genetics, variation and relationships between organisms Flashcards
genetic code is
degenerate, non overlapping, universal
gene is a base sequence of DNA that codes for
amino acid sequence of a polypeptide
functional RNA
mRNA vs tRNA
mRNA- long single strand, has codons
tRNA- single strand folded, has anticodons
describe the process of transcription
- helicase
- one strand= template which is called the antisense strand
- polymerase
- splicing
- mRNA moves out of nucleus
describe the process of translation
- mRNA attaches to ribosomes
- tRNA collects from cytoplasm
- tRNA binds to mRNA (CBP)
- amino acids attach to tRNA
- peptide bonds form
- tRNA detaches
- polypeptide chain forms till stop codon
describe meiosis
- homologous chromosome pair pair up whereby crossing over at the chiasmata may take place
- daughter cells produced with one chromosome from each homologous pair
- chromatids separated producing 4 haploid daughter cells
principles of natural selection in the evolution of populations
- random mutations= new alleles
- the new allele of a gene might benefit its professor leading to increased reproductive success
- advantageous alleles is inherited
- over many generations the new allele increases in frequency in the population
directional selection
- phenotypes best suited will survive
- means population will move in direction of these individuals
stabilising selection
- phenotypes with successful characteristics are preserved
- those of greater diversity are reduced
- individuals closest to the mean are favoured
disruptive selection
- selection pressure toward the extremes creates two modal values
genetic drift
random fluctuation in frequencies of alleles
courtship enables
- recognise other members of the species
- identify a mate that can breed
- form a pair bond
- synchronise mating
phylogenetic classification system
attempts to arrange species into groups based on their evolutionary origins and relationships
Hierarchy
domain
kingdom
phylum
class
order
family
genus
species
species diversity
number of different species and number of different individuals in a community
genetic diversity
number of alleles in gene pool
species richness
a measure of the number of different species in community
index of diversity
describes the relationship between the number of species in a community and the number of individuals in each species
genetic diversity within can be made by comparing
the frequency of measurable or observable characteristics
the base sequence of DNA
the base sequences of mRNA
the amino acid sequence of the proteins encoded by DNA and mRNA
species
group of organisms with similar features;
can (interbreed to) produce fertile offspring
