A1.2 (Nucleic Acids) Flashcards
Nucleic Acid
Polymers of nucleotides such as DNA and RNA
DNA
Deoxyribonucleic acid: Molecule that carries genetic information for development and functioning of an organism
RNA
Ribonucleic acid: A type of nucleic acid that has riobose sugar in its structure and is used by viruses to replicate
How was DNA discovered
Friedrich Miescher performed experiments with white bloodcells which led to DNA extraction as the membrane had to be disintegrated first. this was based on the solubility of DNA in certain substances
Components of as nucleotide
pentose sugar, nitrogenous base, phosphate group
How does sugar phosphate bonding work
nucleotides link together through a covalent bond to form the single strands of DNA/RNA
1. Bond betwen phosphate group and hydroxylgroup attached to 3C
2. releases one molecule of water
3. continuous chain
4. forms strong sugar phosphate backbone
5. forms 2 ends: 3C hydroxyl group and 5C phosphate group
Pure As Gold
Purines: Adenine, Guanine
Nitrogenous bases with two rings
Cut The Pie
Pyrimidines: Cytosine, Thymine, Uracil
Nitrogenous bases with only one ring
features of RNA
- single stranded
*has uracil instead of thymine - has AGUC as nitrogenous bases
- 2C has an OH
Features of DNA
- double stranded
- strands are connected by hydrogen bonds
- has AGTC as nitrogenous bases
- 2C has an H
structure of DNA explained
two polynucleotide chains aree coiled around the same axis in which the bases inside are supported by the sugar phosphate backbone
role of complementary base pairing
- cell division
- gene expression
how does complemetary base pairing affect cell division
dna replicates: CBP maintains base sequnece during copying as it uses 1 strand as template to create a new one (semi conservative)
how does complementary base pairing affect gene expression
Complemetary base pairing ensures that the same protein is produced as the same bases = same code = same protein
Genetic Code
Instructions in a gene in the form of a base sequence that become translated into a functional protein
replication
Copying of DNA to make a new DNA molecule
Translation
Process in which the transcribed DNA is translataed by the ribosomes to produce proteins
Transcription
process in which DNA is used as a template to produce RNA
DNA Base sequences
Processes that happen in the 5’ to 3’ direction
Replication, Translation, Transcription
Example of specific enzyme which replicates DNA in the 5’ to 3’ direction
DNA Polymerase
How does pairing purines and pyrimidines enable DNA stabilisation
As the length stays consistent (around 2nm diameter) the bond specificy is higher resulting
+ hydrogen bonds between bases
= more stable & strong bond
Eukaryotic
A group of organisms whose cells typically contain a nucleus & membrane bound organelles
Prokaryotic
A group of organisms whose cells do not contain a nucleus or membrane bound orgnisms
Histones
Proteins around which DNA strands are wrapped
nucleosomes
structural unit of eukaryotic chromatin in which DNA is double wrapped around 8 histone and H1proteins
-> helps to supercoil and compact DNA
Relationship between nucleosomes and chromosomes
Chromosome>chromatin fibre>Nucleosome>double helix
Hershey Chase Experiment
proved that DNA, not protein, makes up the genetic material
How does the Hershey Chase Experiment work
- used a T2 bacteriophage which injects DNA into a bacterial cell while its protein stays on the outside
- used radioactove phosphorus and sulfur to label the DNA and the protein viruses
- as the DNA was transferred the next generation all contained radioactive phosphor, proving that uit was DNA that was being transferred
Chargaffs Data
proved that DNA is double stranded helix
How was chargaffs data collected
he analysed samples of DNA using paper chromotography and discovered that the relative concentrations of the bases were equal
=> helped explain how DNA can be replicated accurately due to complementary base pairing
hershey chase experiment in short
radioactive phosphorus found in pellet (bacterial sediment)
Direction of DNA synthesis
5 -> 3
Solubility of lipids in water vs sugars
more soluble in sugars than water
All DNA/RNA processes in 5-> 3
- replication
- translation
- transcription
DNA processes in 3 -> 5 direction
- DNA polymerisation (synthesizes DNA during DNA replication)
-> can only attach to ‘3 on -OH molecule
lengths of Dna and its components
- Length of DNA: 2m
- Length of a gene:3.4nm
- Length between two base pairs: 0.34nm
- diameter of coil: 2nm
What stabilises the DNA molecule
- bond specificity of complementary bases
- hydrogne bonds between bases
Significance of the universal genetic code
- proves common ancestory
- universally allows transfer of genetic information across organisms (contributes to advancements in. biotechnology genetic engeneering)
genome
collection of all the genetic information within an organism or a cell
Key words for DNA questions
- double stranded double helix
- anti parallel bonding
- hydrogen bonding between bases
- complmentary base pairing
- purine- pyrimidine bonding
- polymer
- sugar phosphate backbone
reading genetic code
- look at direction = has to be 5 to 3
- translate from DNA to mRNA = change all T’s to U’s
- read code and match to AA
