Your+Cells,+My+Cells,+Everybody's+Cells+2

=The Cell - Part 2 =


 * ===__How and Why do cells grow?__ === || .... || media type="youtube" key="DSBzJVt8Lks" width="425" height="350" || .... ||  ||
 * ====**1. How does a caterpillar turn into a butterfly, and how does this relate to cells?** ====
 * ====**1. How does a caterpillar turn into a butterfly, and how does this relate to cells?** ====

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||  || A caterpillar, when it is fully grown, secretes a long stream of liquid from its glands, called the spinneret, located below its mouth. The liquid stiffens forming a silk like thread which is used to attach its hind end to a twig or leaf. The caterpillar spins the silky thread around its body to form a covering. This outside layer hardens to form a shell called a chrysalis. Inside the cocoon the caterpillar changes into a pupa. In a process called histolysis, the caterpillar digests itself from the inside out, causing its body to die. During this partial death, some of the caterpillar's old tissues are salvaged to form new. This remnant of cells are called the histoblasts and are used to create a new body. Using its digestive juices, the caterpillar turns his old larval body into food which he uses to rebuild its new body. Once the pupa has fully grown inside the cocoon, and the butterfly is ready to emerge, the insect releases a fluid which softens the shell. The butterfly pushes on the walls of the shell until it breaks open. The process of a caterpillar turning into a butterfly can take anywhere from 10 days to several months.

**Link to this text: ** [] ||  ||  || The process of cell reproduction has three major parts. The first part of cell reproduction involves the replication of the parental cell's [|DNA]. The second major issue is the separation of the duplicated DNA into two equally sized groups of [|chromosomes]. The third major aspect of cell reproduction is the physical division of entire cells, usually called [|cytokinesis]. Cell reproduction is more complex in [|eukaryotes] than in other organisms. [|Prokaryotic] cells such as [|bacterial] cells reproduce by [|binary fission], a process that includes DNA replication, chromosome segregation, and cytokinesis. Eukaryotic cell reproduction either involves [|mitosis] or a more complex process called [|meiosis]. Mitosis and meiosis are sometimes called the two "[|nuclear] division" processes. Binary fission is similar to eukaryotic cell reproduction that involves mitosis. Both lead to the production of two daughter cells with the same number of chromosomes as the parental cell. Meiosis is used for a special cell reproduction process of [|diploid] organisms. It produces four special daughter cells ([|gametes]) which have half the normal cellular amount of DNA. A [|male] and a [|female] gamete can then combine to produce a [|zygote], a cell which again has the normal amount of chromosomes. The rest of this article is a comparison of the main features of the three types of cell reproduction that either involve binary fission, mitosis, or meiosis. The diagram below depicts the similarities and differences of these three types of cell reproduction.
 * ====**2.How do cells reproduce to form from one cell to millions?** ==== ||  || Cell reproduction is [|asexual]. For most of the constituents of the cell, growth is a steady, continuous process, interrupted only briefly at [|M phase] when the nucleus and then the cell divide in two.
 * ====**2.How do cells reproduce to form from one cell to millions?** ==== ||  || Cell reproduction is [|asexual]. For most of the constituents of the cell, growth is a steady, continuous process, interrupted only briefly at [|M phase] when the nucleus and then the cell divide in two.

**Link to this text:** [] ||  ||  || . . . . . . . . . . . . . ||  || **Deoxyribonucleic acid** (**DNA**) is a [|nucleic acid] that contains the [|genetic] instructions used in the development and functioning of all known living [|organisms] and some [|viruses]. The main role of DNA [|molecules] is the long-term storage of [|information]. DNA is often compared to a set of [|blueprints] or a recipe, or a code, since it contains the instructions needed to construct other components of [|cells], such as [|proteins] and [|RNA] molecules. The DNA segments that carry this genetic information are called [|genes], but other DNA sequences have structural purposes, or are involved in regulating the use of this genetic information. Chemically, DNA consists of two long [|polymers] of simple units called [|nucleotides], with backbones made of sugars and phosphate groups joined by [|ester] bonds. These two strands run in opposite directions to each other and are therefore [|anti-parallel]. Attached to each sugar is one of four types of molecules called [|bases]. It is the sequence of these four bases along the backbone that encodes information. This information is read using the [|genetic code], which specifies the sequence of the [|amino acids] within proteins. The code is read by copying stretches of DNA into the related nucleic acid RNA, in a process called [|transcription]. Within cells, DNA is organized into structures called [|chromosomes]. These chromosomes are duplicated before cells [|divide], in a process called [|DNA replication]. [|Eukaryotic organisms] ([|animals], [|plants], [|fungi], and [|protists]) store their DNA inside the [|cell nucleus], while in [|prokaryotes] ([|bacteria] and [|archaea]) it is found in the cell's [|cytoplasm]. Within the chromosomes, [|chromatin] proteins such as [|histones] compact and organize DNA. These compact structures guide the interactions between DNA and other proteins, helping control which parts of the DNA are transcribed.
 * ====**3. What is DNA?** ====
 * ====<span style="color: rgb(255, 0, 0); background-color: rgb(113, 249, 113);">**3. What is DNA?** ====

<span style="color: rgb(255, 0, 0); background-color: rgb(113, 249, 113);">**<span style="color: rgb(144, 9, 144); background-color: rgb(255, 255, 0);"><span style="color: rgb(255, 0, 0); background-color: rgb(113, 249, 113);">Link to this text: ** [] ||  ||  || Learning By Mrs. Gratton
 * ====**<span style="color: rgb(255, 0, 0); background-color: rgb(113, 249, 113);">Links to our other pages: <span style="background-color: rgb(255, 255, 255);"> **====
 * ====**<span style="color: rgb(255, 0, 0); background-color: rgb(113, 249, 113);">Links to our other pages: <span style="background-color: rgb(255, 255, 255);"> **====

Your Cells, My Cells, Everybody's Cells

Your Cells, My Cells, Everybody's Cells 3

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<span style="color: rgb(255, 255, 255); background-color: rgb(255, 255, 255);">**<span style="color: rgb(255, 0, 0); background-color: rgb(113, 249, 113);">by Laura Utner and Shannon Schoettle **
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