Dna,genes And Chromosome , Dna And Protein Synthesis Flashcards
Describe two difference between the structure of dna in prokaryotic cell and in a eukaryotic cell?
1)In prokaryotic cell dna is circular whereas in eukaryotic it is linear
2)Prokaryotic is not associated with histones whereas eukaryotic
cells are
What are three differences between DNA in the nucleus of a plant cell and DNA in a prokaryotic cell.
1)prokaryotic does not contain intrones whereas eukaryotic cells do not
2)longer vs shorter
3)does contain plasmids whereas in eukaryotic cells does not contain plasmids
4)prokaryotic cells have fewer genes than eukaryotic cells
Can also have
1)In prokaryotic cell dna is circular whereas in eukaryotic it is linear
2)Prokaryotic is not associated with histones whereas eukaryotic
cells are
What do mitchondria and chloroplast organnels contain although they are within eukaryotic cells?
they contain prokaryotic-like DNA(short,circular no histones etc,)
Endosymbiot theory (just know a little about it)
What is a chromosome?
One molecule of dna with both polynucleotide strands twisted go form a double helix wrapped around histone proteins
What is a gene(genetic code) and what 2 things does it code for and where is it located ?
It is a base sequence arranged in triplets that code for :
1)The amino acid sequence of a polypeptide
2)a fuctional rna (tRNA and rRna)
A gene occupies a fixed position (called locus) on a particular dna molecule.
What is a codon/triplet?
A sequence of three adjacent nucleotides that codes for a specific amino acid
What 3 things is genetic code know us?
Universal -it is the same in nearly every living organism
Non-overlapping - a gene does not share Part of their sequence.so a genes coding sequence will not be within another’s regulatory region
(Each base is only in one codon)
Degenerate (most amino acids are coded for by more than one triplets e.g amino acid F can be coded by triplet TTT or by TTC
-known as degenerate becouse there are four bases so there are possible 64 possible triplet codes (4 to the power of 3) and there is 20 different types of amino acids so more than enough
What are introns and exons?
Introns -non-coding section(DNA) of a gene
Exons -(EXpressed) coding section(DNA) of a gene that code for amino acid
Exons are separated by one or two introns
Describe What happens during transcription ?
(Mark scheme answer)
1)Hydrogen bonding between dna bases breaks by dna helicase
2)Only ONE dna strand acts as a template
3)Free RNA nucleotides align by complementary base
4)In RNA uracil is used instead of thymine
5)RNA polymerase joins adjacent nucleotides by phospholipid bonds
6)so Pre-MRna is made and spliced to form mRNA
What is spliced?
Where does transcription take place ?
How does mRNa move from the nucleus to the cytoplasm?
1)Introns are removed ,so the remaining exon sections join together
2)nucleus
3)through a nuclear pore
What are two steps in protein synthesis?
Transcription followed by translation
Describe how a gene is a code for the production of a polypeptide.
Becouse The base sequence codes in triplets
Which determines the sequence of the primary structure in a polypeptide
d) Not all mutations in the nucleotide sequence of a gene cause a change in the structure of a polypeptide.
Give two reasons why.
1)Triplets code for the same amino acid
2)it occurs in introns
What does homologous pair of chromosomes mean?
Two chromosomes that carry the same gene
Outline how translation work(how the production of mRNA leads to the formation of polypeptides )?
1)(mRNA) attaches to ribosome/RER
2) tRNA anticodons bind to complementary mRNA codons
3)tRNA brings a specific codon
4)amino acid join by peptide bonds
5)amino acid join together with the use of ATP
6)tRNA released after amino acid join to the polypeptide(the other amino acids)
7)the ribosome moves Along the mRNA to continue to form the polypeptide
Where does transcription and translation happen in eukaryotes and prokaryotic?
Transcription
Eukaryotes - nucleus
Prokaryotes- cytoplasm
Translation
Eukaryotes and prokaryotic-ribosomes
Also in rer for eukaryotic
What is t-rna ?
And outline its structure?
It is a Single strand of mRNA that folds on itself using hydrogen bonding .
-Clover shape
-amino acid attached to the top
-at the bottom anticodon
What is a genome and what is a proteome ?
(KNOW THIS DEFINITION OF BY HEARTTT?)
-genome = is all the dna in a cell or organism
Proteome = is the range of proteins a cell can produce
Compare t-RNA shape to m-RNA?
1)mRNA does not have hydrogen bonds tRNA does;
2)mRNA is linear / straight chain, tRNA is clover leaf
3)mRNA does not have an amino acid binding site , tRNA does
4)mRNA is longer than tRNA
4.Different mRNAs have different lengths whereas all tRNAs are similar same length;
- mRNA has codons, tRNA has an anticodon;
