Nucleic Acids Flashcards
What is the structure of a nucleotide and its components?
Made up of,deoxyribose sugar,nitrogenous base and a phosphate
Explain what elements make up nucleic acids and give an example of a nucleic acid?
C,H,O,N,P
DNA is an example
Explain bonding in a nucleotide?
Glycosidic bind between base and sugar
Phosphodiester bond between phosphate and sugar
What are purines and examples?
2 ring nucleotides such as adenine and guanine
What are pyrimidines and some examples?
1 ring nucleotides such as thymine cytosinr and uracil
What are polynucleotides?
Successive condensation reactions of nucleotides result in the formation of polynucleotides
Where the sugar and phosphate are the backbone
What is DNA?
DNA is dioxyribonucleic acid which is a nucleic acid composed of 2 long polynucleotide chains twisted into a double helix
They are held by hydrogen bonds
Double helix of DNA is antiparallel
Explain all the characteristics of DNA?(quite a few)
Large-Cannot easily diffuse out of nucleus
Has complementary bases-For accurate replication
Double stranded-Acts as a template during replication incase 1 copy of DNA is changed by a mutation
Sugar phosphate backbone-helix is strong and compact,bases are protected
Separate strands joined by H bonds-Allows to easily separate from DNA and provides strength
What is a nucleoside?
Nucleotide without phosphate group
What is mRNA and function?
A nucleic acid that is single stranded
Contains ribose instead of deoxyribose
Contains uracil instead of thymine
This is transcription and the first stage of protein synthesis
Delivers a copy of DNA code to a ribosome
Moves from nucleus to ribosome
Explain transcription and codons?
During transcription,mRNA is built up by complementary bases using the DNA template
These DNA bases are converted into mRNA codons
Each triplet has one amino acid
Explain everything about DNA?
Double helix with 2 antiparallel polynucleotide chains
Long and large
Located mainly in nucleus and is most stable
Explain mRNA in detail?
Single helix
Medium size
Linear
Ribose sugar
Found mainly in the cytoplasm
Explain characteristics of tRNA?
Single helix
Smallest
Linear
A,G,C,U base pairings
Found mainly in the cytoplasm
Explain tRNA function?
Located in cytoplasm
Transfers amino acids from cytoplasm to ribosomes
Ribosomes links amino acids together to form a protein during translation
What is rRNA?
Function:main component of ribosomes
rRNA bonds with special proteins to form a ribosome
Ribosome is the organelle that builds proteins
What is ATP and its use?
ATP is Adenosine triphosphate and it is an immediate source of energy for biological processes
Explain what ATP is made up of?
Made of an adenine base,ribose sugar(together called adenosine)and 3 phosphates
Joined by a phosphodiester bond and formed from condensation reaction
What does the hydrolysis of ATP lead to?
ATP plus water turns to ADP plus energy
Explain the properties of ATP?
Releases a small amount of energy at a time
Water soluble
Easily regenerated
Releases energy instantaneously
Uses of ATP?
Used in energy for example:
Metabolic processes-ATP provides energy needed to build up macromolecules
Movement-ATP provides energy for muscle contraction
AT-provides energy to change shape of carrier proteins in plasma membrane
Secretion-ATP is needed to form the lysosomes necessary for secretion
Activation of molecules-Inorganic phosphate released during hydrolysis of ATP can phosphorylate other compounds
Explain DNA replication process?
DNA helicase breaks hydrogen bonds,between complementary bases pairs between 2 strands within double helix
DNA double helix unwinds
DNA strands separate which acts as a template
DNA polymerase catalyses joining of adjacent nucleotides
Catalyses formation of phosphodiester bonds
Explain the importance of DNA replication?
Cell division-how cells need new DNA for growth and repair
Reproduction-Gametes require DNA to pass genetic info
Explain function of DNA helicase in DNA replication?
DNA helicase breaks hydrogen bonds,between bases to open up DNA chains
Explain function of DNA Polymerase in DNA replication?
Catalyses joining of adjacent nucleotides
DNA polymerase binds to 3’ end and grows on 5’ end
Explain the formation of both DNA strands via DNA polymerase?
1 strand is built on continuous replication-where DNA polymerase binds to 3’ end and continues replicating to 5’ end
On the other hand,the other stand DNA polymerase has to stop and start creating short sections of DNA that need to be joined up with DNA ligase
Eventually,DNA polymerase joins all of the nucleotides to form a complete polypeptide chain
Explain the Conservative model for DNA replication?
Suggested that the original DNA molecule remained intact and that a separate daughter DNA copy was built up from new molecules
One daughter strand and one parent strand
Explain the semi Conservative Model in DNA replication?
Proposed that the original DNA molecule split up into two separate strands,each of which acts as a template
DNA unwinds,new strands are synthesised
2 hybrid DNA molecules are produced
Who were meselson and stahl and what did they discover?
They discovered and proved semi Conservative replication of DNA
What 3 facts did Meselson and Stahl been their work on?
All DNA bases contained nitrogen
Nitrogen has 2 isotopes(14N and the heavier 15N)
Bacteria will incorporate nitrogen from their growing medium into any DNA they make
Explain the process of DNA purification and extraction?
If DNA required is from a banana(chop up and blend) if from bacteria(smash to break cell wall)
Add detergent to break down lipid membranes
Add salt to neutralise the charge in DNAs phosphate backbone
Add protease to break histone proteins
Add ethanol so DNA can precipitate to the top
What is a codon?
Sequence of 3 nucleotides which codes for an amino acid
What does universal mean?
Same codons codes for the same amino acids
What does non overlapping mean?
Each base in triplet codes for 1 amino acid
What does degenerate mean?
One amino acid is coded by multiple codons
What is a stop codon?
It’s a triplet of bases/nucleotides where it signals the end of protein synthesis
What is a chromosome?
Linear long molecule of DNA found in the nucleus
What is a gene?
Sequence of DNA bases coding for a polypeptide of DNA/RNA
What are introns?
Sections of DNA that don’t code for amino acids
What are exons?
Bits of gene that do code for amino acids
Describe the structure of a chromosome and how this links to its function?
Chromosomes are threadlike linear DNA molecule
Wound up as its very long
Wound around proteins called histone
Histone proteins help support DNA
Coiled up very tight and compact
