The correct answer is: B) G1
Normal cells (unlike cancer cells), move through the cell cycle in a regulated way in order to make sure that cells don't divide under conditions that are unfavorable for them. Information about their own internal state (nutrients, signal molecules, DNA integrity) is signal to go or not to go through the cell division. Because of that there are few checkpoints in the cell cycle at which the cell examines the signals and makes a “decision”. The major checkpoints are:
• The G1- the first point at which it must choose, once it passes the G1 checkpoint the cell enters S phase
• The G2-the cell checks DNA integrity and checks if replication is done well.
• The spindle checkpoint-at the transition from metaphase to anaphase.
Answer:
1. The prosthetic group of hemoglobin and myoglobin is heme.
2.The organic ring component of heme is porphyrin ring.
3. Under normal conditions, the central atom of heme is Iron (Fe2+).
4. In deoxyhaemoglobin the central iron atom is displaced 0.4 A out of the plane of the porphyrin ring system.
5.The central iron atom has six bonds: four to nitrogen atoms in the porphyrin, one to a histidine residue and one to oxygen.
Explanation:
1. The heme is the prosthetic group common to both the hemoglobin and myoglobin. It is made up of a central iron ring.
2. The porphyrin ring is the organic component of the heme that surrounds the iron ring. Its based on a tetrapyrole ring called porphin commonly found in other biomolecules such as cytochrome and chlorophyll in plants
3. Iron (Fe2+) is central to the heme structure. It has the ability to bind to an oxygen molecule at a time. This gives the protein- hemoglobin the ability to bind to 4 oxygen molecules at a time.
4. Deoxyhaemoglobin is simply a reduced form of hemoglobin which has lost oxygen molecule in red blood cells. It is purple blue in colour.
5. In the middle of the porphyrin ring, the iron binds to 4 nitrogen atoms. 2 free binding sites are available on either side of the plane heme structure with histidine surounding the heme molecule.
Answer:
Prokaryote
Explanation:
The kingdom Eukaryota has a nuclear envelop or a nuclear membrane while the kingdom prokaryote doesnt, this is common knowledge
Answer: C: Contain chloroplast that perform photosynthesis.
Explanation: Process of elimination deems C correct!
Answer:
Mandibular Fossa occurs on temporal bone.
Explanation:
Mandibular fossa also known as glenoid fossa, the depression of temporal bones. Mandibular fossa articulates with the mandible and interacts with mandibular condyle. Glaserian fissure divides the mandibular fossa into two parts.
Articular tubercle bounds the mandibular fossa anteriorly. The mandibular fossa is bounded posteriorly by the temporal bone. Mandibular fossa development may get arrested due to the separation of mandibular condyle.
