The characteristic feature of the semi-conservative replication of DNA is formation of the leading strand and the lagging strand. DNA polymerases are the enzymes that can add nucleotides to the 3 ' end of the DNA strand only. A DNA double helix is anti-parallel in which one strand runs from 5 ' to 3 ' and the other from 3 ' to 5 ' direction. On the strand having a primer with a 3 ' end, the synthesis of DNA is continuous and forms the leading strand. On the other strand, DNA fragments called Okazaki fragments are produced with multiple RNA primers. It is called the lagging strand. The enzyme DNA ligase joins these Okazaki fragments on the lagging strand. Thus, any defect in the enzyme will affect the lagging strand only and not the leading strand as it does not have any Okazaki fragments.
Answer:
True
Explanation:
The plasma membrane does not allow the charged and polar substances to cross through its inner core that is made up of non-polar fatty acid tails of the phospholipids. Therefore, membrane proteins serve as transport proteins. Some of the transport proteins allow the movement of substances down the concentration gradient without any energy input. This passive movement of substances via membrane transport proteins is called facilitated diffusion.
Carriers and channels are the membrane proteins that facilitate the diffusion of substances. Carrier proteins pick the substances from one side of the membrane and undergo a change in shape to deliver the substance on the other side. Channel proteins make a passage for the movement of substances. Examples: aquaporins, ion channels.
Answer:
The correct answer is - stem cells.
Explanation:
Stem cells can give rise to all tissues and organs in the body. These cells can differentiate into any form of cells, which allows them to repair tissues that have been damaged by various physiological or natural ways
There are two types of stem cells: Adult Stem Cells and Embryonic stem cells.
Cells that are present in the bone marrow or umbilical cord of a newborn baby and can be divided as Hematopoietic, a cell that can form blood cells and the immune system, and mesenchymal that form the body's cartilage, bones, muscles and other.
Embryonic stem cells are found on at blastocyst stage of embryo. These cells can transform into any type of tissue in the human body, which increases their treatment potential.
Answer:
Advantage
1)Faster and more certain method of propagation.
2)Quicker and more certain.
3)Produces identical quality as the parent.
4)Plants that do not have viable seed, can be reproduced.
5)Flowers produced are of superior quality.
Disadvantages
1Does not produce new variety.
2Leads to overcrowding around the parent plant.
3Very little possibility of dispersal.
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Talc is the only mineral that can be scratched with a fingernail.