2.1.3 Nucleotides and Nucleic acids Flashcards
What do nucleic acids do?
carry out instructions for photosynthesis
contains genetic switches for the growth and development of cells.
what are the two forms of nucleic acid?
deoxyribonucleic acid DNA
and ribonucleic acid RNA
Describe the difference between purines and pyrimides?
Purines- consist of Adeneine and Guanine
Thier nitrogenous bases have two rings of carbon and nitrogen atoms
Pyrimdes - Made up of thymine, uracil and cytosine creating a single ring of carbon and nitrogen
how many bonds are made between the base pairs?
C and G is 3 hydrogen bonds
A and T is 2 hydrogen bonds
How does the hydrogen bonding cause a double helix to form?
The base pairs run in opposite directions and are connected by hydrogen bonding
This forms a double helix caused by the bonding
Describe the replication of DNA in a semi-conservative form?
Helicase enzyme unzips the double strand
Free nucleotides that will join together to it complementary base
The new nucleotides are joined together by the enzyme of DNA polymerase
And the phosphate backbone is connected by phosphodiester bonds
So the new semi-conservative strand contains one half from the paretal strand and half from the new strand
Evidence for semi - conservative DNA replication
DNA of e.coli has a nitrogen heavy base
Describe the structure of DNA
Molecule twists to form a double helix of 2 deoxyribose polynucleotide strands (so 2 sugar-phosphate backbones)
the Hydrogen bonds form between complimentary bases that run anti-parralell.
Identify features of the genetic code
Non overlapping - Each codon is read as a three
Degenerate- more then one triplet code for the same amino acid
Universal - Same bases and sequences used by all species
Explain how the nucleotides in a DNA molecule are arranged as two polynucleotide strands.
nucleotides joined by
phosphodiester bonds ✓
2 hydrogen bonds between,
complementary / named bases
✓
3 (polynucleotides) are anti
parallel / described ✓
Explain the difference’s between the DNA nucleotide and a molecule of ATP
Both have an adenine base
Both contain a pentose sugar, a phosphate group and a nitrogenous base
ATP has 3 phosphate groups but nucleotides only have one
ATP has ribose sugar, DNA has deoxyribose
Explain how the pairing of nitrogenous bases allow for identical copies of DNA to be made
adenine / A pairs with thymine /
T and cytosine / C pairs with
guanine / G (1)
(because of) hydrogen bonding
(1)
idea that purine can only bind
with pyrimidine because they
are different sizes (1)
idea that if one base is known it
can pair with only one other base
what is the reaction that occurs when ATP is converted into ADP
Hydrolysis
Explain why enzymes are essential to all organisms
enzymes , are (biological)
catalysts / speed up reactions ✓
2 they lower the activation
energy (so reactions can take
place at, low / body,
temperatures) ✓
3 high temperatures (in living
organisms), would denature,
enzymes / proteins ✓
Explain why a process known as transcription is necessary for polypeptide synthesis
The DNA is copied to mRNA
As the DNA is too large to leave the nucleus and go to a ribosome
Compare the functions of fibrous proteins to globular proteins on the body
Fibrous proteins normally form strands. They are insoluble in water and not very metabolically active and have a structural role within the body for example keratin made up in skin hair and nails
Globular proteins are soluble due to their hydrophilic R groups and is more active metabolically then fibrous proteins. For example hamoglobin and insulin that are involved in chemical reactions in the body
Explain how the genetic code in the gene for tubulin codes for the protein tubulin
3 Bases code for 1 amino acid
sequence of bases determine the primary store
the genetic code can be described as universal because it is the same in almost all organisms
describe other features of the genetic code
degenerate- idea that there is more than one Condon for one amino acid
Triplet - 3 bases code for one amino acid
non-overlapping- sequence is read so that each base is only part of one codon
