The hereditary material This is what you get from your parents and what is passed to offspring during reproduction A type of nucleic acid recall 4 main biological molecules A characteristic of all living things ID: 1045602
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1. DNALS 5.3
2. What is DNA?Deoxyribonucleic AcidThe hereditary materialThis is what you get from your parents, and what is passed to offspring during reproductionA type of nucleic acid (recall 4 main biological molecules)A characteristic of all living thingsThe smallest bacteria has DNADNA is very similar between organismsEvidence for common ancestry Contains the instructions for the organism Called genes
3. DNA, Chromosomes and GenesDNA is the hereditary materialUsually long and stringy (chromatin)Wraps around proteins during cell division (chromosomes)A segment of DNA that contains instructions is called a gene
4. Discovery of DNAPeople knew something existed that passed traits on, but didn’t know what it was.Mendel called them factorsDarwin said something would be found that explains how traits are passedIn the early 1900’s, DNA was suspected to be the hereditary materialRosalind Franklin and Maurice Wilkins Took X-ray photographs of DNAJames Watson and Francis CrickTook Franklin and Wilkins’ work and discovered the structure of DNA
5. Structure of DNADNA is a chain of smaller unitsLike links on a chainLooks like a twisted ladderCalled a double helixThe smaller units are called nucleotidesA nucleotide is made up of 3 partsThe backbone is made of:A sugar, called deoxyriboseA phosphate groupThe interior (rungs of the ladder) have:Nitrogen bases
6. Nitrogen Bases4 of themAdenine (A), Thymine (T), Guanine (G), Cytosine (C)Their sequence determines the geneBases come in pairsThey are held together by bondsThey give the DNA molecule its shapeA-T (apple tree)C-G (car garage)
7. DNA ReplicationOccurs whenever the cell splits (mitosis: recall S-phase)DNA unzips (just like a zipper) and splits apartEach ½ provides a template to form another identical moleculeExample: Find the complementary strandA G T C G A T C A G C T
8. RNAAnother nucleic acidRibonucleic AcidSimilar to DNA, but key differencesWhere DNA has 2 sides, RNA is single-sidedWhere DNA has deoxyribose as its sugar, RNA has riboseWhere DNA has Thymine (T), RNA replaces it with Uracil (U)T DOES NOT EXIST IN RNA!
9. Types of RNAmRNA (messenger RNA)-carries message from nucleus to ribosomesrRNA (ribosomal RNA)-RNA in a ribosome that reads the codetRNA (transfer RNA)-carries amino acid to ribosome
10. Making a proteinProteins are chains made of units called amino acidsThe sequence of amino acids determines the protein’s shapeThe shape determines the jobThe sequence of amino acids is determined by the geneBetter definition for gene: a segment of DNA that codes for a specific proteinmRNA is made from a strand of DNA (Called transcription)Practice: What RNA strand would form from this DNA strand?A T G C G T AU A C G C A U Because it is small, mRNA can leave the nucleusIt travels to a ribosome, where rRNA bonds to ittRNA carries amino acids to the ribosome, and place them in the correct spot (translation)The amino acids bond together, forming the protein
11. Central Dogma of BiologyDogma-an idea known to be true that is central to the fieldDNA RNA Proteins Traits
12. MutationsChange in nucleotide sequence on DNADifferent typesNucleotides can be deletedA wrong nucleotide can be addedThe wrong nucleotide can replace the correct oneChromosome parts can be brokenCan be natural, or can be the result of a mutagen (something in the environment that causes a mutation)Smoking, alcohol, disease, excess sunlight, asbestos, etc.
13. Results of MutationsMost mutations are neutralYou’d never even know it happenedThe cell repairs it, or it occurs in noncoding (junk) DNAOther mutations are badCan lead to disease, such as cancerOccasionally, mutations are beneficialGive something to the offspring that they did not previously haveExample: Making an animal’s coat look a little more similar to its surroundingsThis is what natural selection acts on (more to come next chapter)