Ap Bio Notes

AP Bio DNA, RNA, Protein synthesis Study Guide
DNA Structure
Nucleotide structure - sugar, phosphate group, base backbone structure - alternating sugar and phosphate group directionality (5’-3’) - DNA is anti parallel. The side that sticks out s the 5’ side bases - adenine = thymine & guanine=cytosine purines vs Pyrimidines - purines have two rings while pyrimidines have one ring
Bonding - hydrogen bonds
Base Pairing rules - look at bases ^^
DNA Replication
Semi-conservative replication - two strands of the parent DNA separate and synthesis will make a complementary strand directionality of replication know role of all enzymes involved helicase unzips the DNA strand at the replication fork topoisomerase prevents knots ahead of the replication fork
DNA polymerase binds to the 5’-3’ strand to make the daughter strand
DNA ligase adds phosphates in the gaps of the backbone nucleases remoes wrong nucleotides from the daughter strand
Primase initiates replication with short segments of RNA called primers replication forks are where the DNA stead is split role of single strand binding proteins stops the DNA from rebounding with itself primers are segments of RNA, which are placed at origins of replication leading strands is the 3’ to 5’ , while the lagging strands are 5’ to 3’ leading strand will cop without much difficulty because DNA polymerase can read it, but the lag gin strand will have to be done in chunks. RNA Primers are put down every so often and the DNA polymerase will copy it from there. Nucleotides can only be added to the 3’ ends of DNA
Okazaki fragments are the chunks of DNA telomeres are special nucleotide sequenced at the end of DNA molecules; made by telomerase what contain short nucleotide sequences repeated 100-1000 times
Protein Synthesis
Amino acids are composed of an amino group, a carboxylic acid group, a sidechain, and a carbon
Peptide Bonds are the bonds between amino acids structure DNA vs RNA
DNA sugar is deoxyribose, while RNA sugar is ribose
DNA is a double helix while RNA is a single strand in RNA, adenine bonds with Uracil. In DNA, adenine bonds with thymine function of each type of RNA mRNA - messenger RNA; template from producing proteins. They are read in groups of 3 called a codon which will code for a different amino acid rRNA - Ribosomal RNA - - buliding blocks of ribosomes; plays a large role in the linking of amino acids into polypeptides tRNA- transfer RNA; transports an amino acid along with it. It has an anitcodon, which consists of 3 nucleotides together that correspond to the three bases of the codon on the mRNA. enzymes involved transcription - The RNA polymerase enzyme is responsible for transcription, a DNA sequence is read by this enzyme, which then produces a complementary, antiparallel RNA strand.
Transcription is when DNA is transcripted in RNA initiation - RNA polymerase molecules attach to a promoter region (TATA box) of the DNA elongation - RNA Polymerase unzips DNA and builds the complimentary strand in the 5’ to 3’ direction termination - in prokaryotes, RNA polymerase will reach a termination sequence that will cause the transcription to stop and the RNA to remove itself from the DNA. In Eukaryotes- AAUAAA is transcribed by RNA Polymerase 2 mRNA Modification -a 5’ cap (specialized guanine) is added to the 5’ end, while the 3’ end gets 50 to 250 adenines (poly A tail) this will aid in releasing molecules from the nucleus, protect the molecule from enzymes, and help the ribosomes attach to mRNA introns are sec ions that don’t cod for anything and are cut, or split, out of the RNA by small nuclear ribonucleoproteins (snRNP’s) so that all are left are the parts remaining code for amino acids. Exons are basically what code for amino acids, and they are spliced together at the end using snRNP’s aminoacyl tRNA - attatches an amino acid to a specific tRNA translation when the amino acid chain is elongated initiation - small ribosomal subunit attaches to the 5’ end of mRNA
Start codon AUG codes for the amino acid methionine which is brought in by tRNA. Large ribosomal subunit attaches to mRNA to completely form the ribosome elongation starts when the next tRNA comes into the A site of the ribosome
As elongation continues, a tRNA is released from the E site, as another tRNA moves into the A spot; the tRNA that was in he A site moves to the P site. As tRNAs keep coming in the, the amino acid chain is elongated termination occurs when a stop codon is reached stop codon do not code for an amino acid ; stop codons signal in a release factor protein ; release factor proteins bring in a water molecule and releases it from the enzyme
Mutations
gene mutations / point mutations - changes in one or a few nucleotides substitution- one nucleotide is replaced by another insertion - extra nucleotide is added to the DNA sequence
Deletion - one nucleotide is removed chromosomal mutations - a change in the chromosomes genetic material
Deletion - one nucleotide is removed duplication - part of the chromosome is copied or taken from another chromosome and inserted inversion- when the genes on a chromosome are reversed translocation when a part of the chromosome is moved to another chromosome frameshift mutations - mutations that shift the reading frame of the DNA
Protein synthesis: