Question

1) Match the following with their definitions

___ Kinase

___ Methylation

___ DNA ligase

___ Topoisomerases

___ Single- Stranded Binding

___ Exonuclease

A) Protiens that bind to and protect the unpaired DNA strands during replication.

B) Enzyme that relives the supercoiling strain due to the twisting of the DNA strands ahead of the replication fork.

C) Enzyme that removes an incorrect nucleotide from a growing DNA strand

D) Enzyme that phosphorylates other molecules

E) Enzyme that acts as "glue" upon removal of Okazaki fragments or DNA repair, binding the DNA strands back together

F) The method by which we can identify the older, parental DNA strand.

2) Match the following cellular processes with the phases of meiosis. You can only have one answer per question, but answers may be used more than once.

___ The meiotic spindle disappears

___ Synapsis occurs

___ Microtubules from both poles of the spindle move bivalents to the

center of the cell

___ Microtubules attatch to kinetochores at the centromeres on bivalents

___ The nuclear envelope re-forms around the segregated chromosomes

that contain sister chromatids

A.) Prophase I

B) Prophase II

C) Prometaphase I

D) Prometaphase II

E) Metaphase I

F) Metaphase II

G) Telophase I

H) Telophase II

I) Anaphase I

J) Anaphase II

Answer 1

1)

Kinase - D

Kinase is an enzyme that phosphorylate other molecules by adding phosphate group from high energy ,phosphate yielding molecules to a particular substrate .

Methylation - F

DNA methylation is the process by which methyl groups are added to the DNA (Deoxyribonucleic acid) molecule . By detecting methylation ,the older parental strands can be identified because the older DNA strands contain it's methyl group attached to it and the newer DNA strand does not contain it's methyl group.

DNA ligase- E

DNA ligase is an enzyme which acts as a glue in filling the gaps by adding phosphodiester bond and the gaps was created after the removal of okazaki fragments .It also joins the DNA strands together.

Topoisomerase-B

Topoisomerase is an enzyme that releives the torsional strain in the DNA due to the twisting of the DNA against the replication fork .It removes the positive supercoils generated to relieve the negative supercoils occuring downstream.

Single stranded binding - A

Single stranded proteins binds to the seperated individual DNA strand and protect the unpaired strand during replication so that each strand act as template for new DNA synthesis .

Exonuclease- C

Exonuclease is an enzyme that remove excessive or unwanted (incorrect) nucleotides from the growing 3' end of the strand .

2)

A)The meiotic spindle disappears -G)Telophase I

Meiotic spindle involves in the segregation of chromosomes into daughter cells and is made up of microtubules.

B)Synapsis occurs - A) prophase I

Synapsis is the pairing of two homologous chromosomes and during synapsis , the ends of chromosomes are first attached to the nuclear envelope

C)Microtubules from both poles of the spindle move bivalents to the center of the cell - E) Metaphase I

Chromosomes attach to the microtubules from both the poles of the spindle and line up in the center of the metaphase plate for seperation.

D) Microtubules attatch to kinetochores at the centromeres on bivalents- C) Prometaphase I

Microtubules of meiotic spindle attach to the kinetochores at the centromere during prometaphase I. It is the second stage of meiosis I and happens during break down of nuclear envelope so that microtubules reach the chromosomes.

E) The nuclear envelope re-forms around the segregated chromosomes that contain sister chromatids- G) Telophase I

Nuclear envelope reforms in order to allow new cells to produce proteins and to protect DNA.This happens when the cells divide around the seperated chromosomes .