Cells in many-celled organisms.

Adenine, thymine, cytosine and guanine are ___________________ instructions to cells.

const2013 [10]

DNA is essentially a storage molecule. It contains all of the instructions a cell needs to sustain itself. These instructions are found within genes, which are sections of DNA made up of specific sequences of nucleotides. In order to be implemented, the instructions contained within genes must be expressed, or copied into a form that can be used by cells to produce the proteins needed to support life.

The instructions stored within DNA are read and processed by a cell in two steps: transcription and translation. Each of these steps is a separate biochemical process involving multiple molecules. During transcription, a portion of the cell's DNA serves as a template for creation of an RNA molecule. (RNA, or ribonucleic acid, is chemically similar to DNA, except for three main differences described later on in this concept page.) In some cases, the newly created RNA molecule is itself a finished product, and it serves an important function within the cell. In other cases, the RNA molecule carries messages from the DNA to other parts of the cell for processing. Most often, this information is used to manufacture proteins. The specific type of RNA that carries the information stored in DNA to other areas of the cell is called messenger RNA, or mRNA.

How does transcription proceed?

Transcription begins when an enzyme called RNA polymerase attaches to the DNA template strand and begins assembling a new chain of nucleotides to produce a complementary RNA strand. There are multiple types of types of RNA. In eukaryotes, there are multiple types of RNA polymerase which make the various types of RNA. In prokaryotes, a single RNA polymerase makes all types of RNA. Generally speaking, polymerases are large enzymes that work together with a number of other specialized cell proteins. These cell proteins, called transcription factors, help determine which DNA sequences should be transcribed and precisely when the transcription process should occur.

6 0

3 years ago

What are the components that break down nutrients for absorption in order from simplest to more complex

balandron [24]

Digestive juices break down food into the tiniest nutrient components. Proteins are broken down to amino acids; fats are broken down to fatty acids and glycerol; and carbohydrates are broken down into simple sugars for absorption of these vital nutrients. The animal diet needs carbohydrates, protein, and fat, as well as vitamins and inorganic components for nutritional balance. Digestive enzymes are enzymes that break down polymeric macromolecules into their smaller building blocks, in order to facilitate their absorption by the body.

7 0

3 years ago

I am leaving brainly so free 100 points! I am doing more these so, don't worry if you didn't answer first.

mylen [45]

Answer:

I LOVE YOUUUUU THANK YOUUUU

have a blessed day omg thank you SO MUCHHHH

Explanation:

6 0

3 years ago

Read 2 more answers

As distance west of kilauea increases the size of the islands generally appears to decrease. What is likely the reason for this

MakcuM [25]

The reason is two fold, the first is the active volcano of Kilauea implies there is a lot of heat under the big island of Hawaii, and that heat causes the island to be buoyed up. However, the other islands do not have active volcanos, are colder, and have subsided, the 2nd is, because the volcanoes on the older islands are dormant, those islands are and are no longer growing and are steadily eroding away.

4 0

3 years ago

Read each of the sentences that describe what happens either during mitosis or meiosis. Drag each sentence into the correct box.

kiruha [24]

Answer:

MEIOSIS:

- Each replicated chromosome pairs with its corresponding homologous chromosome

- Tetrads form and crossing over sometimes occur

- Paired homologous chromosome line up across the center of the cell.

- Four haploid daughter cells form that are not identical to the parent cell

MITOSIS:

- Homologous chromosomes do not pair

- One row of chromosomes line up at the center of the cell.

- The cell nucleus divides only once

- Two diploid daughter cells form that are identical to the parent cell.

Explanation:

Mitosis and Meiosis are the two cellular divisions that occur in living organisms. Mitosis is the kind of cell division that produces two diploid daughter cells that are genetically identical to the parent cell while Meiosis produces four haploid daughter cells (gametes) that are genetically different from the parent cell.

Based on the general description of the two cell divisions above, the following events take place in them respectively:

1) MEIOSIS:

- Each replicated chromosome pairs with its corresponding homologous chromosome (similar but non-identical chromosome from each parent).

- Tetrads form and crossing over sometimes occur. Tetrads are the structures that form when two homologous chromosomes pair while crossing over is the exchange of chromosome segment between two non-sister chromatids of homologous chromosomes. These two only occur during meiosis.

- Paired homologous chromosome line up across the center of the cell during metaphase I of meiosis.

- Four haploid daughter cells form that are not identical to the parent cell. Note that meiosis reduces the chromosomal number of the parent cell by half.

2) MITOSIS:

- Homologous chromosomes do not pair during mitosis.

- One row of replicated chromosomes (sister chromatids) line up at the center of the cell during metaphase.

- The cell nucleus divides only once in mitosis as opposed to twice during meiosis.

- Two diploid daughter cells form that are identical to the parent cell. Note that mitosis retains the chromosomal number of the parent cell.

4 0

3 years ago