1. The fingerprint that’s inside your body!!!!!!
DNA
The fingerprint that’s inside your body!!!!!!

2. You can tell people apart by their fingerprints…
Because everyone’s fingerprints are different!
So is your DNA!

3. DNA

4. MCAS objectives
Describe the basic structure of DNA, and describe its function in genetic inheritance.
Describe the cell cycle and the process of mitosis.
Explain the role of mitosis in the formation of new cells, and its importance in maintaining chromosome number during asexual reproduction.

5. Fun DNA Facts!
DNA is too small to see, but under a microscope it looks like a twisted up ladder!
(double helix)
DNA stands for:
D: Deoxyribose N: Nucleic A: Acid
Every living thing has DNA. That means that you have something in common with a zebra, a tree, a mushroom and a beetle!!!!

6. DNA - DEOXYRIBONUCLEIC ACID - blueprint of life (has the instructions for making an organism) - established by James Watson and Francis Crick - codes for your genes - shape of a double helix - made of repeating subunits called nucleotides Gene - a segment of DNA that codes for a protein, which in turn codes for a trait (skin tone, eye color..etc), a gene is a stretch of DNA. Nucleotide - consists of a sugar, phosphate and a base

7. DNA by the Numbers Each cell has about 2 m of DNA.
The average human has 75 trillion cells!
If you unravel all the DNA in the chromosomes of one of your cells, it would stretch out 2 meters. If you did this to the DNA in all your cells, it would stretch from here to sun more than 400 hundred times!

8. DNA is present in the nucleus
of all cells in all living organisms
DNA controls all the chemical changes which take place in cells
The kind of cell which is formed, (muscle, blood, nerve etc) is controlled by DNA

9. Organization
Chromatin = combination of DNA and proteins that make up the contents of the nucleus of a cell.
Chromatin condenses into chromosomes

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11. Review: Prokaryotic & Eukaryotic cells
"Prokaryotic" means "before a nucleus," and “Eukaryotic" means "possessing a true nucleus."

12. Prokaryotic & Eukaryotic cells
Eukaryotic cells contain chromosomes
Prokaryotic cells contain plasmid DNA and Nucleoid DNA

13. Prokaryotic cell

14. Prokaryotic DNA
nucleoid - the irregularly-shaped region within a prokaryote cell where the genetic material is localized
• plasmid - a circle of double-stranded DNA that is separate from the chromosomes, which is found in bacteria and protozoa

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chromosomes
Eukaryotic Cell
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16. 1953 Watson and Crick determined the structure of DNA

17. The Shape of the Molecule
The basic shape is like a twisted ladder or zipper.
This is called a double helix.
{Show students a model of the double helix. Explain what a spiral is and a helix is.}

18. DNA Double Helix “Rungs of ladder” Nitrogenous Base (A,T,G or C)
“Legs of ladder”
Phosphate &
Sugar Backbone

19. DNA is a very large molecule made up of a long
chain of sub-units
The sub-units are called nucleotides
Each nucleotide is made up of
a sugar called deoxyribose
a phosphate group and
an organic base

20. Ribose is a sugar, like glucose, but with only five
carbon atoms in its molecule
Deoxyribose is almost the same but lacks one
oxygen atom
Both molecules may be represented by the symbol

21. The bases
The organic bases are
Adenine
(A)
Thymine
(T)
Cytosine
(C)
Guanine
(G)

22. Two Kinds of Bases in DNA
Pyrimidines are single ring bases.
Purines are double ring bases. N C O C C N C C N

23. Thymine and Cytosine are pyrimidines
Thymine and cytosine each have one ring of carbon and nitrogen atoms. C N O
cytosine C N O
thymine

24. Adenine and Guanine are purines
Adenine and guanine each have two rings of carbon and nitrogen atoms. C N O
Guanine C N
Adenine

25. Hydrogen Bonds The bases attract each other because of hydrogen bonds.
Hydrogen bonds are weak but there are millions and millions of them in a single molecule of DNA.
The bonds between cytosine and guanine are shown here with dotted lines C N O

