genetic diversity and adaptation Flashcards
prokaryotic DNA is…
short, circular and NOT associated with proteins
eukaryotic DNA is…
long, linear and IS associated with proteins called HISTONES
mitochondria and chloroplasts have DNA too, which is…
like prokaryotic: short, circular, not associated with proteins
DNA bases are…
A + T (2 hydrogen bonds)
C + G (3 hydrogen bonds)
what is a gene?
base sequence of DNA that codes for: amino acids sequence of a polypeptide, functional RNA (rRNA + tRNA)
occupies a fixed position on a DNA molecule called locus
3 DNA bases form a codon which is…
triplet of bases that encodes for a specific amino acid
properties of genetic code…
universal= same for all organisms
degenerate= more codons that amino acids, so some encode the same amino acid
non-overlapping= each base is only part of one code so each codon is read as a discrete unit
features of DNA are…
most in non-coding
only about 2% of DNA codes for amino acids
coding part called exons
non-coding part called introns
a genome is…
a complete set of genes in a cell
a proteome is…
full range of proteins that a cell is able to produce
the stages of protein synthesis are…
- transcription
- splicing (eukaryotic only)
- translation
transcription is…
DNA to pre-mRNA/mRNA
splicing is…
pre-mRNA to mRNA (eukaryotic only)
translation is…
mRNA to protein using (tRNA)
mRNA structure
short, single-stranded linear chain of ribonucleotides
groups of 3 adjacent bases called codons
tRNA structure
silly polynucleotide strand with a clover shape
has an amino acid attached to it and an anticodon that’s complementary to an mRNA codon
the steps of transcription are…
- DNA helicase unwinds 2 DNA strands by breaking hydrogen bonds between complementary base pairs, one strand acts as a template
- free mRNA nucleotides align and pair with complementary bases
- RNA polymerase joins mRNA nucleotides together to form pre-mRNA
the steps of splicing are…
- introns are removed
- exons attached back together via condensation reaction
- mRNA is formed, m exits nucleus through nuclear pores into cytoplasm
the steps of translation are…
- ribosome attach to start codon of mRNA
- tRNA molecule with complementary anticodon aligns with mNA
- ribosomes move along mRNA, allowing another tRNA to attach to next codon
- 2 amino acids attached to tRNA molecules are joined by peptide bonds (requires ATP)
- process keeps occurring until ribosome reaches a stop codon, where it detaches and translation ceases
- peptide chain/protein has now been created
genetic diversity is…
the no. of different alleles of genes in a population, enables natural selection to occur