matching nucleotide onto a main stem down the length of the molecule
But first it needs a section of nucleotides that fill in the sections that has just been “unzipped”

33. Dna replication
Starting at the beginning of the leading strand DNA polymerase uses a primer to hook onto so it can start building a new DNA chain this is called a RNA primase
RNA primase is only used one time and DNA polymerase copies 1st four nucleotides down the chain

35. DNA Replication New Strand Original strand Nitrogen Bases Growth
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New Strand
Original strand
Nitrogen Bases
Growth
During DNA replication, the DNA molecule produces two new complementary strands. Each strand of the double helix of DNA serves as a template for the new strand.
Replication Fork
Replication Fork
DNA Polymerase

36. Replication of the lagging strand:
DNA REPLICATION
Replication of the lagging strand:
DNA can copy in one direction
Remember the “backbones” are actually in different directions and the lagging strand is backwards

37. Can only be copied in segments and uses enzyme (RNA primase)
DNA REPLICATION
Can only be copied in segments and uses enzyme (RNA primase)
Can only be used for occasional short RNA primer to give DNA polymerase a starting point to work backwards
Strands can only be synthesized in small fragments (Okazaki Fragments)

38. DNA REPLICATION
DNA polymerase has to go back over all the RNA primers and replace them
Finally all the fragments join by enzyme DNA Ligase

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DNA Replication
The principal enzyme involved in DNA replication is DNA polymerase.
DNA polymerase joins individual nucleotides to produce a DNA molecule and then “proofreads” each new DNA strand.

41. Types of RNA Types of RNA There are three main types of RNA:
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Types of RNA
Types of RNA
There are three main types of RNA:
messenger RNA
ribosomal RNA
transfer RNA

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Types of RNA
The three main types of RNA are messenger RNA, ribosomal RNA, and transfer RNA.
Messenger RNA (mRNA) carries copies of instructions for assembling amino acids into proteins.

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Types of RNA
The three main types of RNA are messenger RNA, ribosomal RNA, and transfer RNA. Ribosomal RNA is combined with proteins to form ribosomes.
Ribosomes are made up of proteins and ribosomal RNA (rRNA).

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Types of RNA
Amino acid
The three main types of RNA are messenger RNA, ribosomal RNA, and transfer RNA.
Transfer RNA
During protein construction, transfer RNA (tRNA) transfers each amino acid to the ribosome.

46. DNA molecule DNA strand (template) 3¢ 5¢ TRANSCRIPTION mRNA 5¢ 3¢
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DNA
molecule
DNA strand
(template) 3¢ 5¢
TRANSCRIPTION
mRNA 5¢ 3¢
Codon
TRANSLATION
Protein
Amino acid

47. Transcription DNA is copied in the form of RNA
This first process is called transcription.
The process begins at a section of DNA called a promoter.
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During transcription, RNA polymerase uses one strand of DNA as a template to assemble nucleotides into a strand of RNA.
Transcription

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RNA Editing
Some DNA within a gene is not needed to produce a protein. These areas are called introns.
The DNA sequences that code for proteins are called exons.
RNA Editing

50. The introns are cut out of RNA molecules.
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RNA Editing
The introns are cut out of RNA molecules.
The exons are the spliced together to form mRNA.
Exon
Intron
DNA
Pre-mRNA
mRNA
Many RNA molecules have sections, called introns, edited out of them before they become functional. The remaining pieces, called exons, are spliced together. Then, a cap and tail are added to form the final RNA molecule.
Cap
Tail

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The Genetic Code
The Genetic Code
The genetic code is the “language” of mRNA instructions.
The code is written using four “letters” (the bases: A, U, C, and G).

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The Genetic Code
A codon consists of three consecutive nucleotides on mRNA that specify a particular amino acid.
A codon is a group of three nucleotides on messenger RNA that specify a particular amino acid.

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The Genetic Code
The genetic code shows the amino acid to which each of the 64 possible codons corresponds. To decode a codon, start at the middle of the circle and move outward.

54. Translation Translation
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Translation
Translation is the decoding of an mRNA message into a polypeptide chain (protein).
Translation takes place on ribosomes.
During translation, the cell uses information from messenger RNA to produce proteins.

