Module 4: Diversity Flashcards
biodiversity definition
variety in an ecosystem
variety of habitats and variety of ecosystems
species diversity definition
number of different species
number of individuals within each species
genetic diversity definition
variety of alleles in a species population
larger number of individuals in a species the larger the genetic diversity
benefits 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 won’t 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
larger the species diversity index the larger the species diversity
how does deforestation lower species diversity
deforestation removes trees for wood and 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 the farm
only grow a few plants and keep a few animal species
selectively breed plants and animals
use pesticides to kill other species
classification definition
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 to name organism
genus name first in capital
species name second in lower case
species definition
group of individuals with similar characteristics that can interbreed to produce living fertile offspring
why are offspring from 2 different species mating infertile?
off spring will have an odd number of chromosomes
can’t perform meiosis
can’t produce gametes
therefore infertile
phylogenetic classification definition
based on evolutionary relationships
how closely related different species are and how recent a common ancestor they have
3 ways of comparing relationships between different species
dna hybridisation
amino acids sequence
protein shape
dna hybridisation
compare the dna base sequence take dna from 2 species to be compared radioactively label one of the dna heat so both strands separate cool so single strands join together look for hybrid dna (one from strand a, one from strand b) identify hybrid dna by 50% radioactivity heat hybrid dna to measure similarity
RESULTS: higher temp required more hydrogen bonds present more complementary base pairing more similar base sequence more similar the species more closely related more recent a common ancestor
amino acid sequence
comparing AA sequence for the same protein (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
why is comparing the dna sequence better than comparing the amino acid sequence
dna sequence provides introns and the triplet code is degenerate
protein shape
comparing shape of same protein using immunological technique
comparing species a and b
take albumin from species a and place it in a blood of a rabbit
rabbit will make antibodies against albumin of species a
take these antibodies and place them in blood from species b
if albumin in species a has similar shape to albumin in species b then antibodies will bind to form antigen-antibody complexes, this will form a precipitate
RESULTS: more precipitate more complexes more similar shape more similar the species more closely related more common recent ancestor
variation definition
difference in characteristics between organisms
types of variation
intraspecific
interspecific
intraspecific variation definition
differences between organisms of the same species
interspecific variation definition
differences between organisms of different species
causes of intraspecific variation
genetic factors
same genes but different alleles
environmental factors
causes of interspecific variation
genetic factors
different genes and different alleles
environmental factors
types of characteristics
continuous and discontinuous
properties of discontinuous characteristics
characteristics fall into certain groups with no overlap (blood group) determined by genetics only (a single gene)
properties of continuous characteristics
characteristics show a range (height) determined by genetics (a few genes, polygenes) and their environment
genetic diversity definition
genetic variation
variety of alleles within a population of a species
benefits of high genetic diversity
species able to adapt with changes in the environment
e.g. if a new disease arises some individuals will have the characteristic to survive and reproduce
what can lower genetic diversity
small population size
founder effect, genetic bottleneck
what is the founder effect
where numbers in population start low
genetic bottleneck
where numbers in population decrease
what is natural selection and adaptation
variation in population of species
new allele arises due to random mutation
environment applies a selection pressure on the population
those with favourable alleles have a selection advantage, better adapted will survive and reproduce to pass on their favourable alleles
if this happens for many more generations then that characteristic will become more common
allele will become more frequent (adaptation)
2 types of selection
stabilising
directional
stabilising selection
when environment favours those with the most common characteristic
those on extreme die out
common characteristic will increase in proportion
range (standard deviation) will reduce
directional selection
when environment favours those individuals with characteristic on one of the extremes
this will become the most common characteristic over time
normal distribution will shift to that extreme
gene definition
section of dna that codes for a protein
made out of introns and extrons
intron definition
non-coding dna
turns gene on or off
exon definition
coding part of dna
codes for a 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, triplet code
sequence of bases determines sequence of triplet codes
determines sequence of amino acids
=polpeptide chain=primary structure
then folds to secondary then tertiary then quaternary
properties of triplet code
degenerate= each aa has more than one triplet code
non-overlapping= each base is only read once
stops codes= occur at the end of sequence, don’t code for an amino acid
universal= same amino acids code for same protein everywhere
how does a mutation lead to a non-functional enzyme
change in basde sequence change in sequence of triplet code change in aa sequence change primary structure changes hydrogen/ionic/disulfide bonds changes tertiary structure changes active site shape substrate no longer complementary no longer form enzyme substrate complex
