Chapter 2: Nucleic acids Flashcards
DNA has a double helix structure and carries…
Genetic information
A nucleotide is made up of:
- Pentose sugar
- Phosphate group (deoxyribose for DNA)
- Nitrogen-based organic group
The five nitrogen-based organic groups are:
Adenine, Cytosine, Guanine, Thymine and Uracil
Uracil and Thymine are used by which nucleic acid?
RNA uses Uracil
DNA uses Thymine
The phosphate group, pentose sugar and organic base are bonded through which reaction and to make what?
- Condensation reaction
- To make a mononucleotide
Two mononucleotides can join together through what reaction to make what kind of bond?
- Condensation reaction
- To make a phosphodiester bond
The base groups used for RNA are:
Adenine, Guanine, Cytosine and Urasil
DNA is a stable structure because of?
(Two things)
- The phosphodiester bond protects the chemically active base groups in the double helix
- The hydrogen bonds
Why is a DNA structure more stable the more C-G pairs it has?
The C-G pair has three hydrogen bonds which adds more stability than the A-T pair
Cell division occurs in two main stages:
- Nuclear division (Mitosis, meiosis)
- Cytokinesis ( where the whole cell divides_
The four requirements for semi-conservative replication are:
- All base pairs
- The enzyme DNA polymerase
- A source of chemical energy
- Both strands of the DNA molecule
The two enzymes used in DNA replication are and their functions?
- DNA helicase which breaks apart the strands into two
- DNA polymerase which rebinds the strands together
What does DNA helicase do? (Cause and effect)
It breaks apart the hydrogen bonding between the base pairs
This unwinds the double helix into two separate strands
What happens after the helicase unwinds the strands?
The polynucleotide strand acts as a template for free nucleotides to attach to their complementary base pairing.
What is the protein associated with DNA in a chromosomes
Histones
What is a pentose sugar in a DNA called?
Deoxyribose
How is DNA replicated?
By semi-conservative replication
Be sure to remember all the steps
Why are the strand anti-parallal in Semi-conservative replication?
Why are the strands anti-parallal in Semi-conservative replication?
Because the polymerase can only add a monomer to the 3’ carbon because of its free OH ion
If you wanna know why, ask God
Why does ATP have low activation energy
For hydrolysis of ATP
Because the phosphate ions are unstable so requires low energy to remove
Only the terminal phosphate is removed
This creates ADP, Phosphate ion and energy
Why is ATP better than glucose
ATP releases small amounts of energy so no energy is wasted and cells don’t overheat
Unlike glucose which gives more energy than needed so energy is wasted
Five reasons why water is essential
- Metabolite
- Specific latent heat
- Specific heat capacity
- Cohesion
- Universal solvent
Also that it is transparent so good for underwater photosynthesis
Why is water’s specific latent heat important for organisms?
It takes a lot of energy to change the state of water. It’s good because sweating cools you down because it uses your heat energy
Why is water’s specific heat capacity important for organisms?
It takes a lot of energy to change the temperature so it makes a good buffer for enzymes
Why is water being a universal solvent important for organisms?
Lots of polar molecules can dissolve in water:
- Gases
- Wastes (ammonia and urea)
- Inorganic ions + small molecules (amino acids, monosaccharides, ATP)
- Enzymes
Why is water’s cohesion good for organisms?
It’s tension allows it to go up the xylem vessels and act as a skin for small organisms
This is mad epossible by the strong hydrogen bonds
Why is water being a metabolite important for organisms?
- It is used in hydrolysis and condensation reactions.
- Chemical reactions take place in aqueous medium
- Water is important for photosynthesis
Second bullet point iss why 90% of our cytoplasm is water
Why is water’s transparancy important for organisms?
Its transparancy allows underwater photosynthesis to happen and also allows light to enter our retina
