genetic info, variation and relationships between organisms Flashcards
What are the features of the genetic code?
Degenerate - most amino acids code for mores than one protein
Non-overlapping - each base is only read once
Universal - the same in all living things
What does the order of bases determine?
The sequence of amino acids that form proteins
What is a triplet?
sequence of 3 bases that code for an amino acid
what is a gene?
a small section of DNA that codes for a polypeptide or functional RNA
Describe DNA in prokaryotic cells
short, circular and not associated with proteins
Describe DNA in eukaryotic cells
long, linear and associated with proteins called histones
Describe mitochondrial and chloroplast DNA
short, circular and not associated with proteins
What is a locus?
a fixed position on a strand of DNA
What are exons and introns?
Exons- coding regions of a gene
Introns - non coding regions
What is a genome?
the complete set of genes in a cell
What is a proteome?
the full range of proteins that a cell is able to produce
What is mRNA and its structure ?
a single strand of RNA that reads 3 bases at a time
a single-stranded chain of ribonucleotides with a sugar-phosphate backbone. It contains exons and introns
What is tRNA and its structure?
carries amino acid to ribosomes
clover leaf shape and are composed of a single strand of RNA with several loop structures (sugar phosphate backbone)
Describe the process of transcription
-DNA helicase breaks hydrogen bonds between 2 strands
- one DNA strand acts as a template strand
- -gree floating RNA nucleotides attach to adjacent bases
- RNA polymerase binds 2 strands together making a double helix (dettaches when reaching a stop codon)
- results in the production of mRNA
in eukaryotes it will go through splicing to remove introns
What is splicing?
The use of a spliceometer to remove any non-coding regions in mRNA (introns)
What is the structure of tRNA?
hydrogen bonding between nucleotides creates a clover- leaf shape molecule that has an amino acid binding site and an anticodon
Describe the process of translation
- mRNA attaches to a ribosome
- tRNA anticodon attaches to codon on mRNA
- peptide bond forms after another tRNA is attaches
- cycle will continue until a stop codon is reached
-forms a polpeptide chain
What are gene mutations?
a change in the base sequence of
chromosomes
What are mutagenic agents + examples ?
factors that increase the rate of mutations e.g radiation, carcinogens, viruses
What is base substitution?
when one base replaces another - doesnt cause a frame shift, not the original protein created
What is base deletion?
the removal of a base causing a frame shift
What is base addition?
a new base is randomly inserted into the sequence, causing a frameshift
What is base duplication?
when a whole gene or section of it is duplicated , mutation isnt harmful, and it is a source for evolutionary change
What are advantages and disadvantages of mutations?
A- antibiotic resistence in bacteria, immunity to HIV, rare gene immunity protetctedx against cancer
D- can cause down syndrome, cystic fibrosis or cancers