Paper 2 Flashcards
Describe the general roles of homeobox genes in the human body and suggest the role of these genes in the development of the brain.
General roles:
- determine overall body plan by switching different genes on or off in different cells and tissues
- determine cell identity
- expressed in a set order during development
- regulate levels of apoptosis and mitosis
Role in brain developemnt:
- determine head and tail regions/ posterior and anterior regions and therefore where brain and spinal cord will develop
- expressed in a set order to determine regions of the brain
- switches genes on or off in brain to form specialised neurones
- regulate mitosis and apoptosis of neurones to adjust neural organisation
Outline steps in creating a DNA profile:
- Collect DNA sample from tissue
- Amplify DNA in PCR
- Cut/digest DNA using restriction enzymes to cut DNA fragments
- Use gel electrophoresis to separate DNA fragments by size
- Transfer fragments to paper
- Add fluorescent probe
- Use X - rays to view position of DNA fragments
Why can some regions of DNA be described as non coding?
The editing of primary mRNA removes them so they are not present in mature mRNA so not translated sequences of genes
What is synthetic biology?
Creation of an organism with an artificial genome.
Outline the process of primary succession:
Pioneer community:
Begins with bare rock, arrival as seeds or spores, pioneer species have certain adaptations such as extreme condition tolerance
Intermediate community:
Herb species including grasses, followed by trees and other organisms
Climax community:
Dominance of few tree species, little chance over time
General principles:
Community and decomposition changes composition of the soil, increased organic, nitrate and water content
How can DNA be used to provide support for the theory of evolution?
DNA found in all organisms that is highly conserved comparison of DNA between species, similar base sequences indicates recent common ancestor
How may overcrowding affect a plants growth?
Positive tropism could cause plants shoot to bend towards light so plants grow taller and climb over eachother - positive thigmotropism
Growth of roots towards water
Is providing support to the cell a role do the membrane
No
What could make something conservation not preservation?
If there are people there
There are human activities such as farming
Active measures to maintain biodiversity
When is a result significant in chi squared?
When the calculated value is higher than the critical value
There is a 5% probability that difference is due to chance
What can cause a phenotype ratio to be not the ecpercted one?
Epistasis because the expression of an allele is blocked by another allele for the same trait on a different gene
Autosomal linkage because the two alleles are close together on the same chromosome so are not separated by independent assortment so genes are inherited together and end up in same gamete
Why would an allele be recessive?
Because you need two of it to prevent the functional enzyme being synthesised
How to plants respond to pathogens?
Production of callose
Release of toxic chemical e.g caffeine
Leaf drop / abscission
Rapid death of plant tissue to limit spread
Classification of organisms level of response
They are likely to be related or in the same genus if they are on the same branch of the phylogenic tree or have recent divergence
If divergence so less recent than other species they aren’t in the same genus, different anatomy,
Classification principles:
Phylogeny is the basis of classification
Species that divergences from each other recently, have a similar base sequence
Recognition that biochemical classification is more accurate than comparative anatomy
Scientific knowledge develops over time
Change is justified by new molecules evidence
Difference in the structures of lactose and maltose
Maltose has alpha glucose and alpha glycosidic bonds with lactose is beta
How can galactose be used as a respiratory substrate?
Glycosidic bonds can be broken down by respiratory enzymes
It is so liable so can move within cell and H and OH groups can form bonds with water to allow soluabiluty
Can be converted to pyruvate or used in glycolysis coz it’s easily converted to glucose
How can Benedict’s reagent and colorimeter be used to calibrate and measure the conc of lactose in an unknown sugar
- Zero the colorimeter using a blank and red filter paper
- Use known concentrations of lactose solutions, produce serial dilations and create calibration curve
- Take unknown sample, using the same method and use the calibration curve to determine concentration
Describe process used to produce pesticide resistant plant in genetic engineering.
Method of gene extraction: removals of desired gene using restriction enzymes leaving sticky ends, same restriction enzyme is use to cut plasmid, DNA fragments insteretd to plasmid and anneals through hydrogen bonding with use of DNA Ligase
Electroporation is used to make membrane of host cell more permaeble so the plasmid can enter the host cell
Marker genes used by attaching gfragemnt to a gene that codes for antibiotic resistance and tested in agar gel plate to determine whetehr antibiotic resistant gene is functional or not
