DNA Structure
What does DNA stand for?
Deoxyribonucleic acid.
Which DNA base pairs with adenine?
Thymine
What is DNA replication?
The process by which a DNA molecule makes a copy of itself.
What does RNA stand for?
Ribonucleic acid.
What is a gene?
A segment of DNA that codes for a particular protein; DNA segments that are part of a chromosome and are responsible for inherited traits.
What are the two processes involved in protein synthesis?
Transcription and translation.
What are the three parts of a DNA nucleotide?
A five-carbon sugar called deoxyribose, a phosphate group, and a nitrogenous base.
Which two DNA bases are pyrimidines?
Thymine and cytosine.
What happens to the DNA double helix at the beginning of replication?
It untwists, and the weak hydrogen bonds between bases break so the chains open like a zipper.
Unlike DNA, RNA is made up of how many strands?
One strand
What is a set of three bases in DNA called?
Triplet
Where does transcription take place?
In the nucleus.
What shape does DNA form?
A double helix
How many weak hydrogen bonds join cytosine and guanine?
Three
What joins the exposed bases during replication?
Free DNA nucleotides in the nucleus, following the base-pair rule.
Which base is found in RNA instead of thymine?
Uracil
What is a set of three bases in mRNA called?
Codon
During transcription, what pairs with exposed bases on the original DNA strand?
Free RNA nucleotides, following the RNA base-pair rule.
What are the two types of nitrogenous bases classified by ring structure?
Pyrimidines (single ring) and purines (double ring).
Complete the complementary DNA strand: G-A-T-T-A-C-A.
C-T-A-A-T-G-T.
After the free nucleotides pair with the exposed DNA chains, what forms between their sugars and phosphates?
Bonds that form the nucleotide backbone.
What does mRNA carry, and where does it carry the message?
It carries instructions from DNA in the nucleus to a ribosome.
What is a set of three bases in tRNA called?
Anticodon
What happens during translation?
A protein is assembled according to the code in the mRNA molecule.
What did Watson and Crick's 1953 model show about the two DNA chains?
They are joined by weak hydrogen bonds between nitrogenous bases and spiral around a common center to form a double helix.
A DNA strand reads C-C-T-T-G-A. What is its complementary strand?
G-G-A-A-C-T.
What is the final result of DNA replication?
Two identical copies of the original DNA molecule, twisted into double helices.
Name all three types of RNA and give the main role of each.
mRNA carries the message; tRNA carries amino acids to the ribosome; rRNA is one of the chemicals that ribosomes are made of.
How many possible combinations in the genetic code correspond to how many amino acids?
64 possible combinations code for 20 amino acids.
During translation, what connects adjacent amino acids as the mRNA moves along the ribosome?
Peptide bonds.