VARIATION AND CLASSIFICATION Flashcards
Define interspecific variation
Difference that occurs between members of different species
Define instraspecific variation
Differences that occur within a species
What is genetic variation due to?
Random mutations -chromosomes mutating -DNA mutating Recombination of alleles -crossing over during prophase 1 of meiosis
Describe etiolation
Plants grown without enough light may become etiolated
Grow long and spindly with long internodes
Describe chlorosis
Plants may develop yellow leaves due to
lack of chlorophyll
May be due to lack of magnesium or iron ions in soil, lack of light or viral infection
What is discontinuous variation?
Displayed on bar chart
Phenotypes fall into distinct categories
Often controlled by one gene (monogenic)
Environment is likely to have little or no effect on the phenotype
Examples- blood groups, tongue rolling, sweet pea flower colour
What is continuous variation?
Continuous range of values between two extremes, usually forming normal distribution curve (bell shaped)
Influenced by the environment, more than monogenic characteristics
Example- height, weight (at birth), leaf size
What is another type of variation?
Polygenic variation
Define species
Group of organisms that are similar in appearance, anatomy, physiology, biochemistry and genetics
What can members of a species do?
Breed together (interbreed) to produce fertile offspring
What is phylogeny?
The study of evolutionary relationships between species
Shows how clearly related different species are
How are relationships between species displayed?
On a phylogenetic tree (cladogram)
Species are more closely related to appear closer to one another on the cladogram
Point where two lines diverge away from one another represent a shared common ancestor, which is now extinct
Describe classification
Used to group life on earth
Similarities and differences, between organisms
Relies on OBSERVABLE features of an organism
What is the taxonomic rank for classification?
Domain Kingdom Phylum Class Order Family Genus Species
What is a mnemonic to remember the taxonomic rank?
Dumb King Phillip Came Over From Great Spain
Describe the binomial system
Written in Latin- universal language
Two parts- hence binomial
Why is the binomial system important?
- organisms can have more than one local name
- organisms referred as one thing and something else somewhere else
- local name can refer to wide range of different organisms
- translations of language may give different names
What are the 4 rules of the binomial system?
- first name is the Genus, must have capital letter
- second name is species, must have lower case letters
- if typing, use italics
- if you are handwriting, must be underlined
Briefly describe the kingdom prokaryotes (prokaryotae)
No nucleus Loop of DNA Naked DNA No-membrane bound organelles Smaller ribosomes (70s) Free living
Briefly describe the kingdom protoctists (protoctista)
Eukaryotic
Single celled
Don’t fit in any other kingdoms
Autotrophic or heterotrophic nutrition
Define autotrophic
Organisms that can produce their own food from substances available to them
E.g. light (photosynthesis)
Define heterotrophic
Cannot synthesise their own food and rely on other organisms for nutrients
What are the 5 kingdoms?
Prokaryotes (Prokaryotae) Protoctists (Protoctstista) Fungi Plants (Plantae) Animals (Animalia)
Briefly describe the kingdom fungi
Eukaryotic
Single celled (yeast) or have a mycelium (branching) that consist of hyphae
Cell wall made of chitin
Cytoplasm is multinucleate
Mostly free-living
Use extracellular enzymes to break down matter and then absorb nutrients
Store food as glycogen
Briefly describe the kingdom plantae
Eukaryotic Multi-Cellular Cell walls made of cellulose Autotrophic nutrients (photosynthesis, absorption of mineral ions) Contain chlorophyll Store food as starch
Briefly describe the kingdom Animalia
Eukaryotic
Multicellular
Heterotrophic nutrition- digests large organic molecules
Stores food as glycogen
What are observable features involved in classification?
Morphology- external appearance
Anatomy- internal structures
Behaviour
What are examples of modern technology which have developed classification?
Embryology- how an embryo/foetus develops
Scanning electron microscope
Biological molecule analysis
What is cytochrome C and how does it help classify organisms?
All organisms that respire must have it
Protein not the same in all species
Comparison of amino acid sequence can conclude how related two species- based on similarities in the sequence
Greater number of similarities, the greater the evolutionary distance between species- therefore the less related they are
How does DNA/RNA help classify organisms?
They code for proteins in organisms
Changes to the DNA sequence of bases are called mutations and these occur randomly
Analysing DNA sequence and looking for differences is a way of telling how distant the organisms are
The more similarities, the more closely related they are
What does the kingdom Prokaryotae contain?
All the organisms that DO NOT have a nucleus
Briefly describe the three-domain system of classification
Once all grouped- labelled either eubacteria or archaebacteria
After studying genes that code for RNA that make ribosome’s, and observable features of these organisms
Woese decided splitting group in half would provide more accurate view of how these organisms evolved
What is eubacteria now?
Modern bacteria
What is archaebacteria now?
Archaea
What is placed in the eukarya?
Everything else that isn’t in bacteria and archaea
How is archaea different to bacteria?
Diff cell membrane structure
Diff enzymes for building RNA (RNA polymerase)
No protein bound to their genetic material
Diff RNA/DNA replication mechanism
Why did Woese argue archaea are actually more similar to eukaryotes?
- similar enzymes for building RNA (RNA polymerase)
- similar mechanism for DNA replication
- produce some proteins that bind to their DNA
Who designed the three-drains of classification?
Woese
What are features of Archaea and eukaryotes (part of three-domains)?
Similar enzymes for synthesising RNA
Similar mechanism for synthesising RNA and DNA replication
Production of some proteins that bind to their DNA
What are features of Bacteria (part of three-domains)?
Cell membrane structure is different
Flagella have different internal structures
No proteins bound to DNA
Different enzymes for synthesising RNA
Different mechanism for synthesising RNA and replicating DNA
What are parts of the domain Eukarya?
Kingdom protoctists- unicellular and simple multicellular eukaryotes
Kingdom plantae- multicellular eukaryotes that photosynthesise
kingdom fungi- partly defined by its members absorbing nutrients after decomposing organic material
Kingdom Animalia- multicellular eukaryotes that ingest other organisms
Domain Bacteria is the most…
diverse and widespread prokaryote
Most prokaryotes in domain archaea are…
extremophiles
