Nucleotides And Nucleic Acids Flashcards
Draw the structure of a nucleotide
What are three parts of a nucleotide
Pentose sugar
Nitrogenous base
Phosphate group
What are nucleotides used to make
DNA and rna
Dna-used to store genetic info
Rna-used to make proteins from the instructions of dna
What’s the Pentose sugar in dna and rna
Dna-deoxyribose
Rna-ribose
In a dna nucleotide what could the bases be and in a rna nucleotide what could the bases be
Adenine,thymine,guanine,cytosine
Adenine,uracil,guanine,cytosine
How many polynucleotide chains do rna and dna have
Dna has a two polynucleotide chains
Rna has single polynucleotide chain
Explain how polynucleotide strands are formed and broken down
Condensation reactions between nucleotides form string phosphodiester bonds ( sugar phosphate backbone). Hydrolysis reactions use a molecule of water to break these bonds
Enzymes catalyse these reactions
What’s the purine bases and describe their structure
Adenine c5h5n5
Guanine c5h5n5O
Two carbon nitrogen rings joined together
What’s the Pyramidine bases and describe their structure
Thymine
Cytosine
Uracil
One carbon nitrogen ring
Pyramidine smaler than a purine base
Complementary base pairs in RNA AND DNA and how many hydrogen bonds between them
in dna- T and A and 2 hydrogen bonds
In rna - U and A and 2 hydrogen bonds
They both have C and G with 3 hydrogen bonds between them
What does the double helix looks like before it’s twisted
Two polynucleotide strands that are anti parallel running in opposite directions
How to purify dna
1)break up cells in sample using a blender for eg
2)make up a solution of detergent,salt and distilled water
3)add broken up cells to a beaker with the detergent solution
4)incubate beaker in water bath at 60* for 15 mins.( detergent in mixture breaks down the membranes at this point,the salt binds to DNA and causes it to clump together. Temp high enough to stop enzymes in cells from working properly and breaking down DNA)
5 ) AFTER incubated put beaker in an ice bath to cool down mixture
6)once it’s cooled filter mixture w filter paper and funnel and transfer a sample of your filtered mixture to a clean boiling tube and discard contents of filter paper
7)add protease enzymes to mixture (these will break down the proteins bound to the dna in mixture)
8)slowly dribble cold ethanol down the side of tube so it forms a layer on top of dna detergent mixture
8)leave tube for a few mins and a stringy white DNA precipitate will form which can be removed using a glass rod
Why does dna replicate?
It copies itself before cell division so each new cell has the full amount of dna. Important for making new cells and for genetic info from gen to gen
When does dna replication occur
During S phase in cell cycle
How is dna replicated
1) dna helicase enzyme breaks down the hydrogen bonds between the two polynucleotide strands so dna unzips to form two nucleotide strands
2)each original strand acts as a template for a new strand so the free nucleotides bind to the template strand with complementary base pairing.(atcg) Hydrogen bonds form between exposed based on template strands and free nucleotides.
3)nucleotides on new strand are joined together by DNA polymerase as it seals the sugar phosphate backbone and binds to the 3’ end of template strands.
4)It catalyses the formation of phosphodiester bonds between phosphate group and deoxyribose sugars of adjacent molecules forming a polynucleotide chain 5’ to 3’direction.
5)Dna ligase seals gap in the sugar phosphate backbone between Ozaki fragments on the lagging strand to form a continuous strand.
6) identical daughter strands are made through semi conservative replication as 1 original strand is kept in each daughter strand.
Why does dna replication have to be accurate
To make sure genetic information is conserved, each time DNA in a cell is replicated.
what’s the effect of mutations
They alter the sequence of amino acids In a protein. This causes an abnormal protein to be procured. This abnormal protein could be better than original protein or worse
What is inorganic ions
An ion w an electric charge that doesn’t contain carbon
What are the cations
Ca2+-involved in transmission of nerve impulses and the release of insulin
from pancreas and acts a cofactor for many enzymes.important in bone formation
Na+-important for generating nerve impulses for muscle contraction and for regulating fluid balance in the body
K+-important for generating nerve impulses for muscle contraction and for regulating fluid balance in the body. It activates essential enzymes need for photosynthesis
H+-affects Ph of substance(more H+ than OH- =acid) also needed for photosynthesis reactions that occur in thylakoid membranes inside chloroplasts and respiration reactions that occur in inner membrane of mitochondria
NH4+-absorbed from soil plants and important source of nitrogen =used to make amino acids and nucleic acids
What are the anions
NO3- absorbed from soil by plants and important source of nitrogen -used to make..
HCO3- acts as a buffer which helps to maintain PH of blood
Cl- involved in chloride shift which helps maintain Ph of blood during gas exchange. Acts as a cofactor for amylase.involved in nerve impulses too
PO43- -involved in photosynthesis and respiration . Needed for synthesis of many biological molecules like nucleotides (and atp) phospholipids and calcium phopshate(strengthens bones)
OH- -affects PH of substances ( more oh creates an alkali)
Compare rna and dna
DNA has double stranded and RNA has single strand
DNA found in nucleus and RNA found in ribsomes
DNA bases are ATCG and rna bases are AUCG
DNA has a deoxyribose sugar and RNA has a ribose sugar
Rna’s C2 is bonded to an o and dnas C2 isn’t
Both have phosphate group
Both have phopshodiester bonds
What materials are needed for dna replication
DNA polymerase enzyme,helicase enzyme,ligase enzymes
Free nucleotides(actg)
Intact dna-this is because both strands act as a template for replication
Energy source(atp) to phosphorylase nucleotides which activates them
Function of dna helicase
Unwinds the dna by braking the hydrogen bonds between complementary base pairs on the two strands of dna
Function of dna ligase
DNA ligase catalyses condensation reactions between the new nucleotides to create a polynucleotide chain.
