DNA and Protein synthesis Flashcards
(39 cards)
What is the structure of a nucleotide
3 points
1) It is made of a pentose sugar; phosphate and nitrogenous base
2) It is held together by covalent bonds
3) It has a phosphodiester and glycosidic bond
What are the key features of nucleotides?
4 points
1) they become phosphorylated when they contain more then one phosphate group
2) Form the monomer of nucleic acids = DNA and RNA
3) Help regulate metabolic pathways i.e ATP; ADP
4) May be components of co- enzymes
What is the structure of DNA?
4 points
1) Polymer made up of many nucleotides
2) Consists of two polynucleotide strands that form a double helix
3) The strands are antiparrallel are in a ‘5 3’ formation
4) Tightly wound around histone proteins in chromosomes
Why does the purine always pair with the pyrimidine?
It gives equal size rungs on the DNA ladder that form the double helix and helps enable stability
What is the key word to describe chromosomes if there identical?
Homologus
What are the key features of genes?
3 points
1) Sections of DNA
2) Codes for a particular characteristic
3) alternate forms of the gene arising in mutations are called alleles
How many bonds does adenine and thymine form?
Cytosine and guanine?
A and T = 2
C and G = 3
these are held together by hydrogen bonds
What is the formation of the double helix?
5’ 3’ from the 5 prime end (phosphate attached to the 5th carbon) to the 3 in an antiparrallel structure
What are the purines and what are the pyrimidines and what are there structures?
Purine = A + G = double ringed structure Pyrimidines = C + T = single ringed structure
What are the differences between DNA and RNA
4 points
1) RNA is single stranded
2) It uses uracil instead of thymine
3) It is made from ribosomes
4) it is oxygenated
What does the glycosidic and phosphodiester bond require?
A condensation reaction
What is semi conservative, conservative, dispersive?
Semi conservative = One new daughter strand and one complementary to the parent strand
Conservative = entirely new / entirely old
Dispersive = Dotted DNA molecules all broken up
What enzymes are involved in DNA replication and what are there functions?
Gyrase - unwinds DNA
Helicase - unzips DNA = hydrogen bonds are broken
Primase - Signals where the nucleotides are added
DNA polymerase- adds the nucleotides in a 5’ 3’ direction
DNA Ligase - sticks the lagging strand fragments
Good Hearts Pour Pots of Love
Which is the leading and lagging strand?
5'-3' = leading 3'-5' = lagging
What are okazaki fragments
Short sequences of DNA nucleotides which are synthesized discontinuously on the lagging strand during DNA replication.
This happens as only a certain amount of the lagging strand can unzip before it can be synthesized further
What supplies the energy for phosphodiester bonds?
Hydrolysis of nucleotides activates them to release extra phosphate groups
Mutations
3 points
1) Occurs in 1 to 10(8) base pairs/ every 100,000 nucleotides
2) During replication enzymes can be proof read editing out the incorrect nucleotides, reducing the rate of mutations
3) Different versions of the genes are called alleles
What is the process of transcription?
3 points
1) RNA polymerase binds to DNA strand and unwinds a short section (about 12 pairs long)
2) This then travels along the DNA strand building an RNA molecule from the template strand
3) Non coding strands of mRNA (introns) are cut out just leaving coding strands( exons) in a process called splicing
What is translation?
The process by which the mRNA is read to produce a protein chain
What is tRNA ?
1) short strand of RNA
2) Carries the anti-codon which matches up to a codon
3) There are 64 tRNA molecules for each combination of bases
How does tRNA work?
The tRNA anticodons link to the right codon of the mRNA. The amino acid is then made and then drop off next to other amino acids forming a chain held together by peptide bonds. These then fold into a complex 3D shape to form a protein
How does RNA polymerase begin?
It attaches to the part of the gene called the promoter then separates the strand and starts to code for RNA
What stops the polymerase?
The terminator
What will the mRNA look like?
the mRNA will be pre- mRNA till the introns are spliced out and all is left is the exons, the guanine and the poly A tail
