Topic 1B: More Biological Molecules Flashcards
What is the function of DNA?
To store all of your genetic information.
What is the function of RNA?
To transfer genetic information from DNA to the ribosomes.
What is the structure of nucleotides?
Made of a pentose sugar, a nitrogen containing organic base, and a phosphate group.
What are nucleotides?
The monomers which make up DNA and RNA.
What is the structure of polynucleotides?
Many nucleotides are joined together by phosphodiester bonds (which form between the pentose sugar and phosphate group of another nucleotide) produced in condensation reactions.
What is the structure of a DNA nucleotide?
A deoxyribose, phosphate group and a nitrogen-containing organic base: Adenine Thymine Cytosine Guanine
What is the structure of DNA?
DNA has a double helix structure made of anti parallel strands of polynucleotides, which are joined by hydrogen bonds which form between complementary bases.
Which bases pair together?
Cytosine and guanine are joined together by 3 hydrogen bonds.
Adenine and thymine are joined together by 2 hydrogen bonds.
What is the structure of an RNA nucleotide?
A ribose, phosphate group and a nitrogen-containing organic base: Adenine Uracil Cytosine Guanine
What is the structure of RNA?
A short singular polynucleotide strand.
What is the process of DNA replication?
1) DNA helicase breaks hydrogen bonds between bases on the two polynucleotide DNA strands.
2) This causes the helix to unwind and form two single strands which act as templates for new strands to form.
3) Complementary base pairing occurs with free DNA nucleotides matching up to their complementary exposed bases.
4) DNA polymerase catalyses condensation reactions, which joins together the free nucleotides.
5) Hydrogen bonds form between bases on the original and new strands to produce two new DNA molecules.
How does DNA polymerase function?
DNA polymerase moves down the template strand in a 3’ to 5’ direction, meaning in a double helix it works in opposite directions on each strand.
Evidence for the semi-conservative replication theory: Meselson and Stahl’s experiment.
1) Two samples of bacteria are grown for many generations - one in a nutrient broth containing light nitrogen and one in a broth containing heavy nitrogen.
2) DNA from each bacteria were spun in a centrifuge, with DNA from the heavy nitrogen bacteria settling lower down the centrifuge tube than the DNA from the light nitrogen bacteria.
3) The DNA from the heavy nitrogen broth were then moved to a light nitrogen broth and left to replicate.
4) DNA from this bacteria sample were spun in the centrifuge.
5) Because DNA replication is semi-conservative, this DNA contains one strand of heavy DNA and one strand of light DNA.
6) Because of this, the DNA settled in between both of the old samples
What is the structure of ATP?
ATP is made of an adenine base, a ribose sugar and 3 phosphate groups which are held together by phosphate bonds.
How is ATP created?
ATP synthase catalyses a condensation reaction between ADP and an inorganic phosphate to form a phosphate bond.
How is ATP used?
ATP hydrolase catalyses a hydrolysis reaction in ATP to break a phosphate bond and produce ADP and an inorganic phosphate.
Why is water so important?
- It is an important metabolite involved in hydrolysis and condensation reactions.
- It is a good solvent allowing organisms to take up useful substances.
- It buffers changes in temperature to help organisms maintain a constant internal body temperature.
- It is very cohesive helping water to flow, allowing plants to transport substances.
What is the structure of water?
A molecule made up of one oxygen atom and two hydrogen atoms.
Why is a water molecule polar?
Electrons in the hydrogen atom are pulled towards the oxygen atom, meaning the opposite side is more positively charged. Therefore, the other side of the oxygen atom is more negatively charged.
How are water molecules held together?
Weak hydrogen bonds form between the slightly positively charged side of the hydrogen atom and the slightly negatively charged side of the oxygen stoke of another molecule.
What is an ion and what are the different types of ions?
An ion is an atom which has an electric charge.
Cation = an ion with a positive charge. Anion = an ion with a negative charge.
What are inorganic ions?
An ion which doesn’t contain a carbon and has a specific role depending on its properties.
What are the adaptations of a DNA molecule?
Long:
Able to code for many amino acids.
Double helix:
Makes the molecule more compact so that it can store more information.
Strong backbone:
Means chemicals are unable to reach the bases inside.
Hydrogen bonds:
Allows it to be broken down easily for DNA replication.
