Genetics and organic evolution Flashcards
What are the characteristics of a eukaryotic cell (animal)?
- nucleus present
- chromosome is in nucleic acid and covers covered in protein
- has chloroplast
- has mitochondria,Golgi bodies and E.R
What is a gene ?
A fundamental physical ad functional unit of heredity that carries info from one generation to next
A gene segment can?
- Transcribe
- regulate hormone+vitamin production
- Regulate surface absorption in cells
What are purines?
Double ringed nitrogen bases , they are adenine and guanine
What are Pyrimidines?
Single ringed nitrogen bases, they are thymine and cytosine
What is the backbone of a polypeptide chain?
The phosphate sugar group
What links the 3’ and 5’ carbon atoms of neighbouring sugars ?
As phosphodiester
A DNA molecule is made up of what ?
- A nitrogenous base
- a phosphate base
- a pentose sugar/deoxyribose
A sequence of 3 bases in a single strand of DNA is called?
Triplets
What are the Characteristics of a prokaryotic cell(plant)?
- no nucleus but has nuclear material
- no nuclear membrane
- chromosome is onto nucleic acid
- has chlorophyll but no plastids
- no mitochondria,Golgi bodies/E.R
What does the enzyme ‘helicase’ do ?
Unwinds original parent strands by breaking the hydrogen bonds between base pairs
What does the enzyme “gyrase” do ?
Releases tension in strands
What does the enzyme DNA polymerase do ?
Only join phosphate group at 5’ carbon of new nucleotide to the hydroxyl group of the 3’ carbon of old nucleotide in chain
How is DNA synthesised ?
In a 5’ to 3’ direction while copying a parent strand from a 3’ to 5’ direction
What is the operon ?
Is a portion of DNA molecule where information required to regulate timing of action is contained
Who first proposed the operon theory how ?
Jacob N Monad explained how genes can be turned off and on in response to the needs of the cell and was done on bacteria
What is an operon made up of ?
Consists of 3 groups of closely linked genes that act together and code for various enzymes that control a particular pathway
What is the regulator gene ?
It is a gene that produces a repressor molecule
What is the promotor in the operon ?
Controls the transcription process by initiating of the formation of mRNA
What is the operator in the operon ?
Helps to control the action of the structural gene
What is the structural gene ?
Contains information on the formation of enzymes ad are transcribed as single transcription units
How to turn off the operon
Regulator gene produced a substance known as a repressor which bind to the operator making it impossible for the RNA polymerase from starting the transcription process from structural gene
To switch on operon
Operator gene will do its work of intimating transcription when repressor not present . Repressor will not bind if prevented by another chemical
What is transcription ?
It is the decoding of information from DNA onto mRNA
What are the 3 gene regions of a gene ?
- The promotor
- The coding region
- The terminator sequence
What is splicing ?
The removal of introns(non coding portions of the message) from the primary strand
What is translation ?
Is the change of form of a base order of RNA into a peptide bond
What is proteins function ?
For catalytic activity and structure forming
What is mutation ?
It is the change of genetic structure due to outside or internal effects
Differentiate between gametic cells and somatic cells.
Gametic cells have information that can be passed onto the next generation whereas somatic cells are body cells so cannot be carried onto offsprings
Why is point mutation ?
When there is a change In a single base along the DNA molecule.
What is crossing-over ?
The exchange of information when non sister chromatids tangle their arms
Points at which inter-twining occurs are called?
Chiasma
Differentiate between cystic fibrosis an sickle cell disease .(a harmful mutation)
Sickle cell mutation involves a change to only a base in a DNA. Sequence, whereas cystic fibrosis involves the lost of a single triplet
What is albinism ?
Mutation in the gene producing an enzyme in the metabolic pathway to melanin
Give An example of a beneficial mutation
Tolerance To high cholesterol levels in humans in a village of limone. The mutation alters a protein by one amino acid making it withstand excess cholesterol .
What are mutagens ?
Chemicals or radiation that cause mutation .
What are the four main classes of mutagens?
- Ionising radiation
- Viruses and microorganisms .
- Alcohol and dietary components
- Environmental poisons and irritants
Effects of mutation
Add,delete or rearrange genetic material .
What Is chimera ?
An organism with a mixture of genetically different cells due
to a mutation in body cell beyond zygote stage
Difference between gametic mutation and somatic mutation
Gametic mutation can be inherited and occurs in the tested and ovary whereas the somatic cells occur in body cells and aren’t inherited but affects the person during lifetime
What is point mutation ?
A change in a single nucleotide or changes to a triplet
What is aneuploidy ?
