1. Unit 5: DNA and Protein Synthesis
DNA- deoxyribonucleic acid *stores and transmits genetic information from one generation to the next -DNA is very large *there is about 9 feet of DNA in the nucleus of each of your cells

2. -DNA is composed of smaller units called nucleotides nucleotides- building blocks (monomers) of DNA Each nucleotides consists of: *5-carbon sugar (deoxyribose) *phosphate group *nitrogenous base

3. *two groups/four types Pyrimidines cytosine(C) and thymine(T)
Nitrogenous Bases
*two groups/four types
Pyrimidines
cytosine(C) and thymine(T)
*contain one ring in their structure
Purines
adenine(A) and guanine(G)
*contain two rings in their structure

4. -DNA consists of two strands of nucleotides wound around each other like a twisted ladder -this is known as a double helix *discovered by Watson and Crick

5. -the nitrogenous bases from both strands of nucleotides join together to form double helix -this is called base pairing (Chargaff’s Rule) -in base pairing, A bonds with T, G bonds with C

6. Prokaryotes -DNA is located in the cytoplasm -single circular DNA molecule -referred to as the cell’s chromosome

7. Eukaryotes -have 1000 times the DNA as prokaryotes -DNA not found free in the cytoplasm -DNA found in nucleus (as chromosomes) -chromosome # varies by species ex: humans =46 sequoia tree = 22 fruit fly = 8

8. -DNA is a very long molecule -there is about 6-9ft of DNA in one nucleus of one cell -it must fold to fit into cell -eukaryotic cells have both DNA and protein -the two together form chromatin -in chromatin, DNA wraps around proteins called histones

9. -DNA wrapped around 8 histones is called a nucleosome -histones then coil upon themselves to make a fiber that supercoils into the chromosome structure -nucleosomes allow long lengths of DNA to fold into the tiny space

10. DNA Replication -copying of DNA -each strand of DNA has what it needs to reconstruct the other half by base pairing -the sites where separation and replication occur are called replication forks

11. -before a cell divides, it replicates its DNA
-this ensures each cell will have a complete set of DNA
During DNA replication:
DNA separates into two strands
two new complementary strands are produced using rules of base pairing
each strand serves as a model/template for the new strand

12. -DNA replication is carried out by enzymes -the enzymes unzip a molecule of DNA -occurs when hydrogen bonds are broken between the base pairs -main enzyme is DNA polymerase *joins individual nucleotides to produce DNA molecule *proofreads each DNA strand to make sure the new strands are identical to the original

15. genes- coded DNA instructions that control the production of proteins within the cell -the first step in decoding genes is to copy DNA to RNA -RNA contains coded info for making proteins

16. RNA (ribonucleic acid) -consists of a long chain of nucleotides like DNA -5 carbon sugar – ribose -phosphate group -nitrogenous bases: *NO THYMINE (T) *instead is uracil *A pairs with U -is single-stranded unlike double-stranded DNA

18. Types of RNA
mRNA- (messenger RNA)
*copies DNA and delivers code/instructions from DNA in nucleus to the rest of the cell
rRNA- (ribosomal RNA)
*makes up ribosomes
tRNA- (transfer RNA)
*carries amino acid to the ribosome coded to build protein

20. Protein Synthesis
Two steps needed for DNA to create a protein:
1. transcription
2. translation

21. Step One: Transcription- Making mRNA -requires RNA polymerase (an enzyme) -RNA polymerase binds to DNA at a promoter site and separates the DNA strands promoter- area that has specific base sequences -RNA polymerase uses one strand as a template from which nucleotides are made into a strand of RNA -this is mRNA

23. RNA Editing -RNA needs some editing before it is ready
RNA Editing -RNA needs some editing before it is ready *DNA is made of introns- non-coding regions and exons- coding regions -both introns and exons are copied from DNA when RNA is formed -introns are then cut out and exons are spliced together to form final mRNA

24. cut
spliced

25. -proteins are made by joining amino acids into long chains called polypeptides -each polypeptide contains a combo of any or all of the 20 amino acids -sequence of amino acids determined by group of 3 bases on mRNA = codon -sometimes several codons code for the same amino acid -64 codons possible ex: UCG CAC GGU

26. -there is one codon, AUG, that can either be methionine or serve as a “start” codon for protein synthesis -there are three stop codons that signify the end of a polypeptide

27. For what amino acid does the codon UGC code?
cysteine
For what amino acid does the codon CCU code?
proline
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28. Step Two: Translation- Making Proteins
-the cell uses info from mRNA to produce proteins
-mRNA is read by the ribosome
-the code “calls” for amino acids to create a protein
-amino acids brought into place by tRNA

29. Mutations
-changes in genetic material
-mistakes made by cell in copying DNA
Types of Mutations
Gene Mutations
-produce changes in a single gene
Examples:
point mutations- involve changes in one or a few nucleotides
-include substitutions (one base is changed to another) and insertions and deletions (a base is inserted or removed from DNA sequence)

30. -substitutions affect usually no more than a single amino acid -insertions and deletions can be more dramatic because it shifts codons -these changes are called: frameshift mutations because they shift the reading frame of the genetic message and changes every amino acid that follows

31. Substitution, Insertion and Deletion

32. Chromosomal Mutations
-involves changes in the number or structure of chromosomes
Examples:
deletion: loss of all or part of a chromosome
duplication: produces extra copies of part of a chromosome
inversion: reverse the direction of parts of a chromosome
translocation: occur when part of one chromosome breaks off and attaches to another

33. Chromosomal Mutations