26. Hydrogen Bonds, cont.
When making hydrogen bonds, cytosine always pairs up with guanine
Adenine always pairs up with thymine
Nucleotides pair in a specific way - called the Base-Pair Rule T A G C

27. Joined nucleotides
PO4
sugar-phosphate
backbone
+ bases
A molecule of DNA is formed by millions of nucleotides joined together in a long chain

28. Although each individual repeating unit is very small, DNA polymers can be very large molecules containing millions of nucleotides. For instance, the largest human chromosome, chromosome number 1, is approximately 220 million base pairs long

29. 2-stranded DNA
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4

30. The bases always pair up in the same way
Bonding 1
The bases always pair up in the same way
Adenine forms a bond with Thymine
Adenine
Thymine
and Cytosine bonds with Guanine
Cytosine
Guanine

31. Bonding 2
PO4
adenine
cytosine
PO4
thymine
PO4
guanine
PO4
PO4

32. Pairing up
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4

33. THE DOUBLE HELIX
bases
sugar-phosphate
chain

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35. Attached to each sugar is one of four types of molecules called bases
Attached to each sugar is one of four types of molecules called bases. It is the sequence of these four nucleobases along the backbone that encodes information.
This information is read using the genetic code.
The code is read by copying stretches of DNA into the related nucleic acid RNA in a process called transcription.

36. Replication The process where DNA makes a copy of itself.
During INTERPHASE of Mitosis
Why does DNA need to copy?
Cells divide for an organism to grow or reproduce
Every cell needs a BLUEPRINT of the DNA
- DNA replicates right before a cell divides.
- Before a cell divides, the DNA strands unwind and separate

37. DNA replication is semi-conservative
DNA replication is semi-conservative. That means that when it makes a copy, one half of the old strand is always kept in the new strand. This helps reduce the number of copy errors

38. New DNA consists of 1 PARENTAL (original) & 1 NEW strand of DNA
Enzyme Helicase unwinds and separates the 2 DNA strands by breaking the weak hydrogen bonds
Replication
Fork
Parental DNA Molecule 3’ 5’

39. To carry the genomic information to daughter cells
DNA Duplication
Using itself as template

41. The strands separate
PO4
PO4

42. Each strand builds up its partner by adding the appropriate nucleotides
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
The nucleotides are present in the nucleoplasm. The nuclear equivalent of cytoplasm
PO4
PO4
PO4
PO4
PO4

43. DNA to Protein
Genome: the complete set of information in an organism’s DNA
Total length of DNA about 2 meters long in a human cell, encoding about proteins

44. Human Chromosome:
Complex of DNA is called chromatin
44 homologous chromosomes and 2 sex chromosomes
Complementary DNA with different Dyes
The arrangement of the full chromosome set is called a
karyotype

45. RNA
DNA remains in the nucleus, but in order for it to get its instructions translated into proteins, it must send its message to the ribosomes, where proteins are made. The chemical used to carry this message is Messenger RNA
RNA = ribonucleic acid.
RNA is similar to DNA except:
1. has one strand instead of two strands. 2. has uracil instead of thymine 3. has ribose instead of deoxyribose
mRNA has the job of taking the message from the DNA to the nucleus to the ribosomes.

46. Transcription - RNA is made from DNA
Translation - Proteins are made from the message on the RNA

47. DNA vs. RNA
DeoxyriboNucleicAcid vs RiboNucleicAcid
A difference between DNA and RNA is the sugar present in the molecules. While the sugar present in an RNA molecule is ribose, the sugar present in a molecule of DNA is deoxyribose.
A fifth base, called uracil (U), takes the place of thymine in RNA

48. DNA vs. RNA
DeoxyriboNucleicAcid vs RiboNucleicAcid
Transfer the genetic code needed for the creation of proteins from the nucleus to the ribosome.
RNA strands are continually made, broken down and reused.
Long-term storage and transmission of genetic information
DNA is protected in the nucleus, as it is tightly packed.

49. DNA Damage & Repair
Chemicals & ultraviolet radiation damage the DNA in our body cells
Cells must continuously repair DAMAGED DNA

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