1. Structure, Function, Replication
DNA
Structure, Function, Replication

2. What is the genetic material?
DNA (deoxyribonucleic acid)
DNA is an organism’s genetic information
DNA carries instructions for all cellular functions, how to form cells, for the chemical and structures that cells must make and for everything that the cell does.
It also stores genetic material – information that is passed on from one generation to another when organisms reproduce.
Structure is two long stands shaped like a twisted ladder (double helix)

3. DNA The book of you Ted Ed video

4. Video Ameba Sisters: DNA Structure and Function
Stated Clearly: What is DNA?

5. Discovery of DNA Structure:
Rosalind Franklin: DNA's unsung hero

6. DNA Structure phosphate group, sugar, nitrogenous base
DNA is made up of copies of four different chemical building blocks called nucleotides.
Nucleotides are made up of:
phosphate group,
sugar,
nitrogenous base

7. Nucleotides are the building blocks of DNA

8. Nitrogenous Bases adenine (A), thymine (T), guanine (G) and
four types of nitrogen bases are
adenine (A),
thymine (T),
guanine (G) and
cytosine (C).

9. DNA Structure
The sides of the ladder are made of the sugar and phosphate molecules joined to each other.
The rungs of the ladder are made up of pairs of nitrogenous bases, one from each of the strands.
The nitrogenous bases pair up in the middle
A only pairs with T
C only pairs with G
The base pairs are held together by Hydrogen bonds

10. How is DNA related to chromosomes?
DNA exists in a tightly condensed form called chromatin within the nucleus of every cell in the body
When a cell is ready to reproduce, the DNA condenses even more into structures called chromosomes
These chromosomes exist in pairs
Humans have 23 pairs of chromosomes
When an organism reproduces, copies of its chromosomes (DNA) are transferred to the offspring.
What is DNA?
What is the function of DNA?
How is sexual reproduction different from asexual reproduction?

11. Karyotype
A Karyotype is the number and visual appearance of the chromosomes in the cell nuclei of an organism.

12. What is a gene?
A gene is a short section of the DNA molecule that contains the instructions to make a specific protein.
Proteins determine our characteristics and are building component of cellular structures
In humans, genes vary in size from a few hundred DNA bases to more than 2 million bases
An organism’s genome is its complete set of genes
What is DNA?
What is the function of DNA?
How is sexual reproduction different from asexual reproduction?

13. Genetic Code
It is the specific order (sequence) of nitrogenous bases that is the code that holds the instructions for all cellular processes.
Each group of three bases codes for a specific amino acid. Amino acids are the small molecules that are the building blocks of proteins.
Different combinations of amino acids form different proteins.

14. The Human Genome Project
Found three billion base pairs in the human genome
Aim to identify all the genes in the human genome
To develop faster methods for sequencing DNA
finished in 2001
The project involved scientists from 18 different countries

15. What is the importance of proteins?
Proteins are made up of smaller building blocks called amino acids, joined together in chains. 
Proteins are molecules that all the cells of the body need in order to work properly.
Proteins determine the characteristics of the organism.
Some proteins carry out cell functions
Other proteins are parts of cell structures.
Humans have as many as proteins.

16. Where are proteins made?
Proteins are made in the cytoplasm of the cell by ribosomes.
Ribosomes are made in the nucleolus and then move to the cytoplasm.

17. Check your understanding
What is the function of DNA?
How is sexual reproduction different from asexual reproduction?
DNA is an organisms genetic information
Carries instructions for how we look and behave

18. Homework
Read page 42-43, Answer CYU p47 #1, 2, 4, 5, 7

19. Build your own DNA Activity

20. How can each cell have the same copy of DNA?

21. DNA Replication

22. Video Amoeba Sisters DNA Replication

23. DNA REPLICATION
Before a cell divides, it must first replicate (copy) its DNA DNA REPLICATION is the process by which DNA copies itself before a cell divides
MGH:

24. DNA Replication DNA helix unwinds
Complementary nucleotides attach, elongating each strand
Result is two new DNA molecules identical to the original, each with one new strand and one old.
Remember it is the sequence of bases is the code that determines the trait or protein.

25. DNA Replication is “Semi-Conservative”
Semi-conservative Replication means that each of the two copies produced contain one of the original strands and one new strand.

28. It is the sequence of bases that is the code that determines what protein is made.
Who knows how this is done?
3 bases make a codon

29. How does the message become protein?
Gene Expression: DNA Transcription and Translation

30. Video Amoeba Sisters Protein Synthesis

32. From DNA to Proteins
2.3
VOCABULARY
nucleotide
nitrogenous bases
amino acids
gene
genome
traits
Genes are segments of DNA containing instructions to make proteins.
Proteins help determine an individual’s unique characteristics.
RNA is a copy of the genetic information in a gene.
RNA carries the instructions for making proteins from genes in the nucleus to ribosomes in the cytoplasm, where proteins are actually produced.
Once a cell is large enough to divide, DNA replicates before cell division begins.

33. Gene Expression: genetic code to protein in TWO steps: Transcription and Translation

34. DNA TRANSCRIPTION
When a particular protein is needed, the section of DNA that codes for that protein (gene) is copied and taken out of the nucleus and into the cytoplasm to the ribosomes. This process is called Transcription.
Transcription is the first step in “gene expression” (creating a protein).

35. Converting the code into protein
Proteins are made by ribosomes in the cytoplasm.
(Ribosome are made in the nucleolus but move to the cytoplasm once assembled)
But DNA never leaves the nucleus.
So the code or message must be copied and carried out to the ribosomes.

36. DNA Transcription: Copying the message
The code is copied when the two strands of DNA unwind,
The portion (gene of interest) is copied by mRNA (messenger RNA)
mRNA leaves nucleus and carries the “message” to the ribosomes.

37. What is RNA? RNA stands of ribonucleic acid
Like DNA, it is also a strand of nucleic acids except:
it is single-stranded,
instead of thymine it uses Uracil to pair with adenine.
It’s sugar is ribose instead of deoxyribose
mRNA is called messenger RNA because it takes the copied message out to the ribosomes to make protein.

38. Video
Amoeba Sisters – RNA

39. Transcription

40. How does the message become a protein?
Translation is the process in which the sequence of bases on the RNA is “read” by ribosomes to build a protein.
Translation is the second step in “gene expression” (protein formation).

41. Translation
Once the RNA is in the cytoplasm, a ribosome binds to the RNA and ‘reads” the sequence of nucleotides (read as three letter words – codons).
Each codon codes for a specific amino acid. The ribosome adds an amino acids as it moves down the RNA strand.

44. Gene Expression

45. CYU p47 # 8-15