Difference between Catabolic and Anabolic Pathways
* Catabolic Pathways release energy by breaking down complex molecules into simpler compounds. (eg Glucose catabolism)
* Anabolic Pathways consume energy to build complex molecules from simpler ones. (eg amino acids to proteins)
Exergonic and Endergonic Reactions
* An exergonic reaction proceeds with a net release of free energy and is spontaneous (energy released)
* An endergonic reaction absorbs free energy from its surroundings and is nonspontaneous. (energy required)
Spontaneous Process
* Can occur without net energy input, can occur quickly or slowly.
* During a spontaneous change, free energy decreases and the ...view middle of the document...
* Both strands are complementing to each other.
* Adenine on one strand is always opposite thymine on the other.
* Guanine always lines up opposite cytosine.
* Both strands run in opposite directions.
* They are held together by hydrogen bonds.
RNA
* Nitrogenous bases on RNA undergo hydrogen bonding with complimentary bases on the same strand.
* Can form double helixes and a loop called a hairpin.
* Form tertiary and quaternary structures unlike DNA.
* Very versatile molecule.
Translation: What happens in the ribosome?
* mRNA forms complex with ribosome and first tRNA.
* Anticodon or tRNA pairs with codon on mRNA.
* The second tRNA arrives. A peptide bond forms between first/second amino acid.
* mRNA shifts left and the first tRNA leaves.
* Third tRNA arrives. Peptide bond forms between second/third amino acid.
* mRna shifts leaves and the second tRNA leaves and it continues.
Difference between Hormones and Neurotransmitters
* Hormones are made in specialised organs called endocrine glands
* Hormones are carried by the blood to their target cells (up to 20cm away)
* Neurotransmitters are chemicals made in neurons.
* Neurotransmitters travel very short distances between neighbouring neurons.
DNA REPLICATION
* DNA molecule unwinds into two halves.
* Each strand acts as a template for a complementary strand
* to form.
* Follows the strict rules of base-pairing to form two identical
DNA molecules.
* Involves many enzymes for eg. DNA polymerase
Difference between Two types of chemical messengers:
Primary: they bring the message to the target cell.
Secondary: they pass the message on.
Difference Lysosomes and peroxisomers...
