The best answer is A. The purpose of the cell wall is to hold the cell in a specific shape, usually rectangular or square. For example, a plant cell's wall keeps it rigid so that the plant can stand up.
If the cell does not have a wall, it can easily change shape to accommodate for things coming in and out of the cell.
Hope this helps!
Answer:
In order for pregnancy to happen, sperm needs to meet up with an egg.
Answer: DNA is a molecule made up of two strands, twisted around each other in a double helix shape. The two strands are complementary which have a 5 prime end and a 3 prime end. To understand this question you must first understand the steps that follow.
DNA Replication:
<u>Step one: </u>
DNA Helicase (unzips) separates the strands.
<u>Step two:</u>
DNA Primase starts the process and makes a small piece of RNA called a primer. This marks the starting point for the DNA.
<u>Step three:</u>
DNA Polymerase binds to the primer and will make the new strand of DNA. DNA Polymerase can only add DNA bases in one direction, from the 5 prime end to the 3 prime end.
- The leading strand is made continuously.
- The lagging strand does not run continuously because it runs in the opposite direction. Each fragment is started with an RNA primer. DNA Polymerase then adds a short row of DNA bases from the 5 prime to 3 prime direction. This results in okazaki fragments because it can only replicate in small chunks. The process is repeated.
<u>Step four:</u>
Once the new DNA is complete the enzyme exonuclease removes all the RNA primers from both strands of DNA.
<u>Step five:</u>
Another DNA Polymerase fills in the gaps that are left behind with DNA.
<u>Step six:</u>
DNA Ligase seals up the fragments in DNA, in both strands to make a continuous double strand.
<u>Final answer:</u>
DNA Replication cannot replicate at the same time due to the leading and lagging strand.
Good luck!
Answer:
ACA: Threonine
CAC: Histidine
Explanation:
To answer this question we need to remember that the ribosome reads every three bases or 'codon' in order to assign the right tRNA carrying the amino acid.
In the first artificial mRNA we see two patterns of three letter:
CAC and ACA.
In the second artificial mRNA we are able to identify three different patterns:
CAA
AAC
ACA
And they repeat, so we end with three different polypeptides: polythreonine, polyglutamine and polyasparagine. This will depend on the initial letter the ribosome starts reading.
The only amino acid that repeats in both artificial mRNAs is Threonine, and we see its pattern ACA also repeated.
So, we could assign this codon (ACA) to threonine.
We can then assume that the pattern CAC codifies for histidine since we only get this two polypeptides in the first mRNA.
Lastly with the information provided we cannot determine the codons AAC and CAA for glutamine or asparagine. We would need further experiments.
