Unit 4 - populations genetics
A population of 3 sparrows has 150 individuals with red beaks (RR), 60 individuals with brown beaks (rr), and 90 individuals with reddish- brown beaks (Rr), What is the allele frequency of allele r in the population?
[60 + (90/2)]/300 = 0.35
How often an allele occurs in a gene pool, relative to the other allele for the gene
The genetic code is described as a degenerate code. This means that
Some amino acids may be encoded by more than one codon
The proteome is
the entire set of proteins expressed by an organism at a given time
Defence mechanisms against bacterial pathogens include
A - the production of interferon
B- neutralisation by histamines
C- destruction by complement proteins
D - agglutination by cytotoxic T cells
C - destruction by complement proteins.
The role of the lymphatic system in an immune response includes
transport of antigen-presenting cells, including dendritic cells.
(Mast cells are found in connective tissue, platelets are found in the blood and the blood delivers monoclonal antibodies to target cells. The antigen-presenting cells travel to the lymph nodes via lymph vessels.)
A population of beetles in an evergreen forest had individuals who were green or brown in color. As a result of deforestation, the forest turned into grassland over several years. After a few years, all the green beetles in the population perished and only the brown-colored beetles remained in the population as they blended well with the surroundings and could escape better from predators. What force of evolution could led to this?
Natural Selection
The part of a molecule referred to as an anticodon can be found in
transfer RNA.
In animal cells, tight junctions are multi-protein complexes that mediate cell-to-cell adhesion and regulate transport through the extracellular matrix. Proteins that form these complexes are made within the cell.
One pathway for the production of protein for these junctions is
nucleus – ribosome – endoplasmic reticulum – vesicle – Golgi apparatus.
Neutrophils
migrate to the site of infection and engulf invading pathogens.
(Neutrophils are phagocytes and their role is to engulf and destroy pathogens such as bacteria.)
The role of T helper cells is to
Control the adaptive immune response.
(The clue is in the name – helper cells. T helper cells signal other cells to gather and respond to an infection. This may result in the production of antibodies by B cells and the attraction of phagocytes.)
A group of elephants in a population were born without tusks. A few of the tusk-less elephants migrated to a distant forest where tress had fewer woody branches and more green leaves. Their population gradually increased and it had mostly tuck-less elephants. What forces of evolution could have resulted in this?
Random mutation in the population could have led to the appearance of tusk-less elephants
The trp operon in prokaryotes illustrates the switching off and on of genes. The operator within the trp operon
is the binding site for the repressor protein and tryptophan.
(The regulatory gene codes for the production of a repressor protein.)
DNA ligase
joins two DNA fragments together by forming phosphodiester bonds (covalent) between the two fragments.
Interferon is a chemical that
protects uninfected cells from viral attack.
Rabies is a viral disease spread to people by infected animals. A person bitten by an infected animal should be given an injection of specific antibodies.
Following the injection, this person should have
artificial passive immunity.
(The person has immunity because they have received antibodies. The immunity is passive rather than active because the person has received antibodies rather than making their own.)
A Siberian goat and the Himalayan goat were thought to belong to the same species. However, they are known to be two different species. What might have resulted in the origin of the Himalayan goat?
Allopatric Speciation - Geographical separation.
Transcription of the structural genes within the trp operon will occur when
RNA polymerase is attached to the promotor.
The process in which the bacterial cell takes up the plasmid is called
Transformation
Nonspecific defenses of the immune system that act against bacteria include
Phagocytes.
Phagocytes are large white blood cells that have a general role in removing potential threats such as bacteria.)
How to reliably test for HIV?
HIV antigen has a complementary shape specific to the HIV antibody.
(This allows the HIV antigen to attach to the HIV antibody. If the antibody and the antigen had the same shape, they would not bind together.)
In a population of birds, a group of females chooses to mate with those males that have long tail feathers. Over a period of time, this resulted in the formation of new species of birds in which all males have long tail feathers, in the same region. The new species could no longer interbreed with existing species of birds with short-tailed males. What type of speciation is described here?
Sympatric Speciation - no geographical separation, but changes in reproductive behavior.
The artificial insulin gene may have a different nucleotide sequence from the human insulin gene. This is because the DNA code is
A redundant. (Redundant refers to the fact that a number of DNA triplets may code for the same amino acid.)
Bacteria are used in gene cloning because they
can replicate non-bacterial sequences of DNA in a short time
Major Histocompatibility Complex (MHC) class 1 molecules
present foreign antigens to B and T cells.
Monoclonal antibodies can be produced and used to treat different types of cancers. What makes Monoclonal antibodies special and useful in cancer?
Monoclonal antibodies produced from the same clone of a cell are specific to the same antigen.
(Monoclonal literally means from one clone – identical antibodies (made of protein) that are specific to the same antigen. They will attach to specific antigens on the outside of the target cancer cells.)