1.3 Genome, Mutations, Evolution, Genomic Sequencing Flashcards
describe what is meant by the term genome
the genome of an organism is its entire hereditary information encoded in DNA
what a genome is composed of
genome is made of genes and and other DNA sequences that do not code for a protein
what type of gene sequence make up the majority of a eukaryotic genome
most of the eukaryotic genomes consists of non coding sequences
two forms of non translated RNA
- regulation of the transcription of a gene
- sequences are transcribed but never translated
describe the term “mutation”
mutations are changes in the genomes (dna) that can result in no protein or altered protein being exposed or synthesized.
describe what a single gene mutation is and how it is caused
single gene mutations alter the dna nucleotide sequence of a single gene as a result of substitution, deletion,
insertion of nucleotides.
name three different type of single gene mutations caused by nucleotide substitutions
substitution - one nucleotide is replaced with another and only one amino acid is altered.
deletion - one nucleotide is removed from nucleotide sequence, every amino acid after point of deletion will be put out of sequence.
insertion - nucleotide is added to nucleotide sequence, every amino acid after point of insertion will be put out of sequence.
single nucleotides substitutions can result in missense, nonsense & splice site mutations.
describe the effects of a missense mutation on the amino acid sequence and on the structure of the final protein produced
missense mutation involves only one amino acid changed to another amino acid. May result in non functional protein or have very little effect on protein.
describe the difference between coding and non coding DNA regions
coding DNA are sequences of DNA bases that code for proteins.
non coding DNA are sequences of DNA that do not code for proteins.
describe the effects of a nonsense mutation on mRNA transcript and the effect on the structure of final protein produced
nonsense mutations create a premature stop codon which can stop protein synthesis,
results in a shorter protein missing many amino acids.
describe the effect of a splice site mutation on a mature mRNA transcript
splice site mutations can result in an intron appearing in a mature mRNA transcript molecule and some exons not being included in a mature mRNA transcript after RNA splicing.
May result in non functioning protein.
describe the effects of frameshift mutations on the amino acid sequence and on the structure of final protein produced
frame shift mutations are caused by insertions and deletions of nucleotides.
All of the codons and amino acids after the point of mutation is altered
This has a major effect on the protein produced
describe what is meant by a chromosome mutation
during gamete formation (meosis) the pairs of chromosome line up on the equator. This is the point where you get mutations involving changes to the chromosome structure.
describe each type of chromosome mutation
duplication - section of chromosome is added to its homologous partner
deletion - section of chromosome is removed.
translocation - section of chromosome is added to chromosome which is not its homologous partner.
inversion - section of chromosome is reversed
state the effect of chromosome mutations on an organism
the substantial changes caused by chromosome mutations can be lethal to an organism
explain the importance of mutations and gene duplication on evolution
this type of mutation (duplication) is thought to be a major driving force during evolution as it may confer advantages to a organism and increase its adaptability and subsequent chances of survival.
Mutations provide new genetic material for variation. This is done by mutations producing new alleles. without mutations there would be no new variation.
define the term evolution
evolution describes the changes in organisms over many generations as a result of genomic variations. This can lead to offspring that are better adapted to survive in its environment than the previous generation.
describe the process natural selection
natural selection is the non random increase in frequency of dna sequences that increase survival and the non random reduction in frequency of deleterious sequences
describe the changes in phenotype frequency as a result of stabilising, directional and disruptive selection
stabilising selection - average phenotype is selected for and extremes are selected against, leads to a reduction in genetic diversity
directional selection - one extreme phenotype is selected for, common during environmental change
disruptive - two or more extreme phenotypes, can result in population being spilt into two distinct groups
explain why natural selection is more rapid in prokaryotes
Natural selection is more rapid in prokaryotes. Prokaryotes can exchange genetic material
horizontally, resulting in faster evolutionary change than in organisms that only use vertical
transfer
explain the difference vertical and horizontal gene transfer
vertical gene transfer - transfer of genes from parents to offspring, from one generation to the next by sexual or asexual reproduction
horizontal gene transfer - where genes are transferred between individuals in the same generation
define the term species
a group of organisms capable of interbreeding and producing fertile offspring which normally doesn’t breed with other groups
define the term speciation
is the generation of new biological species by evolution as a result of isolation, mutation and selection
describe the importance of isolation barriers during speciation
isolation barriers prevent gene flow between two sub-populations during speciation