Function of dna polymerase
nucleotides on new strand are joined together by DNA polymerase as it seals the sugar phosphate backbone and binds to the 3’ end of template strands.
It catalyses the formation of phosphodiester bonds between phosphate group and deoxyribose sugars of adjacent molecules forming a polynucleotide chain 5’ to 3’direction.
Two main forms of nitrogen
What does the position of the dna band in the test tube depend on
N14-(light nitrogen)
N15-( heavy nitrogen )
It depends on how heavy the dna is
Why is dna semi conservative
In each new dna molecule one old strand is conserved paired with 1 new strand
Three thujgs a mutation can be
Harmful beneficial neutral
What’s carbon 5 attach to
What’s carbon 3 attached to
Why’s proportion of AT and CH the same
Phosphatw
Hydroxyl group
Due to complimentary pairing
Difference between semi conservative replication and conservative replication
And what do all bases in dna contain
In semi each new DNA molecule contains one official strand and one new strand. In cons one new DNA molecule contains both original strands and other contains two strands
Hydrogen
What’s genetic code-
Features of the genetic code
Sequence of base triplets in dna or mRNA coding for specific AA.
Non overlapping-each triplet is only read once
Degenerate:more than one triplet codes for same amino acid(64 trips for 20 AA)
Universal: same bases and sequences used by all species
What is a gene
What’s each amino acid codes for by
A sequence of dna nucleotides that codes for a polypeptide. Sequence of AA in a polypeptide forms primary structure of a protein.
Triplet base
Why does protein synthesis occur
DNA molecules found in nucleus of cell but organelles that make proteins are in cytoplasm. DNAs too large to leave nucleus so a section is copied into mRNA . This is transcription. mRNA leaves nucleus via nuclear pore and joins ribosomes to synthesis protein -translation.
What is RNA
A single polynucleotide strand,ribose sugar contains U instead of T
And involved in protein synthesis
Different types of rna
Messenger rna-single PN strand.made in nucleus during transcription. It carried genetic code form dna in nucleus to cytoplasm to make a protein during translation. In it triplet bases are called codons
tRNA-single PN strand folded into clover shape. H bonds between specific base pairs hold molecule in this shape. Every tRNA molecule has specific sequence of triplet bases at one end called anticodon . It has an amino acid binding site on other end.its found in cytoplasm where it’s involved in translation. Carries AA for making proteins to ribosomes
Rrna-forms two subunits in a ribosome along w proteins. Ribosome moves along mRNA strand during protein synths. Rrna in ribosome helps to catalyse formation of peptoide bonds between AA
What happens in transcription
RNA polymerase attached to dna double helix at beginning of gene. H bonds between 2 dna strands break seperating the strands and dna molecules uncoils atp.one of strands is ues to make a template of mrna
RNA polymerase lines up free rna nucleotides alongside template strand. Complimentary base pairing means mRNA strand ends up being complementary copy of dna template strand.(T replaced any U)
Once rna nucleotides paired up w specific bases on dna strand they joined tg by rna polymerase forming mrna strand.
RNA polymerase moves along dna assembling mrna strand. H bonds between uncoiled strands of dna reform once rna polymerase passed and strands coil back into double helix
RNA polymerase reaches a stop codon doesn’t make mrna anymore and detaches from dna.moves out of nucleus via nuclear pore attached to ribosome in cytoplasm
What happens when dna polymerase is inhibited to protein synthesis
Inhibits dna replication as mrna strands can’t be created from dna template strands
Lack of mrna inhibits cell from making new proteins
Without ability to replicate dna cell cycle is disrupted leading to cell growth arrest or death inni
What happens in translation
mRNA attached itself to ribosome and tRNA molecules carry AA to ribosome.TRNA molecule w anticodon that’s complimentary to start of mrna attached itself to mrna by complimentary base pairing.second tRNA molecule attached itself to the next codon on mrna in same way.
Rrna in ribosome catalyses formation of a peptide bond between two AA attached to tRNA molecule .joins AA tg. First tRNA mol moves away leaving its aa.3rd tRNA molecule binds to codon on mrna and its aa binds to the first two aa and second tRNA molecule moves away and thus continues to make a polypeptide chain until there’s a stop codon on mrna molecule
Effect of mutation of ribosomal proteins on protein synthesis
Ribosomes job is to read mRNA strand and assemble aa into polypeptide chain. Mutation can affwcr the way it’s read changing the chain order and forming an abnormal prowhin from alteration of aa sequence.
If there’s an accidental stop codon in middle of mean sequence what happens
Stop codons signal end of translation releasing polypeptide chain so when it appears ribosome will encounter it early on and release truncated protein as its missing important aa sequences and it will be nonfunctional.
Initiation codon
3 triplets that determine where translation stops
Aug
Uaa uag uga
Structure of atp and adp
Atp has 3 inorganic groups
Adp has 2
They’re both nucleotide derivatives of adenine
why do base triplets not share their code
It’s non overlapping as each nucleotide is only part of 1 triplet codon
so fewer mistakes - no mutations
codons are regenerate what does this mean
There will be a neutral effect on protein outcome as point mutations will give rise to same amino acids