Change in chromosome number in an organism or cel. A failure to separate and can be sex chromosomes or an autosome .
What is non-disjunction ?
Process where cells fail to separate due to meiosis 1
What is turners syndrome (X0) ?
An N-1 gamete is fertilised by a normal gamete resulting in a zygote with two N-1 chromosome (45). Known as MONOSONIC. Female,short,sterile, slow learner. 1/1500 an have
What is kleinfleters syndrome(XXY)?
Fertilisation between an (XX or X) egg and a (Y OR XY) sperm(47). Male, femaleness secondary characteristics, limbs longer then average, penis and testis under developed . Known as. Tri-sonic. 1/1000 have .
What is Down syndrome(trisomy 21) ?
Failure to separate the pair of chromosome 21 in the egg . Have abnormal ears,slanting eyes,short skull,long tongue and low intelligence
What is polyploidy ?
Is the multiple copies of extra whole set of chromosome(xsome).
What is auto polyploidy ?
Is the multiplication of the entire genome within a single species because of chromosomes failing to separate during cell division.
What is allo polyploidy?
Involved the combination Of chromosomes from 2/more species producing a sterile hybrid .
What is natural selection ?
Is the differential fertility in Nature favouring individuals that are better adapted to the environment .
What is stabilisation selection ?
The elimination of both extreme phenotypes and stabilising the composition of the gene pool thus decreasing genetic diversity
What is directional selection ?
The favouring of one extreme phenotype over average and other extreme phenotype. Occurs when the environment is changing steadily in a particular direction leading to evolution .
What is disruptive selection ?
The favouring of both the extreme phenotypes over average, and separating a single population into 2 sub population. This increase genetic variation
What is speciation ?
The rise of new species from an existing one where the two cannot interbreed due to gene exchange being impossible
What is a ‘race’?
A population which differ from each other that is easy observed by the characteristics .
Where Are GMOs applied ?
- Shelf life extension
- pest/herbicide resistance
- crop improvement
- environmental clean-up
- bio factories
- vaccine development
- livestock improvement using transgenic animals
What is meiosis ?
Is a special type of cell division concerned with producing sex cell for the purpose of sexual reproduction .
Daughter cells have half of info of parent cell.
What is mitosis ?
It is the replication of parent cell to produce two daughter cells identical to parent cell .
What is synapsis?
The pairing up of two sister chromatids to form bivalents
What is chiasma ?
The point where chromatids have crossed
What is recombination ?
The arising of new gene combinations from crossing over
What are GMOs ?
Are Organisms with artificially altered DNA . It can modified by:
addition
Alternation
Deletion
What is transgenic ?
The insertion of a foreign gene from another species to express that taut coded by the new gene
What is micropropagation/plant tissue culture ?
Method used in cloning plants
Micropropagation adavatages
- Used in Recovery programmes for endangered plants
- improvement of plant productivity+quality
- resistant to disease, pollutants ad insects
Micropropagation disadvantages
- reduction in genetic variation
- labour intensive
- need optimal conditions for growth and regeneration
What are explants ?
Small pieces from plants
What is a callus ?
An undifferentiated mass of cells.
What is gene cloning ?
A process of making large quantities of desired piece of DNA once it had been isolated .
-purpose to yield large quantities of either an individual gene
What is a molecular clone ?
The insertion of DNA fragment of interest into a DNA of a vector
What is a genetic marker ?
A part that allows them to e easily identified
What are epistatic genes/supplementary ?
Are genes that mask the effect of other genes
Define organic evolution
The total Change in the characteristics of population , occurring over many generations
What are coacervate droplets?
A cluster of macromolecules surrounded by a shell of water molecules
Who proved spontaneous generation false ?
Louis Pasteur
Who propose the heterotroph hypothesis ? And who proved it ?
Oparin and was proved by stab miller
What are viruses ?
They are a sub-cellular d life . That has to reproduce by a host and can crystallise.
What are the three stages of a virus ?
Virion
Provirus
Vegatative
What is a Virion ?
It is the fee particle stage where the virus is ready to invade a cell
What is a provirus ?
It is the incorporation of viral nucleus acid into the chromosome
What is the vegetative virus ?
It is the replication of viral nucleus acid inside a host cell using the hosts raw materials and metabolic machinery.
What are bacteriophages ?
They are virus that attach ad destroy bacteria
What is the lyric cycle ?
It is the attachment, incorporation and replication of viral nucleic acid and release of new phage viruses by lyses or extrusion
What is extrusion ?
The envelopment of viruses into the hosts membrane and the pushing out of the host cell
What is the lysogenic cycle ?
