Many people know that DNA is the molecule of heredity and that each human's DNA is unique, but how does DNA encode for the proteins that may be unique? This is much more complex concept that fewer people understand. Let's look closely at how your sequence of DNA can create the proteins that are essential to building you and your phenotype. DNA is a double-helix that has base pairs facing the interior of the molecule, and it is the carrier of genetic information within each cell. The sequence of nucleotides contains nitrogenous bases, adenine, thymine, cytosine, and guanine, and is unique to each individual. It is the order of these bases that carries the information to build proteins. 0:00:58.3: In order to synthesize proteins, DNA must send a code to the ribosomes, which are in the cell's cytoplasm. Since DNA does not leave the nucleus of eukaryotic cells, it must have its code copied so that the message can leave the nucleus. This process is called transcription. On the double-stranded DNA, one of the sides is considered the template for a gene. The double-stranded DNA will open up and RNA polymerase will build an RNA template based on the order of the DNA nucleotides. As shown here, the order of the RNA bases is determined by the DNA sequence. 0:01:46.5: TAC, on the DNA template, causes the RNA sequence of AUG to be synthesized. The completed molecule of RNA can leave the nucleus and travel to the cytoplasm. This molecule is called messenger RNA or mRNA for short. The process of translation is where the mRNA is used to build a protein. Shown here is a ribosome made of a large and a smaller sub-unit. It's reading the mRNA. Three bases on the mRNA strand are called a codon. The ribosome reads the mRNA 3 bases at a time. The first codon is AUG, which is the start codon. A tRNA molecule, shown on the left of the image, brings an amino acid to the ribosome. The amino acid that is brought to the ribosome is specific to which codon is being read by the ribosome. For example, if AUG is the codon being read by the ribosome, methionine is the amino acid that is brought to the ribosome. The process of translation continues as the next three bases or codon is read by the ribosome. The next amino acid will be brought by a tRNA or transfer RNA molecule. The next amino acid will be bonded to the first amino acid with a peptide bond. 0:03:24.6: The process continues as the ribosome continues to translate the next three bases on the mRNA, causing the protein to grow. The process of elongation during translation continues until a stop codon is reached by the ribosome. The genetic code is universal for organisms on earth, meaning that the same codon codes for the same amino acids for all cells during the process of translation. As shown here, AUG is the only codon that codes for the amino acid methionine. UGG is the only codon that codes for tryptophan. Other than those two amino acids, all other amino acids can be coded by multiple codons. This allows for some redundancy in the genetic code. Let's check your knowledge. If the ribosome encounters the codon CCA, which amino acid will be brought to the ribosome and added to the growing polypeptide chain? 0:04:37.1: CCA codes for proline. Using this codon chart, anyone can translate the genetic code if given a linear sequence of mRNA. Since the process of translation is universal for life on earth, all organisms will build proteins using the same key shown here. This is one of those fundamental processes shared by all life on earth, and now you have the ability to decode the genetic code, and you can translate an mRNA molecule just like a ribosome.

Question

DNA is made of four different bases: _______, _______, _______, and ______.
Responses
A A. B. C. DA. B. C. D
B A, C, G, TA, C, G, T
C A, C, G, UA, C, G, U
Question 2
Are humans genetically similar to chimpanzees?
Responses
A YesYes
B NoNo
Question 3
In terms of DNA. one living organism is different from another because of the order of the ____________________ in the genetic code.
Responses
A chromosomeschromosomes
B nitrogenous basesnitrogenous bases
C DNA and RNADNA and RNA

Answer 1

Here are the answers to your questions based on the information provided:

Question 1:
DNA is made of four different bases: Adenine, Thymine, Cytosine, and Guanine.
So the correct fill-in would be: A, T, C, G.

Question 2:
Are humans genetically similar to chimpanzees?
A. Yes (Humans and chimpanzees share about 98-99% of their DNA.)

Question 3:
In terms of DNA, one living organism is different from another because of the order of the nitrogenous bases in the genetic code.
So the correct answer is: B. nitrogenous bases.