DNA, Genes and Protein Synthesis Flashcards
What is the name for the position of a gene on a chromosome?
Locus/loci
Why is mRNA shorter than pre-mRNA?
Introns have been spliced out
Name 3 types of RNA
Messenger RNA (mRNA) Transfer RNA (tRNA) Ribosomal RNA (rRNA)
Name 4 bases found in RNA
Adenine, guanine, cytosine and uracil
What are ribosomes formed from?
Ribosomal RNA and protein
Name the parts of a RNA nucleotide
Ribose sugar, phosphate and nitrogenous base
What is the function of mRNA
Carry genetic information from DNA in the nucleus to ribosomes in the cytoplasm
What similarities do mRNA and tRNA have?
Both single stranded
Both have A, G, C and U bases
Both consist of RNA nucleotides
What differences do mRNA and tRNA have?
mRNA is linear, tRNA is folded
tRNA as hydrogen bonds holding the clover leaf shape in place
tRNA has anticodon and amino acid attachment site
tRNA is shorter
How many amino acid molecules exist?
20
How many bases are there?
5
Thymine, adenine, cytosine, guanine and uracil
If one base coded for an amino acid, how many possible sequences would there be?
4
If two bases coded for an amino acid, how many possible sequences would there be?
16
If three bases coded for an amino acid, how many possible sequences would there be?
64
How many bases code for one amino acid?
3
What is a triplet of bases called?
Codon
Explain what the term degenerate means
Most amino acids are coded for by more than one codon
The genetic code is described as being universal. What does this mean?
The same triplet code is used for all amino acids in all organisms
The genetic code is described as being non-overlapping. What does this mean?
Each base in the sequence is read only once
What are coding sequences called?
Exons
What are non-coding sequences called?
Introns
How many bases are needed to code for a chain of 8 amino acids?
24
What is a gene?
A section of DNA that codes for a polypeptide
What is meant by the term genome?
A complete set of genes in a cell
What is meant by the term proteome?
The full range of proteins produced by the genome
How many different types of tRNA molecules must exist?
64 - one for each of the possible codons
What is an advantage of mRNA being broken down quickly?
The correct amount of the protein is synthesised
What is the monomer of a protein?
Amino acids
Name the two processes in protein synthesis
Transcription
Translation
Which process occurs first in protein synthesis?
Transcription
What is produced in transcription?
mRNA/pre-mRNA
What is produced in translation?
Polypeptide
Which enzyme unwinds the DNA helix in transcription?
DNA helicase
If the base sequence on the DNA coding strand during transcription is AAGTCGGAT, what is the base sequence on the mRNA strand?
AAGUCGGAU
Which enzyme moves along the DNA non-coding/template strand joining RNA nucleotides together to form mRNA?
RNA polymerase
What is the role of RNA polymerase in transcription?
Moves along the DNA non-coding/template strand joining RNA nucleotides together to form mRNA
If the base sequence of the DNA coding strand in transcription is AATGCTTTC, what is the base sequence on the template/non-coding strand?
TTACGAAAG
How does mRNA leave the nucleus?
Via a nuclear pore
Where does mRNA attach to in the cytoplasm?
Ribosomes
Name the cell organelle involved in translation
Ribosome
If a mRNA codon has the base sequence AUC, what would the tRNA anticodon be that attaches to it?
UAG
A strand of mRNA has 65 codons but the polypeptide produced has only 63 amino acids. Suggest why.
One codon is the stop codon that does not code for an amino acid