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Topic: Modern Genetics. What are the components of nucleic acids? How do we replicate DNA?. Looking at DNA and RNA. http://www.brainpop.com/health/geneticsgrowthanddevelopment/dna/ http://www.dnatube.com/video/3447/DNA-double-helix http://www.youtube.com/watch?v=EqBB8PHHI_0.
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Topic: Modern Genetics What are the components of nucleic acids? How do we replicate DNA?
Looking at DNA and RNA • http://www.brainpop.com/health/geneticsgrowthanddevelopment/dna/ • http://www.dnatube.com/video/3447/DNA-double-helix • http://www.youtube.com/watch?v=EqBB8PHHI_0
What are nucleic acids? • Biochemical molecules that hold hereditary information • Two types • DNA= deoxyribonucleic acid • RNA=ribonucleic acid
DNA Composition • Phosphate group, sugar, nitrogeneous baseNUCLEOTIDE • Bunches of nucleotides come together to make……the DNA molecule
DNA Composition • Backbone (legs) made from sugar (deoxyribose) and phosphate • 4 possible nitrogen bases hold the two strands together • adenine, guanine classified as purines • thymine, cytosineclassified as pyrimidines • bases held together by hydrogen bonding • double helix shape
The 4 nitrogeneous bases adenine guanine cytosine thymine phosphate sugar
Chargaff’s Rule • In a sequence of DNA, approximately • The percentage of A present is the same as T • The percentage of C present is the same as G
Chargaff’s rule • http://www.hhmi.org/biointeractive/dna/DNAi_chargaff_ratio.html
Composition of RNA • RNA contains the same sugar and phosphate backbone BUT… • The sugar is called RIBOSE • Bases of RNA are: adenine, uracil, cytosine, and guanine • No thymine in RNA uracil is in place of thymine
RNAmRNA, t-RNA, r-RNA • RNA= Ribonucleic Acid • Ribonucleic Acid takes the information from DNA and converts a message to our cell for different instructions (traits). Ex: hair color, eye color, body type by making proteins from amino acids linking together • RNA is located in the nucleus(m-RNA), t-RNA, r-RNA( associated with ribosome) • All types of RNA are single stranded
DNA ReplicationPurpose of DNA replication • Mitotic division for cell growth of new somatic cells • We replicate DNA in the S- phase of the cell cycle in order to prepare for mitosis
DNA Replication • http://www.youtube.com/watch?v=zdDkiRw1PdU
More More More DNA- DNA Replication • Double stranded DNA unwinds using the enzyme helicase (unzips), H-bonds are broken. EACH STRAND IS NOW A TEMPLATE STRAND!!.. A short RNA piece initiates the synthesis • A series of enzymes (helicase, polymerase) help to separate the DNA strand • Free nucleotides present in nucleus attach themselves by forming new H-bonds (DNA polymerase is the enzyme involved) • Enzymes work to create new base pairing with a complementary strand of DNA. • The enzyme ligase helps to bind the new strands of DNA together • Each strand results in an exact copy • DNA replication occurs on the opposite strand in the same way, but in the opposite direction.
Watch this tutorial to visualize the process http://www.stolaf.edu/people/giannini/flashanimat/molgenetics/dna-rna2.swf http://www.hhmi.org/biointeractive/dna/DNAi_replication_vo1.html