Same process as lytic cycle but the bacteria does not burst however it just replicates the viral DNA until they are exposed to UV or chemicals
Importance of viruses
Causes diseases-chicken pox, HIV.
Used as biological control
What are the characteristics of a proaryotic cell ?
- No nuclear membrane
- Only one circular chromosome
- may have chlorophyll no chloroplast
- no internal organelles
- flagella present in some cells
- no cytoplasmic streaming
- cell wall contains muramic acid
Wha are bacteria ?
Are procaryotic organisms belonging to Kindom monera which has DNA & RNA.
What are the various shapes of bacteria ?
Cocci Bacillu Spirilla Bacterial clusters & chains Filament
What are he endoscopes present in bacteria ?
Allows bacteria to survive harsh conditions
Many bacteria reproduce asexually through binary fussion, what is binary fussion ?
It is the splitting of the parent cell into two new cells . Mitosis in single celled organisms
What is conjugation ?
It is the fussion of two bacterial cell membranes by laying side by side and exchanging genetic material Through the cytoplasmic bridge
What is transformation ?
It is the bacterial cell receiving DNA fragments that have entered the bacterial cell env from dead cells .
What is transduction ?
The transportation of DNA from one bacterial cells into another by viruses
How does genetic recombination take place in bacteria ?
Conjugation
Transformation
Transduction
Ecological importance of bacteria ?
Aid in nitrogen cycle Decompose material Control populations Assist in antibiotic production Help in producing bread and yogurt
Blue-green algae structure
- Have all pigments
- Chlorophyll packed in vesicles called chromatophores
- cell wall made up of muramic acid
- Either rod or spherical
- independent or colonel smt filament
Sponges (phylum polifera)
Sessile aquatic organisms
Live single or in colonies
Opening is osculum collar cells have flagella cause water current
Skeleton-spicules
Amoeboid cells digest & distribute food
What are diploblastic conditions ?
Body made up of two cellular layers only-(endo & ecto- primary/ germ later )
Non cellular layers exist between both called meosglea.
Porifera & coelenterates exhibit this
What are coelenterates/cnidarians?
Cells showing specialisation and division of labour
What are tribloblastic conditions ?
Body made up of three cellular layers hat are laid down in the embryo itself
-all meta pans except cnidarians are This
What is the blastocoel?
It is the inner cavity of the hollow sphere
What is the blastula ?
It is the cell arrangement into hollow sphere due to continuous cleavage
What is the morula ?
It is the formation of a cluster of cells from rapid mitotic division
The cells on one side of the sphere that are larger are called ?
The vegetal hemisphere
The side of the sphere that has smaller cells are called ?
The animal hemisphere
What is the gastrula ?
It is a structure for me after cell movement occuring after blastula formation
What is the archenteron ?
A new cavity that forms after the invaginate cell layer is pushed right in against the outer layer
What are protostomes?
Blastocoel forms mouth
New opening Anus
Ex-earthworm
What are Deutrostomes ?
The blastocoel forms Anus
The new opening is the mouth
Ex-chordates higher animals
What is the neurula?
The name of the Embryo when the nervous system starts to develop
What are analogous structures ?
Are different structures that serve same function . Have no close evolutionary relationship .
What are homologous structures ?
Same structures that serve different functions
What is a fossile record ?
Preserved remains and imprints that reveal past biological events
Define morphogenic movement
Movement of masses of cells to different positions gives shape and form to the developing embryo
What is cellular differentiation ?
Process of cell specialisation and hence division labour
What is a colony and why it is not truly considered as multicellular ?
It is a loose association of cells and not considered multicellular bey as each is independent and has to look after all it’s physiological needs
What is a cistron?
A length of DNA that specifics one polypeptide chain in Protein synthesis
What are chromatophores ?
Resides that contain chlorophyll in blue-green algae (Cyanobacteria )
State The hardy Weinberg equilibrium principle
At equilibrium , both allele ad genotype frequency remain costs by from generation to generation
What is a vector ?
DNA that serves a s a carrier for a gene. Which Is incorporated into it
What are plasmids ?
Autonomous replicating extra-chromosomal DNA molecule found in bacteria
Define epistasis and dominance
Epistasis- interaction between different genes )non-allele(
Dominance-result of interaction between two different alleles of the same gene
What is ligation ?
Is a process of reassembling DNA fragments produced by the use of restriction enzymes . Pieces joined together by DNA ligase.
DNA produced this way called recombinant DNA
What are sticky ends ?
Ends with exposed nucleotide bases at each end .
What is annealing ?
The jointing of two matching sticky ends by base pairing