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Translation
The ribosome binds new tRNA molecules and amino acids as it moves along the mRNA.
Phenylalanine
tRNA
Ribosome
During translation, or protein synthesis, the cell uses information from messenger RNA to produce proteins. The cell uses all three main forms of RNA during this process.
mRNA
Start codon

56. Lysine tRNA Translation direction Protein Synthesis Translation mRNA
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Lysine
tRNA
Protein Synthesis
During translation, or protein synthesis, the cell uses information from messenger RNA to produce proteins. The cell uses all three main forms of RNA during this process.
Translation direction
mRNA
Ribosome

57. The process continues until the ribosome reaches a stop codon.
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Translation
The process continues until the ribosome reaches a stop codon.
Polypeptide
Ribosome
tRNA
During translation, or protein synthesis, the cell uses information from messenger RNA to produce proteins. The cell uses all three main forms of RNA during this process.
mRNA

58. Amino acids within a polypeptide
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Codon
Codon
Codon
GENES AND PROTIEN
DNA
mRNA
Protein
Single strand of DNA
Codon
Codon
Codon
mRNA
This diagram illustrates how information for specifying the traits of an organism is carried in DNA. The sequence of bases in DNA is used as a template for mRNA. The codons of mRNA specify the sequence of amino acids in a protein, and proteins play a key role in producing an organism’s traits.
Alanine
Arginine
Leucine
Amino acids within a polypeptide

59. 12–4 Mutations 12-4 Mutations
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12–4 Mutations

60. Mutations are changes in the genetic material. Kinds of Mutations
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Mutations are changes in the genetic material.
Kinds of Mutations
Mutations that produce changes in a single gene are known as gene mutations.
Mutations that produce changes in whole chromosomes are known as chromosomal mutations.

61. Kinds of Mutations
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Gene Mutations 
Gene mutations involving a change in one or a few nucleotides are known as point mutations because they occur at a single point in the DNA sequence.
Point mutations include substitutions, insertions, and deletions.

62. Substitutions usually affect no more than a single amino acid.
Kinds of Mutations
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Substitutions usually affect no more than a single amino acid.
Gene mutations result from changes in a single gene. In a substitution, one base replaces another.

63. The effects of insertions or deletions are more dramatic.
Kinds of Mutations
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The effects of insertions or deletions are more dramatic.
The addition or deletion of a nucleotide causes a shift in the grouping of codons.
Changes like these are called frameshift mutations.

64. In an insertion, an extra base is inserted into a base sequence.
Kinds of Mutations
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In an insertion, an extra base is inserted into a base sequence.
Gene mutations result from changes in a single gene. In an insertion, an extra base is inserted into a base sequence.

65. Kinds of Mutations
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In a deletion, the loss of a single base is deleted and the reading frame is shifted.
Gene mutations result from changes in a single gene. The loss of a single letter in a sentence models the effects of the deletion of one base in a DNA sequence.

66. Chromosomal Mutations
Kinds of Mutations
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Chromosomal Mutations 
Chromosomal mutations involve changes in the number or structure of chromosomes.
Chromosomal mutations include deletions, duplications, inversions, and translocations.

67. Deletions involve the loss of all or part of a chromosome.
Kinds of Mutations
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Deletions involve the loss of all or part of a chromosome.
Chromosomal mutations involve changes in whole chromosomes.

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Kinds of Mutations
Duplications produce extra copies of parts of a chromosome.
Chromosomal mutations involve changes in whole chromosomes.

69. Inversions reverse the direction of parts of chromosomes.
Kinds of Mutations
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Inversions reverse the direction of parts of chromosomes.
Chromosomal mutations involve changes in whole chromosomes.

70. Kinds of Mutations
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Translocations occurs when part of one chromosome breaks off and attaches to another.
Chromosomal mutations involve changes in whole chromosomes.

71. Significance of Mutations
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Significance of Mutations
Many mutations have little or no effect on gene expression.
Some mutations are the cause of genetic disorders.
Polyploidy is the condition in which an organism has extra sets of chromosomes.