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DNA & RNA
DNA & RNA are the 2 types of nucleic acid.
They are made up of structures: the pentose sugar, phosphate group and the nitrogen
base.
Nitrogen Base
Phosphate Group
Pentose Sugar
Keywords:• DNA
• Deoxyribonucleic acid.
• RNA (mRNA, tRNA)• Ribonucleic acid (mRNA stands for messenger RNA,
tRNA stands for transfer RNA).
• Nucleotide• A compound containing a pentose sugar, phosphate
group and a nitrogen base.
• Polynucleotide• A polymer made up of many nucleotides.
• Pentose Sugar• A sugar that contains 5 carbon atoms.
• Phosphate Group• A group important in energy transfer.
Keywords:• Nitrogenous or Nitrogen-containing Base
• A base that contains nitrogen and is necessary for protein synthesis.
• Semi-conservative• When a or chromatid is kept from the mother and its
joining chromatid is made from the free nucleotides in the nucleus.
• Codon• A series of 3 adjacent bases that code for a certain amino
acid.
• Anticodon• A series of 3 adjacent bases that correspond through
complementary base pairing to the codon on a RNA strand.
• Triplet• A series of 3 adjacent bases on a DNA strand.
Nucleotides and Polynucleotides
Nucleotides are a small cluster of molecules that build up a strand of DNA and RNA. Nucleotides can have 5 different bases and 2 different sugars, however this changes whether if they are DNA or RNA.
There are 2 groups of bases and 2 groups of sugars.• Pyrimidine
• Thymine• Cytosine• Uracil (only in RNA, replaces Thymine)
• Purine• Adenine• Guanine
There are two sugars, deoxyribose and ribose, the previous is in DNA (deoxyribonucleic acid) and the latter in RNA (ribonucleic acid).
Complementary-base PairingDNA and RNA structure uses complementary-base pairing
to pair the bases perfectly, such as adenine on one end and thymine on the other, similar to guanine being on one
side and cytosine being on the other as such:
Adenine Thymine
Cytosine Guanine
Don’t forget that A to T only have
2 hydrogen bonds while C to
G have 3!
TranscriptionTranscription is the process in which DNA uses mRNA to make a code in which they will collect amino acids via the
ribosome and create a protein, this is succeeded by translation.
The process starts with the DNA breaking up to unveil a strand in which it houses a code for a certain amino acid. Then through RNA
polymerase, a mRNA strand is created, nucleotide by nucleotide with complimentary
base pairing, Uracil replaces Thymine as you can see in the image. And then the mRNA leaves the nucleus to proceed to
translation.
TranslationTranslation takes place in the cytoplasm, it is when the mRNA
strand that was transcribed then goes to a ribosome to enter the translation phase. The ribosome collects tRNA which are made up of 3 adjacent bases that compliment the bases on the mRNA strand. These 3 bases create an amino acid which is then held onto the other amino acids being created by a peptide bond.
Remember that mRNA always ends with a ‘stop’
codon!The codon is always one of
three:• UAG• UAA• UGA
DNA ReplicationThis diagram shows how nucleotides free in the nucleus bind with the DNA to create a second strand.
The two phosphates are left free to bind
with another nucleotide to bind with another DNA
strand.
DNA Replication ~ pt.2DNA replication is a simple process, it takes place during the interphase after a cell has divided, due to the small number of chromosomes and only chromatids, nucleotides bind with the DNA chromatid and start its evolution into a chromosome.
A certain enzyme, DNA polymerase, will act upon the nucleotides to cause this process. And as told, DNA is a polynucleotide, with the smaller subunits being the nucleotides.
And from this we know that DNA is semi-conservative, in that it keeps one strand from the original cell and the other being fully created from nucleotides in the nucleus.
DNA Replication ~ diagram
The strands were once the same,
identical in every way. While now
they are 2 different strands.We say they are
semi-conservative.
Questions?
Thank you!