B4 protein synthesis Flashcards
Compare and contrast the DNA in eukaryotic cells with the DNA in prokaryotic cells
Comparisons
1. Nucleotide structure is identical;
- Nucleotides joined by phosphodiester bond;
- DNA in mitochondria / chloroplasts same / similar (structure) to DNA in prokaryotes;
Contrasts
4. Eukaryotic DNA is longer;
- Eukaryotic DNA contain introns, prokaryotic DNA does not;
- Eukaryotic DNA is linear, prokaryotic DNA is circular;
- Eukaryotic DNA is associated with histones, prokaryotic DNA is not;
What is the name of the proteins that eukaryotic DNA is coiled around?
Histones
What name is given to the DNA and associated proteins?
chromosome
What is mitochondrial DNA like?
short
circular
not associated with proteins
Give five ways in which the DNA in a chloroplast is different from DNA in the nucleus.
- DNA shorter;
- Fewer genes;
- DNA circular not linear;
- Not associated with protein/histones, unlike nuclear DNA;
- Introns absent but present in nuclear DNA;
What is a gene?
Sequence of DNA that codes for: - the amino acid sequence of a polypeptide
- a functional RNA (including ribosomal RNA and tRNAs)
What term is given to the fixed position of a gene?
locus
What are different versions of a gene called?
allele
What is a triple of DNA bases?
A sequence of three DNA bases that code for a specific amino acid
The genetic code is universal. What does this mean?
The same triplet codes for the same amino acid in all organisms
The genetic code is degenerate. What does this mean?
More than one triplet codes for each amino acid
How many different triplets are there?
64
Identify one other feature of the genetic code and explain what it means.
Non-overlapping: each base is part of only one triplet
Within a gene only some of the bases code for amino acids. What are these parts called.
exons
Some parts of the gene are “non-coding”. What are they called?
introns
What is the difference between the genome and the proteome of an organism?
The genome is the complete set of genes in a cell and the proteome is the full range of proteins that a cell is able to produce
What are the components of an RNA nucleotide?
Ribose sugar
Nitrogenous organic bases – cytosine, uracil, guanine and adenine
Phosphate group
What do the following mean? rRNA tRNA mRNA
Ribosomal RNA
Transfer RNA
Messenger RNA
What are the roles of rRNA, tRNA and mRNA?
rRNA – part of the ribosome structure
mRNA – carries copy of the gene to ribosome from nucleus
tRNA – carries specific amino acid to ribosome
Where would you find the following?
Triplet
Codon
Anticodon
Triplet = DNA
Codon = mRNA
Anticodon = tRNA
Describe the structure of tRNA
Small – around 80 nucleotides Single stranded
Folded into a clover shape
Contains amino acid binding site
Contains an anticodon
What is the anticodon complimentary to?
The codon in mRNA
What name is given to the process by which a sequence of RNA is synthesised that is complimentary to the base sequence of the gene.
Transcription
What name is given to the RNA molecule produced immediately at the end of this process?
Pre- mRNA
What needs to happen to this RNA before it leaves the nucleus?
The introns need to be spliced out forming mRNA
Describe how mRNA is produced in a plant cell
- Helicase breaks hydrogen bonds between the 2 strands
- Only one of the strands used as a template
- Complementary base pairing so A ⟶ U, T ⟶ A, C ⟶ G, G ⟶ C;
- RNA nucleotides joined by RNA polymerase;
- pre-mRNA formed;
- Splicing removes introns to form mRNA;
What is a codon?
Sequence of three nucleotides in mRNA that codes for one amino acid
