Unit 1 - Biological Molecules - Nucleic Acids, ATP and Water Flashcards
What makes up a nucleotide?
A pentose sugar - eg. deoxyribose
A nitrogen containing base - eg. adenine
A phosphate group
How are di and polynucleotides formed?
Condensation reactions
Phosphodiester bond is formed between
Structure of DNA x3
Double helix structure
Two polynucleotide chains which are antiparallel
Two strands held together by hydrogen bonds between the complementary base pairs
Why is the Structure of DNA important for its function:
4 nucleotide bases….
DNA can carry coded info
Why is the Structure of DNA important for its function:
The DNA double helix molecule has two strands of DNA…
Strands are easily separated for DNA replication
How is DNA stable to carry information?
Hydrogen bonds between complimentary bases
DNA is tightly coiled around histone proteins
Phosphodiester backbone protects the more chemically reactive bases
What is the pentose sugar in DNA and what is it RNA
Deoxyribose
Ribose
Differences between DNA and RNA x6
RNA contains ribose instead of deoxyribose
RNA contains the base uracil instead of Thymine
DNA is permanent
DNA is longer
DNA is stable
There are 4 forms of RNA and only 1 form of DNA
Requirements for semi-conservative replication x3
4 types of nucleotide must be present with their bases of Thymine, adenine, cytosine and guanine
The enzyme DNA polymerase
Source of energy to drive the process
Steps of semi-conservative replication
DNA helicase breaks the hydrogen bonds linking the base pairs of DNA
As a result the double helix separates into two strands
Each exposed polynucleotide strand acts as a template for free complementary bases to bond to.
Nucleotides are joined together in a condensation reaction by the DNA polymerase
What makes up an ATP molecule?
Adenine - Nitrogen containing organic base
Ribose - Pentose sugar
Phosphates - A chain of 3 phosphate groups
The bonds between phosphates in ATP are …
Use?
They are unstable so have a low activation energy meaning they are easily broken.
When they break release energy in small and manageable amounts.
What is produced when ATP is hydrolysed?
ADP and a phosphate group
Which enzyme catalyses the hydrolysis of ATP?
ATP hydrolase
How do we make ATP?
By phosphorylating ADP in a condensation reaction.
This happens in 3 ways:
Photophosphorylation - Photosynthesis
Oxidative phosphorylation - late stages of Aerobic respiration
Substrate level phosphorylation - anaerobic/ early aerobic respiration
3 reasons why ATP is a useful energy carrier?
Releases energy in small manageable amounts
Its soluble and can be transported to where its needed in the cell
Hydrolysis of ATP to ADP is a single step fast reaction which releases small amounts of energy quickly
4 processes where ATP is required
Metabolic processes - building up larger molecules from smaller ones eg. starch from glucose
Movement - for muscle contraction
Active transport
Secretion - ATP is needed to for the lysosomes which are required to secrete cell products
Is water a charged molecule?
Yes dipolar
What kind of bonds do water molecules make?
Hydrogen bonds
As the hydrogens are slightly positive and they can bond with the slightly negative oxygen atoms of other water molecules.
This causes water to stick together
5 roles of water
High specific heat capacity makes it a stable environment for aquatic life
Latent heat of vaporisation - allows sweat to cool us down
Cohesive and surface tension in water - due to strong hydrogen bonds - allows water to be drawn into tubes such as the xylem
Metabolism - used in hydrolysis to break down complex reactions. Water also a major reactant in photosynthesis
Solvent - water readily dissolves other substances
What is an ion?
An atom or group of atoms with a charge
What is an inorganic ion?
An ion that doesn’t contain carbon
Similarities between RNA and DNA?
Both polymers of nucleotides
Both contain phosphodiester bonds
Both contain Adenine, cytosine and guanine
Both contain pentose sugar, nitrogenous base and a phosphate group
Difference between semi conservative and conservative DNA replication?
Conservative suggests that the original DNA molecule is replicated and remains completely intact whilst a daughter molecule with a complete new set of DNA is produced.
Semi conservative suggests that the original DNA molecule is split in 2 separate strands. Which then replicates using complementary base pairs.
This leaves two new molecules each containing half the original parental DNA and half new daughter DNA.
