Question

1. Which of the following is/are required for retrotransposons to move from one location to another in the genome?

Select one or MORE:

a. RNA polymerase

b. DNA polymerase

c. ribosomes

d. reverse transcriptase

2.

Which of the following is/are not commonly used in gene expression and cell replication in human cells?

Select one or MORE:

a. ribosomes

b. reverse transcriptase

c. DNA-dependent RNA polymerase (DNA-->RNA)

d. DNA-dependent DNA polymerase (DNA-->DNA)

e. RNA-dependent RNA polymerase (RNA --> RNA)

3.

Ubiquitin can be added to lysine, cysteine, serine and threonine residues in proteins. The ubiquitination (addition of ubiquitin) of a protein would:

Select one:

a. target the protein to be translocated to the rough endoplasmic reticulum to continue translation of the peptide.

b. trigger the hydrolysis of its complementary mRNA sequence.

c. trigger alternative splicing of mRNA by snRNP.

d. trigger the removal of the pro-segment of a enzyme, activating it.

e. target the protein for breakdown by proteasomes in the cell.

4.

miRNA can:

Select one or MORE:

a. form a complex with proteins that will block translation of mRNA containing complementary sequence

b. form a complex with proteins that will break down mRNA containing complementary sequence

c. remove introns from pre-mRNA in eukaryotes

d. fluoresce when complementary mRNA is present

5.

Coordination of gene expression of enzymes required in a single metabolic pathway in eukaryotes would require:

Select one or MORE:

a. organization of genes into operons

b. the same combination of control elements for all genes in the pathway

c. alternative splicing of a single gene to produce all enzymes in a pathway

d. presence of the correct combination of activator proteins for the genes in the pathway

Answer 1

a)Why is distillation necessary to create high concentrations of alcoholic drinks?

Answer

Source Words by: Simon Difford

Distillation does not produce alcohol, it merely concentrates it. T o produce a distilled spirit you need to
start with an alcoholic liquid ('wash') to distil your spirit from. The majority of vodkas and all whiskies
are distilled from a wash which is essentially beer made by fermenting cereal grains.
Potable (a fancy word for 'drinkable') alcohol is a liquid called ethanol. And because ethanol alcohol boils
at a lower temperature than water the two liquids can be separated by evaporation. So by heating the
wash in an enclosed environment (the still) and capturing the alcohol vapours emitted it is possible to
concentrate the alcohol by boiling it off from the water which is left behind as it needs more energy before
it can evaporate.
This process is complicated by the fact there are different types of alcohol and other chemical compounds
present besides ethanol, all with different boiling points. These are collectively known as congeners and these
chemicals give spirits character and flavour . Some congeners are desirable in small quantities, others should be
removed as completely as possible during distillation.
In vodka production more of these congeners will need to be removed than if you were making a less pure, more
characterful spirit such as tequila or cachaça, or a spirit that will undergo a prolonged maturation process such as
cognac or whiskey , as evaporation during aging process will facilitate the removal of some congeners while
others are softened by interaction with the wood.
Ethanol alcohol, the potable alcohol which the distiller wants to capture has a boiling point of 78.2?C. Other, less
tasty and often harmful congeners have boiling points that are slightly higher or lower than Ethanol.
During the distillation process the first vapours to boil off the water are the more volatile alcohols, those with the
lowest boiling point. These are variously known as 'heads' or 'foreshots' depending on the part of the world you
are in and the product being distilled.
Next comes the desirable ethanol alcohol, usually described as being the heart. By diverting the flow of spirit
emerging from the condenser the heads can be discarded and the heart separated and saved.
As the alcohols with the lower boiling points have now evaporated, this leaves water, proteins, carbohydrates
and less volatile alcohols with higher boiling points, better known as 'tails', or 'faints'. The still will be run to
separate these less volatile alcohols from the watery wash until the liquid left in the still is around 1% alcohol by
volume. It is not economical to further separate the little remaining alcohol and the 'pot ale' left in the still will
be sent for processing or simply spread over fields as fertiliser. The tails and sometimes also the heads will be
retained and added to the wash of the next distillation so recycling any trapped ethanol.

One of the skills of a distiller is judging the right moment to "cut" the stills outflow from heads to hearts and
hearts to tails.

The smaller the percentage of heart so the greater the purity of the heart but this means sacrificing
more valuable ethanol distillation is necessary.

b) The distillate was clear, but what is proof that more than just water and ethanol are in the distillate?

Answer : The mixture of distillate heated in a flask. Ethanol has a lower boiling point than water so it evaporates first. The ethanol vapour is then cooled and condensed inside the condenser to form a pure liquid. The thermometer shows the boiling point of the pure ethanol liquid. When all the ethanol has evaporated from the solution, the temperature rises and the water evaporates.( Main prof for ethanol in water)

This is the sequence of events in distillation:

heating ? evaporating ? cooling ? condensing