Enzymes catalyze reactions by lowering the activation energy of the reaction. Enzymes are made of proteins, and therefore the answer here is B. Protein molecules.
Answer:
Prions causes abnormal folding of the prion proteins in the brain.
Explanation:
Prions are the abnormal infectious agents composed only of the proteins and no nucleic acids. The prions cause several neurodegenerative diseases in the humans as well as the mammals.
The prions cause the cow mad disease in the cows by affecting the brain of the cow as the prions act on the prion proteins present in the brain only and change their conformation. This leads to the degeneration of the neurons and causes tiny pores in the brain giving sponge-like appearance.
This slows down the mental activity and thus ultimately leads to the death of the cow.
[No image given – I found the
attached image in other source]
From right to left.
1) Cytokinesis is almost
finished, so it’s the end of Telophase
2) The chromatids have just
split up and are migrating to each pole, so it’s Anaphase
3) All chromosomes are in the
equatorial plane, so it’s the end of Metaphase
4) The chromosomes are in the
poles and cytokinesis has just started, so it’s the beginning of Telophase
5) The spindle apparatus is
complete and the chromosomes are moving to the equatorial plate, so it’s the
beginning of Metaphase
6) The spindle apparatus is forming,
so it’s Prophase
If you want to put them in
chronological order, it’s like this:
6-5-3-2-4-1
Answer:
Substitution, missense mutation
Explanation:
Mutation is a change in the DNA sequence that can subsequently alter the genetic message.
Substitution mutations occurs when a base is replaced with another different base.
A good example is the one given in the question where the third A in the sequence ACAAAC is replaced by a T.
If this kind of mutation occurs in a protein-coding gene, it will be classified as a frameshift mutation.
Missense mutation is caused when there is a change in a single nucleotide that results to the coding of a different Amino acid
Answer;
Acetylcholine.
Nicotine mimics the action of neurotrasmitter acetylcholine.
Explanation;
Many drugs interact with receptors to either activate them or prevent their activation by their normal neurotransmitters. The drug nicotine mimics the action of acetylcholine at the nicotinic acetylcholine receptors.
