Chapter 2 - Nucleic Acids Flashcards
What is the structure of a nucleotide?
•phosphate group
•pentose sugar
•nitrogenous bases (C/A/T/G/U)
These three components join together by condensation reaction forming a mononucleotide and two molecules of water
What does a mononucleotide +mononucleotide form?
Dinucleotide + H20
What bond does a dinucleotide have?
Phosphodiester bond
Complete the sentence:
Polynucleotide forms ……………….
The bases of DNA
What is the purine?
- Guanine
* Adenine
What is a pyrimidine?
- cytosine
- thymine
- uracil
What base goes with cytosine?
Guanine
What base goes with adenine?
Thymine (uracil)
Describe a ribonucleic acid (RNA)
- polymer of nucleotides
- ribo sugar attaches to phosphate group and nucleotide
- contains A/U/C/G
- NO T
- shorter than DNA
What are the three types of RNA? And describe each type
- mRNA - messenger RNA carries DNA code from nucleus to ribose
- tRNA - transfer RNA carries amino acid across cytoplasm
- rRNA - ribosomal RNA makes up tinosomes
Describe a deoxyribonueic acid (DNA)
- Made up of deoxyribose/phosphate group/nucleotide bases
- contains A/T/C/G
- made up of two strands
- longer than RNA
Describe complimentary base pairing
•To DNA polynucleotide strands join by hydrogen bonds •can only pair to specific -A/T (two hydrogen bonds) -G/C (three hydrogen bonds) •always equal amounts
Describe how the DNA is stable
- Phosphodiester backbone protects the more chemically reactive organic bases - You would have to And why the double helix to expose the DNA
- The hydrogen bonds form bridges between nucleotide bases
- There are three hydrogen bonds between C and G – the more C and G bonds the more stable helix
- Anti-parallel arrangement - 5’ to 3’ - nucleic acids can only synthesised in this direction
What are the two main stages of cell division?
- nuclear division
* cytokinesis
Before the first stage of cell division what takes place?
Semi-conservative replication
What is semi-conservative replication?
DNA makes exact copies of itself by undermining the double helix so that each chain acts as a template for the next.
DNA Replication
What are the four requirements for DNA replication?
- Four types of nucleotides (constant supply)
- Strands to act as a template
- DNA polymerase-> catalyse reaction
- source of chemical energy
Describe the process of DNA replication
- Enzyme DNA helicase breaks down hydrogen bonds linking pairs
- As a result double helix unwinds into two strands
- each exposed polynucleotide strands acts as a template to which complimentary nucleotides are attracted
- Energy used to activate these nucleotides
- activated nucleotides are joined together by enzyme DNA polymerases
- each of the new DNA molecules contain one of the original DNA strands
What is pentose sugar is found in DNA?
Deoxyribose
What is the nitrogen and carbon containing molecules compromising to ring structures?
Purine
What is the nitrogen and carbon containing molecules containing molecule comprising a one ring structure?
Pyrimidine
What are the strong bonds formed between adjacent to nucleotides in a polynucleotide?
Phosphodiester
What is the general name for five carbon sugar?
Pentose
What are the following enzymes used for?
•DNA Polymerase:
•DNA Helicase:
- joins the free nucleotides together forming hydrogen bonds
* breaks the hydrogen bonds
What is the structure of ATP?
- phosphorylated macromolecule
- adenine – nitrogen – containing organic base
- ribose – pentose sugar acting as backbone
- phosphate – chain of three phosphate group
How does ATP store energy?
•ATP is a nucleotide
• phosphate bonds are important:
– They are unstable (low activation energy)
– Releases a decent amount of energy
What are the products of a hydrolysed ATP?
ADP + P + E
Catalysed by the enzyme ATP hydrolase
What synthesises ATP?
- Chlorophyll – contained in plant cells
- respiration
- substrate-level phosphorylation -> phosphate groups are transferred from donor molecules
What is the role of ATP?
- ATP is an immediate energy source – it releases less energy than glucose molecules (hydrolysis is a single reaction was glucose is much longer)
- ATP cannot be stored – continuously made in the mitochondria
List five ways ATP energy is required: • • • • •
- metabolic processes – energy needed to build up macromolecules from basic units
- movement – energy for muscle construction provides energy for the filaments of muscles to slide past one another
- Active transport – changes the shape of carrier proteins in plasma membrane allowing molecules/ions to move against a concentration gradient
- secretion – needed to form lysosomes necessary for secretion of cell products
- activation of molecules – inorganic phosphate is released during hydrolysis of ATP can be used to phosphorylate other compounds
What is the structure of water?
- covalent bond
- polar molecule – electrons not evenly distributed across molecule
- attraction between these charges from hydrogen bonds between water molecules
What are the five properties of water?
- High heat capacity
- Large latent heat of vaporisation
- Strong cohesion between water molecules
- am important solvent
- A metabolic in many reactions
Describe high heat capacity in water
- heat needed to raise the temperature of 1 kg of water by 1 °C in terms of specific heat capacity
- Large specific heat = absorb large amounts of heat energy before temperature rate is a significant amount
How is high heat capacity important to living organisms?
- body = mostly water
- water = absorbs a lot of heat without temperature rising too much
- water ‘buffers’ heat changes
- Advantageous for aquatic organisms – don’t change temperature quickly
How is large latent heat of vaporisation important to living organism?
- animals can sweat = keep cool as water evaporates off surface
- plants cool = water evaporates from leaves
Describe large latent heat of vaporisation in water
- Body = some water molecules move faster - kinetic energy - some have enough energy to move into the air and evaporate
- evaporated molecules take energy causing the water to cool as energy decreases
Describe the strong cohesion between water molecules in water
The polarity - Water molecules are attracted to each other forming hydrogen bonds. The bonds hold the water together allowing the continuous stream known as mass flow
How is the strong cohesion between water molecules important to living organisms?
- plants – water moves up the xylem vessels as a mass flow (roots to leaves)
- Water cohesion = surface tension - water behaves as if there is a skin where the water meets the air allowing small animals to survive on the surface of water
Describe the water as an important solvent
- solvent = liquid that other substances can dissolve
- positive/negative charges of water attract other molecules – they separate from each other
- substance are dissolved in water - free to move and react
How is the water being an important solvent important to living organisms?
- metabolic reaction that happened - only happens in water where reactants are dissolved
- dissolved substance can be transported around body
Describe the water as a metabolite in many reactions
Water can be dissolved in chemical reactions directly
•condensation - water released (small to large)
•hydrolysis - water is added (large to small)
How is water being a metabolite important living organisms?
- hydrolysis allows digestion
* condensation allows synthesis of important molecules e.g protein
