[Unit 4.1] DNA, genes and chromosomes Flashcards
Genetic information, variation and relationships between organisms
define “genes”
section of DNA located on a locus that codes for amino acid sequence of polypeptide
define “chromosome”
long strand of DNA carrying all the genes
define “locus”
position of gene on a choromosome
define “genome”
all the genetic information in an organism
define “proteome”
full range of proteins that a cell is able to produce
define “allele”
different forms of the same gene
define “exon”
coding sections of DNA that leave the nucleus (as mRNA)
define “introns”
non coding sections of DNA that stay inside the nucleus
what are the differences between DNA structure in eukaryotic and prokaryotic cells
Euk:
-many chromosomes
-linear
-nuclear membrane
-wrapped around histone proteins
-no plasmids
-DNA in mitochondria/chloroplast
-Double stranded
Pro:
-single chromosome
-circular
-no nuclear membrane
-not associated with histone proteins
-DNA in plasmids
-No mitochondria/chloroplasts
-Double stranded
why cant DNA leave the cell
it is too large
it would risk being damaged by enzymes
what are the stages of transcription
start of each gene marked by promoter region. RNA polymerase binds here
Section of DNA unzips (H bonds break)
Free nucleotides line up to complementary bases on anti-sense strand
U replaces T in mRNA
RNA polymerase joins the nucleotides
pre mRNA is formed
pre mRNA is modified - introns removed, exons spliced by enzymes
mature mRNA leaves nucleus
what are the stages of translation
-mature mRNA moves into cytoplasm through nuclear pore and into ribosome
-mRNA read by ribosome in codons
-anticodon of complementary tRNA and codon of mRNA form base pairs
-ATP is used in joining amino acids in condensation polymerisation
-amino acids joined by peptide bonds
-sequence of codons determines sequence of amino acids in polypeptide.
what are the features of genetic code
universal
degenerate
non overlapping
read in same direction
start code is ATG
multiple stop codes
what is meant by saying genetic code is “universal”
all living organisms share the same bases
what is meant by saying the genetic code is “degenerate”
one amino acid can be coded for by more than one triplet
what is meant by saying the genetic code is “non-overlapping”
triplets are all sequential. it matters where you start. triplets dont share bases
