1. July 19th On a white board tell me:
1. What are homologous chromosomes?
2. How are they inherited?
3. What is a karyotype?
4. How are male and female karyotypes different?
Quiz tomorrow on transport and chromosomes

2. 1. What are homologous chromosomes? 2. How are they inherited?
Paired chromosomes
2. How are they inherited?
One from your mother and one from father
3. What is a karyotype?
Diagram of a full set of chromosomes
4. How are male and female karyotypes different?
Female XX male Xy
Quiz tomorrow on transport and chromosomes

3. DNA (Deoxyribonucleic Acid)

4. Chromosomes Are how organisms pass on traits Humans have 46 Chromosome
Horses have 64
Cats 32

5. DNA is organized into chromosomes which are found in the nucleus of the cell
A gene is a segment of DNA that codes for a specific protein that determines a trait

6. Genetic material of cells…
GENES – units of genetic material that CODES FOR A SPECIFIC TRAIT
Called NUCLEIC ACIDS
DNA is made up of repeating molecules called NUCLEOTIDES

7. DNA Nucleotide made up of: Phosphate group, Nitrogenous base and deoxyribose sugar
O=P-O
Phosphate
Group N
Nitrogenous base
(A, G, C, or T)
CH2 O C1 C4 C3 C2 5
Sugar
(deoxyribose)

8. Watson & Crick proposed…
DNA had specific pairing between the nitrogen bases:
ADENINE – THYMINE
CYTOSINE - GUANINE
DNA was made of 2 long stands of nucleotides arranged in a specific Pairing called the “Complementary Rule” A bonds to T and G bonds to C

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

10. DNA (sides) backbone made out of sugar-phosphate with a covalent bond1 2 3 4 5 P O 1 2 3 4 5 G C T A

11. Rungs made out of: Nitrogenous Bases
Two Kinds:
1.PURINES
Adenine (A)
Guanine (G)
2. PYRIMIDINES
Thymine (T)
Cytosine (C)
A or G
T or C

12. Chargaff’s Rule Adenine must pair with Thymine
Guanine must pair with Cytosine
Their amounts in a given DNA molecule will be about the same. T A G C

13. BASE-PAIRINGS held together with a hydrogen bondC G
H-bonds T A

14. Genetic Diversity…
Different arrangements of NUCLEOTIDES in a nucleic acid (DNA) provides the key to DIVERSITY among living organisms.

15. The Code of Life… A T C G T A T G C G G…
The “code” of the chromosome is in the SPECIFIC ORDER that bases occur.
A T C G T A T G C G G…

16. DNA Replication A-T, G-C
DNA must be copied before cell division
To provide each cell with its own copy of DNA
The DNA molecule produces 2 IDENTICAL new complementary strands following the rules of base pairing:
A-T, G-C
Each strand of the original DNA serves as a template for the new strand

17. DNA Replication
Semiconservative Model: (ON THE RIGHT HAND SIDE OF YOUR PAPER)
1. Watson and Crick showed: the two strands of the parental molecule separate, and each functions as a template for synthesis of a new complementary strand. .
DNA Template
New DNA
Parental DNA

18. DNA Replication - creates the replication fork
How:
1. Enzymes called helicases separate the DNA strand
- creates the replication fork
Another enzyme DNA polymerase adds
complementary nucleotides to each original strand

19. 1. Why is replication necessary? 2. When does replication occur?
Replication Quiz
1. Why is replication necessary?
2. When does replication occur?
3. Describe how replication works.
Use the complementary rule to
create the complementary strand:
A---?
G---?
C---?
T---?

20. Replication Quiz 1. Why is replication necessary?
So both new cells will have the correct DNA
2. When does replication occur?
before cell division
3. Describe how replication works.
Enzymes unzip DNA and complementary nucleotides join each original strand.
4. Use the complementary rule to
create the complementary strand:
A---T
G---C
C---G
T---A

21. (1961) Watson & Crick proposed…
…DNA controlled cell function by serving as a template for PROTEIN structure.
3 Nucleotides = a triplet or CODON
(which code for a specific AMINO ACID)
AMINO ACIDS are the building blocks of proteins.

22. DNA Transcription
DNA can “unzip” itself and RNA nucleotides match up to the DNA strand.
Both DNA & RNA are formed from NUCLEOTIDES and are called NUCLEIC acids.
See p.301

23. We will discuss details of this on a later date
DNA Translation
The cell uses information from “messenger” RNA to produce proteins
We will discuss details of this on a later date

24. Transcription/Translation Quiz
Why is transcription necessary?
Describe transcription.
Why is translation necessary?
Describe translation.
What are the main differences between DNA and RNA.
Using the chart, identify the amino acids coded for by these codons:
UGGCAGUGC

25. 1. Why is transcription necessary?
Transcription makes messenger RNA (MRNA) to carry the code for proteins out of the nucleus to the ribosomes in the cytoplasm.
2. Describe transcription.
RNA polymerase binds to DNA, separates the strands, then uses one strand as a template to assemble MRNA.
3. Why is translation necessary?
Translation assures that the right amino acids are joined together by peptides to form the correct protein.

26. 4. Describe translation.
The cell uses information from MRNA to produce proteins.
5. What are the main differences between DNA and RNA.
DNA has deoxyribose, RNA has ribose; DNA has 2 strands, RNA has one strand; DNA has thymine, RNA has uracil.
Using the chart, identify the amino acids coded for by these codons: UGGCAGUGC
tryptophan-glutamine-cysteine

27. (a library of about 1,000 books)
AMAZING DNA FACTS…
DNA from a single human cell extends in a single thread for almost 2 meters long!!!
It contains information equal to some 600,000 printed pages of 500 words each!!!
(a library of about 1,000 books)

28. LET’S REVIEW DNA… LM p.44
List the conclusions Griffith & Avery, Hershey & Chase drew from their experiments.
Summarize the relationship between genes & DNA.
Describe the overall structure of the DNA molecule.
What are the 4 kinds of bases?