DNA

Nucleic acid found in the nucleus

Carries hereditary information

Chromosome

Nucleic acid

Polynucleotide

Nucleotide

Phosphategroup

Nitrogenous base

pentose sugar

Nucleotide

OC

C

Polymer of nucleotides

Phosphate-sugar “backbone”

Sequence of bases - unique- genetic code.

Polynucleotides

Deoxyribonucleic Acid

DNA

2 polynucleotide strands

• double helix

• deoxyribose

• A, T, G, C

PyrimidinePurine

Adenine

Guanine Cytosine

Thymine

http://www.youtube.com/watch?v=ZXt4pDVb2W0&feature=related

(DNA structure, 10 min)

DNA replication

1. chromatin condenses chromosomes.

2. Section of the DNA helix unwinds

3. Free nucleotides bind with complementary bases on the DNA strand.

4. DNA double helix rewinds

Original DNA helix

DNA strands separate

New anti-code strand

Original (parent) anti-code strand

Original code strand

New (daughter) code strand

DNA REPLICATION

New cells have exact copy of original DNA

Nucleotides building new strand

New nucleotides

• DNA replication is semi-conservative. - new DNA = 1 old strand + 1 new strand

• helps reduce the number of copy errors.

• Enzymes control all processes, including “proofreading”

genes

DNA Replication

centromere

Single chromosome – 1 DNA double helix

Sister chromatids – 2 DNA double helices

One chromosome

DNA Replication

Each chromosome in an homologous pair

replicates to form sister chromatids

MENU

Key Words

Exercises

Quick Quiz

Videos

KEY WORDS

• Pentose sugars• Phosphate• Nitrogenous base• Purine• Pyrimidine• Adenine• Thymine• Guanine• Cytosine• Double helix

• Chromosome• Chromatin• Replication• Base pairing• Complementary• Semi-conservative• Chromatids• Centromere

EXERCISES

Workbook• Read pp 78-80• Questions 6-16

Pathfinder• Read p 53

QUICK QUIZ 11. The building blocks of organic molecules ....

2. The building blocks of nucleic acids .....

3. How many polynucleotide strands in DNA?

4. Sugar found in RNA.

5. Base found in RNA but not DNA.

6. Chromosome found in men but not women.

7. A picture of a complete set of chromosomes.

8. Number of chromosome pairs in humans.

9. Two identical DNA molecules joined at a centromere.

10.Two chromosomes with the same genes.

QUICK QUIZ ANSWERS

1. The building blocks of organic molecules ....

2. The building blocks of nucleic acids .....

3. How many polynucleotide strands in DNA?

4. Sugar found in RNA.

5. Base found in RNA but not DNA.

6. Chromosome found in men but not women.

7. A picture of a complete set of chromosomes.

8. Number of chromosome pairs in humans.

9. Two identical DNA molecules joined at a centromere.

10. Two chromosomes with the same genes.

1. monomers

2. nucleotides

3. 2

4. ribose

5. uracil

6. Y

7. karyotype

8. 23

9. sister chromatids

10. homologous

VIDEOS

• http://www.icyou.com/topics/cancer/chromosomes-dna+ (47 sec)

http://www.allthingsscience.com/video/715/Human-Chromosomes (chromosomes, 4min)

http://videos.howstuffworks.com/hsw/6090-the-cell-the-nucleus-video.htm

Nucleus• Control centre of cell

• Contains chromosomes (DNA)

• http://videos.howstuffworks.com/hsw/6090-the-cell-the-nucleus-video.htm (nucleus, 1 min)