Answer:
about 5 billion years ago
Explanation:
Our solar system formed about 5 billion years a go from a dense cloud of interstellar gas and dust.
That would be the Endoplasmic Reticulum my good friend hope this helped... :D
3A)Amino acids-peptide
3B)Enzymes–speed up
3C)Active sites–substrate
3D)Unchanged
3E)[follow the instructions given]
4A)DNA—RNA
4B)Nucleotide—Deoxyribose–Phosphate–Nitrogen base
4C)DNA
4D)Thymine–Adenine—Cytosine–Guanine
4E)Hydrogen bonds
Phosphorus. It's not abundant, but it's important. There are traces of it in our bones and in the "phospho-lipid bilayer" of the membrane.
Hope that helps!
Answer:
Explanation:
The main function of the plasma membrane is to protect the cell from its surroundings. Made of a phospholipid bilayer with embedded proteins, the plasma membrane is selectively permeable to ions and organic molecules it also regulates the movement of substances in and out of cells. Plasma membranes must be very flexible in order to allow certain cells, such as red blood cells and white blood cells, to change shape as they pass through narrow capillaries. Membrane receptors provide extracellular attachment sites for effectors like hormones and growth factors, which then trigger intracellular responses. Some viruses, such as Human Immunodeficiency Virus (HIV), can intercept these receptors to get into the cells, causing infections.