How DNA codes for polypeptides Flashcards
(22 cards)
What is a polypetide?
A polymer made of amino acids joined together by peptide bonds.
What is transcription?
The process of making mRNA from a DNA template.
What is translation?
The formation of a proteins by assembling amino acids into a particular sequence according to the coded instructions carried from the DNA to the ribosome by mRNA.
How is RNA different to DNA?
It contains a ribose sugar as opposed to a deoxyribose sugar.
Nitrogenous base of uracil instead of thymine.
Strands are usually shorter than DNA.
They are also single stranded
What are the three forms of RNA?
mRNA, tRNA and rRNA.
Where are proteins made?
At the ribosome.
What does it mean that genetic code is near universal?
In almost all living things the same triplet of DNA bases codes for the same amino acid.
Genetic code is degenerate. What does this mean?
For all amino acids there are more than one base triplet.
How many bases are read at a time?
Groups of three.
DNA replication is similar to transcription but how is it different?
RNA polymerase instead of DNA polymerase.
RNA nucleotide bases instead of DNA free floating nucleotide bases.
Describe the journey of mRNA starting in the nucleus.
Packaged by vesicle and moves out of the nucleus through the nuclear envelopes and attaches to the ribosome.
What are ribosomes made of?
Ribosomal RNA (rRNA)
What is tRNA?
A molecule made in the nucleolus.
Describe the structure of tRNA.
They are single stranded polynucleotides, but can twist into a hairpin shape.
One end is a trio of nucleotide bases.
The other end is another trio of bases called an anticodon.
What does the trio of nucleotide bases on the tRNA do?
It recognises and attaches to a specific amino acid.
What does the anti codon do?
It is specific to a codon of bases on the mRNA.
When the anti codon attaches to the codon on a complementary length of RNA how does it attach?
With temporary hydrogen bonds.
When two tRNA molecules are next to each other so are their amino acids. What happens between the amino acids?
A peptide bond is formed between the two and a chain of amino acids begins.
What is the process called when polpeptides are made?
Polypeptide synthesis.
Energy in the form of (blank) is needed for polypeptide synthesis.
ATP
What happens to the length of mRNA after it has been used in protein synthesis?
It is broken down and recycled.
What protein helps the polypeptide to fold into its tertiary structure?
Chaperone proteins.
