Chapter 15 - Inheritance (Extended Version)

Question 1

What is a Triplet?

Answer 1

It is a sequence of three bases which is the code for a particular amino acid and is called a triplet. (base triplet)

Question 2

Why is the amino acid taken from the DNA to the ribosomes by the RNA?

Answer 2

Because the DNA molecules are too large to leave the nucleus.

Question 3

What is Transcription?

Answer 3

• It is the process by which the mRNA is formed using the code in a DNA molecule.
  1. The genetic instructions are copied (or transcribed) from the DNA to the mRNA molecule.
  2. Transcription is triggered by chemical messengers that enter the nucleus from the cytosol and bind to the DNA at the relevant gene.
  3. This causes an enzyme called RNA polymerase to being the process of making mRNA.
  4. RNA polymerase then transcribes (copies) the bases on one strand of the DNA to make a complementary molecule of mRNA.
  5. At the end of the gene, a sequence of bases tells the RNA polymerase to stop copying, and as a result the mRNA molecule is released.

Question 4

What is the strand being copied called?

Answer 4

• It is called the template strand because it is the template from which the mRNA is made.
• The other strand is known as the coding strand, because the base always form complementary pairs, the order of bases on the coding strand will be the same as in the mRNA molecule (except that uracil will be present in place of thymine.)

Question 5

What is Translation?

Answer 5

It is the production of a protein using the information that is coded in the mRNA molecule.

Question 6

What do tRNA do?

Answer 6

Transfer RNA bring the individual amino acids to the ribosome to be joined together as proteins.

Question 7

What is Adenosine Triphosphate (ATP)?

Answer 7

It i s a molecule that stores energy for use in cell processes.

Question 8

Define Gene expression.

Answer 8

It is the process of copying information from DNA onto messenger RNA and then translating the message into a series of amino acids.

Question 9

How do antibiotics work?

Answer 9

They work by blocking translation during the process of protein synthesis.

Question 10

How do the synthesis of Lipid and Carbohydrates work?

Answer 10

• The synthesis of these substances requires enzymes, and enzymes are proteins.
• Since the DNA in the genes carries the code for protein manufacture, thus it is indirectly controlled by genes.

Question 11

What is a mitochondria?

Answer 11

Mitochondria are the organelles in the cell where the aerobic phase of respiration occurs to release energy for use by the cell.

Question 12

What are the 2 important differences between DNA and mtDNA (DNA located in the mitochondria)?

Answer 12

1. Nuclear DNA is in the form of very long strands that are bound to proteins, the histones.
2. Mitochondrial DNA is in the form of small circular molecules that are not bound to proteins.

Question 13

Define Deoxyribonucleic acid (DNA).

Answer 13

• Very large molecule made of two strands of nucleotides that are joined by bonds between the nucleotide bases.
• The two strands are twisted into a double helix. Found in the nucleus and mitochondria of cells.

Question 14

Define Nuclear DNA (nDNA).

Answer 14

DNA found in the nucleus of cells.

Question 15

Define Mitochondrial DNA (mtDNA).

Answer 15

DNA found in the mitochondria of cells.

Question 16

Define Ribonucleic Acid (RNA).

Answer 16

Large molecule composed of a single strand of nucleotides.

Question 17

Define Messenger RNA (mRNA).

Answer 17

RNA molecule that carries the code for protein synthesis from the DNA in the nucleus to the ribosomes where the protein is made.

Question 18

Define Transfer RNA (tRNA).

Answer 18

A small RNA molecule that transfers the correct amino acid to the ribosome for inclusion in the protein molecule being made.

Question 19

Define Epigenetics.

Answer 19

Epi means ‘on top of’, or ‘in addition to’, so epigenetics refers to changes in the gene expression that result from mechanisms other than changes in the genes - that is, in the DNA.

Question 20

What is Epigenetics?

Answer 20

Epigenetics is an important area of research where scientists try to find out the factors that help to make us who we are and what disease we might acquire.

Question 21

What is a person’s genome and epigenome?

Answer 21

• A person’s genome is the hereditary information that is encoded in their DNA.
• Their epigenome is the sum of all factors that determine when, where and which genes are ‘switches on’ or expressed.
• The epigenome helps to control which genes are active in a particular cell and therefore which proteins will be produced.

Question 22

How can a person’s epigenome be changed?

Answer 22

By exposure to certain environmental stimuli