2.7 DNA Replication, Transcription, Translation Flashcards
DNA polymerase
Catalyses the formation of covalent bonds between two ajoining nucleotides
DNA replication
Separation of double helix into 2 single strands by breaking hydrogen bonds with the help of an enzyme, Helicase. It is semi-conservative
Protein synthesis
Determines the control the DNA has over the cell, some proteins are enzymes, if some or not produced it has a dramatic effect on the cell. Proteins synthesised in the cytoplasm, mRNA carries msg
Genes
Section of DNA that codes for polypeptides. Any one gene is a specific sequence of nitrogenous bases found in a specific location of DNA
Nucleoplasm
An area containing free nucleotides used for DNA and RNA replication
Transcription
Same as replication except only area of DNA of one gene is unzipped and then sent to cytoplasm for protein synthesis.
RNA polymerase
Used as a catalyst for transcription, like helicase
Difference between DnA replication and transcription
- only 1 of 2 strands of DNA is copied
- mRNA always single stranded, shorter
- Uracil in RNA, thymine in DNA
Polypeptides
Composed of amino acids covalently bonded together in a specific sequence
mRNA
Contains a msg written in it that determines the order of the amino acids
Triplet
A set of 3 bases contains information enough to code for one of 20 amino acids, when found in mRNA called a “codon triplet”
rRNA
Ribosomal RNA, each ribosome is composed of rRNA and ribosomal protein
tRNA
Transfer RNA, each type of tRNA transfers 1 of 20 amino acids to the ribosome for polypeptide formation, only carry one amino acid
Translation step 1
mRNA is posted out of nucleus attaches to rinosome with first 2 codon triplets. Ribosomes use complementary base pairing to red codons on the mRNA. tRNA anticodon complementary to first codon triplet of mRNA. First amino acid brought into the process. Then a second tRNA brings another amino acid which matches its 3 anticodon bases with the second codon triplet of mRNA. An enzyme catalyses condensation between the amino acids.
Peptide bond
The covalent bond between the two amino acids catlysed by an enzyme
Translation step 2
Breaking bond between tRNA and amino acid it transferred in, not neede cause 2nd tRNa bonded to its own amino acid which is bonded to 1st amino acid. The 1st tRNA floats away into cytoplasm reloads with another amino acid of same type
Translation step 3
The ribosome that has only one tRNA in it now moves one codon triplet down the mRNA molecule. The second tRNA is in the place of the first, there’s room for a 3rd to float in, with a 3rd specific amino acid then repetitive.
The final codon triplet
A triplet that does not act as a code for an amino acid, it signals “stop” to the process of translation, the polypeptide breaks from the tRNA molecule and becomes a free floating polypeptide in the cytoplasm
Polymerase chain reaction
DNA replication carried out artificially, only replicate short segments of DNA, scientist can produce huge numbers to analyse. Used for forensics, only limited dna found at crime scene.
Taq DNA polymerase
An enzyme stable at high temperatures. Discovered from a bacterium called taq found in hot springs not denatured at high temperatures, used for discovery in gene technology.
Genes
Instructions for proteins or messages, codes gor making polypeptides
Genetic code
Sequence of bases which tells ribosomes which amino acid to use
64 different combinations infinite polypeptides
Anti codons
Complementary base pairs to codons on mRNA
General info summary
64 codons
20 amino acids
Same amino acid more than one codon
Base substitution mutation
Reduced impact of wrongg base Amino acid produced could be the same
Translation
The synthesis of polypeptides on ribosomes
Transcription
The synthesis of mRNA
Polypeptides
composed of amino acids covalently bonded together in a specific sequence
