Answer:
1. While Biology is the study of living things, living things themselves are made up of chemical composition. Our survival is dependant on the reactions taking place inside and outside the body. Hence, to understand living things, biologists needs a good understanding of chemistry.
2. 170 pm is the radius of a Carbon Atom.
3. The vast majority of the mass of an atom is concentrated in its nucleus
4. Protons are found in the nucleus of the atom. This is a tiny, dense region at the center of the atom. Protons have a positive electrical charge of one (+1) and a mass of 1 atomic mass unit (amu), which is about 1.67×10−27 kilograms.
5. Neutrons are located with protons in the nucleus; they too exchange mesons with protons and with each other to form the strong nuclear force, but they do not have to overcome the repulsion from Coulomb forces since neutrons are not charged.
Answer:
We mean that a cell changes to another type of cell.
Explanation:
<em>Stem cells </em>are a type of cell that has the potential to become a specialized cell, this change or differentiation, is possible thanks to the activation or deactivation of certain genes that promote (or inhibit) the expression of certain proteins that origins different types of cells (fmuscle cells, osteocytes, neurons). This differentiation happens when the cells receive cues internally ( through signals or contact between a group of cells and another or through transcription factors) or externally.
Then, a differentiated cell is a cell that had gone under the previously described process.
I hope this information is useful to you!
Answer:
Channel proteins and Carrier proteins
Explanation:
These are type of membrane proteins that transcend the entire length of phosphoslipid bi- layer in the plasma membrane.They facilitate the movement of ions and molecules across the walls of the plasma membranes.
Generally, substances like glucose, amino acids, are too large to pass through the phopholipid bilayers. Likewise ions of potassium, sodium calcium, because of their polarities can not pass through either. They are ferried across the phospholipid by group of protein structures called channel proteins. Some are also transported across by carrier proteins. The process by which these protein structures aided the diffusion of substances across the phospholipid bilayer is called Facilitated diffusion.
Channel proteins are pores, that are filled with water molecules with the entrance well gated. That is the entrance is controlled by part in the inner structure of the protein which can open or close the pores like a gate to control the movement of ions across it. e.g Sodium channels are gated for movement of sodium ions by voltage or ligands(chemicals) during nervous transmission to elicits action potential. Like wise Potassium channels allow diffusion of potassium ions across the phospholipid bilayers. it gates are shut when sodium channels are open; this regulate ion exchange.
Their structures are well fixed in shape , specific to the substance or ions being transported;and the rate of diffusion depends on the like hood of opening of the gate or closure.
Carrier molecules also in the membranes do not have a fixed shape, and their transport direction is determined by the direction of concentration gradients. Thus they can flip on either sides of the membranes to aid diffusion across. Their movement can be both passive and active, and the rates of diffusion depends on the number of available carrier proteins in the membrane. They are also specific to the ions they transport.And are not gated,
Therefore these two membrane integral proteins facilitate movements of substances across the phospholipild bilayers
