Unit 4

1. Unit 4 DNA  RNA  Proteins

2. DNA/ RNA/ Proteins Word Meanings • Deoxy • a molecule containing less oxygen than another • ribose • A pentose sugar, C5H10O5 • Complementary • to “match up” • Subunit • a piece or small part of a larger unit. • replication • the act of duplicating, copying, or reproducing • transcription • the act or process of rewriting in a different script. • translation • to rewrite in a second language having the same meaning as the original source.

3. DNA: Deoxyribonucleic Acid • Complete instructions for manufacturing all the proteins for an organism. (which determine all your other characteristics) • The “recipe” for life! • structure of DNA proved that it was in fact the molecule of heredity • Analogy:1000 textbooks= all the info (DNA/genes) of 1 single organism

4. Structure • Watson & Crick • proposed that DNA is made of chains • nucleotides held together by nitrogenous bases (teeth of zipper) • proposed that DNA is shaped like a long zipper that is twisted into a coil like a spring → helix • DNA is a double helix

5. Nucleotide = monomer of DNA • Subunits of DNA • 3 parts • phosphate group • simple sugar: deoxyribose • nitrogenous base • A= adenine • G= guanine • C=cytosine • T=thymine • Complementary base pairs → A-T & C-G • Phosphate groups & Deoxyribose sugar form backbone of DNA • Chargaff’s Rule: • The number of Adonines = number of Thymines • The number of Guanines = number of Cytosines

6. The Base pairing rules: (A binds to T and G binds to C).

7. DNA→DNA • Replication • Helicase unzips the double helix, forming replication forks. • DNA polymerase is an enzyme that joins individual nucleotides to produce a new strand of DNA. • New bases are added, base pairing rules: (A with T and G with C). • This is a Semi-Conservative process = One old strand of DNA with one new strand of DNA

8. Mutations • Any changes in the DNA sequences • This could be: • Deletion of bases • Duplicating bases • Ceratain bases changing places • New bases being inserted where they do not belong. • Mutations can result in: • Genetic diseases • Cancer • New genetic traits • No harm at all

9. Genetic Disorders caused by mutations to the DNA:

10. Manipulating DNA • How do we manipulate DNA? • We can literally cut the DNA into pieces. • This is done through the use of proteins known as restriction enzymes • They cut the DNA at certain Base Pair sequences • We use the cut up DNA for all sorts of things. • Paternity test • Criminal Investigation • Genetic Engineering • Cloning

11. Paternity Test and Criminal Investigations • Cut up fragments of certain DNA segments are put into a gel electrophoresis. • Depending on how big the segment of DNA, the further down the gel a fragment of DNA will move. • Doctors and scientist can then compare one persons DNA to another persons to see if they’re related.

12. Genetic Engineering • Cut up fragments of DNA segments with specific genes can be added to the DNA of a fertilized egg. • This can give rise to organisms with new traits. • Ex. Mice that can glow Here the gene for insulin is being put into the plasmid of a bacterial cell. The bacteria will now produce insulin for human use.

13. Cloning • Theoretically, any organism can be cloned to make a genetically identical organism. • This is done by a process called Nuclear Transfer • Extract the nucleus of an unfertilized egg. • Insert a nucleus (DNA) from a cell of the organism you want to clone. • Cause the egg cell with the novel nucleus to start dividing by stimulating the egg with a shock of electricity. • After the embryo grows for a few days it is placed inside a serogate mother and allowed to develop there until birth. These two cats are clones: But they look different. This is because different genes on the same DNA can be activated by the different environments the organism grew up in.

14. RNA • Ribonucleic Acid • Single stranded • RNA is a special copy of DNA used to make proteins. Single RNA strand

15. RNA Nucleotides (monomer) • Subunit of RNA • 3 parts: • phosphate group • simple sugar= ribose • nitrogenous base • U= uracil (Replaces T) • A= adenine • G= guanine • C=cytosine • Complementary base pairs → A-U & C-G

16. Transcription(DNA→RNA) • Creating RNA from DNA • RNA polymerase is an enzyme that • uses only one side of DNA (one DNA strand) to create a single strand of RNA. • Uses DNA as a template to lay RNA nucleotides in a specific order according to the DNA code. • New bases are added according to the base pairing rules: (A with U, G with C, T with A). Ex. DNA = ATTCGCATT RNA = UAAGCGUAA

17. 3 Types of RNA • mRNA → messenger • carries a copy of the DNA’s instructions (code) for the creation of proteins.

18. rRNA→ ribosomal • Makes up ribosomes- structures where proteins are assembled. • tRNA→ transfer • carries amino acids to the ribosome and matches them to the coded mRNA message.

19. Translation(mRNA → proteins) • Converting mRNA into amino acids then into a protein • To begin Translation the rRNA must binds to the mRNA • translation begins at the start codon[AUG]-(three bases in a row) on the mRNA. • tRNA contains an anti-codon that binds to the mRNA’s codon and carries one kind of amino acid.

20. The amino acids bond together and stop when a “stop codon” is reached. • The newly formed polypeptide (protein) is then released.

21. Amino Acids • Basic building blocks of proteins carried by tRNA • Codon: 3 bases on mRNA code for 1 amino acid • 64 different combinations can create 20 different amino acids.

22. What does a Protein look like?

23. DNA-RNA Differences DNA→RNA DNA→DNA