They are composed of many different things. Structurally, they are each made up of two chromatids connected by a centromere. It is also made up of DNA(deoxyribonucleic acid), which is our genetic material.
Answer:
Cell wall
only plant cells contain a cell wall
Answer and Explanation:
A gene is a section of DNA. The change in the sequence of the DNA is known as mutation. Mutation always changes the sequence of the DNA. Sunlight can cause mutation. Sunlight produces structures named thymine dimers. Thymine dimers produce twist in the shape of DNA. These twists make DNA hard to copy, which can lead to mutation. It is essential to use sunscreen to block UVA and UVB rays to prevent thymine dimers from emerging in our cells. The US Food and Drug Agency recommends an SPF (sun protection factor) to defend against skin aging and skin cancer. X-ray radiation is a form used in x-rays. The energy level of the X-ray radiation is very high that can produce free radicals. Free radicals can steal electrons from DNA that can cause mutation. By using medical images, we can decrease exposure to X-rays. Less exposure to X-rays prevents mutation and also prevents the production of gene protein in other body parts.
Three lines of evidence that support the endosymbiotic theory:
1. The presence of membrane- Organelles like mitochondria and plastids have their own cell membranes, just like a prokaryotic cell does,
2. The presence of DNA- Each of these organelles have its own DNA genome, like a bacteria's genome, but much smaller.
<span>3. Reproduction (division)-Multiplication of the organelles occurs just like in bacteria, by division.</span>
