2.3 DNA Flashcards
What are nucleic acids
Large polymers formed by many nucleotides linked together in a chain and contain the elements: C, H, O, N, P
What is the roles of Nucleic acid
Storage + transfer of genetic info + Synthesis of polypeptide
What is the structure of nucleic acid
- Contains a Phosphate group that’s acidic & negative
- Pentose sugar containing 5 carbons
- Nitrogenous base containing 1 or 2 carbon rings in structure
What are the 2 types of nucleic acid
DNA
RNA
What is the differences between them the 2 types of Nucleic acid
DNA: The sugar is called Deoxyribose (Has 1 less O)
RNA: The sugar is called Ribose
Pyrimidines
The smaller bases which contain single carbon ring structure (T&C)
Purines
The larger bases which contain double carbon ring structure (A&G)
Role of RNA
Plays essential role in the transfer of genetic information from DNA to the proteins that make up the enzymes + tissues of the body
What bond joins nucleotides together
Phosphodiester
Steps to DNA extraction
- Grind sample using mortar & pestle to break cell wall
- Mix sample with detergent which breaks down cell membrane releasing cell contents to solution
- Add salt to break down hydrogen bonds between DNA & water molecules
- Add protease enzyme breaks down proteins associated with DNA in nuclei
- Add ethanol which causes DNA to precipitate out the solution
- The DNA should be seen as white strands forming between the layer of sample & layer of alcohol. The DNA can be picked up by stirring rod
After protein synthesis what happens to protein molecules
RNA molecules are degraded in the cytoplasm. The phosphodiester bonds are hydrolysed and the RNA nucleotides are released + reused
What is semi-Conservative repliaction
for DNA to replicate. The double Helix structure must unwind and then separate into two strands, so the hydrogen bonds holding the complementary bases together must be broken.
Free DNA nucleotides will then pair with their complementary basis which have been exposed as a strength are separate.
Hydrogen bonds are formed between them.
The new nucleotides join to the adjacent nucleotides with the phosphodiester bond.
what is the roles of enzymes in replication
DNA replication is controlled by enzymes, a class of proteins that act as catalysts for biochemical reactions.
Enzymes are only able to carry out their function by recognising and attaching to specific molecules or parts of the molecule
Before replication can occur, the unwinding and separating of the two strands of the DNA double Helix is carried out by enzyme DNA helicase, it travels along the DNA backbone, catalysing reactions that break the hydrogen bond between complementary base pairs as it reaches them. This can be thought as the strand of unzipping new line
Free nucleotide spare with the newly exposed basis on the template strands during the unzipping process, a second enzyme, DNA polymerase, catalyses the formation of first four dice to bonds between these nucleotides.
what is mutation
Random & spontaneous errors in the DNA bases
What is the degenerate code
The degenerate code refers to the fact that multiple codons or sets of three nucleotides can code for the same amino acid during protein synthesis.
This is due to their being more codons than amino acids.
What happens in transcription
- DNA is contained in a double-membrane called the nuclear envelope to protect it from being damaged by cytoplasm
- Chromosomal DNA molecule it too large to leave through nuclear pores and must make a shorter version of itself
- The section of gene that is needed unwinds & unzips using DNA Helicase which breaks the hydrogen bonds
- The 2 strands are separated and the first (5’ to 3’) is called the sense strand and contains the correct coding for the amino acid sequence. The other strand (3’ to 5’) is called the template / antisense strand
- Free RNA nucleotides that are complementary to the bases attach to the template strand and RNA polymerase binds them together and forms phosphodiester bonds
- There is no Thymine, so Adenine is paired with Uracil
- This completed strand is called mRNA and de-attaches itself from the template strand and leaves through nuclear pores and travels to ribosome in the cytoplasm
what happens in translation
In ribosomes there is ribosomal RNA. (rRNA)
This is important in maintaining the structural stability of the protein synthesis sequence and plays a biochemical role in catalysing the reaction.
After leaving the nucleus, the mRNA binds to a specific site on the small subunit of a ribosome. The ribosome holds mRNA in position while is decoded or translated into a sequence of amino acids. This is known as translation
Transfer RNA (tRNA) Is necessary for the translation of mRNA. It is composed of a strand of RNA folded in such way that three bases, called the anticodon, are at one end of the molecule. This anticodon will bind to a complementary codon on mRNA following the normal base pair rules. The tRNA molecules carry an amino acid corresponding to that codon.
When the tRNA anticodon binds to the complementary codon along with the mRNA, the amino acids are brought together in the correct sequence to form a primary structure of the protein coded for by the mRNA.
What 3 activities do cells require energy for
Synthesis
Transport
Movement
what is the structure of Adenosine Triphosphate (ATP)
An ATP molecule is composed of a nitrogenous base. A pentose, sugar and three phosphate groups.
The base is always adenine, and the sugar is ribose.
How is energy released
In a condensation reaction one of the phosphate groups is removed to from ADP (Adenosine diphosphate)
Chemical Equation
ATP + Water = Inorganic Phosphate + ADP + Energy
What is phosphorylation
the energy released in the breakdown of these fats & carbohydrates in cellular respiration is used to create ATP. This occurs by reattaching A phosphate group to an ADP molecule. T
Properties of ATP
Small- Move easily into and out of cells
Water soluble- energy requiring processes happening aqueous environments.
Contains bond between phosphates with intermediate energy- large enough to be useful for cellular reactions, but not so large that energy is wasted as heat.
Releases energy in small quantities- quantities also suitable to more cellular needs, so that energy is not wasted as heat.
Easily Regenerated- can be recharged with energy.
