Question

27) Proteins that are involved in eins that are involved in the regulation of the cell cycle and that show fluctuations in concentration during the cell cycle are called A) cyclins B) kinases C) estrogen receptors D) ATPases E) kinetochores 28) 28) What is the difference between an aldose sugar and a ketose sugar? A) the position of the carbonyl group B) the number of carbons C) the position of the hydroxyl groups D) One is a ring form; the other is a linear chain. E) They are mirror images of each other.

Answer 1

ANSWER:--

27. Proteins that are involved in the regulation of cell cycle and that show fluctuations in concentration during cell cycle are called CYCLINS.

EXPLANATION --

$\bullet$CYCLINS -

• Cell cycle are regulated by two type of proteins cyclins and cyclins-dependent protein kinases.
• cyclins are the cell cycle regulators.
• cyclins are the family of proteins that control the progression of cell in cell cycle.
• There are four cyclin proteins are found G₁ cyclins,G₁/S cyclins ,S cyclins and M cyclins.
• each cyclins is associated with a specific phase of cell cycle.
• G1 cyclins- triggers cells to move from G₀ TO G1 and from G1 to S phase.
• G₁/S cyclins - it ready the cell for dna replication in s phase.
• S cyclins- starts dna replication in the nucleus in s phase .
• M cyclins- help in joining of mitotic spindle and other process in cytoplasm to prepare for mitosis.
• the concentration of cyclins fluctuate during cell cycle.

below diagram amount of fluctuation of cyclins during cell cycles--

als cyclin scycling G cyclin Imcyclin concentration Giphane Sphane G₂ phone m phare

and other option

kinase - it is an enzyme.which involves in phosphorylation reaction,addition of phosphate group to a molecules.

estrogen receptors - it is found in nucleus. no such specific role in regulation of cell cycle.

ATPAses- it is types of enzyme that hydrolyzed ATP into ADP.

Kinetochores- it is found in chromosomes.it is a protein which is associated with centromere of chromosomes.it helps in attachment of chromosomes to microtubules.

28. What is difference between an aldose sugar and an ketose sugar -

ANSWER- The position of carbonyl group. option A is correct

EXPLANATION-

$\bullet$Aldose -

• it is a monosaccharides with a carbon backbone chain with a carbonyl group at terminal carbon atom.
• hydroxyl group are connected to others carbons atoms.
• the carbonyl group in aldose is aldehyde.
• in seliwonoff's test aldose reacts slowly and produce light pink color.
• in aldose the carbonyl group at first carbon atom.

$\bullet$Ketose-

• it is a mono saccharides contains one ketone group per molecule.
• ketone group is connected to second carbon atom.
• the simplest ketose is dihydroxyacetone .
• in seliwonoff;s test ketone give deep cherry color.

4-6=0 SCH₂OH CHOH H-4-04 or stayo 40-5H or X 4-49-0H 4 4-6-04 OH ICH OH 2c=0 Ho 36-4 H - 04 H-sc-04 HEHoH 04 SCH, OH Aldoxe 6CH₂OH carbonyl group present at terminal carbon atom or first co carbon atom Ketore carbonyl group predent at cecond (C2) Cardon atom.

now back to your question , the correct answer is position of carbonyl group.

in aldoses the carbonyl group present at first carbon atom .

in ketoses the carbonyl group is present at second carbon atom.

so from this ,we conclude that option a is correct.

x

another option -

option B - NUMBER OF CARBON ATOMS IS SAME IN RESPECTIVE ALDOSES AND KETOSES. SO THIS OPTION IS WRONG.

option C - position of hydroxyl group is not differ among ketoses andaldoses.

option D- both can form linear as well as ring structure.

option E- they are not mirror image.