True or false cells use the instructions in nuvleic acids to carry out all life functions

What percentage of errors does your body’s ""auto correct"" system detect?

AveGali [126]

Answer:

99%

Explanation:

5 0

2 years ago

Figure 1 represents a segment of DNA. Radiation can damage the nucleotides in a DNA molecule. To repair some types of damage, a

Ne4ueva [31]

Answer:

Explanation:

This question is incomplete. However, what is described in this question is a method of DNA damage repair mechanism. The method described is called base excision repair. Generally, glycosylases play important roles in base excision repair (as they detect and remove these damaged bases).

One thing that can be considered while identifying the bond to be broken is the codon that will be formed after the removal of base. If this codon (a three base sequence) will still produce the same protein as when a normal cytosine was present.

NOTE: During this base excision repair, a glycosylase will detect and remove the damaged cytosine. Once removed, the remaining nucleotide backbone (of the removed cytosine) is also removed and the gap is filled and sealed by other enzymes in this repair mechanism.

6 0

2 years ago

You find a fossil that you think is about 350 million years old. You decide to use 235U to date a volcanic ash bed just below th

devlian [24]

Answer:

I would expect that the sample has only 50% of the original 235 U.

Explanation:

That is because 235 U has a half-life of 700 million years and I expect that my sample be 350 million years old. 350 is half of 700.

8 0

2 years ago

Compare and contrast the differences between mature human eggs and sperm in the following questions. For each prompt, determine

Llana [10]

Answer:

QUESTION 1:

a. They undergo unequal cytoplasmic division during meiosis- eggs

b. Their chromosomes have undergone genetic recombination and independent assortment- both gamete types

c. They contain specialized secretory vesicles called cortical granules just under the plasma membrane- eggs

d. They are characterized by a flagellum. Most of these gametes die without ever completing meiosis- sperm

e. The acrosomal reaction occurs in these cells- sperm

f. They can be derived from any adult cell type- neither gametes

QUESTION 2:

c) The egg is surrounded by a mineralized shell added before the egg exits the body.

Explanation:

a) Female reproductive cells undergo meiosis to produce one large egg and three polar bodies. However, an unequal cytoplasmic division occurs in favour of the large egg.

b) Since both egg cell and sperm cell are produced via meiosis and meiotic division involves the processes of genetic recombination and independent assortment, hence, both gamete types have their chromosomes underg genetic recombination and independent assortment.

c) Egg cells contain specialized secretory vesicles called cortical granules just under the plasma membrane. This cortical granules help prevent more sperms from fertilizing the same egg after it has been fertilized.

d) Sperm cells possess flagellum for motility in the female reproductive tract. Most of the sperm cells die without ever completing meiosis.

e) Sperm cells possess an head-covering structure called ACROSOME. Acrosome reaction is the process undergone by sperm cells permeate the zona pellucida of the egg.

f) Gametes are specifically derived from adult reproductive cells and hence, NEITHER TYPE OF GAMETE can be derived from any adult cell type

QUESTION 2:

The egg in Sea urchins is surrounded by a mineralized shell added before the egg exits the body to the external environment. This does not occur in the humans because the egg does not leave the body but fertilized internally.

8 0

2 years ago

The yellow ring inside the bacterial cell represents the bacterial DNA. Why does this structure disappear by step 3 of the lytic

adell [148]

Answer:

The bacterial DNA gets degraded at step 3 of the viral lytic cycle.

Explanation:

Viruses are organisms that are incapable of replicating on their own, hence, they require a living host which they infect and use its replicational ability to reproduce theirselves. The infection cycle of this virus is regarded as its replication cycle. Viruses employ either the LYTIC or LYSOGENIC cycle for infection.

The lytic cycle involves killing of their host cell at the end of the cycle. Generally, the cycle starts with the attachment of my the virus to the cell membrane of its host using specific receptor sites (step 1). It then penetrates the host cell as seen in step 2.

After penetration, the virus then secretes certain degrading enzymes called ENDONUCLEASES that degrades the bacterial DNA. After which the virus uses the replicational and gene expressing ability of the host to transcibe its genetic material and replicate itself. This process called SYNTHESIS occurs in step 3.

Hence, the yellow ring in the image that represents bacterial DNA disappears in step 3 (synthesis stage) because it gets degraded by viral digesting enzymes.

6 0

2 years ago