DNA

Page history last edited by KaiY 3 years, 2 months ago

Deoxyribonucleic acid

DNA,or deoxyribonucleic acid, resides within the cells of every living organism. It consists of four main bases:adenine, guanine, thymine, and cytosine. It is structured as a double-helix spiral made of carbon,oxygen,hydrogen,nitrogen, and phosphorus. Within it, the four bases connect with each other:adenine with thymine and guanine with cytosine. DNA holds the information for cells to create proteins, grow, maintain itself,reproduce,and replicate.

How DNA replicates:

DNA replicates in a process called...replication. Pretty,original,huh? Anyway,a single strand of DNA "unzips" itself-it gets cut in half.Then, free-floating nucleotides/bases join with the pieces of DNA. As DNA is enclosed within the nucleus, the nucleotides can only connect to DNA.After both strands of DNA are created,the DNA spins itself back into chromosomes.

What is RNA?

RNA, or ribonucleic acid, is a reverse copy of a portion of DNA. RNA is used in protien synthesis to copy information from DNA as DNA cannotactually replicate protiens: it is enclosed within the nucleus. It has the exact same bases, except for thymine which it replaces for uracil.there are three types of RNA: messenger ribonucleic acid, transfer ribonucliec acid, and ribosomal ribonucleic acid. Messenger RNA transcribes a portion of DNA.Transfer RNA connects to mRNA after having found the correct amino acid.Later, a ribosome slides down the strand, connecting the amino acids.WIthin it, rRNA resides allowing the amino acids to connect.

Mitosis & mieosis:

Mitosis:the process in which a parent cell splits to become two daughter cells (diploid).

grow phase: In order to prepare for mitosis,the cell increases its mass while carrying out its normal functions.This stage is not actually part of mitosis.
interphase: DNA has replicated,but strands are not in chromosome form(see above).
prophase: the strands of DNA have become chromosomes.
metaphase: centriols connect to chromosomes with spindle fibres;chromosomes move to the center of the cell.
anaphase: the chromosomes are yanked apart into identical chromatids.
telophase: two membranes envelope all chromatids;spindle fibres dissolve.
cytokinasis: the cell splits apart-each new cell has the same genetic content. To see more,visit Mitosis

Mieosis:the process in which a cell goes through cell division twice to produce four cells (hapliod).

Interphase: the DNA has replicated.
prophase 1: DNA has become chromosomes and, in turn, chromosomes have become tetrads (basically, a double chromosome wall.).
metaphase 1: spindle fibers have connected to tetrads which are moving to the center of the cell.
anaphase 1: the tetrads are pulled apart and are becoming chromosomes again.
telophase 1: membranes have enclosed the chromosomes; spindle fibers have dissolved.
cytokinasis 1: cell splits into two,both cells go directly to prophase 2; skipping interphase.
prophase 2: the chromosomes have moved to the center of the cell.
metaphase 2: centriols connect to chromosomes with spindle fibers.
anaphase 2: chromosomes are pulled to opposite ends of the cell, then are yanked into chromotids.
telophase 2: as fibers dissolve, two membranes cover the chromatids.
cytokinasis 2: the cells divide.Inside a male, all will be sperm.Inside a female, at least one will be an egg- the rest will be polar cells.To see more,visit Meiosis.

tRNA

Protien synthesis:protien creation

Since DNA cannot actually create protiens ,RNA (see above)does the work.
In a process called transcription, DNA "unzips" aportion of itself-the protien which is to be replicated.Then,mRNA matches up to the open section of DNA.This process may be repeated many times.After this, the portion closes.
tRNA gathers amino acids.After this, it travels to the ribosome in which the mRNA has already migrated tofrom the nucleus.
The tRNA connects to the mRNA.
A ribosome connects to the now complete strand.It travels down the strand, connecting the amino acids into a chain with the help of rRNA(in case you don't know, protiens are a chain of connected amino acids.).This process may also be repeated after tRNA has connected back to mRNA with another amino acid. To see more, visit Protein Synthesis

Important terms:

DNA:see deoxyribonucliec acid

RNA:see ribonucleic acid

mRNA:see message ribonucleic acid

rRNA:see ribosomal ribonucleic acid

tRNA:see transfer ribonucleic acid

Amino acids:molecules that contain the elements carbon, oxygen, hydrogen, nitrogen, and (sometimes)sulfur.

Protiens:a molecule made of chains of amino acids.

Mitosis:the phase during a cell cycle in which the nucleus divides.

Meiosis:the process in which a cell divides into haploid cells/gametes.

Chromosomes:the physical structure within a cell containing that cell's genetic material.

Chromatids:to put it bluntly- half a chromosome with equalinformation to its "twin."

Tetrads:Chromosomes tangled in a web two chromosomes thick.

Deoxyribonuceic acid:the genetic material found in every living cell that has the information needed for a cell to grow, live, and reproduce.

Transfer ribonucleic acid:ribonucleic acid that "finds" amino acids.It's appearance is of three nucleotides attatched to a single sugar base.

Message ribonucleic acid:ribonucleic acid that that copies a information off doexyribonucleic acid.

Ribosomal ribonucleic acid:ribonucleic acid found within a ribosome-it connects amino acids together in protien synthesis.

Haploid cells:see gametes

Diploid cells:any type of regular cell with a regular amount of chromosomes.

Gametes:a sperm, egg,or polar cell containig half the usual amount of chromosomes of an organism.Gametes are found only in the reproductive organs of a organism.

Fun facts:

We share approximately 50% of our DNA with a banana.
When stretched out and put end to end, our DNA could reach the sun600 times.
DNA usually twists to the right.
A nucleoside is a base and a sugar.A nucleotide has this and a phosphate.
Red blood cells hacve no DNA.
mtDNA is found in mitochondria- they have different DNA!
A gene takes up 10,000 to 15,000 bases.
Genes are made of extrons and introns-extrons are the information, introns are the "jump"in between them. Introns are sometimes called 'junk DNA" because they have no known purpose.
Unravel a cell's DNA-it will be approx. 6ft. wide...and 50 trillionths of an inch long!
An mb-or megabase(one million DNA bases) fills about one megabyte of computer space.
Over 99% of our DNA has no known purpose.