Advanced Bio topic 2

components of DNA

phosphate group, deoxyribose sugar and nitrogenous base

phase one of gene expression

transcription occurs in the nucleus, RNA polymerase unwinds DNA, reads one of the strands and makes a complimentary copy of messenger RNA which travels to the cytoplasm

phase two of gene expression

translation occurs at the ribosomes where the mRNA is read is read one codon at a time and tRNA brings the specific amino acid to assemble the polypeptide connect by peptide bonds

what is a mutation

a change in DNA leads to a mutation causing an altered mRNA sequence after transcription which may lead to an altered amino acid potentially causing a protein that doesn't function properly

what are restriction endonucleases

they naturally occur in bacterial cells and scientists use them to cut DNA at restriction sites

how do restriction enzymes work

restriction enzymes have specific sequences where they cut the DNA called restriction sites

different cuts of DNA

blunt ends is when the DNA is cut in a straight line whereas sticky ends is when the DNA is cut in a staggered line leaving overhanging bases

types of mutation

substitution when a base is substituted by another one, insertion when another base is inserted into the DNA and deletion when a base is removed from the DNA

how do the mutations affect the DNA

substitution only alters one codon and one amino acid, insertion and deletion impact all the codons after resulting in multiple different amino acids

polymerase chain reaction phase one

during denaturation the DNA target is heated to 95 which breaks hydrogen bonds creating two single strands of DNA

polymerase chain reaction phase two

during annealing the temperature is reduced to 55 allowing artificially synthesized primers to attach to the templates on either side of the target sequence

polymerase chain reaction phase three

during extension the temperature is raised to 72 to allow Taq polymerase to copy each template strand starting from each primer

last phase of PCR

the cycle is repeated at least 25 times to create many copies of the target DNA

why do we do gel electrophoresis

to figure out the size and charge of the DNA fragments

components in gel electrophoresis tray

DNA ladder sorted by base pairs, wells, DNA fragments and positive and negative electrodes

what type of mutation is sickle cell anemia caused by

substitution

symptoms of sickle cell disease

pain in oxygen deprived tissue, if lungs are affected difficulty breathing, if eyes are affected blindness, if brain is affected stroke and a constant depletion of red blood cells

primary structure

the amino acid sequence or polypeptide resulting from translation

secondary structure

secondary structure is when the hydrogen bonds can form between neighbouring amino acids to create structures call a-helices and b-pleated sheets

tertiary structure

chemical bonds including H bonds can form between any amino acids in the polypeptide to give the unique 3D shape of the protein

quaternary structure

sometimes two or more polypeptides can join together to form the protein

bonds between bases

hydrogen bonds

bonds between the sugar base and phosphate

Phosphodiester bonds

bonds that connect amino acids

peptide bonds