The type of joint that allows bones to move backward and forward in only one direction is the hinge joints. Ball and socket are the joints that allows movement in all directions. Gilding joints are type of joints that are the vertebral disks that allow twisting, turning, and sliding. Hinge joints are formed between two or more bones where the bones can only move along one axis to flex or extend. They include the ankle, elbow and knee joints.
Answer:
The correct answer is D)RNA polymerase
Explanation:
In DNA replication many enzymes and proteins are required to replicate a DNA template. For initiation of DNA synthesis the two DNA strands must be separated which is done by helicase.
Then primase adds short nucleotide sequence and initiate DNA replication. After that DNA polymerase acts and adds nucleotide at the 3' end of growing DNA strand. Ligase is the enzyme that joins the two Okazaki fragments that are created in the lagging strand.
RNA polymerase is not required in DNA replication and it works in transcription therefore the correct answer is RNA polymerase.
Answer:
C) Through genomic imprinting, methylation regulates expression of the paternal copy of the gene in the brain.
Explanation:
The pattern of gene expression wherein either paternal or maternal gene is expressed in specific cells while the other one is prevented from expression is known as genomic imprinting.
In the given example, the maternal copy of the gene on chromosome 15 is expressed in brain cells while its paternal copy is not expressed in these cells. Hence, the pattern of expression of this gene is regulated through genome imprinting. One of the mechanism is methylation of cytidine residues of CpG islands of the DNA that are more frequently present within promoters of the genes.
When the cytidine residues of these sequences are methylated into 5-methylcytidine, the transcription factors do not bind to these promoters preventing the expression of these genes.
Hence, methylation of cytidine residue in CpG islands of the promoters of the gene present on chromosome 15 could have silenced its expression in brain cells.
Use binomial distribution with p=0.25, n=5, x=2
P(X=x)=C(n,x)p^x (1-p)^(n-x)
P(X=2)=C(5,2) 0.25^2 0.75^(5-2)
=10*0.0625*0.421875
=0.26367
So the probability of 2 of 5 children having type-O blood from these parents is 0.26367.
