1. Chapter 11 DNA Within the structure of DNA is the information for life- the complete instructions for manufacturing all the proteins for an organism. DNA 15min video.asf DNA 15min video.asf

2. DNA is a polymer made of repeating subunits called nucleotides. Nucleotides have three parts: simple sugar, phosphate group & a simple sugar, phosphate group & a nitrogenous base. DNA polymer known as CGCGTTTTCGCG

4. The simple sugar in DNA, called deoxyribose, gives DNA is name: deoxyribose nucleic acid.

5. The phosphate group is composed of an atom of phosphorous surrounded by 4 oxygen atoms. A nitrogenous base is a carbon ring structure that contains one or more atoms of nitrogen. In DNA there are four possible nitrogen bases: adenine (A), guanine (G), cytosine (c), and thymine (T). In DNA there are four possible nitrogen bases: adenine (A), guanine (G), cytosine (c), and thymine (T).

6. Replication of DNA The DNA in the chromosomes is copied in a process called DNA replication. Without DNA replication, new cells would have only 1/2 of the DNA of their parents.

7. During replication, each strand serves as a pattern, or template, to make a new molecule. Replication begins as an enzyme that breaks the hydrogen bonds between that breaks the hydrogen bonds between bases that hold the two strands together, thus “unzipping” DNA. thus “unzipping” DNA.

8. Genes & Proteins The sequence of nucleotides in DNA contains information. This information is put to work through the production of proteins.

9. RNA RNA, like DNA, is a nucleic acid. However they differ in three ways: 1. RNA is a single strand – DNA is double 2. RNA’s sugar is ribose – DNA’s sugar is deoxyribose. 3. Both RNA & DNA have 4 nitrogenous bases, but rather than thymine, RNA contains a similar base called uracil

10. RNA vs DNA half min video.asf RNA vs DNA half min video.asf RNA vs DNA half min video.asf RNA vs DNA half min video.asf

11. If DNA is what provides “workers” with the instructions for making the proteins- what does RNA do? RNA is the workers for protein synthesis- they take DNA instructions on how the protein should be assembled then, amino acid by amino acid, they assemble the protein.

12. What are the three types of RNA and what do they do? 1. mRNA – messenger – brings instructions from the DNA in the nucleus to the cells cytoplasm and then it moves it to a ribosome. 2. rRNA – ribosomal – binds to the mRNA and uses the instructions to assemble the amino acids in the correct order. 3. tRNA – transfer – delivers amino acids to the ribosome to be assembled into a protein.

13. The diagram below shows a ribosome attach to mRNA, and then move along the mRNA adding amino acids to the growing polypeptide chain.

14. Transcription In the nucleus, enzymes make an RNA copy of a portion of the DNA strand in a process called transcription.

15. The main difference between transcription and DNA replication : Transcription results in the formation of one single-stranded RNA molecule rather than a double-stranded DNA molecule.

16. Genetic Code The nucleotide sequence transcribed from DNA to a strand of messenger RNA acts as a genetic message, the complete information for the building of a protein

17. Translation The process of converting the information in a sequence of nitrogenous bases in mRNA into a sequence of amino acids in protein is known as translation. translation 2min video.asf translation 2min video.asf translation 2min video.asf translation 2min video.asf

18. Genetic Changes Mutations can be caused by errors in replication, transcription, cell division, or by external agents

19. Mutations in Reproductive Cells Mutations can affect the reproductive cells of an organism by changing the sequence of an organism by changing the sequence of nucleotides within a gene in a sperm or an egg cell. egg cell.

20. If this cell takes part in fertilization. The altered gene would become part of the genetic makeup of the offspring. The mutation may produce a new trait or it may result in a protein that does not work correctly, resulting in structural or functional problems in cells & in organisms.

21. In rare cases, a gene mutation may have positive effects, helping an organism by making it stronger or faster, better able to survive in it’s environment.

22. Mutations in Body Cells If a cell’s DNA is changed, this mutation would not be passed on to offspring. However, the mutation may cause problems for the individual.

23. Give 2 examples: 1. stop stomach acid production needed for digestion digestion 2. cause skin cells to lose elasticity

24. Some mutations of DNA in body cells affect genes that control cell division. This can result in the cells growing and dividing rapidly, producing cancer.

25. Point mutation is a change in a single base pair in DNA. A change in a single amino acid can affect the shape of the protein. Frameshift Mutation is when a single base is added of deleted from DNA. Frameshift mutation is more harmful than point mutation.

26. Chromosomal Mutations Chromosomal mutations can take place during either mitosis or meiosis. They result in structural changes in They result in structural changes inchromosomes.

27. Causes of mutations Some mutations seem to just happen, however many mutations are caused by factors in the environment. Any agent that can cause a change in DNA is called a mutagen.

28. Three examples are: 1. radiation 1. radiation 2. chemicals 2. chemicals 3. high temperatures 3. high temperatures