18.2 Protein Synthesis and Gene Expression Flashcards
What do proteins consist of?
Sequence molecules called Amino Acids
What determines the chemical properties of proteins?
The specific sequence of Amino Acids
What do the specific proteins synthesized by a cell determine?
The structure, function and development of the cell
What makes is the Genetic code?
The order of the base pairs in a DNA molecule
What does the genetic code determine for Amino Acids?
It determines how amino acids are strung together and how proteins are made
What is the Central Dogma of Gene expression?
The theory that genetic information flow from DNA to RNA to protein
What is Transcription?
When DNA is copied into an RNA molecule
Where does Transcription take place?
In the nucleus
What does Transcription require?
A special type of RNA molecule called RNA messenger (mRNA)
What does mRNA do?
Moves into the cytoplasm of the cell where the mRNA nucleotide sequence directs the synthesis of a polypeptide with the aid of another RNA molecule, Transfer RNA (tRNA)
What is the process of Translation?
When mRNA moves into the cytoplasm of the cell where the mRNA nucleotides sequence direct the synthesis of a polypeptide with the help of tRNA
What are Polypeptides?
Long chains of amino acids
What is a Codon?
In a gene, a set of 3 bases ex. ACC
What is the Genetic code always interpreted in?
The mRNA codon instead of the nucleotide sequence of the original DNA strand
What are the 3 important characteristics for the Genetic Code?
- More than one codon can code for the same amino acid
- It is continuous so it reads without spaces or punctuation
- It is universal for all organisms
What happens in Transcription?
Information in a segment of DNA is copied into mRNA which carries it to the cytoplasm
How many strands of DNA are transcribed during Transcription?
Only one from each strand of DNA
What is the Sense Strand?
The strand that is transcribed during transcription. The other is called the Anti-sense strand
Which enzymes catalyse the synthesis of RNA?
RNA polymerases
What is the Promoter Region?
A sequence of nucleotides on the DNA molecule that tell the RNA polymerase where to bind
What happens once the RNA polymerase binds to the sense strand on DNA?
It opens a seperates a section of the double helix where it works its way along the DNA where it creates a section of mRNA that is complementary to the sense strand
What is changed on the mRNA strand during translation?
Thymine is replaced with Uracil on the mRNA strand
What signals RNA polymerases to stop producing mRNA?
A specific nucleotide sequence on the on the sense strand
What needs to happen for proteins to be created?
The information on the mRNA strand must be translated into amino acid sequnces
What works to translate the mRNA sequence when it reaches the cytoplasm?
A translator and protein synthesis equipment
What does tRNA do?
Links each mRNA codon to its specific amino acid
What tRNA made of?
A single strand that folds into a characteristic shape
What is the Anti-codon?
A lobe of tRNA that contains three nucleotides that are complementary to the mRNA codon
What is at the opposite end of tRNA?
The binding site for the Amino acid that corresponds to the codon
What do ribosomes do?
They bring together mRNA strand and the tRNA molecules that carry the amino acids to build the polypeptides
What is the third type of RNA found in ribosomes?
rRNA, which is a linear strand of RNA that remains associated with ribosomes
When is Translation activated?
When an mRNA molecule binds to an active ribosome complex
How does the mRNA bind to the ribosome complex?
In a way so that two adjacent codons are exposed
What happens once the mRNA binds with the ribosome?
The tRNA molecule carrying an amino acid with the base pairs with the first exposed codon
What happens once the first tRNA binds with the mRNA?
The second tRNA arrives at the next codon and binds. Enzymes then catalyze the formation of that joins the two amino acids. The the ribosome moves one codon down and the last tRNA molecule detaches leaving the amino acid
What is Genomics?
The study of entire genomes, including interactions among multiple genes
What is Proteomics?
The study of all the proteins that are produced by a given genome
What is the function of mRNA?
Carries genetic info from DNA to protein synthesis equipment in the cytoplasm
What is the function tRNA?
Carries a particular amino acid to the correct codon site in the protein synthesis equipment
What is the function of rRNA?
Combines with a complex of proteins to form a ribsome
