Nucleotides And Nucleic Acids Flashcards
What is mRNA
Produced by transcription from the dna template strand
It has a base sequence is complementary to the DNA from which it is transcribed (except u replaces t)
tRNA
tRNAs function at specific sites in the ribosome during translation
3 bases at one end of the molecule
Corresponding amino acid on other side
Transcription
The process of copying sections of DNA base sequence to produce smaller/free molecules ,RNA nucleotides
Complementary base-pairs line up creating a template/sense strand
Making of mRNA
Translation
mRNA moves out of the nucleus, with genetic code, to ribosomes
Binds to ribosome
mRNA is held in position while it is translated into a sequence of amino acids
Function of mRNA
carries genetic code from DNA in a cell’s nucleus to ribosomes
Why ribosomes are necessary in protein synthesis
- mRNA binds to start codon
- tRNA binds to anti codon
- tRNA positioned to decode mRNA to synthesise amino acids
What base letter is replaced
And for which is it replaced for
U for t
How many DNA bases are needed to code for an amino acid
3
What is the use for the other 44 amino acid combinations
they are degenerate meaning they code for the same amino acid (overlapping)
Why is DNA replication considered to be semi conservative
One strand from original DNA and one newly formed
Original strand acts as template
Means replicated strand is half the same strand as the original one
Why complementary base pairing is important
DNA can be replicated without error/ formation of identical DNA
Reduces the occurrence of mutation
Allows reformation of h bonds
Chemical elements that can make up a nuclei acid
Carbon, hydrogen , oxygen, nitrogen, phosphorus
Job of DNA
Sequence of nuclei acids that store genetic information and synthesis of proteins
Pyrimidines
Smaller bases contains single ring carbon structures
Thymine (T) and cytosine (C)
Purines
Larger bases that contain a double ring carbon structure adenine (A) and guanine (G)
Role of RNA
Transfer of genetic information from DNA to proteins that make up the enzymes and tissues of the body.
components of nucleotides
Pentose monosaccharide contains 5 carbon atoms
A phosphate group -PO4*2-, and inorganic molecule that is acidic and negatively charged
Nitrogenous base- a complex organic molecule containing one or 2 carbon rings in its structure as well as nitrogen
Polynucleotides are linked together by phosphodiester bonds a strong sugar phosphate backbone ( between phosphate and ribose)
Structure of DNA
Deoxyribose
1 less oxygen atom than ribose
2 antiparallel polynucleotide chains twisted to form a double helix
H bonds hold together bases C-G, A-T
Role of the DNA helicase
Unwinding and separating of double helix
Role of DNA polymerase
Catalyses the formation of phosphodiester bonds between nucleotides pairing with newly exposed bases ( double strand just been unzipped by helicase)
Carbon 3 on 1 sugar molecule + carbon 5 on another
DNA replication
Helicase separates double strand
Free nucleotides that have been activated are attracted to their complementary bases
Once nucleotides line up DNA polymerase joins them
Polynucleotide chain is completed , 2 identical chains
Replication errors
sequences of bases are not always matched exactly
An incorrect sequence may occur in the new strand
Genetic code
Carried by mRNA during transcription
DNA codes for a sequence of amino acids
This was found out as DNA is contained within the cells of all organisms, scientists determined that this molecule was the means which genetic info was passed on
Triplet code
Sequence 3 pairs of bases are called codons
Each codon codes for an amino acid
A section of DNA that contains the complete sequences of bases (codons) to code for an entire protein is called a gene
(t)RNA
Necessary for translation of mRNA
When codon enters the ribosomes tRNA will bring a complimentary anticodon to some and bind with it
Explained translation process
- mRNA, carrying genetic code from the nucleus, binds to ribosome at start codon
- tRNA with complimentary anticodon binds to mRNA start codon
- Another tRNA with the anticodon (UGC), threonine, carrying the corresponding amino acid bind to the next codon on the mRNA (ACG)
- First amino acid, methionine, is transferred to the amino acid threonine on the second tRNA by the formation of a peptide bond
how the structure of DNA allows replication
Double stranded , both strands act as a template
Hydrogen bonds easily broken
Complementary base pairing
Nature of genetic code
Universal - same bases in all organisms
Triplet- base pairs are read 3 at a time which have a complimentary amino acid
Non overlapping - once one codon is read the next3 bases are read
Degenerate
Structure of ATP
Ribose sugar
3 phopshates
Nucleotide base
How is ATP used
Hydrolysis reaction
ATP + water = ADP + inorganic phosphate + energy (energy released used by cells)
Condensation
ADP + inorganic phosphate + energy supplied from respiration= ATP
Properties of ATP
small - moves in and out of cells easily
Water soluble- energy requiring processes happen in aqueous environments
Contain bonds between phosphates enough energy to be used for cellular reactions but not too much that it is wasted as heat
Easily regenerated
Bonds between nucelotides
Phosphodiester between phosphate and sugar
Sturcure of DNA
Pentose monosaccharide
Negatively charged phoshate group
Nitrogenous base
Which of mRNA, tRNA, rRNA Bind to an amino acid by condensation Carries DNA transcript Found in nucleus Present in ribosome Structural element of an organelle
Binds to amino acids- tRNA Carries transcript - mRNA Found in nucleus - all 3 Present in ribosome - all 3 Structural element - rRNA
Describe the structural relationship between deoxyribose and the other components of the DNA molecule
Backbone of the polypeptide
Monomer is a repeat unit
Bonded to 2 phosphates via phosphodiester bonds
