Protein synthesis and selection Flashcards
eukaryotic vs prokaryotic DNA
Linear: Circular
Associated with histones: Not associated with histones
Contains introns: doesn’t
definition of a gene
sequence of DNA that codes for the amino acid sequence of a polypeptide
contrasting and comparing DNA and mRNA
Both: Polymers made from nucleotides
linked by phosphodiester bond
Contrast
Double stranded: single stranded
Longer:shorter
Thymine:uracil
Dexyribose:ribose
Hydrogen bonds: no hydrogen bonds
Introns: no introns
tRNA
Amino acid binding site, anticodon binding site, hydrogen bonds between complementary bases- sugar phosphate backbone
genome definition
complete base sequence of all DNA found within a cell
chromosome definition
single molecule of DNA which contains some of the genetic material of an organism
locus definition
fixed position of a gene on a chromosome
histone
a protein that linear DNA coils around to form a DNA- histone complex
proteome
full range of proteins that a cell is able to produce
Where does transcription occur
prokaryotes: Cytoplasm
Eukaryotes: Nucleus
Introns definition vs exon definition
introns- non-coding sequence with a gene of DNA
Exon- coding sequence within a gene of DNA
Describe the process of transcription
DNA helicase breaks hydrogen bonds between complementary bases
only one strand acts as a template
RNA nucleotide attracted to exposed bases
Adenine- uracil
cytosine-guanine
RNA polymerase joins RNA nucleotides together forming phosphodiester bond through condensation reaction
pre-mrna spliced to remove introns
describe the process of translation
mRNA binds to ribosome
ribosome finds the start codon
trna with complementary anticodons bind to codon
catalyzes the formation of a peptide bond between amino acids using energy from ATP
tRNA released as ribosome moves along
ribosome releases polypeptide into RER when stop codon is reached
Universal definition
the same three bases on mRNA code for the same three amino acids in all organisms
non-overlapping definition
each base is read once in a triplet
degenerate definition
more than one triplet for each amino acid
mutations
gene mutation is a change in the base sequence that may change primary structure of a polypeptide. Ultimately leading to the change of the tertiary structure making the shape of the active site not complementary to the substrate
types of mutations
substitution- in third base will not alter the amino acid coded for. in second base will be a silent mutation, in first base will change amino acid base sequence
addition/deletion
1 full DNA nucleotide is lost- results in an alteration of base triplet
mutagenic agents
High energy ionization energy- alter DNA structure by interfering with DNA replication
DNA reactive chemicals- nitrous acid can remove NH2 group from cytosine converting base to Uracil
Biological agents such as some viruses and bacteria
Chromosomal mutations
inversion-when a segment of bases is reversed end to end
duplication- doubling part of a chromosome
translocation- when groups of base pairs relocate from one area of the genome to another- usually between non-homologous chromosomes
allele definition
different version of the same gene
Phenotype vs genotype
an organisms characteristics, phenotype, is determined by the genotype and its interaction with the environment
gene pool/ genetic diversity
the number of differnt alleles of genes in a population
natural selection definition
process by which organisms that are better adapted to their environment survive and reproduce in greater numbers, resulting in the increase of the frequency of the advantageous allele within the population
natural selection process
variation exists within a population caused by mutation, better adapted individuals more likely to survive and reproduce, these organisms are more likely to pass on their alleles, those which are less adapted fail to survive and reproduce, these organisms are less likely to pass on their alleles
organisms subject to selective pressures, selection pressure determines the spread of an allele within the gene pool
Biotic factors that influence selection
predator, pathogen, food source, human activity, competition
abiotic factors that effect selection
temperature of…, light intensity, soil PH, wind speed, O2 concentration, salinity, precipitation, humidity, ASPECT
stabilizing vs directional selection
stabilising- against both extremes- only mean phenotype will have reproductive success, alleles for mean phenotype are passed on to future generations, frequency of mean alleles increases. alleles coding for extreme phenotype decreases
directional- selection for one extreme, individuals with advantageous allele have increased reproductive success, alleles for one extreme passed on, frequency of this allele increases, alleles coding for both extremes decreases
