2.0 Nucleic acids Flashcards
What are the two types of nucleic acid?
RNA and DNA
What is the role of DNA?
Carries genetic information
What is the role of RNA?
Carries genetic information from DNA to the ribosomes
Name the monomer of a nucleic acid
Nucleotide
State the three components of a nucleotide
Penrose sugar, phosphate group, nitrogen-containing base
State the five possible bases for a nucleotide
Adenine, thymine, cytosine, guanine, uracil
What is a pentose sugar?
A sugar containing 5 carbons
What pentose sugar is present in DNA?
Deoxyribose
What pentose sugar is present in RNA?
Ribose
What reaction combines the pentose sugar, organic base, and phosphate group?
Condensation reaction
What reaction combines two nucleotides?
Condensation reaction
What bond is formed when two nucleotides are combined?
Phosphodiester bond
What is one nucleotide called?
Mononucleotide
What are two bonded nucleotides called?
Dinucleotide
What is a long chain of bonded nucleotides called?
Polynucleotide
Describe the structure of DNA
- Double helix
- Two polynucleotide chains held together by hydrogen bonds between complimentary base pairs
State the complimentary base pairings
- Adenine and Thymine
- Cytosine and Guanine
How is the structure of DNA related to its functions?
- Two separate strands held by weak hydrogen bonds allows for separation
2 large molecule so carries a lot of information - Sugar phosphate backbone to protect genetic information
How many hydrogen bonds form between Adenine and Thymine?
2
How many hydrogen bonds form between Cytosine and Guanine?
3
Describe the structure of RNA
Relativity short polynucleotide chain
What are the three differences between DNA and RNA?
- DNA is double stranded, RNA is single stranded
- DNA has deoxyribose, RNA has ribose
- DNA has thymine, RNA has uracil
How does complimentary base pairing allow is to work out the frequency of relative bases?
Knowing the frequency of one allows us to find out the frequency of its complimentary base, frequency of all bases equal 100% which allows others to be calculated
State the mechanism of DNA replication
Semi-conservative replication
Describe semi-conservative replication
- DNA helicase breaks hydrogen bonds which unwinds the double helix
- Free floating nucleotides bind to their complimentary pair
- DNA polymerase forms new phosphodiester bonds between adjacent nucleotides
Why is semi-conservative replication important in the genetic continuity between cells?
There will always be a strand of the former DNA molecule used as a template
What are the main stages ofDNA replication?
- DNA unwinds
- Hydrogen bonds break
- Each strand acts as a template
- New nucleotides attach to the template strand
- Condensation reactions bond nucleotides together
State the two enzymes involved in DNA replication
- DNA helicase
- DNA polymerase
What does DNA helicase do?
Unwinds the DNA by breaking hydrogen bonds
What does DNA polymerase do?
Catalyses the condensation reaction which forms phosphodiester bonds between adjacent nucleotides
In what direction do DNA strands in the double helix run?
Anti parallel
What are the new strands of DNA formed from?
Free floating nucleotides
How do free floating nucleotides get in the right order to form a complimentary strand?
Original strand acts as a template and the free nucleotides attach to their complimentary base pair
How was semi-conservative replication proven to be correct?
- DNA marked with heavy nitrogen isotope then replicated with a light nitrogen isotope
- Mass of DNA determined by which isotopes it contained
- DNA spun in a centrifuge, results showed the strands were separating and forming a new strand each generation
Why is ATP a suitable energy source for cells?
- Releases manageable amounts of energy
- Phosphorylates other compounds
- can be rapidly re synthesised
State the roles of ATP
- Metabolic processes
- Movement
- Active transport
- Activation of molecules
What are the properties of water?
- Dipolar molecule
- Hydrogen bonds to other molecules
- High specific heat capacity
- Cohesion and surface tension
What is the importance of water to living organisms?
- Hydrolyses complex molecules
- Universal solvent