Section 4 Diversity Flashcards
What is Biodiversity?
variety in an ecosystem
variety of habitats and variety of species
What is Species Diversity?
number of different species
number of individuals for each species
What is Genetic Diversity?
variety of alleles in a species population
the larger number of individuals in a species, the larger the genetic diversity
Benefit of high species diversity?
Stable ecosystem
each species is less likely to become extinct (due to high genetic diversity)
& if a species does become extinct it will not affect the food chain as there are other species available
How to measure Species Diversity for an area?
Species Diversity Index
takes into account the number of different species and how many individuals there are for each species
the larger the species diversity index, the larger the species diversity
How does deforestation lower species diversity?
(deforestation is the removal of trees for wood & space)
decreases plant species diversity
less variety of habitats
less variety of food sources
decreases animal species diversity
How does agriculture/farming lower species diversity?
deforestation to make space for farm
only grow a few plants & keep a few animal species
selectively breed plants & animals
use pesticides to kill other species
What is Classification?
placing organisms into groups
What is Hierarchical Classification?
large groups divided into smaller groups with no overlap
domain, kingdom, phylum, class, order, family, genus, species
What is Binomial Naming System?
using Genus name and Species name to name organism
Genus name first in capital, Species name second in lower case
What is a Species?
a group of individuals with similar characteristics that can interbreed to produce fertile offspring
Why are the offspring from 2 different species mating infertile?
offspring will have a odd number of chromosomes
therefore, cannot perform meiosis, cannot produce gametes
What is Phylogenetic Classification?
based on evolutionary relationships – how closely related different species are and how recent a common ancestor they have
DNA hybridisation (comparing the relationship between different species 1)
take DNA from 2 species to be compared
- radioactively label one of the DNA
- heat both sets so double strand separates
- cool so single strands join together
- look for Hybrid DNA (one strand from species A, one strand from species B)
- identify Hybrid DNA by 50% radioactivity
- heat Hybrid DNA to measure similarity
results = higher temperature
required more hydrogen bonds present more complementary base pairing
more similar the base sequence
more similar the species
more closely related
more recent a common ancestor
AA sequence (comparing the relationship between different species 2)
: comparing AA sequence for the same protein (e.g. haemoglobin in mammals)
results = more similar the AA sequence
more similar the DNA base sequence
more similar the species
more closely related
more recent a common ancestor
Protein shape (comparing the relationship between different species 3)
comparing shape of the same protein (e.g. albumin) using immunological technique
- comparing species A and species B - take albumin from species A - place in a blood of rabbit - rabbit will make antibodies against
albumin of species A
- takes these antibodies and place in blood from species B
- if the albumin in species B has a similar shape to species A,
the antibodies will bind to form antigen-antibody complexes,
this will then form a precipitate
results = more precipitate more complexes more similar shape more similar the species more closely related more common recent ancestor
What is Variation?
difference in characteristics between organisms
Types of Variation?
intraspecific = differences between organisms of the same species
interspecific = differences between organisms of different species
Causes of Intraspecific Variation?
Genetic Factors = same genes but different alleles (allele are different type/forms of genes)
Environmental Factors
Types of Characteristics?
Discontinuous and Continuous
Discontinuous: characteristics fall into certain groups with no overlap (e.g. blood group) – determined by genetics only (a single gene)
Continuous: characteristics show a range (e.g. height) – determined by genetics (a few genes, polygenes) and environment
What is Genetic Diversity?
genetic variation, the variety of alleles within a population of a species
Benefit of high genetic diversity?
species able to adapt with changes in the environment
e.g. if a new disease arises, some individuals will have characteristics to survive, and will reproduce passing on their alleles, so the species does not become extinct
What can lower genetic diversity?
small population size (e.g. founder effect – where the numbers
start low, or genetic bottleneck – where the numbers decrease)
What is natural selection and adaptation?
variation in population of species
(genetic diversity/genetic variation/variety in gene pool)
new alleles arise by random mutation
environment applies a selection pressure on the
population
those with favourable characteristics/favourable alleles/selection advantage/better adapted survive, the others die [natural selection]
the ones that survive will reproduce, passing on their favourable alleles
if this happens for many generations, then that characteristic will become most common – the allele will become more frequent [adaptation]
What are the 2 types of selection?
stabilising and directional
What is stabilising selection?
when the environment favours those with the most common characteristic – those on the extreme dies out
the common characteristic increases in proportion
the range (standard deviation) will reduce
What is directional selection?
when the environment favours those individuals with characteristics on one of the extremes
over time this will become the most common characteristic
normal distribution will shift to that extreme
What is a Gene?
a section of DNA that codes for a protein
made out of intron and exon
intron = non-coding DNA (function e.g. turns gene on or off)
exon = coding DNA (codes for protein)
How does a Gene/Exon code for a Protein?
made out of a sequence of bases
each 3 bases code for 1 amino acid (called triplet code)
therefore,
sequence of bases
determines sequence of triplet codes
which determine the sequence of AAs
= polypeptide chain/primary structure (folds to secondary, then to tertiary/quaternary)
Favourable properties of triplet code?
degenerate = each AA has more than one triplet code
non-overlapping = each base is read only once
stop codes = occur at end of sequence – do not code for an AA
How does a mutation lead to a non-functional enzyme?
change in base sequence
change in sequence of triplet codes
change in sequence of AAs
change in primary structure
change in hydrogen/ionic/disulfide bonds
change in tertiary structure (3D shape)
change in active site shape
substrate no longer complementary
can no longer form enzyme-substrate complex
How is a protein assembled?
by transcription and translation
transcription = production of a single stranded complementary copy of a gene (called mRNA)
translation = use sequence of codons on mRNA to assemble protein (tRNA brings in AAs)
DNA vs RNA?
deoxyribose sugar vs ribose sugar
thymine vs uracil
double stranded vs single stranded
one type vs two types (mRNA and tRNA)
What is a Chromosome Mutation?
In plants, inherit more than one diploid set of chromosomes – called polyploidy
In animals, homologous pair of chromosome do not separate in meiosis, so either inherit one extra or one less chromosome – called non-disjunction
What is a Gene Mutation?
a change in the base sequence of DNA
2 types = substitution and insertion/deletion
substitution = replace one base for another, changes one triplet code
can be silent (new triplet code codes for same AA), mis-sense (codes for a different AA, so protein shape changes slightly), non-sense (codes for a stop codon, so polypeptide chain not produced)
insertion = adding a base, deletion = removing a base both insertion/deletion causes frameshift, all the triplet codes after the mutation changes, so normal polypeptide chain/protein not produced
