Flashcards in DNA and RNA Deck (26):
What does RNA, mRNA and tRNA stand for?
Ribonucleic acid, messenger ribonucleic acid and transfer ribonucleic acid
A sequence of three adjacent nucleotides in mRNA that codes for one amino acid.
Define stop codon
A codon that tells the ribosome to stop adding amino acids to the protein.
Each base in the sequence is read only once
More than one codon codes for the production of one amino acid.
Same codon codes the same amino acid in all organisms.
What type of chain is DNA, mRNA and tRNA?
DNA- Double polynucleotide chain
mRNA- Single polynucleotide chain
tRNA- Single polynucleotide chain
What is the size order of mRNA, DNA and tRNA?
DNA, mRNA, tRNA
What type of shape is DNA, mRNA and tRNA?
DNA- Double helix molecule
mRNA- Single helix molecule
tRNA- Clover shaped
What is the pentose sugar in DNA, mRNA and tRNA?
What are the organic bases in DNA, mRNA and tRNA?
DNA- adenine, guanine, cytosine and thymine
mRNA- adenine, guanine, cytosine and uracil
tRNA- adenine, guanine, cytosine and uracil
Where is DNA, mRNA and tRNA found?
DNA- found mostly in the nucleus
mRNA- forms in the nucleus and leaves via pores in the nuclear envelope and enters the cytoplasm.
tRNA- formed in the nucleus but found around the cell.
What is the quantity of DNA, mRNA and tRNA?
DNA- Quantity is constant for all cells of a species
mRNA- Quantity varies from cell to cell and with level of metabolic activity
tRNA- Quantity varies from cell to cell and with level of metabolic activity
What is the stability of DNA, mRNA and tRNA?
DNA- Chemically very stable
mRNA- Chemically unstable- easily broken down
tRNA- More stable than mRNA but less than DNA.
What is the structure of a nucleotide?
Each nucleotide is made from a phosphate group, a pentose sugar (with 5 carbon atoms) and a nitrogenous base.
What are polynucleotide strands?
Many nucleotides join together to form the polynucleotide strands.
The nucleotides join up between the phosphate group of one nucleotide and the sugar of another, creating a sugar phosphate backbone.
What is specific base pairing?
Two DNA polynucleotide strands join together by hydrogen bonds between the bases.
Each base can only join with one particular partner (specific base pairing).
A-T and G-C
What are genes?
Genes are sections of DNA found on chromosomes.
Genes code for proteins (polypeptides)- they contain the instructions to make them.
It's the order of nucleotide bases in a gene that determines the order of amino acids in a particular protein.
Where are DNA molecules found?
In the nucleus of the cell.
What is transcription?
DNA is too larger to move out of the nucleus, so a section is copied into a molecule called mRNA.
What is translation?
When the mRNA leaves the nucleus and joins with a ribosome in the cytoplasm, where it can be used to synthesise a protein.
What is the structure of RNA?
Like DNA, it's made up of nucleotidees that contain one of four different bases. The nucleotides also form a polynucleotide strand with a sugar phosphate backbone. But RNA differs from DNA in these ways:
- The sugar in RNA is a ribose sugar (not deoxyribose)
- The nucleotides form a single polynucleotide strand (not a double one)
- Uracil (U) replaces thymine as a base. Uracil always pairs with adenine during protein synthesis.
What bonds hold the tRNA in its clover shape?
Where does the synthesis of proteins take place?
The cytoplasm- sections of the DNA code are transcribed onto a single stranded molecule called RNA.
What is mRNA?
The RNA that transfers the DNA code from the nucleus to the cytoplasm because it is small enough to leave the nucleus through the nuclear pores and to enter the cytoplasm.