4A- DNA, RNA and Protein Syntheis Flashcards
Gene
a section of DNA nucleotide base sequences that codes for a polypeptide protein or functional RNA
Eukaryotic DNA storage
1-long, linear DNA associates with histones proteins
2-Histones support DNA
3-DNA coiled up tightly into a compact chromosome so fits in nucleus
Prokaryotic DNA Storage
1- carry DNA as chromosomes
2-short and circular DNA molecules
3-DNA not associated with histone proteins
4-condenses to fit into cell via supercoilling
Role of histones
1-long, linear DNA associates with Histones proteins to make DNA compact so it can fit into the nucleus
2- supports DNA
Gene codes for
1-amino acid base sequence of polypeptide
2-functional RNA - ribosomal RNA +tRNA
genome
complete set of genes in a cell
Proteome
full range of proteins a cell is able to produce
Triplet/codon
series of 3 bases that codes for a specific amino acids
Functional RNA
RNA that doesn’t code for a polypeptide chain (NOT mRNA)
-tRNA + rRNA
ribosomal RNA
- mRNA binds to ribsosme which is made of RNA so translation occurs
- part of the ribosomes
Ribosome made of
- RNA nucleotides
- amino acids
role of ribosome in polypeptide synthesis
- mRNA binds to ribosome
- Idea of two codons/binding sites;
- (Allows) tRNA with anticodons to bind/associate;
- (Catalyses) formation of peptide bond between
amino acids (held by tRNA molecules); - Moves along (mRNA to the next codon)/translocation described
why isnt mRNA not a functional RNA
it codes for polypeptide chain
Introns
a section of DNA base sequences in a gene that doesn’t code for an amino acid
exons
section of DNA base sequences in a gene that codes for an amino acid
prokaryotic DNA doesnt have
introns
alleles
alternative forms of the same gene
why do different alleles code for slightly different versions of the same polypeptide chain
-different sequence of DNA bases
Homologous chromosome pair
- both same size
- same genes from each parents
- may have different alleles
chromosome
-
locus
- position on a chromosome where a particular allele of a gene is found on each chromosome in a pair.
- alleles coding for the same characteristic found at same fixed position
Multiple repeats
DNA sequences that repeat outside the gene that don’t code for an amino acid
mRNA structure (messenger)
1-carries the genetic code from the DNA in nucleus to the ribosome via leaving nuclear pore
2-single RNA nucleotide strands
3-3 adjacent bases = codons
tRNA structure
1-carries amino acids to the ribosomes
2-single RNA polynucleotide strand
3-H bonds between specific base pairs holds folded clover shape
4-anticodon specific base sequence
5-amino acid binding site which requires energy from ATP to bind to tRNA
eukaryotic DNA structure
1-non-coding DNA a base sequence of multiple repeats between genes
2-introns non coding DNA base sequences in a gene between exons that is removed via splicing of pre-mRNA
3-DNA Base sequence that codes for amino acids
Transcription occurs
-nucleus
translation occurs
at the ribsomes in the nucleus
Transcription
1-RNA Polymerase attaches to the DNA double helix at the start of the gene.
2-H bonds between the 2 DNA strands in the gene break via DNA Helicase
3-one strand with exposed bases used as template
4-RNA Polymerase lines up free floating RNA nucleotides and complementary base pairing occurs
5-RNA Polymerase joins RNA nucleotides together via condensation reactions forming phosphodiester bonds
6-pre-RNA polynucleotide is a complementary copy of the template strand
7-H bonds between uncoiled DNA strands reform once RNA Polymerase has passed a recoil double helix
8-RNA Polymerase reaches specific DNA triplet Nuceotide base sequence a stop signal
9-stops making Pre-mRNA
11-Splicing -Introns are removed and exons joined together
12-mRNA acts as messenger and moves out of the nucleus into cytoplasm via nuclear pore
Prokaryotic DNA Transcription
1-same as transcription of eukaryotes
2-No splicing as doesn’t contain introns so mRNA produced directly from DNA
Translation
1-mRNA leaves nucleus via nuclear pore to the ribosomes in the cytoplasm
2-mRNA attaches to a ribosome
3-tRNA molecules carry amino acids to mRNA
4-ATP PROVIDES THE ENERGY NEEDED FOR AMINO ACIDS TO BIND TO tRNA
5-tRNA with anti-codon that’s complementary to the first codon on mRNA attaches
6-2nd tRNA molecule attaches to next mRNA codon in the same way
7-2 amino acids attached to tRNA form peptide bond via the ribosomes
8-first tRNA moves away leaving first amino acid behind
9- tRNA molecules move along mRNA to next codon
10-until stop codon is reached
11-ribsomes joins amino acids together in polypeptide chain via condensation reactions which moves away from the ribosome
Role of ribosomes in transcription
1-mRNA is read at for translation
2-Once amino acids line up in the correct order it joins amino acids together via condensation reactions forming peptide bonds between each in a polypeptide structure
Non-overlapping
base triplets don’t share bases so no overlap of bases in a codon
degenerate
there are more possible combinations of bases in a triplet than there are amino acids so multiple base triplets can code for the same amino acids
Universal
same specific base sequences code for the same amino acids in all organisms
stop signals
sequences of bases that stop production of a protein
Histones
a protein that associates with DNA so it can condense into chromatin
Nucleosome
structural unit of eukaryotic chromosomes with DNA coiled around histone proteins
