1-2 Nucleic acid, water & ATP Flashcards
What are the 5 adaptations of a DNA molecule?
- stable structure
- h bonds easily break
- large molecule
- protective backbone
- base pairing for RNA
Which direction is the strand joined up?
5’-3’
Why is ATP better than glucose?
- released in small manageable amounts
- the hydrolysis of ATP to ADP is a single reaction
What are the three ways in which ADP -> ATP?
- photophosphorylation
- substrate level phosphorylation
- respiration - oxidative phosphorylation
How does water support an organism’s metabolism?
- raw material for photosynthesis
- hydrolysis
- aqueous chemical reactions
What are nucleotides made of?
A pentose sugar (has 5 carbon atoms)
A phosphate group
A nitrogen-containing organic base (includes Cytosine, Thymine, Uracil, Adenine and Guanine)
These parts are joined by a condensation reaction
How do you join two nucleotides together?
A condensation reaction between a deoxyribase sugar and a phosphate group
For each mole of dinucleotide formed, one mole of water is formed
Called a dinucleotide
Joined by a phosphodiester bond
What are the types of RNA?
tRNA: Transfers information from DNA to the ribosomes
mRNA: Makes up ribosomes alongside protein
Involved in protein synthesis
What is the structure of DNA?
The two polynucleotide chains wind around eachother to form a double helix which forms the structural backbone
Pentose sugars are anti-parallel (in the opposite direction)
What breaks up a dinucleotide?
A hydrolysis reaction
How does DNA’s structure relate to its function?
Very stable structure: rarely mutates
Two strands: allows it to seperate during DNA replication and protein synthesis
Extremely large molecule: carries an immense amount of genetic information
Base pairs within the helical cylinder: genetic information is partly protected from being corrupted by outside chemical/physical forces
Base pairing: DNA can replicate and transfer information as mRNA
When does the synthesis of DNA occur?
In mitosis during interphase
What are the steps of the semi-conservative method?
- DNA helicase (an enzyme) unwinds the double helix by breaking the hydrogen bonds and splitting the helix into two strands
- Free nucleotides which have been activated bind to the complimentary bases on the seperate strands- parental strand acts as a template for the synthesis of a new strand
- DNA polymerase makes phosphodiester bonds and hydrogen bonds are naturally formed between the bases
- Two identical polynucleotide chains are formed
- This is called the semi conservative method because half the DNA is from the original DNA molecule
What are the steps of the Meselson and Stahl experiment?
- Grew E. coli in a nutrient broth containing 15N
- E.coli took it up and used it to build their DNA
- After many generations they had pure strands of 15N bacteria and 14N bacteria
- They measured the density of the DNA using density gradient centrifugation (seperating molecules based on density by spinning it, allows for small changes in density)
What were the results of the Meselson and Stahl experiment?
G0: 100% heavy
G1: 100% mixed, single band
G2: 50% mixed, 50% light, two strands
G3: 25% mixed, 75% light ^
G4: 12.5% mixed, 87.5% light ^
How did the conservative and semi-conservative methods differ?
The conservative method predicted that there would always be one band of heavy and one of light, without any mixing of densities
Why does the breakdown of ATP release so much energy?
The bonds are broken which requires very little energy
The bonds formed between H20 and the two phosphate groups releases large amounts of energy
H goes to the larger molecule and OH goes to the phophate that is leaving ADP
Therefore the net release of energy is large
What are the uses of ATP?
Metabolic processes: building macromolecules from basic units
Movement: energy for muscle contraction
Secretion: formation of lysosomes for secreting cell products
Activation of molecules: phosphate released can go on to form other molecules
Energy: for any active processes within the cell
What are the uses of phosphate in the body?
To make RNA
To make DNA;
To make ATP/ADP
To make membranes
For phosphorylation
What is the structure and bonding of water?
Two atoms of hydrogen and one atom of oxygen
Dipolar molecule
Hydrogen = positive, oxygen = negative
Hydrogen bonding is the attractive force between molecules
Covalently bonded so don’t conduct electricity
What are the properties of water which aid life? (No explanation)
Dipolar
Has hydrogen bonding
Covalently bonded High boiling point due to hydrogen bonding High specific heat capacity High latent heat of vaporisation Cohesion Not easily compressed Transparent
How do the properties of water aid life?
High boiling point: buffer against sudden temperature changes
High latent heat of vaporisation: sweating provides an effective cooling effect
Cohesion: xylem can transport water
Not easily compressed: provides support for organisms
Transparent: light can reach aquatic plants
How is water used in the metabolism?
Used to break down many complex molecules by hydrolysis
Chemical reactions take place in an aqueous medium
Water is a major raw material in photosynthesis
How is water used as a solvent?
It readily dissolves some substances including gases, wastes, inorganic ions, small hydrophilic molecules and enzymes
