Nucleic acids and Protein synthesis Flashcards
what does DNA stand for?
deoxyribonucleic acid
what are the three components of DNA?
deoxyribose (pentose sugar)
phosphate group
nitrogenous base (A, T, C, G) (and U but only in RNA)
what is the function of DNA?
- the function of DNA is to hold or store the genetic information
- DNA is the molecule that contains the instructions for the growth and development of all organisms
what are the 4 nitrogenous bases in DNA?(full names)
adenine, thymine, cytosine and guanine
what are purines?
nitrogenous bases (adenine and guanine) that have two carbon rings
what are pyrimidines?
nitrogenous bases (thymine and cytosine) that have a single carbon ring
when two mononucleotides form to make a dinucleotide, where is the bond?
between the carbon 3 on the deoxyribose and the phosphate group the bond is called phosphodiester
what are the bonds between bases?
hydrogen bonds
what are the pairings of the bases?
A=T 2 hydrogen bonds
C-G 3 hydrogen bonds
how does the stability of DNA help it carry out its function?
ensure correct order and keep bases safe for mitosis and meiosis
longevity - lives as long as the cell
how does the length of DNA help it carry out its function?
to be able to hold a lot of genetic information
how does the hydrogen bond between strands of DNA help it carry out its function?
to enable DNA to be opened up for protein synthesis
also provide strength and stability
how do the base pairs on the inside of the molecule of DNA help it carry out its function?
so that they can be protected so the order of bases don’t get destroyed
what is protein synthesis?
using DNA to create proteins (transcription and translation)
Overview of protein synthesis:
DNA helicase breaks the H bonds between the complimentary bases in the DNA strand
RNA nucleotide - complimentary copy of the coding strand using base pair theory (A=U)
RNA polymerase will help the condensation reaction between RNA nucleotides - form phosphodiester bonds
complimentary strand of the gene needed is called mRNA - messenger RNA
the mRNA will move out between the two DNA strands and an enzyme DNA ligase will help hydrogen bonds reform between the DNA
pre mRNA gets edited to form mRNA
mRNA leaves nucleus through nuclear pores
transfer RNA molecules - 64 different tRNA
3 bases + 1 amino acid = base triplet theory
ribosomes help tRNA anticodon to sit on top of correct codon with specific order of amino acids to form primary structure of protein
what structural feature does RNA have that DNA doesn’t?
RNA molecules are single stranded
what does the enzyme RNA polymerase do?
to create poly RNA nucleotides –> condensation reactions form phosphodiester bonds
what does degenerate mean?
two codons bond to same amino acid
what is the purpose of transcription?
we want to end up with mRNA complimentary strand of the DNA coding strand for a protein
beginning and end regions of the gene?
beginning of the gene - promoter region
end of gene - terminator region
Transcription overview:
- identify the gene in the DNA strand (double-stranded, alpha helix)
- DNA helicase enzyme unwinds this section of the DNA strand breaking the H bonds between the complimentary bases of the two strands
- RNA nucleotides come between the two DNA strands the RNA bases line up opposite the bases of the coding strand in complimentary sequencing then they form H bonds
- RNA polymerase joins the RNA nucleotides together with a phosphodiester bond
- this forms single-stranded pre messenger RNA molecule (helix structure) - move out from in between the two DNA strands (H bonds broken)
- DNA strand recoils - H bonds with DNA ligase reform between complimentary DNA nucleotides on strands
Splicing overview:
still within the nucleus splicing takes place
this is where the gene is ‘edited’ sections of RNA nucleotides are cut out from mRNA
cut out = INTRONS (these are non-coding sections within the gene)
remain = EXONS
then the mRNA leaves the nucleus via the nuclear pores
Translation overview:
translation happens in the cytoplasm - mRNA with the help of ribosomes and tRNA to get to the amino acids in specific sequencing - primary structure of protein
- in cytoplasm ribosome attaches to mRNA and it covers 6 bases - 2 codons
- tRNA with the complimentary anti-codons to the first codon sits on the mRNA - complimentary RNA nucleotide bases, the bases form H bonds
- tRNA will have a specific amino acid attached to its amino acid attachment site - determined by the anti-codon
-tRNA with the complimentary anti-codon to the next codon is also attracted - it attaches bringing specific amino acid
-two adjacent amino acid will form a peptide bond
-once peptide bond is formed the amino acid disassociates form the tRNA - the tRNA leaves the mRNA and ribosomes and goes into the cytoplasm to attach another specific amino acid
- the ribosome then moves down the mRNA strand to cover the next codon
steps 2-7 are repeated until the whole mRNA strand has been translated, the ribosome will drop off the mRNA at a stop codon this results in a specific order of amino acids - primary structure of a protein
