4A dna rna protein synthesis Flashcards
Describe DNA in eukaryotic cells
carry DNA as chromosomes- threadlike- made up of one long molecule of DNA found in nucleus
- the DNA molecule is rlly long it has to be wound up to fit in nucleus
- wound around proteins called histones
- DNA and histones coiled up v tightly to make compact chromosome
why are histones helpful in DNA
help support the DNA
mitochondria and chloroplasts in eukaryotic cells have there own DNA - describe it
circular and shorter than DNA in nucleus and not associated to histones
similar to prokaryotic DNA
describe dna molecules in prokaryotic cells
- also carry DNA as chromosomes but the DNA is shorter and circular
- not wound around histones-condenses to fit in cell via supercoiling
what is a gene
Sequence of DNA bases that code for either a polypeptide or functional RNA
What do the sequence of amino acids in a polypeptide form
The primary structure of a protein
What determines the order of amino acids in a particular polypeptide
Different polypeptides have different numbers and orders of amino acids -the order of bases in a gene determines the order of amino acids
What is each amino acid is coded by
A sequence of three bases in a gene called a triplet
What is a triplet
A sequence of three bases in a gene
What is functional RNA
RNA MOLECULES OTHER THAN MRNA WHICH PERFORM SPECIAL TASKS DURING PROTEIN SYNTHESIS LIKE T RNA AND RIBOSOMAL RNA
What is a Genome
The complete set of genes in the cell
What is a cells proteome
The full range of proteins that the cells able to produce
What are introns
In eukaryotic DNA genes that code for polypeptides contain sections that don’t code for amino acids these are introns
what are exons
sections in gene that do code for amino acids
When are Introns removed
During protein synthesis
do prokaryotic cells have introns
no
What are non-coding repeats
DNA sequences that repeat over these don’t code for Amino acids
What is another form of gene can exist in
alleles
How can alleles code for different versions of the same polypeptide
The order of bases in each allele is different
What is a homologous pair
Pairs of matching chromosomes
what do chromosomes in a homologous pair have
same genes, same size but can have different alleles
summary of genetic code
each triplet of bases coding for a particular amino acids known as a codon. amino acids are then joined together by peptide bonds and form a polypeptide chain. Therefore a gene is a sequence of bases on a DNA molecule coding for a sequence of amino acids in a polypeptide chain.
describe first stage of protein synthesis - transcription
During- mRNA copy of gene made from DNA
1- starts when RNA polymerase attaches to DNA double helix at begin of gene
2- H bonds between the complementary bases break via DNA he w/ RNA po so DNA uncoils, separating two strands exposing some bases
3-one of the strands then used as template to make mrna copy
4-RNA po lines up free RNA nucleotides by exposed bases and joins them, complementary base pairing causes mRNA molecule to be formed -being a copy of DNA template
5-H bonds reform between uncoiled DNA strands once rna po has passed- the strands then coil back to double helix
6-when rna po reaches stop signal it detaches-stopping making mRNA
7-mrna moves out of nucleus via nuclear pore & attaches to ribosome in cytoplasm
what is mRNA
Made during transcription
carries genetic code from DNA to ribosome is then used to make protein during translation
single polynucleotide strand
