genetic information (RNA and protein synthesis) Flashcards
what does mRNA stand for?
messenger RNA
when is mRNA made?
during transcription
what does mRNA do?
carries the genetic code from the DNA to the ribosomes, where it makes a protein in translation
what is a group of 3 bases called in mRNA?
codons
what does tRNA stand for?
transfer RNA
what does tRNA do?
used in translation
carries the amino acids to the ribosomes
what is the structure of tRNA?
single polynucleotide clover shape hydrogen bonds between base pairs anticodon amino acid binding site
what is a sequence of 3 bases called in a tRNA molecule?
anticodon
what are the stages of transcription?
DNA helix unwinds to expose bases and act as a template
chain of DNA acts as a template
catalysed by DNA helicase
which breaks hydrogen bonds between bases
free mRNA nucletoides in the nucleus align with exposed complementary bases
RNA polymerase bonds RNA nulceotides by phosphodiester bonds
pre mRNA spliced to form mRNA
mRNA moves out of the nuclear pore and attaches to a ribosome in the cytoplasm
what are the stages of translation?
mRNA attaches to a ribosome at the start codon
tRNA has an anticodon complementary to the mRNA codon
tRNA brings along a specific amino acid
amino acids joined by peptide bonds using ATP
tRNA released
ribosome moves along mRNA to form a polypeptide
detaches at the stop codon
enters the golgi for folding and modification
what is genetic diversity?
the number of different alleles of genes in a species/population
what is genetic diversity in a population increased by?
mutations in the DNA
different alleles being introduced to a population after migration (gene flow)
what is a genetic bottleneck?
event that causes a big reduction in a population
why does a genetic bottleneck reduce genetic diversity?
reduces the number of alleles in the gene pool, survivors reproduce and a larger population is created from fewer individuals
what is the founder effect?
type of genetic bottleneck where there is only a small number of alleles in the initial gene pool
what is the purpose of natural selection?
to increase advantageous alleles within a population
what happens during natural selection?
not all individuals in a population are as likely to reproduce
different alleles increase an individual’s chance of survival
greater proportion inherit the beneficial allele
more likely to survive, reproduce and pass on useful genes
what are behavioural adaptations?
ways an organism acts to increase its chance of survival and reproduction
eg) play dead
what are physiological adaptations?
processes inside an organisms body that increase its chance of survival
eg) hibernation
what are anatomical adaptations?
structural features of an organisms body that increase its chance of survival
eg) thick blubber layer
what is an example of directional selection?
antibiotic resistance
what is an example of stablilising selection?
human birth weight
what is directional selection?
individuals with alleles for characteristics of an extreme type are more likely to survive and reproduce
could be in response to an environmental change
what is stabilising selection?
individuals with alleles for characteristics towards the middle of the range are more likely to survive and reproduce
when the environment isn’t changing- reduces the range of characteristics
