G10 DNA Keypoints Flashcards
Nucleic acids are composed of smaller units called
nucleotides
Nucleic acids are composed of smaller units called nucleotides. They are compounds with three components: _ _ _
a five-carbon sugar,
a phosphate group
a nitrogenous base.
A strand of nucleic acids is formed by linked nucleotides together via
phosphodiester bonds
A DNA strand has a 5’ end where the _ _ is found and a 3’ end where the sugar molecule is located.
phosphate group
A DNA strand has a 5’ end where the phosphate group is found and a 3’ end where the _ _ is located.
sugar molecule
If the sugar is deoxyribose, then the nucleotides make up the deoxyribonucleic acid (DNA). The genetic material of all living organisms is stored in the DNA.
a five-carbon sugar molecule without a hydroxyl (-OH) group at the second carbon
Deoxyribose
The nitrogenous base of a DNA has four types
cytosine
thymine
adenine
guanine
A DNA molecule has two antiparallel strands referred as the _ and the _ strand. The nitrogenous bases on one strand form hydrogen bonds with the complementary nitrogenous bases on the other strand to form a double helix.
coding, template
The double helix is right-handed. It twists in the clockwise direction which results in the formation of major and minor grooves.
The DNA sequence can be represented by its nitrogenous bases.
are nucleic acids involved in protein synthesis. It uses uracil instead of thymine as one of its nitrogenous bases.
Ribonucleic acid (RNA)
is an accepted principle stating that the genetic information contained in the DNA is copied into daughter cells and transferred to RNA molecules that direct the synthesis of protein molecules
central dogma of molecular biology
is the process wherein DNA molecules are duplicated during cell division and passed on to each daughter cell.
Replication
Replication is semiconservative, which means that each new copy would contain a strand from the original DNA.
Replication occurs in three stages
initiation
elongation
termination
helicases unwind the DNA helix while SSBs keep them from reforming the helix
initiation of replication
primase attaches an RNA primer at the replication fork where the DNA polymerase starts incorporating free nucleotides and elongating the strands. The leading strand is synthesized continuously while the lagging strand is synthesized in small, short fragments.
elongation of replication
the primers are removed and the nicks and the fragments in the lagging strand are sealed by DNA ligase. After replication, two exact copies of DNA are produced
termination of replication
Enzymes proofread the strand and correct any mismatch in the sequence. When the process of DNA replication is completed, the cell is ready to divide.
are nucleic acids involved in the translation and transcription of genetic information from DNA
Ribonucleic acids or RNA
RNA contains _ instead of thymine
uracil
There are three kinds of RNA involved in the synthesis of proteins.
messenger RNA (mRNA) ribosomal RNA (rRNA) transfer RNA (tRNA)
carries the genetic sequence information and transfers it from the DNA to the ribosomes
messenger RNA (mRNA)
the major component of the ribosomes. It catalyzes the peptide bond formation during the protein synthesis
ribosomal RNA (rRNA)
serves as the carrier molecules of the amino acids that make up the protein.
transfer RNA (tRNA)
the process of converting the genetic information in DNA to synthesize protein
Transcription
_ _ produces a complementary RNA strand called a primary transcript
RNA polymerase
Transcription occurs in three stages
initiation
elongation
termination
the RNA polymerase, with the help of transcription factors, binds to the promoter region
initiation of transcription
addition of the nucleotides starts at the +1 site and continues until it reaches the terminator site
elongation of transcription
nucleotides in the resulting strand usually form a hairpin pre-mRNA structure by forming hydrogen bonds to complementary bases present on the same strand.
termination of transcription
undergoes post-transcriptional modification where its ends are modified and introns are spliced
premature mRNA
The mature mRNA which is composed of exons capped with a _ cap at the 5’-end and a poly-A tail in the 3’-end is transported from the nucleus to the cytoplasm for translation.
guanine triphosphate (GTP)
The mature mRNA which is composed of exons capped with a guanine triphosphate (GTP) cap at the 5’-end and a _ tail in the 3’-end is transported from the nucleus to the cytoplasm for translation.
poly-A
the process of synthesizing protein as directed by the mRNA. It happens in the cytoplasm, near where the ribosomes stay
Translation
brings amino acids from the cytoplasm to the ribosomes
transfer RNA (tRNA)
hold the tRNA and the mRNA together and translate the mRNA to polypeptides
Ribosomes
The tRNA reads the three-base sequence (called _) in mRNA and links the amino acids.
codon
The tRNA similarly uses another set of three-base sequence (called _) that binds to the codon of the mRNA following the base pairing rules.
anticodon
The tRNA reads the three-base sequence (called codon) in mRNA and links the amino acids. The tRNA similarly uses another set of three-base sequence (called anticodon) that binds to the codon of the mRNA following the base pairing rules.
The amino acids are produced from the mRNA sequence following the genetic code.
Translation occurs in three stages
initiation
elongatiob
termination
the large and small ribosomal units combine with the mRNA to form initiation complex
initiation of translation
an initiator tRNA which encodes for Met recognizes the start codon and enters the P site of the initiation complex. A new tRNA recognizes the next codon and enters the A site. A chemical reaction will combine the two amino acids. The ribosomes will shift into the next codon, and the initiator tRNA exits the E site. This process continues until a stop codon is reached.
elongation of translation
the polypeptide is released as the initiation complex dissociates from one another
termination of translation
The polypeptide undergoes post-translational modifications where it may be chemically altered to facilitate folding. Properly folded amino acids are then transported to areas where they need to perform their given task.