how is a protein assembled
transcription and translation
transcription definition
production of a single stranded complementary copy of a gene called mrna
translation defiition
use sequence of codons on mrna to assemble protein, trna brings in amino acids
dna vs rna
deoxyribose sugar vs ribose sugar
thymine vs uracil
double stranded vs single stranded
one type vs two types (mrna and trna)
names of nucleotide bases
adenine thymine cytosine guanine uracil
what is mrna
messenger rna
single stranded complementary copy of a gene
carries the code for assembling protein (on dna called triplet code, on mrna called codon)
what is trna
transfer rna
single stranded rna folded over into a clover leaf shape held together by hydrogen bonds between bases
has aa attachment site on the top
has 3 specific bases on the bottom (anti codon)
anticodon binds to complementary codons on mrna
what is transcription
occurs in nucleolus of nucleus
dna helicase breaks hydorgen bonds between complementary bases in the gene
the double strand of the gene unwinds
leaves 2 separate strands (1 coding and 1 template)
complementary rna nucleotides bind to exposed bases on the template strand
rna polymerase joins the sugar-phosphate backbone of rna strand
leaves pre-mrna (containing introns and exons)
copies of the introns are removed by splicing
leaves mrna
what is translation
takes place on the ribosomes of rough endoplasmic reticulum
mrna leaves nucleus via nuclear pore
mrna attaches to a ribosomes
complementary trna carrying specific amino acids bind to the codons on the mrna via their anti codon
amino acids on trna are joined by peptide bonds
what does meiosis produce
4 genetically different cells
haploid
benefits of meiosis
produces gametes which are used in sexual reproduction
2 gametes fuse to form a zygote which develops into an organism
stages of meiosis
interphase
meiosis 1
meiosis 2
cytokinesis
process of meiosis
interphase:
- g1:protein synthesis
- S:dna replication
- G2: organelle synthesis
meiosis 1:
- prophase 1:dna coils to form chromosomes, nucleus breaks down, spindle fibres form, crossing over occurs
- metaphase 1: homologous pair of chromosomes line up at the equatoe and attach to spindle fibre via centrometre
- anaphase 1: spindle fibres shorten and pull, homologous pair of chromosomes separate to opposite poles by independent assortment
- telophase 1: chromosomes uncoil, nucleus reforms (2 nuclei)
meiosis 2:
- prophase 2: dna coils to form chromosomes, nucleus breaksdown, spindle fibres form
- metaphase 2: chromosomes line up in middle of cell and attach to spindle fibres via centromere
- anaphase 2: spindle fibres shorten and pull, centromere splits, sister chromatids move to opposite poles by independent assortment
- telophase 2: chromatids uncoil, nucleus reforms, left with 4 genetically different nuclei
cytokinesis:
- separating each cell into 4, with a nucleus and organelles
how does meiosis produce variation
crossing over and independent assortment
crossing over
occurs in prophase 1 of meiosis 1
homologous pairs of chromosomes wrap around each other and swap equivalent sections of chromatids- produces a new combination of alleles
independent assortment
in anaphase 1 of meiosis 1- homologous pairs of chromosomes separate
in anaphase 2 of meiosis 2- chromatids separate
independent assortment produces a mix of alleles from paternal and maternal chromosomes in gamete
what happens to dna mass in meiosis
quarters
what happens to chromosome number in meiosis
halves
mutation definition
change in the dna sequence
2 tpyes: chromosome mutation and gene mutation
what causes mutations
random
or due to mutagenic agents (chemicals, radiation)
chromosome mutation
in plants inherit more than one diploid set of chromosomes (polploidy)
in animals homologous pair of chromosome do not separatew in meiosis either inherit one extra or one less chromosome (non-disjunction)
what is a gene mutation
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 so new triplet code codes for same aa
mis-sense codes for different aa s slightly different protein shape
non-sense codes for stop codon so chain isn’t produced
insertion and deletion
adding a base
or deleting a base
cause frameshift, all triplet codes after mutation changes so normal polypeptide chain/protein isn’t produced
Prokaryotic DNA
Shorter
Circular
Not associated with histones
No chromosomes
Eukaryotic DNA
Longer
Linear
Associated with his tones
Form chromosomes
DNA in mitochondria and chloroplasts
Short
Circular
Not associated with his tones
What do courtship behaviors allow individuals to do
Recognize members of their own species Identify a mate capable of breeding Form a pair bond Synchronize mating Become able to breed
Recognizing members of their own species
To ensure mating only takes place between members of the same species so they can produce fertile offspring
Identify a mate that is capable of breeding
Both partners need to be sexually mature, fertile and receptive to mating
Form a pair bond
Lead to successful mating and raising of offspring
Synchronize mating
So it takes place where there is the maximum probability of the egg and sperm meeting
Become able to breed
Bringing a member of the opposite sex into a physiological state that allows breeding to occur
Artificial classification
Divides organisms due to characteristics that are useful at the time
Analogous characteristics
Same function but not the same evolutionary origins
Bacteria
Absence of membrane bound organelles Unicellular Ribosomes are 70 s which are smaller Cell walls present and made of Murein Single loop of dna no histone
Archaea
Differ from bacteria as
Genes and protein synthesis are similar to eukaryotes
Membranes contain fatty acid chains with ester bonds to glycerol
No murein in cell walls
More complex rna polymerase
Eukarya
Cells have membrane bound nucleus and organelles
Membranes containing fatty acids with ester bonds to glycerol
Not all possess cell wall but if they do there is no murein present
Ribosomes are larger 80s
3 domains i should know
Bacteria
Archaea
Eukarya
