Genetic information, variation and relationships between organisms Flashcards
(38 cards)
what is DNA?
deoxyribose nucleic acid
what bonds hold together nitrogenous bases?
hydrogen bonds
what bonds hold together the nucleotides?
phosphodiester bonds
Eukaryotic DNA vs Prokaryotic DNA
Eukaryotic larger/longer associated with proteins (histomes) found in linear chromosomes contained within the nucleus
Prokaryotic shorter no protein not in chromosomes not in a nucleus
what are chromosomes
23 pairs
maternal and paternal chromosomes
diploid if 23 pairs except gametes (sex cells as 23 in each)
what are homologous chromosomes
two chromosomes that are the same by structure but they are not genetically identical
what is a gene
a section of DNA that codes for a polypeptide or functional RNA
what is an allele
a version of a gene
what is the locus
position of an allele, same on maternal and paternal gene
what does homologous mean
the same structure but not genetically identical
MRNA vs DNA
MRNA single strand of DNA AUCG bases polymer ribose sugar short molecule
DNA double helix structure ATCG bases polymer deoxyribose sugar long molecule
what is transcription
the formation of MRNA in the nucleus
what is translation
the formation of a polypeptide chain (a protein)
how does DNA replicate
hydrogen bonds break by DNA helicase enzyme
free nucleotides complementary base pair with the template strand
RNA/DNA polymerase re-synthesizes the sugar phosphate back bone and forms phosphodiester bonds
what does DNA helicase do
breaks hydrogen bonds and unzips double helix structure into a single strand
what does RNA/DNA polymerase do
re-synthesizes the phosphate back bone and forms phosphodiester bonds
what is a template strand
the strand which is being read
what happens in transcription
- DNA helicase breaks the hydrogen bonds into single strands and forms pre MRNA
- RNA nucleotides complementary base pair
- RNA polymerase re-synthesizes the suger phosphate backbone forming phosphodiester bonds
- Non-coding DNA is removed (exons removed)(splicing)
- MRNA then goes to the ribosomes
what does MRNA and pre MRNA contain
MRNA - coding DNA (introns)
pre MRNA - non coding and coding DNA (introns and exons)
what does universal mean
all triplet codes can code for the same amino acid
what does degenerate mean
triplet codes can code for more than one amino acid
what happens in translation
- MRNA attaches to ribosome
- ribosomes move to start codon
- TRNA brings specific amino acid
- anti-codon on TRNA is complementary to codon on MRNA
- ribosome moves along to the next codon
- ribosome fits around two codons
- condensation reaction occurs
- process repeated and amino acids joined by peptide bonds
how is TRNA adapted to suit its role
- transports specific amino acids
- 20 different TRNA’s (degenerate)
- all share the same structure
three types of mutation
- insertion
- deletion
- substitution
